3200 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 86 

[OAR–2005–0047; FRL–8256–9] 

RIN 2060–AL92 

Control of Air Pollution From New 

Motor Vehicles and New Motor Vehicle 

Engines; Regulations Requiring 

Onboard Diagnostic Systems on 2010 

and Later Heavy-Duty Engines Used in 

Highway Applications Over 14,000 

Pounds; Revisions to Onboard 

Diagnostic Requirements for Diesel 

Highway Heavy-Duty Vehicles Under 

14,000 Pounds 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Notice of proposed rulemaking. 

SUMMARY: In 2001, EPA finalized a new, 

major program for highway heavy-duty 

engines. That program, the Clean Diesel 

Trucks and Buses program, will result 

in the introduction of advanced 

emissions control systems such as 

catalyzed diesel particulate filters (DPF) 

and catalysts capable of reducing 

harmful nitrogen oxide (NOX) 

emissions. This proposal would require 

that these advanced emissions control 

systems be monitored for malfunctions 

via an onboard diagnostic system (OBD), 

similar to those systems that have been 

required on passenger cars since the 

mid-1990s. This proposal would require 

manufacturers to install OBD systems 

that monitor the functioning of emission 

control components and alert the 

vehicle operator to any detected need 

for emission related repair. This 

proposal would also require that 

manufacturers make available to the 

service and repair industry information 

necessary to perform repair and 

maintenance service on OBD systems 

and other emission related engine 

components. Lastly, this proposal 

would revise certain existing OBD 

requirements for diesel engines used in 

heavy-duty vehicles under 14,000 

pounds. 

DATES: If we do not receive a request for 

a public hearing, written comments are 

due March 26, 2007. Requests for a 

public hearing must be received by 

February 8, 2007. If we do receive a 

request for a public hearing, we will 

publish a notice in the Federal Register 

and on the Web at http://www.epa.gov/ 

obd/regtech/heavy.htm containing 

details regarding the location, date, and 

time of the public hearing. In that case, 

the public comment period would close 

30 days after the public hearing. Under 

the Paperwork Reduction Act, 

comments on the information collection 

provisions must be received by OMB on 

or before February 23, 2007. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–HQ– 

OAR–2005–0047, by one of the 

following methods: 

• http://www.regulations.gov: Follow 

the on-line instructions for submitting 

comments. 

• Mail: Onboard Diagnostic (OBD) 

Systems on 2010 and Later Heavy-Duty 

Highway Vehicles and Engines, 

Environmental Protection Agency, 

Mailcode: 6102T, 1200 Pennsylvania 

Ave., NW., Washington, DC, 20460, 

Attention Docket ID No. EPA–HQ– 

OAR–2005–0047. In addition, please 

mail a copy of your comments on the 

information collection provisions to the 

Office of Information and Regulatory 

Affairs, Office of Management and 

Budget (OMB), Attn: Desk Officer for 

EPA, 725 17th St. NW., Washington, DC 

20503. 

Instructions: Direct your comments to 

Docket ID No. EPA–HQ–OAR–2005– 

0047. EPA’s policy is that all comments 

received will be included in the public 

docket without change and may be 

made available online at http:// 

www.regulations.gov, including any 

personal information provided, unless 

the comment includes information 

claimed to be Confidential Business 

Information (CBI) or other information 

whose disclosure is restricted by statute. 

Do not submit information that you 

consider to be CBI or otherwise 

protected through http:// 

www.regulations.gov or e-mail. The 

http://www.regulations.gov Web site is 

an ‘‘anonymous access’’ system, which 

means EPA will not know your identity 

or contact information unless you 

provide it in the body of your comment. 

If you send an e-mail comment directly 

to EPA without going through http:// 

www.regulations.gov your e-mail 

address will be automatically captured 

and included as part of the comment 

that is placed in the public docket and 

made available on the Internet. If you 

submit an electronic comment, EPA 

recommends that you include your 

name and other contact information in 

the body of your comment and with any 

disk or CD–ROM you submit. If EPA 

cannot read your comment due to 

technical difficulties and cannot contact 

you for clarification, EPA may not be 

able to consider your comment. 

Electronic files should avoid the use of 

special characters, any form of 

encryption, and be free of any defects or 

viruses. 

Docket: All documents in the docket 

are listed in the http:// 

www.regulations.gov index. Although 

listed in the index, some information is 

not publicly available, e.g., CBI or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

will be publicly available only in hard 

copy. Publicly available docket 

materials are available either 

electronically in http:// 

www.regulations.gov or in hard copy at 

the Air Docket, EPA/DC, EPA West, 

Room B102, 1301 Constitution Ave., 

NW., Washington, DC. The Public 

Reading Room is open from 8:30 a.m. to 

4:30 p.m., Monday through Friday, 

excluding legal holidays. The telephone 

number for the Public Reading Room is 

(202) 566–1744, and the telephone 

number for the Air Docket is (202) 566– 

1742. 

Note: The EPA Docket Center suffered 

damage due to flooding during the last week 

of June 2006. The Docket Center is 

continuing to operate. However, during the 

cleanup, there will be temporary changes to 

Docket Center telephone numbers, addresses, 

and hours of operation for people who wish 

to make hand deliveries or visit the Public 

Reading Room to view documents. Consult 

EPA’s Federal Register notice at 71 FR 38147 

(July 5, 2006) or the EPA Web site at http:// 

www.epa.gov/epahome/dockets.htm for 

current information on docket operations, 

locations and telephone numbers. The 

Docket Center’s mailing address for U.S. mail 

and the procedure for submitting comments 

to www.regulations.gov are not affected by 

the flooding and will remain the same. 

FOR FURTHER INFORMATION CONTACT: U.S. 

EPA, National Vehicle and Fuel 

Emissions Laboratory, Assessment and 

Standards Division, 2000 Traverwood 

Drive, Ann Arbor, MI 48105; telephone 

(734) 214–4405, fax (734) 214–4816, 

email sherwood.todd@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Regulated Entities 

This action will affect you if you 

produce or import new heavy-duty 

engines which are intended for use in 

highway vehicles such as trucks and 

buses, or produce or import such 

highway vehicles, or convert heavy-duty 

vehicles or heavy-duty engines used in 

highway vehicles to use alternative 

fuels. 

The following table gives some 

examples of entities that may have to 

follow the regulations. But because 

these are only examples, you should 

carefully examine the regulations in 40 

CFR part 86. If you have questions, call 

the person listed in the FOR FURTHER

INFORMATION CONTACT section of this 

preamble: 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3201 

Category NAICS Codesa SIC Codesb Examples of potentially regulated 

entities 

Industry ............................................ 336111 

336112 

336120 

3711 Motor Vehicle Manufacturers; Engine and Truck Manufacturers. 

Industry ............................................ 811112 

811198 

541514 

7533 

7549 

8742 

Commercial Importers of Vehicles and Vehicle Components. 

Industry ............................................ 336111 3592 Alternative fuel vehicle converters. 

336312 3714 

422720 5172 

454312 5984 

811198 7549 

541514 8742 

541690 8931 

aNorth American Industry Classification Systems (NAICS). 

bStandard Industrial Classification (SIC) system code. 

What Should I Consider as I Prepare 

My Comments for EPA? 

Submitting CBI. Do not submit this 

information to EPA through 

www.regulations.gov or e-mail. Clearly 

mark the part or all of the information 

that you claim to be CBI. For CBI 

information in a disk or CD ROM that 

you mail to EPA, mark the outside of the 

disk or CD ROM as CBI and then 

identify electronically within the disk or 

CD ROM the specific information that is 

claimed as CBI). In addition to one 

complete version of the comment that 

includes information claimed as CBI, a 

copy of the comment that does not 

contain the information claimed as CBI 

must be submitted for inclusion in the 

public docket. Information so marked 

will not be disclosed except in 

accordance with procedures set forth in 

40 CFR part 2. 

Tips for Preparing Your Comments. 

When submitting comments, remember 

to: 

• Identify the rulemaking by docket 

number and other identifying 

information (subject heading, Federal 

Register date and page number). 

• Follow directions—The agency may 

ask you to respond to specific questions 

or organize comments by referencing a 

Code of Federal Regulations (CFR) part 

or section number. 

• Explain why you agree or disagree; 

suggest alternatives and substitute 

language for your requested changes. 

• Describe any assumptions and 

provide any technical information and/ 

or data that you used. 

• If you estimate potential costs or 

burdens, explain how you arrived at 

your estimate in sufficient detail to 

allow for it to be reproduced. 

• Provide specific examples to 

illustrate your concerns, and suggest 

alternatives. 

• Explain your views as clearly as 

possible, avoiding the use of profanity 

or personal threats. 

• Make sure to submit your comments 

by the comment period deadline 

identified. 

Outline of this Preamble 

I. Overview 

A. Background 

B. What Is EPA Proposing? 

1. OBD Requirements for Engines Used in 

Highway Vehicles Over 14,000 Pounds 

GVWR 

2. Requirements That Service Information 

Be Made Available 

3. OBD Requirements for Diesel HeavyDuty Vehicles and Engines Used in 

Vehicles Under 14,000 Pounds 

C. Why Is EPA Making This Proposal? 

1. Highway Engines and Vehicles 

Contribute to Serious Air Pollution 

Problems 

2. Emissions Control of Highway Engines 

and Vehicles Depends on Properly 

Operating Emissions Control Systems 

3. Basis for Action Under the Clean Air Act 

D. How Has EPA Chosen the Level of the 

Proposed Emissions Thresholds? 

E. World Wide Harmonized OBD (WWHOBD) 

F. Onboard Diagnostics for Diesel Engines 

Used in Nonroad Land-Based Equipment 

1. What Is the Baseline Nonroad OBD 

System? 

2. What Is The Appropriate Level of OBD 

Monitoring for Nonroad Diesel Engines? 

3. What Should the OBD Standardization 

Features Be? 

4. What Are the Prospects and/or Desires 

for International Harmonization of 

Nonroad OBD? 

II. What Are the Proposed OBD Requirements 

and When Would They Be Implemented? 

A. General OBD System Requirements 

1. The OBD System 

2. Malfunction Indicator Light (MIL) and 

Diagnostic Trouble Codes (DTC) 

3. Monitoring Conditions 

4. Determining the Proper OBD 

Malfunction Criteria 

B. Monitoring Requirements and Timelines 

for Diesel-Fueled/Compression-Ignition 

Engines 

1. Fuel System Monitoring 

2. Engine Misfire Monitoring 

3. Exhaust Gas Recirculation (EGR) System 

Monitoring 

4. Turbo Boost Control System Monitoring 

5. Non-Methane Hydrocarbon (NMHC) 

Converting Catalyst Monitoring 

6. Selective Catalytic Reduction (SCR) and 

Lean NOX Catalyst Monitoring 

7. NOX Adsorber System Monitoring 

8. Diesel Particulate Filter (DPF) System 

Monitoring 

9. Exhaust Gas Sensor Monitoring 

C. Monitoring Requirements and Timelines 

for Gasoline/Spark-Ignition Engines 

1. Fuel System Monitoring 

2. Engine Misfire Monitoring 

3. Exhaust Gas Recirculation (EGR) 

Monitoring 

4. Cold Start Emission Reduction Strategy 

Monitoring 

5. Secondary Air System Monitoring 

6. Catalytic Converter Monitoring 

7. Evaporative Emission Control System 

Monitoring 

8. Exhaust Gas Sensor Monitoring 

D. Monitoring Requirements and Timelines 

for Other Diesel and Gasoline Systems 

1. Variable Valve Timing and/or Control 

(VVT) System Monitoring 

2. Engine Cooling System Monitoring 

3. Crankcase Ventilation System 

Monitoring 

4. Comprehensive Component Monitors 

5. Other Emissions Control System 

Monitoring 

6. Exceptions to Monitoring Requirements 

E. A Standardized Method To Measure 

Real World Monitoring Performance 

1. Description of Software Counters To 

Track Real World Performance 

2. Proposed Performance Tracking 

Requirements 

F. Standardization Requirements 

1. Reference Documents 

2. Diagnostic Connector Requirements 

3. Communications to a Scan Tool 

4. Required Emissions Related Functions 

5. In-Use Performance Ratio Tracking 

Requirements 

6. Exceptions to Standardization 

Requirements 

G. Implementation Schedule, In-Use 

Liability, and In-Use Enforcement 

1. Implementation Schedule and In-Use 

Liability Provisions 

2. In-Use Enforcement 

H. Proposed Changes to the Existing 8,500 

to 14,000 Pound Diesel OBD 

Requirements 


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3202 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

1. Selective Catalytic Reduction and Lean 

NOX Catalyst Monitoring 

2. NOX Adsorber System Monitoring 

3. Diesel Particulate Filter System 

Monitoring 

4. NMHC Converting Catalyst Monitoring 

5. Other Monitors 

6. CARB OBDII Compliance Option and 

Deficiencies 

I. How Do the Proposed Requirements 

Compare to California’s? 

III. Are the Proposed Monitoring 

Requirements Feasible? 

A. Feasibility of the Monitoring 

Requirements for Diesel/CompressionIgnition Engines 

1. Fuel System Monitoring 

2. Engine Misfire Monitoring 

3. Exhaust Gas Recirculation (EGR) 

Monitoring 

4. Turbo Boost Control System Monitoring 

5. Non-Methane Hydrocarbon (NMHC) 

Converting Catalyst Monitoring 

6. Selective Catalytic Reduction (SCR) and 

NOX Conversion Catalyst Monitoring 

7. NOX Adsorber Monitoring 

8. Diesel Particulate Filter (DPF) 

Monitoring 

9. Exhaust Gas Sensor Monitoring 

B. Feasibility of the Monitoring 

Requirements for Gasoline/SparkIgnition Engines 

1. Fuel System Monitoring 

2. Engine Misfire Monitoring 

3. Exhaust Gas Recirculation (EGR) 

Monitoring 

4. Cold Start Emission Reduction Strategy 

Monitoring 

5. Secondary Air System Monitoring 

6. Catalytic Converter Monitoring 

7. Evaporative System Monitoring 

8. Exhaust Gas Sensor Monitoring 

C. Feasibility of the Monitoring 

Requirements for Other Diesel and 

Gasoline Systems 

1. Variable Valve Timing and/or Control 

(VVT) System Monitoring 

2. Engine Cooling System Monitoring 

3. Crankcase Ventilation System 

Monitoring 

4. Comprehensive Component Monitoring 

IV. What Are the Service Information 

Availability Requirements? 

A. What Is the Important Background 

Information for the Proposed Service 

Information Provisions? 

B. How Do the Below 14,000 Pound and 

Above 14,000 Pounds Aftermarket 

Service Industry Compare? 

C. What Provisions Are Being Proposed for 

Service Information Availability? 

1. What Information Is Proposed To Be 

Made Available by OEMs? 

2. What Are the Proposed Requirements for 

Web-Based Delivery of the Required 

Information? 

3. What Provisions Are Being Proposed for 

Service Information for Third Party 

Information Providers? 

4. What Requirements Are Being Proposed 

for the Availability of Training 

Information? 

5. What Requirements Are Being Proposed 

for Reprogramming of Vehicles? 

6. What Requirements Are Being Proposed 

for the Availability of Enhanced 

Information for Scan Tools for 

Equipment and Tool Companies? 

7. What Requirements Are Being Proposed 

for the Availability of OEM—Specific 

Diagnostic Scan Tools and Other Special 

Tools? 

8. Which Reference Materials Are Being 

Proposed for Incorporation by Reference? 

V. What Are the Emissions Reductions 

Associated With the Proposed OBD 

Requirements? 

VI. What Are the Costs Associated With the 

Proposed OBD Requirements? 

A. Variable Costs for Engines Used in 

Vehicles Over 14,000 Pounds 

B. Fixed Costs for Engines Used in 

Vehicles Over 14,000 Pounds 

C. Total Costs for Engines Used in Vehicles 

Over 14,000 Pounds 

D. Costs for Diesel Heavy-Duty Vehicles 

and Engines Used in Heavy-Duty 

Vehicles Under 14,000 Pounds 

VII. What are the Updated Annual Costs and 

Costs per Ton Associated With the 2007/ 

2010 Heavy-Duty Highway Program? 

A. Updated 2007 Heavy-Duty Highway 

Rule Costs Including OBD 

B. Updated 2007 Heavy-Duty Highway 

Rule Costs Per Ton Including OBD 

VIII. What Are the Requirements for Engine 

Manufacturers? 

A. Documentation Requirements 

B. Catalyst Aging Procedures 

C. Demonstration Testing 

1. Selection of Test Engines 

2. Required Testing 

3. Testing Protocol 

4. Evaluation Protocol 

5. Confirmatory Testing 

D. Deficiencies 

E. Production Evaluation Testing 

1. Verification of Standardization 

Requirements 

2. Verification of Monitoring Requirements 

3. Verification of In-Use Monitoring 

Performance Ratios 

IX. What Are the Issues Concerning 

Inspection and Maintenance Programs? 

A. Current Heavy-Duty I/M Programs 

B. Challenges for Heavy-Duty I/M 

C. Heavy-Duty OBD and I/M 

X. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act (RFA), as 

Amended by the Small Business 

Regulatory Enforcement Fairness Act of 

1996 (SBREFA), 5 U.S.C. 601 et. seq. 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

and Safety Risks 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer 

Advancement Act 

XI. Statutory Provisions and Legal Authority 

I. Overview 

A. Background 

Section 202(m) of the CAA, 42 U.S.C. 

7521(m), directs EPA to promulgate 

regulations requiring 1994 and later 

model year light-duty vehicles (LDVs) 

and light-duty trucks (LDTs) to contain 

an OBD system that monitors emissionrelated components for malfunctions or 

deterioration ‘‘which could cause or 

result in failure of the vehicles to 

comply with emission standards 

established’’ for such vehicles. Section 

202(m) also states that, ‘‘The 

Administrator may, in the 

Administrator’s discretion, promulgate 

regulations requiring manufacturers to 

install such onboard diagnostic systems 

on heavy-duty vehicles and engines.’’

On February 19, 1993, we published 

a final rule requiring manufacturers of 

light-duty applications to install such 

OBD systems on their vehicles 

beginning with the 1994 model year (58 

FR 9468). The OBD systems must 

monitor emission control components 

for any malfunction or deterioration that 

could cause exceedance of certain 

emission thresholds. The regulation also 

required that the driver be notified of 

any need for repair via a dashboard 

light, or malfunction indicator light 

(MIL), when the diagnostic system 

detected a problem. We also allowed 

optional compliance with California’s 

second phase OBD requirements, 

referred to as OBDII (13 CCR 1968.1), for 

purposes of satisfying the EPA OBD 

requirements. Since publishing the 1993 

OBD final rule, EPA has made several 

revisions to the OBD requirements, most 

of which served to align the EPA OBD 

requirements with revisions to the 

California OBDII requirements (13 CCR 

1968.2). 

On August 9, 1995, EPA published a 

final rulemaking that set forth service 

information regulations for light-duty 

vehicles and light-duty trucks (60 FR 

40474). These regulations, in part, 

required each Original Equipment 

Manufacturer (OEM) to do the 

following: (1) List all of its emissionrelated service and repair information 

on a Web site called FedWorld 

(including the cost of each item and 

where it could be purchased); (2) either 

provide enhanced information to 

equipment and tool companies or make 

its OEM-specific diagnostic tool 

available for purchase by aftermarket 

technicians, and (3) make 

reprogramming capability available to 

independent service and repair 

professionals if its franchised 

dealerships had such capability. These 

requirements are intended to ensure that 

aftermarket service and repair facilities 


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Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3203 

1Note that the 2007HD highway rule contained 

new emissions standards for gasoline engines as 

well as diesel engines. 

2See ‘‘On-Board Diagnostics, A Heavy-Duty 

Perspective,’’ SAE 951947; ‘‘Recommended Practice 

for a Serial Control and Communications Vehicle 

Network,’’ SAE J1939 which may be obtained from 

Society of Automotive Engineers International, 400 

Commonwealth Dr., Warrendale, PA, 15096–0001; 

and ‘‘Road Vehicles-Diagnostics on Controller Area 

Network (CAN)—Part 4: Requirements for emissionrelated systems,’’ ISO 15765–4:2001 which may be 

obtained from the International Organization for 

Standardization, Case Postale 56, CH–1211 Geneva 

20, Switzerland. 

have access to the same emissionrelated service information, in the same 

or similar manner, as that provided by 

OEMs to their franchised dealerships. 

These service information availability 

requirements have been revised since 

that first final rule in response to 

changing technology among other 

reasons. (68 FR 38428) 

In October of 2000, we published a 

final rule requiring OBD systems on 

heavy-duty vehicles and engines up to 

14,000 pounds GVWR (65 FR 59896). In 

that rule, we expressed our intention of 

developing OBD requirements in a 

future rule for vehicles and engines 

used in vehicles over 14,000 pounds. 

We expressed this same intention in our 

2007HD highway final rule (66 FR 5002) 

which established new heavy-duty 

highway emissions standards for 2007 

and later model year engines. In June of 

2003, we published a final rule 

extending service information 

availability requirements to heavy-duty 

vehicles and engines weighing up to 

14,000 pounds GVWR. We declined 

extending these requirements to engines 

above 14,000 pounds GVWR at least 

until such engines are subject to OBD 

requirements. 

On January 18, 2001, EPA established 

a comprehensive national control 

program—the Clean Diesel Truck and 

Bus program—that regulates the heavyduty vehicle and its fuel as a single 

system. (66 FR 5002) As part of this 

program, new emission standards will 

begin to take effect in model year 2007 

and will apply to heavy-duty highway 

engines and vehicles. These standards 

are based on the use of high-efficiency 

catalytic exhaust emission control 

devices or comparably effective 

advanced technologies. Because these 

devices are damaged by sulfur, the 

regulation also requires the level of 

sulfur in highway diesel fuel be reduced 

by 97 percent.1

Today’s action proposes new OBD 

requirements for highway engines used 

in vehicles greater than 14,000 pounds. 

Today’s action also proposes new 

availability requirements for emissionrelated service information that will 

make this information more widely 

available to the industry servicing 

vehicles over 14,000 pounds. 

In addition to these proposed 

requirements and changes, we are 

seeking comment on possible future 

regulations that would require OBD 

systems on heavy-duty diesel engines 

used in nonroad equipment. Diesel 

engines used in nonroad equipment are, 

like highway engines, a major source of 

NOX and particulate matter (PM) 

emissions, and the diesel engines used 

in nonroad equipment are essentially 

the same as those used in heavy-duty 

highway trucks. Further, new 

regulations applicable to nonroad diesel 

engines will result in the introduction of 

advanced emissions control systems like 

those expected for highway diesel 

engines. (69 FR 38958) Therefore, 

having OBD systems and OBD 

regulations for nonroad engines seems 

to be a natural progression from the 

proposed requirements for heavy-duty 

highway engines. We discuss this issue 

in greater detail in section I of this 

preamble with the goal of soliciting 

public comment regarding how we 

should proceed with respect to nonroad 

OBD. 

B. What Is EPA Proposing? 

1. OBD Requirements for Engines Used 

in Highway Vehicles Over 14,000 

Pounds GVWR 

We believe that OBD requirements 

should be extended to include over 

14,000 pound heavy-duty vehicles and 

engines for many reasons. In the past, 

heavy-duty diesel engines have relied 

primarily on in-cylinder modifications 

to meet emission standards. For 

example, emission standards have been 

met through changes in fuel timing, 

piston design, combustion chamber 

design, charge air cooling, use of four 

valves per cylinder rather than two 

valves, and piston ring pack design and 

location improvements. In contrast, the 

2004 and 2007 emission standards 

represent a different sort of 

technological challenge that are being 

met with the addition of exhaust gas 

recirculation (EGR) systems and the 

addition of exhaust aftertreatment 

devices such as diesel particulate filters 

(DPF), sometimes called PM traps, and 

NOX catalysts. Such ‘‘add on’’ devices 

can experience deterioration and 

malfunction that, unlike the engine 

design elements listed earlier, may go 

unnoticed by the driver. Because 

deterioration and malfunction of these 

devices can go unnoticed by the driver, 

and because their primary purpose is 

emissions control, and because the level 

of emission control is on the order of 50 

to 99 percent, some form of diagnosis 

and malfunction detection is crucial. 

We believe that such detection can be 

effectively achieved by employing a 

well designed OBD system. 

The same is true for gasoline heavyduty vehicles and engines. While 

emission control is managed with both 

engine design elements and 

aftertreatment devices, the catalytic 

converter is the primary emission 

control feature accounting for over 95 

percent of the emission control. We 

believe that monitoring the emission 

control system for proper operation is 

critical to ensure that new vehicles and 

engines certified to the very low 

emission standards set in recent years 

continue to meet those standards 

throughout their full useful life. 

Further, the industry trend is clearly 

toward increasing use of computer and 

electronic controls for both engine and 

powertrain management, and for 

emission control. In fact, the heavy-duty 

industry has already gone a long way, 

absent any government regulation, to 

standardize computer communication 

protocols.2 Computer and electronic 

control systems, as opposed to 

mechanical systems, provide 

improvements in many areas including, 

but not limited to, improved precision 

and control, reduced weight, and lower 

cost. However, electronic and computer 

controls also create increased difficulty 

in diagnosing and repairing the 

malfunctions that inevitably occur in 

any engine or powertrain system. 

Today’s proposed OBD requirements 

would build on the efforts already 

undertaken by the industry to ensure 

that key emissions related components 

will be monitored in future heavy-duty 

vehicles and engines and that the 

diagnosis and repair of those 

components will be as efficient and cost 

effective as possible. 

Lastly, heavy-duty engines and, in 

particular, diesel engines tend to have 

very long useful lives. With age comes 

deterioration and a tendency toward 

increasing emissions. With the OBD 

systems proposed today, we expect that 

these engines will continue to be 

properly maintained and therefore will 

continue to emit at low emissions levels 

even after accumulating hundreds of 

thousands and even a million miles. 

For the reasons laid out above, most 

manufacturers of vehicles, trucks, and 

engines have incorporated some type of 

OBD system into their products that are 

capable of identifying when certain 

types of malfunctions occur, and in 

what systems. In the heavy-duty 

industry, those OBD systems 

traditionally have been geared toward 


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3204 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

detecting malfunctions causing 

drivability and/or fuel economy related 

problems. Without specific 

requirements for manufacturers to 

include OBD mechanisms to detect 

emission-related problems, those types 

of malfunctions that could result in high 

emissions without a corresponding 

adverse drivability or fuel economy 

impact could go unnoticed by both the 

driver and the repair technician. The 

resulting increase in emissions and 

detrimental impact on air quality could 

be avoided by incorporating an OBD 

system capable of detecting emission 

control system malfunctions. 

2. Requirements That Service 

Information Be Made Available 

We are proposing that makers of 

engines that go into vehicles over 14,000 

pounds make available to any person 

engaged in repair or service all 

information necessary to make use of 

the OBD systems and for making 

emission-related repairs, including any 

emissions-related information that is 

provided by the OEM to franchised 

dealers. This information includes, but 

is not limited to, manuals, technical 

service bulletins (TSBs), a general 

description of the operation of each 

OBD monitor, etc. We discuss the 

proposed requirements further in 

section IV of this preamble. 

The proposed requirements are 

similar to those required currently for 

all 1996 and newer light-duty vehicles 

and light-duty trucks and 2005 and 

newer heavy-duty applications up to 

14,000 pounds. While EPA understands 

that there may be some differences 

between aftermarket service for the 

under 14,000 pound and over 14,000 

pound applications, we believe that any 

such differences would not substantially 

affect the implementation of such 

requirements and that, therefore, it is 

reasonable to use EPA’s existing service 

information regulations as a basis for 

proposing service information 

requirements for the over 14,000 pound 

arena. See section IV for a complete 

discussion of the service information 

provisions being proposed for the 

availability of over 14,000 pound 

service information. 

Note that information for making 

emission-related repairs does not 

include information used to design and 

manufacture parts, but it may include 

OEM changes to internal calibrations 

and other indirect information, as 

discussed in section IV. 

3. OBD Requirements for Diesel HeavyDuty Vehicles and Engines Used in 

Vehicles Under 14,000 Pounds 

We are also proposing some changes 

to the existing diesel OBD requirements 

for heavy-duty applications under 

14,000 pounds (i.e., 8,500 to 14,000 

pounds). Some of these changes are 

being proposed for the 2007 and later 

model years (i.e., for immediate 

implementation) because we believe 

that some of the requirements that we 

currently have in place for 8,500 to 

14,000 pound applications cannot be 

met by diesels without granting 

widespread deficiencies to industry. 

Other changes are being proposed for 

the 2010 and later model years since 

they represent an increase in the 

stringency of our current OBD 

requirements and, therefore, some 

leadtime is necessary for manufacturers 

to comply. All of the changes being 

proposed for 8,500 to 14,000 pound 

diesel applications would result in OBD 

emissions thresholds identical, for all 

practical purposes, to the OBD 

thresholds being proposed for over 

14,000 pound applications. 

C. Why Is EPA Making This Proposal? 

1. Highway Engines and Vehicles 

Contribute to Serious Air Pollution 

Problems 

The pollution emitted by heavy-duty 

highway engines contributes greatly to 

our nation’s continuing air quality 

problems. Our 2007HD highway rule 

was designed to address these serious 

air quality problems. These problems 

include premature mortality, 

aggravation of respiratory and 

cardiovascular disease, aggravation of 

existing asthma, acute respiratory 

symptoms, chronic bronchitis, and 

decreased lung function. Numerous 

studies also link diesel exhaust to 

increased incidence of lung cancer. We 

believe that diesel exhaust is likely to be 

carcinogenic to humans by inhalation 

and that this cancer hazard exists for 

occupational and environmental levels 

of exposure. 

Our 2007HD highway rule will 

regulate the heavy-duty vehicle and its 

fuel as a single system. As part of this 

program, new emission standards will 

begin to take effect in model year 2007 

and phase-in through model year 2010, 

and will apply to heavy-duty highway 

engines and vehicles. These standards 

are based on the use of high-efficiency 

catalytic exhaust emission control 

devices or comparably effective 

advanced technologies and a cap on the 

allowable sulfur content in both diesel 

fuel and gasoline. 

In the 2007HD highway final rule, we 

estimated that, by 2007, heavy-duty 

trucks and buses would account for 

about 28 percent of nitrogen oxides 

emissions and 20 percent of particulate 

matter emissions from mobile sources. 

In some urban areas, the contribution is 

even greater. The 2007HD highway 

program will reduce particulate matter 

and oxides of nitrogen emissions from 

heavy-duty engines by 90 percent and 

95 percent below current standard 

levels, respectively. In order to meet 

these more stringent standards for diesel 

engines, the program calls for a 97 

percent reduction in the sulfur content 

of diesel fuel. As a result, diesel 

vehicles will achieve gasoline-like 

exhaust emission levels. We have also 

established more stringent standards for 

heavy-duty gasoline vehicles, based in 

part on the use of the low sulfur 

gasoline that will be available when the 

standards go into effect. 

2. Emissions Control of Highway 

Engines and Vehicles Depends on 

Properly Operating Emissions Control 

Systems 

The emissions reductions and 

resulting health and welfare benefits of 

the 2007HD highway program will be 

dramatic when fully implemented. By 

2030, the program will reduce annual 

emissions of nitrogen oxides, 

nonmethane hydrocarbons, and 

particulate matter by a projected 2.6 

million, 115,000 and 109,000 tons, 

respectively. However, to realize those 

large emission reductions and health 

benefits, the emission control systems 

on heavy-duty highway engines and 

vehicles must continue to provide the 

90 to 95 percent emission control 

effectiveness throughout their operating 

life. Today’s proposed OBD 

requirements will help to ensure that 

emission control systems continue to 

operate properly by detecting when 

those systems malfunction, by then 

notifying the driver that a problem 

exists that requires service and, lastly, 

by informing the service technician 

what the problem is so that it can be 

properly repaired. 

3. Basis for Action Under the Clean Air 

Act 

Section 202(m) of the CAA, 42 U.S.C. 

7521(m), directs EPA to promulgate 

regulations requiring 1994 and later 

model year light-duty vehicles (LDVs) 

and light-duty trucks (LDTs) to contain 

an OBD system that monitors emissionrelated components for malfunctions or 

deterioration ‘‘which could cause or 

result in failure of the vehicles to 

comply with emission standards 

established’’ for such vehicles. Section 


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202(m) also states that, ‘‘The 

Administrator may, in the 

Administrator’s discretion, promulgate 

regulations requiring manufacturers to 

install such onboard diagnostic systems 

on heavy-duty vehicles and engines.’’

Section 202(m)(5) of the CAA states 

that the Administrator shall require 

manufacturers to, ‘‘provide promptly to 

any person engaged in the repairing or 

servicing of motor vehicles or motor 

vehicle engines * * * with any and all 

information needed to make use of the 

emission control diagnostics system 

prescribed under this subsection and 

such other information including 

instructions for making emission related 

diagnosis and repairs.’’

D. How Has EPA Chosen the Level of the 

Proposed Emissions Thresholds? 

The OBD emissions thresholds that 

we are proposing are summarized in 

Tables II.B–1, II.C–1, II.H–1 and II.H–2. 

These tables show the actual threshold 

levels and how they relate to current 

emissions standards. Here, we wish to 

summarize how we chose those 

proposed thresholds. First, it is 

important to note that OBD is more than 

emissions thresholds. In fact, most OBD 

monitors are not actually tied to an 

emissions threshold. Instead, they 

monitor the performance of a given 

component or system and evaluate that 

performance based on electrical 

information (e.g., voltage within proper 

range) or temperature information (e.g., 

temperature within range), etc. Such 

monitors often detect malfunctions well 

before emissions are seriously 

compromised. Nonetheless, emissions 

thresholds are a critical element to OBD 

requirements since some components 

and systems, most notably any 

aftertreatment devices, cannot be 

monitored in simple electrical or 

temperature related terms. Instead, their 

operating characteristics can be 

measured and correlated to an 

emissions impact. This way, when those 

operating characteristics are detected, 

an unacceptable emissions increase can 

be inferred and a malfunction can be 

noted to the driver. 

Part of the challenge in establishing 

OBD requirements is determining the 

point—the OBD threshold—at which an 

unacceptable emissions increase has 

occurred that is detectable by the best 

available OBD technology. Two factors 

have gone into our determination of the 

emissions thresholds we are proposing: 

technological feasibility; and the costs 

and emissions reductions associated 

with repairs initiated as a result of 

malfunctions found by OBD systems. 

The first of these factors is discussed in 

more detail in section III where we 

present our case for the technological 

feasibility of the thresholds. In 

summary, we believe that the thresholds 

we are proposing are, while challenging, 

technologically feasible in the 2010 and 

later timeframe. We have carefully 

considered monitoring system 

capability, sensor capability, emissions 

measurement capability, test-to-test 

variability and, perhaps most 

importantly, the manufacturers’

engineering and test cell resources and 

have arrived at thresholds we believe 

can be met on one engine family per 

manufacturer in the 2010 model year 

and on all engine families by the 2013 

model year. 

We believe that the proposed 

thresholds strike the proper balance 

between environmental protection, OBD 

and various sensor capabilities, and 

avoidance of repairs whose costs could 

be high compared to their emission 

control results. One must keep in mind 

that increasingly stringent OBD 

thresholds (i.e., OBD detection at lower 

emissions levels) may lead to more 

durable emission controls due to a 

manufacturer’s desire to avoid the 

negative impression given their product 

upon an OBD detection. Such an 

outcome would result in lower 

fleetwide emissions while increasing 

costs to manufacturers. However, 

increasingly stringent OBD thresholds 

may also lead to more OBD detections 

and more OBD induced repairs and, 

perhaps, many OBD induced repairs for 

malfunctions having little impact on 

emissions. Such an outcome would 

result in lower fleetwide emissions 

while increasing costs to both 

manufacturers and truck owners. 

E. World Wide Harmonized OBD 

(WWH–OBD) 

Within the United Nations (UN), the 

World Forum for Harmonization of 

Vehicle Regulations (WP.29) 

administers the 1958 Geneva Agreement 

(1958 Agreement) to facilitate the 

adoption of uniform conditions of 

approval and reciprocal recognition of 

approval for motor vehicle equipment 

and parts. As a result, WP.29 has 

responsibility for vehicle regulations 

within Europe and, indirectly, many 

countries outside of Europe that have 

voluntarily adopted the WP.29 

regulations. The United States was 

never a party to the 1958 Agreement, 

but EPA has monitored the WP.29 

regulations developed under the 1958 

Agreement and we have benefited from 

a reciprocal consultative relationship 

with our European counterparts. More 

recently, WP.29 took on the 

responsibility of administering the 1998 

Global Agreement that established a 

process to permit all regions of the 

world to jointly develop global technical 

regulations without required mutual 

recognition of approvals or designated 

compliance and enforcement. The 

United States is a signatory of the 1998 

Global Agreement (1998 Agreement), 

and EPA has responsibility for 

representing the U.S. with respect to 

environmental issues within WP.29 as 

they pertain to the 1998 Agreement. 

During the one-hundred-and-twentysixth session of WP.29 of March 2002, 

the Executive Committee (AC.3) of the 

1998 Global Agreement (1998 

Agreement) adopted a Programme of 

Work, which includes the development 

of a Global Technical Regulation (GTR) 

concerning onboard diagnostic systems 

for heavy-duty vehicles and engines. An 

informal working group—the WWH–

OBD working group—was established to 

develop the GTR. The working group 

was instructed that the OBD system 

should detect failures from the engine 

itself, as well as from the exhaust 

aftertreatment systems fitted 

downstream of the engine, and from the 

package of information exchanged 

between the engine electronic control 

unit(s) and the rest of vehicle and/or 

powertrain. The working group was also 

instructed to base the OBD requirements 

on the technologies expected to be 

industrially available at the time the 

GTR would be enforced, and to take into 

account both the expected state of 

electronics in the years 2005–2008 and 

the expected newest engine and 

aftertreatment technologies. 

In November 2003, AC.3 further 

directed the working group to structure 

the GTR in such a manner as to enable 

its future extension to other functions of 

the vehicle. In so doing, AC.3 did not 

revise the scope of the task given to the 

working group (i.e., the scope remained 

emissions-related heavy-duty OBD). As 

a result, the GTR is structured such that 

OBD monitoring and communications 

could be extended to other systems such 

as vehicle safety systems. This has been 

achieved by dividing the GTR into a set 

of generic OBD requirements to be 

followed by specific OBD requirements 

concerning any future desired OBD 

systems. The generic OBD requirements 

contain definitions and other OBD 

regulatory elements that are meant to be 

applicable throughout the GTR and all 

of its modules, annexes, and 

appendices. This generic section is 

followed by the first specific OBD 

section—emission-related OBD—which 

contains definitions and OBD regulatory 

elements specific to emissions-related 

OBD. 

EPA has been active in the WWH–

OBD working group for more than three 


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3Note that, while the WWH–OBD GTR is 

consistent with many of the specific requirements 

we are proposing, it is not currently as 

comprehensive as our proposal (e.g., it does not 

contain the same level of detail with respect to 

certification requirements and enforcement 

provisions). For that reason, at this time, we do not 

believe that the GTR would fully replace what we 

are proposing today. 

4 ‘‘Revised Proposal for New Draft Global 

Technical Regulation (gtr): Technical Requirements 

for On-Board Diagnostic Systems (OBD) for Road 

Vehicles;’’ ECE/TRANS/WP.29/GRPE/2006/8/Rev.1; 

March 27, 2006, Docket ID# EPA–HQ–OAR–2005–

0047–0004. 

years. Because that group has been 

developing a regulation at the same time 

that we have been developing the 

requirements in this proposal, our 

proposed OBD requirements are 

consistent, for the most part, with the 

current efforts of the WWH–OBD group. 

The WWH–OBD working group 

submitted a draft GTR as a formal 

document in March of 2006. During the 

months immediately following, the 

WWH–OBD working group has made 

final revisions to the GTR and will 

submit it to WP.29 for consideration. If 

approved by WP.29 and adopted as a 

formal global technical regulation, we 

would intend to propose any revisions 

to our OBD regulations that might be 

necessary to make them consistent with 

WWH–OBD.3

The latest version of the draft WWH–

OBD GTR has been placed in the docket 

for this rule.4 While it is not yet a final 

document, we are nonetheless 

interested in comments regarding the 

current version. More specifically, we 

are interested in comments regarding 

any possible inconsistencies between 

the requirements of the draft GTR and 

the requirements being proposed today. 

We believe that if such inconsistencies 

exist, they are minor. WWH–OBD 

provides a framework for nations to 

establish a heavy-duty OBD program. It 

has the potential to result in similar 

OBD systems, but the WWH–OBD GTR 

must fit into the context of any 

country’s existing heavy-duty emissions 

regulations. For example, at this time, 

the draft GTR does not specify 

emissions threshold levels, 

implementation dates, or phase-in 

schedules. As such, our proposal today 

is much more detailed than the draft 

WWH–OBD GTR, but we believe there 

exist no major inconsistencies between 

the two regulations. 

F. Onboard Diagnostics for Diesel 

Engines Used in Nonroad Land-Based 

Equipment 

We are also considering regulations—

although we are not making any 

proposals today—that would require 

OBD systems on heavy-duty diesel 

engines used in nonroad land-based 

equipment. The pollution emitted by 

diesel nonroad engines contributes 

greatly to our nation’s continuing air 

quality problems. Our recent Nonroad 

Tier 4 rulemaking was designed to 

address these serious air quality 

problems from land-based diesel 

engines. (69 FR 38958) Like with diesel 

highway emissions, these problems 

include premature mortality, 

aggravation of respiratory and 

cardiovascular disease, aggravation of 

existing asthma, acute respiratory 

symptoms, chronic bronchitis, and 

decreased lung function. And, as noted 

above, we believe that diesel exhaust is 

likely to be carcinogenic to humans by 

inhalation and that this cancer hazard 

exists for occupational and 

environmental levels of exposure. 

In our preamble to the Nonroad Tier 

4 final rule, we estimated that, absent 

the nonroad Tier 4 standards, by 2020, 

land based nonroad diesel engines 

would account for as much as 70 

percent of the diesel mobile source PM 

inventory. As part of our nonroad Tier 

4 program, new emission standards will 

begin to take effect in calendar year 

2011 that are based on the use of highefficiency catalytic exhaust emission 

control devices or comparably effective 

advanced technologies. As with our 

2007HD highway program, a cap is also 

included on the allowable sulfur 

content in nonroad diesel fuel. 

The diesel engines used in nonroad 

land-based equipment are, in certain 

horsepower ranges, often essentially the 

same as those used in heavy-duty 

highway trucks. In other horsepower 

ranges—e.g., very large nonroad 

machines with engines having more 

than 1,500 horsepower—the engine is 

quite different. Such differences can 

include the addition of cylinders and 

turbo chargers among other things. 

Notably, the new nonroad Tier 4 

regulations will result in the 

introduction of advanced emissions 

control systems on nonroad land-based 

equipment; those advanced emissions 

control systems will be the same type of 

systems as those expected for highway 

diesel engines. 

Therefore, having OBD systems and 

OBD regulations for nonroad diesel 

engines seems to be a natural 

progression from the proposed 

requirements for heavy-duty highway 

engines. Nonetheless, we believe that 

there are differences between nonroad 

equipment and highway applications, 

and differences between the nonroad 

market and the highway market such 

that proposing the same OBD 

requirements for nonroad as for 

highway may not be appropriate. 

Therefore, we are providing advance 

notice to the public with the goal of 

soliciting public comment regarding 

how we should proceed with respect to 

nonroad OBD. This section presents 

issues we have identified and solicits 

comment. We also welcome comment 

with respect to other issues we have not 

addressed here, such as service 

information availability. 

1. What Is the Baseline Nonroad OBD 

System? 

We know that highway diesel engines 

already use a sophisticated level of OBD 

system. For nonroad diesel engines in 

the 200 to 600 horsepower range—i.e., 

the typical range of highway engines—

are the current OBD system identical to 

their highway counterparts? How would 

the proposed highway OBD 

requirements change this, if at all? Do 

diesel engines outside the range typical 

of highway engines use OBD? 

2. What Is the Appropriate Level of OBD 

Monitoring for Nonroad Diesel Engines? 

The proposed OBD requirements for 

highway engines are very 

comprehensive and would result in 

virtually every element of the emissions 

control system being monitored. Is this 

appropriate for nonroad diesel engines? 

And to what degree should such 

monitoring be required? The emissions 

thresholds proposed for highway 

engines will push OBD and sensor 

technology beyond where it is today 

because of their stringency. Is a similar 

level of stringency appropriate for 

nonroad engines? Should emissions 

thresholds analogous to those presented 

in Table II.B–1 of this preamble even be 

a part of any potential nonroad OBD 

requirements or should nonroad OBD 

rely more heavily on comprehensive 

component monitoring as discussed in 

section II.D.4 of this preamble? This 

latter question is particularly 

compelling given the incredibly broad 

range of operating characteristics for 

nonroad equipment. Similar to the issue 

of emissions thresholds, certain aspects 

of the proposed highway OBD 

requirements carry with them serious 

concerns given the range of use for 

heavy-duty highway trucks (line-haul 

trucks versus garbage trucks versus 

urban delivery trucks, etc.). As 

discussed in various places in section II 

of this preamble, this broad range of 

uses makes it difficult for manufacturers 

to design a single approach that would, 

for example, ensure frequent monitoring 

events on all possible applications. This 

difficulty could be even more 

pronounced in the nonroad industry 

given the greater number of possible 

applications. 


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5What constitutes a ‘‘malfunction’’ for over 

14,000 pound applications under today’s proposal 

is covered in section II.B for diesel engines, section 

II.C for gasoline engines, and section II.D for all 

engines. 

We request comment regarding what 

any potential nonroad OBD monitoring 

requirements should look like. More 

specifically, we request comment 

regarding the inclusion of emissions 

thresholds versus relying solely on 

comprehensive component monitoring. 

From commenters in favor of emissions 

thresholds, we request details regarding 

the appropriate level of emissions 

thresholds including data and strong 

engineering analyses for/against the 

suggested level. We request comment 

regarding the comprehensiveness of 

monitoring (i.e., the entire emissions 

control system, aftertreatement devices 

only, feedback control systems only, 

etc.). 

3. What Should the OBD 

Standardization Features Be? 

Should nonroad OBD include a 

requirement for a dedicated, OBD-only 

malfunction indicator light? Should 

nonroad OBD require specific 

communication protocols for 

communication of onboard information 

to offboard devices and scan tools? 

What should those protocols be? What 

are the needs of the nonroad service 

industry with respect to standardization 

of onboard to offboard communications? 

4. What Are the Prospects and/or 

Desires for International Harmonization 

of Nonroad OBD? 

Nonroad equipment is perhaps the 

most international of all mobile source 

equipment. Land based nonroad 

equipment, while not as much so as 

marine equipment, tends to be designed, 

produced, marketed, and sold to a world 

market to a greater extent than is 

highway equipment. Given that, is there 

a sense within the nonroad industry that 

international harmonization is 

important? Imperative? Is the proper 

avenue for putting into place nonroad 

OBD regulations the WWH–OBD 

process discussed above? If so, is 

industry prepared to play a role in 

developing a nonroad OBD element to 

the WWH–OBD document? Are other 

government representatives prepared to 

do so? 

II. What Are the Proposed OBD 

Requirements and When Would They 

Be Implemented? 

The following subsections describe 

our proposed OBD monitoring 

requirements and the timelines for their 

implementation. The requirements are 

indicative of our goal for the program 

which is a set of OBD monitors that 

provide robust diagnosis of the emission 

control system. Our intention is to 

provide industry sufficient time and 

experience with satisfying the demands 

of the proposed OBD program. While 

their engines already incorporate OBD 

systems, those systems are generally less 

comprehensive and do not monitor the 

emission control system in the ways we 

are proposing. Additionally, the 

proposed OBD requirements represent a 

new set of technological requirements 

and a new set of certification 

requirements for the industry in 

addition to the 2007HD highway 

program and its challenging emission 

standards for PM and NOX and other 

pollutants. As a result, we believe the 

monitoring requirements and timelines 

outlined in this section appropriately 

weigh the need for OBD monitors on the 

emission control system and the need to 

gain experience with not only those 

monitors but also the newly or recently 

added emission control hardware. 

We request comment on all aspects of 

the requirements laid out in this section 

and throughout this preamble. As 

discussed in Section IX, we are also 

interested in comments concerning state 

run HDOBD-based inspection and 

maintenance (I/M) programs, the level 

of interest in such programs, and 

comments concerning the suitability of 

today’s proposed OBD requirements 

toward facilitating potential HDOBD I/ 

M programs in the future. 

A. General OBD System Requirements 

1. The OBD System 

We are proposing that the OBD 

system be designed to operate for the 

actual life of the engine in which it is 

installed. Further, the OBD system 

cannot be programmed or otherwise 

designed to deactivate based on age 

and/or mileage of the vehicle during the 

actual life of the engine. This 

requirement is not intended to alter 

existing law and enforcement practice 

regarding a manufacturer’s liability for 

an engine beyond its regulatory useful 

life, except where an engine has been 

programmed or otherwise designed so 

that an OBD system deactivates based 

on age and/or mileage of the engine. 

We are also proposing that computer 

coded engine operating parameters not 

be changeable without the use of 

specialized tools and procedures (e.g. 

soldered or potted computer 

components or sealed (or soldered) 

computer enclosures). Upon 

Administrator approval, certain product 

lines may be exempted from this 

requirement if those product lines can 

be shown to not need such protections. 

In making the approval decision, the 

Administrator will consider such things 

as the current availability of 

performance chips, performance 

capability of the engine, and sales 

volume. 

2. Malfunction Indicator Light (MIL) 

and Diagnostic Trouble Codes (DTC) 

Upon detecting a malfunction within 

the emission control system,5 the OBD 

system must make some indication to 

the driver so that the driver can take 

action to get the problem repaired. The 

proposal would require that a dashboard 

malfunction indicator light (MIL) be 

illuminated to inform the driver that a 

problem exists that needs attention. 

Upon illumination of the MIL, the 

proposal would require that a diagnostic 

trouble code (DTC) be stored in the 

engine’s computer that identifies the 

detected malfunction. This DTC would 

then be read by a service technician to 

assist in making the necessary repair. 

Because the MIL is meant to inform 

the driver of a detected malfunction, we 

are proposing that the MIL be located on 

the driver’s side instrument panel and 

be of sufficient illumination and 

location to be readily visible under all 

lighting conditions. We are proposing 

that the MIL be amber (yellow) in color 

when illuminated because yellow is 

synonymous with the notion of a 

‘‘cautionary warning’’; the use of red for 

the MIL would be strictly prohibited 

because red signifies ‘‘danger’’ which is 

not the proper message for malfunctions 

detected according to today’s proposal. 

Further, we are proposing that, when 

illuminated, the MIL display the 

International Standards Organization 

(ISO) engine symbol because this 

symbol has become accepted after 10 

years of light-duty OBD as a 

communicator of engine and emissions 

system related problems. We are also 

proposing that there be only one MIL 

used to indicate all malfunctions 

detected by the OBD system on a single 

vehicle. We believe this is important to 

avoid confusion over multiple lights 

and, potentially, multiple 

interpretations of those lights. 

Nonetheless, we seek comment on this 

limitation to one dedicated MIL to 

communicate emissions-related 

malfunctions. We also seek comment on 

the requirement that the MIL be amber 

in color since some trucks may use 

liquid crystal display (LCD) panels to 

display dashboard information and 

some such panels are monochromic and 

unable to display color. 

We are also interested in comments 

regarding the malfunction indicator 

light and the symbol displayed to 


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6 Generally, a ‘‘driving cycle’’ or ‘‘drive cycle’’

consists of engine startup and engine shutoff or 

consists of four hours of continuous engine 

operation. 7A ‘‘continuous’’ monitor—if used in the context 

of monitoring conditions for circuit continuity, lack 

of circuit continuity, circuit faults, and out-of-range 

values—means sampling at a rate no less than two 

samples per second. If a computer input component 

is sampled less frequently for engine control 

purposes, the signal of the component may instead 

be evaluated each time sampling occurs. 8A ‘‘non-continuous’’ monitor being a monitor 

that runs only when a limited set of operating 

conditions occurs. 9 Different industry standards organizations—the 

Society of Automotive Engineers (SAE) and the 

International Standards Organization (ISO)—use 

different terminology to refer to a ‘‘MIL-on’’ DTC. 

For clarity, we use the term ‘‘MIL-on’’ DTC 

throughout this preamble to convey the concept and 

not any requirement that standard making bodies 

use the term in their standards. 10Throughout this proposal, we refer to MIL 

illumination to mean a steady, continuous 

illumination during engine operation unless stated 

otherwise. This contrasts with the MIL illumination 

logic used by many engine manufacturers today by 

which the MIL would illuminate upon detection of 

a malfunction but would remain illuminated only 

while the malfunction was actually occurring. 

Under this latter logic, an intermittent malfunction 

or one that occurs under only limited operating 

conditions may result in a MIL that illuminates, 

extinguishes, illuminates, etc., as operating 

conditions change. 

11A permanent DTC must be stored in a manner 

such that electrical disconnections do not result in 

their erasure (i.e., they must be stored in nonvolatile random access memory (NVRAM)). 

12This general ‘‘three trip’’ condition for 

extinguishing the MIL is true for all but two diesel 

systems/monitors—the misfire monitor and the SCR 

system—and three gasoline systems/monitors—the 

fuel system, the misfire monitor, and the 

evaporative system—which have further conditions 

on extinguishing the MIL This is discussed in more 

detail in sections II.B and II.C. 

13For simplicity, the discussion here refers to 

‘‘previous-MIL-on’’ DTCs only. The ISO 15765 

standard and the SAE J1939 standard use different 

terms to refer to the concept of a previous-MIL-on 

DTC. Our intent is to present the concept of our 

proposal in this preamble and not to specify the 

terminology used by these standard making bodies. 

communicate that there is an engine 

and/or emission-related malfunction. As 

noted, we are proposing use of the ISO 

engine symbol as shown in Table II.A–

1. The U.S. Department of 

Transportation has proposed use of an 

alternative ISO symbol to denote, 

specifically, an emission-related 

malfunction. (68 FR 55217) That symbol 

is also shown in Table II.A–1. While we 

are not proposing that this alternative 

symbol be used, comments are solicited 

regarding whether this alternative 

symbol provides a clearer message to 

the driver. 

Generally, a manufacturer would be 

allowed sufficient time to be certain that 

a malfunction truly exists before 

illuminating the MIL. No one benefits if 

the MIL illuminates spuriously when a 

real malfunction does not exist. Thus, 

for most OBD monitoring strategies, 

manufacturers would not be required to 

illuminate the MIL until a malfunction 

clearly exists which will be considered 

to be the case when the same problem 

has occurred on two sequential driving 

cycles.6

To keep this clear in the onboard 

computer, we are proposing that the 

OBD system make certain distinctions 

between the problems it has detected, 

and that the system maintain a strict 

logic for diagnostic trouble code (DTC) 

storage/erasure and for MIL 

illumination/extinguishment. Whenever 

the enable criteria for a given monitor 

are met, we would expect that monitor 

to run. For continuous monitors, this 

would be during essentially all engine 

operation.7 For non-continuous 

monitors, it would be during only a 

subset of engine operation.8 In general, 

we are proposing that monitors make a 

diagnostic decision just once per drive 

cycle that contains operation satisfying 

the enable criteria for the given monitor. 

When a problem is first detected, we 

are proposing that a ‘‘pending’’ DTC be 

stored. If, during the subsequent drive 

cycle that contains operation satisfying 

the enable criteria for the given monitor, 

a problem in the components/system is 

not again detected, the OBD system 

would declare that a malfunction does 

not exist and would, therefore, erase the 

pending DTC. However, if, during the 

subsequent drive cycle that contains 

operation satisfying the enable criteria 

for the given monitor, a problem in the 

component/system is again detected, a 

malfunction has been confirmed and, 

hence, a ‘‘confirmed’’ or ‘‘MIL-on’’ DTC 

would be stored.9 Section II.F presents 

the requirements for standardization of 

OBD information and communications. 

Upon storage of a MIL-on DTC and, 

depending on the communication 

protocol used—ISO 15765–4 or SAE 

J1939—the pending DTC would either 

remain stored or be erased, respectively. 

Today’s proposal neither stipulates 

which communication protocol nor 

which pending DTC logic be used. We 

are proposing to allow the use of either 

of the existing protocols as is discussed 

in more detail in section II.F. Upon 

storage of the MIL-on DTC, the MIL 

must be illuminated.10 Also at this time, 

a ‘‘permanent’’ DTC would be stored 

(see section II.F.4 for more details 

regarding permanent DTCs and our 

rationale for proposing them).11

We are also proposing that, after three 

subsequent drive cycles that contain 

operation satisfying the enable criteria 

for the given monitor without any 

recurrence of the previously detected 

malfunction, the MIL should be 

extinguished (unless there are other 

MIL-on DTCs stored for which the MIL 

must also be illuminated), the 

permanent DTC should be erased, but a 

‘‘previous-MIL-on’’ DTC should remain 

stored.12 We are proposing that the 

previous MIL-on DTC remain stored for 

40 engine warmup cycles after which 

time, provided the identified 

malfunction has not been detected again 

and the MIL is presently not illuminated 

for that malfunction, the previous-MILon DTC can be erased.13 However, if an 

illuminated MIL is not extinguished, or 

if a MIL-on DTC is not erased, by the 

OBD system itself but is instead erased 

via scan tool or battery disconnect 

(which would erase all non-permanent, 

volatile memory), the permanent DTC 

must remain stored. This way, 

permanent DTCs can only be erased by 

the OBD system itself and cannot be 

erased through human interaction with 

the system. 

We are proposing that the 

manufacturer be allowed, upon 


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Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3209 

14 ‘‘Ignition Cycle’’ means a drive cycle that 

begins with engine start and includes an engine 

speed that exceeds 50 to 150 rotations per minute 

(rpm) below the normal, warmed-up idle speed (as 

determined in the drive position for vehicles 

equipped with an automatic transmission) for at 

least two seconds plus or minus one second. 

15Note that we use the term ‘‘abnormal’’ to refer 

to an operating mode that the engine is designed to 

enter upon determining that ‘‘normal’’ operation 

cannot be maintained. Therefore, the term 

‘‘abnormal’’ is somewhat of a misnomer since the 

engine is doing what it has been designed to do. 

Nonetheless, the abnormal operating mode is 

clearly not the operating mode the manufacturer 

has intended for optimal operation. Such operating 

modes are sometimes referred to as ‘‘default’’

operating modes or ‘‘limp-home’’ operating modes. 

Administrator approval, to use 

alternative statistical MIL illumination 

and DTC storage protocols to those 

described above (i.e., alternatives to the 

‘‘first trip—pending DTC, second strip—

MIL-on DTC logic). The Administrator 

would consider whether the 

manufacturer provided data and/or 

engineering evaluation adequately 

demonstrates that the alternative 

protocols can evaluate system 

performance and detect malfunctions in 

a manner that is equally effective and 

timely. Alternative strategies requiring, 

on average, more than six driving cycles 

for MIL illumination would probably 

not be accepted. 

Upon storage of either a pending DTC 

and/or a MIL-on DTC, we are proposing 

that the computer store a set of ‘‘freeze 

frame’’ data. This freeze frame data 

would provide a snap shot of engine 

operating conditions present at the time 

the malfunction occurred and was 

detected. This information serves the 

repair technician in diagnosing the 

problem and conducting the proper 

repair. The freeze frame data should be 

stored upon storage of a pending DTC. 

If the pending DTC matures to a MIL-on 

DTC, the manufacturer can choose to 

update the freeze frame data or retain 

the freeze frame stored in conjunction 

with the pending DTC. Likewise, any 

freeze frame stored in conjunction with 

any pending or MIL-on DTC should be 

erased upon erasure of the DTC. Further 

information concerning the freeze frame 

requirement and the data required in the 

freeze frame is presented in section 

II.F.4, below. 

We are also proposing that the OBD 

system illuminate the MIL and store a 

MIL-on DTC to inform the vehicle 

operator whenever the engine enters a 

mode of operation that can affect the 

performance of the OBD system. If such 

a mode of operation is recoverable (i.e., 

operation automatically returns to 

normal at the beginning of the following 

ignition cycle 14), then in lieu of 

illuminating the MIL when the mode of 

operation is entered, the OBD system 

may wait to illuminate the MIL and 

store the MIL-on DTC if the mode of 

operation is again entered before the 

end of the next ignition cycle. We are 

proposing this because many operating 

strategies are designed such that they 

continue automatically through to the 

next key-off. Regardless, upon the next 

key-on, the engine control would start 

off in ‘‘normal’’ operating mode and 

would return to the ‘‘abnormal’’

operating mode only if the condition 

causing the abnormal mode was again 

encountered. In such cases, we are 

proposing to allow that the MIL be 

illuminated during the second 

consecutive drive cycle during which 

such an ‘‘abnormal’’ mode is engaged.15

Whether or not the ‘‘abnormal’’ mode 

of operation is recoverable, in this 

context, has nothing to do with whether 

the detected malfunction goes away or 

stays. Instead, it depends solely on 

whether or not the engine, by design, 

will stay in abnormal operating mode on 

the next key-on. We are proposing this 

MIL logic because often the diagnostic 

(i.e., monitor) that caused the engine to 

enter abnormal mode cannot run again 

once the engine is in the abnormal 

mode. So, if the MIL logic associated 

with abnormal mode activation was 

always a two-trip diagnostic, abnormal 

mode activation would set a pending 

DTC on the first trip and, since the 

system would then be stuck in that 

abnormal operating mode and would 

never be able to run the diagnostic 

again, the pending DTC could never 

mature to a MIL-on DTC nor illuminate 

the MIL. Hence, the MIL must 

illuminate upon the first entry into such 

an abnormal operating mode. If such a 

mode is recoverable, the engine will 

start at the next key-on in ‘‘normal’’

mode allowing the monitor to run again 

and, assuming another detection of the 

condition, the system would set a MILon DTC and illuminate the MIL. 

The OBD system would not need to 

store a DTC nor illuminate the MIL 

upon abnormal mode operation if other 

telltale conditions would result in 

immediate action by the driver. Such 

telltale conditions would be, for 

example, an overt indication like a red 

engine shut-down warning light. The 

OBD system also need not store a DTC 

nor illuminate the MIL upon abnormal 

mode operation if the mode is indeed an 

auxiliary emission control device 

(AECD) approved by the Administrator. 

There may be malfunctions of the MIL 

itself that would prevent it from 

illuminating. A repair technician—or 

possibly an I/M inspector—would still 

be able to determine the status of the 

MIL (i.e., commanded ‘‘on’’ or ‘‘off’’) by 

reading electronic information available 

through a scan tool, but there would be 

no indication to the driver of an 

emissions-related malfunction should 

one occur. Unidentified malfunctions 

may cause excess emissions to be 

emitted from the vehicle and may even 

cause subsequent deterioration or 

failure of other components or systems 

without the driver’s knowledge. In order 

to prevent this, the manufacturer must 

ensure that the MIL is functioning 

properly. For this reason, we are 

proposing two requirements to check 

the functionality of the MIL itself. First, 

the MIL would be required to illuminate 

for a minimum of five seconds when the 

vehicle is in the key-on, engine-off 

position. This allows an interested party 

to check the MIL’s functionality simply 

by turning the key to the key-on 

position. While the MIL would be 

physically illuminated during this 

functional check, the data stream value 

for the MIL command status would be 

required to indicate ‘‘off’’ during this 

check unless, of course, the MIL was 

currently being commanded ‘‘on’’ for a 

detected malfunction. This functional 

check of the MIL would not be required 

during vehicle operation in the key-on, 

engine-off position subsequent to the 

initial engine cranking of an ignition 

cycle (e.g., due to an engine stall or 

other non-commanded engine shutoff). 

The second functional check 

requirement we are proposing requires 

the OBD system to perform a circuit 

continuity check of the electrical circuit 

that is used to illuminate the MIL to 

verify that the circuit is not shorted or 

open (e.g., a burned out bulb). While 

there would not be an ability to 

illuminate the MIL when such a 

malfunction is detected, the 

electronically readable MIL command 

status in the onboard computer would 

be changed from commanded ‘‘off’’ to 

‘‘on’’. This would allow the truck owner 

or fleet maintenance staff to quickly 

determine whether an extinguished MIL 

means ‘‘no malfunctions’’ or ‘‘broken 

MIL.’’ It would also serve, should it 

become of interest in the future, 

complete automation of the I/M process 

by eliminating the need for inspectors to 

input manually the results of their 

visual inspections. Feedback from 

passenger car I/M programs indicates 

that the current visual bulb check 

performed by inspectors is subject to 

error and results in numerous vehicles 

being falsely failed or passed. By 

requiring monitoring of the circuit itself, 

the entire pass/fail criteria of an I/M 

program could be determined by the 

electronic information available through 

a scan tool, thus better facilitating quick 


sroberts on PROD1PC70 with PROPOSALS
3210 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

16See 40 CFR part 86, subpart N for details of 

EPA’s test procedures. 

and effective inspections and 

minimizing the chance for manuallyentered errors. 

At the manufacturer’s option, the MIL 

may be used to indicate readiness status 

in a standardized format (see Section 

II.F) in the key-on, engine-off position. 

Readiness status is a term used in lightduty OBD that refers to a vehicle’s 

readiness for I/M inspection. For a 

subset of monitors—those that are noncontinuous monitors for which an 

emissions threshold exists (see sections 

II.B and II.C for more on emissions 

thresholds)—a readiness status indicator 

must be stored in memory to indicate 

whether or not that particular monitor 

has run enough times to make a 

diagnostic decision. Until the monitor 

has run sufficient times, the readiness 

status would indicate ‘‘not ready’’. 

Upon running sufficient times, the 

readiness status would indicate 

‘‘ready.’’ This serves to protect against 

drivers disconnecting their battery just 

prior to the I/M inspection so as to erase 

any MIL-on DTCs. Such an action 

would simultaneously set all readiness 

status indicators to ‘‘not ready’’

resulting in a notice to return to the 

inspection site at a future date. 

Readiness indicators also help repair 

technicians because, after completing a 

repair, they can operate the vehicle until 

the readiness status indicates ‘‘ready’’

and, provided no DTCs are stored, know 

that the repair has been successful. We 

are proposing that HDOBD systems 

follow this same readiness status logic 

as used for years in light-duty OBD both 

to assist repair technicians and to 

facilitate potential future HDOBD I/M 

programs. 

We are also proposing that the 

manufacturer, upon Administrator 

approval, be allowed to use the MIL to 

indicate which, if any, DTCs are 

currently stored (e.g., to ‘‘blink’’ the 

stored codes). The Administrator would 

approve the request if the manufacturer 

can demonstrate that the method used 

to indicate the DTCs will not be 

unintentionally activated during any 

inspection test or during routine driver 

operation. 

3. Monitoring Conditions 

a. Background 

Given that the intent of the proposed 

OBD requirements is to monitor the 

emission control system for proper 

operation, it is logical that the OBD 

monitors be designed such that they 

monitor the emission control system 

during typical driving conditions. While 

many OBD monitors would be designed 

such that they are continuously making 

decisions about the operational status of 

the engine, many—and arguably the 

most critical—monitors are not so 

designed. For example, an OBD monitor 

whose function is to monitor the active 

fuel injection system of a NOX adsorber 

or a DPF cannot be continuously 

monitoring that function since that 

function occurs on an infrequent basis. 

This OBD monitor presumably would be 

expected to ‘‘run,’’ or evaluate the active 

injection system, during an actual fuel 

injection event. 

For this reason, manufacturers are 

allowed to determine the most 

appropriate times to run their noncontinuous OBD monitors. This way, 

they are able to make an OBD evaluation 

either at the operating condition when 

an emission control system is active and 

its operational status can best be 

evaluated, and/or at the operating 

condition when the most accurate 

evaluation can be made (e.g., highly 

transient conditions or extreme 

conditions can make evaluation 

difficult). Importantly, manufacturers 

are prohibited from using a monitoring 

strategy that is so restrictive such that it 

rarely or never runs. To help protect 

against monitors that rarely run, we are 

proposing an ‘‘in-use monitor 

performance ratio’’ requirement which 

is detailed in section II.E. 

The set of operating conditions that 

must be met so that an OBD monitor can 

run are called the ‘‘enable criteria’’ for 

that given monitor. These enable criteria 

are often different for different monitors 

and may well be different for different 

types of engines. A large diesel engine 

intended for use in a Class 8 truck 

would be expected to see long periods 

of relatively steady-state operation 

while a smaller engine intended for use 

in an urban delivery truck would be 

expected to see a lot of transient 

operation. Manufacturers will need to 

balance between a rather loose set of 

enable criteria for their engines and 

vehicles given the very broad range of 

operation HD highway engines see and 

a tight set of enable criteria given the 

desire for greater monitor accuracy. 

b. General Monitoring Conditions 

i. Monitoring Conditions for All Engines 

As guidance to manufacturers, we are 

proposing the following criteria to assist 

manufacturers in developing their OBD 

enable criteria. These criteria would be 

used by the Agency during our OBD 

certification approval process to ensure 

that monitors run on a frequent basis 

during real world driving conditions. 

These criteria would be: 

• The monitors should run during 

conditions that are technically 

necessary to ensure robust detection of 

malfunctions (e.g., to avoid false passes 

and false indications of malfunctions); 

• The monitor enable criteria should 

ensure monitoring will occur during 

normal vehicle operation; and, 

• Monitoring should occur during at 

least one test used by EPA for emissions 

verification ‘‘ either the HD Federal Test 

Procedure (FTP) transient cycle, or the 

Supplementary Emissions Test (SET).16

As discussed in more detail in 

sections II.B through II.D, we are 

proposing that manufacturers define the 

monitoring conditions, subject to 

Administrator approval, for detecting 

the malfunctions required by this 

proposal. The Administrator would 

determine if the monitoring conditions 

proposed by the manufacturer for each 

monitor abide by the above criteria. 

In general, except as noted in sections 

II.B through II.D, the proposed 

regulation would require each monitor 

to run at least once per driving cycle in 

which the applicable monitoring 

conditions are met. The proposal would 

also require certain monitors to run 

continuously throughout the driving 

cycle. These include a few threshold 

monitors (e.g., fuel system monitor) and 

most circuit continuity monitors. While 

a basic definition of a driving cycle (e.g., 

from ignition key-on and engine startup 

to engine shutoff) has been sufficient for 

passenger cars, the driving habits of 

many types of vehicles in the heavyduty industry dictate an alternate 

definition. Specifically, many heavyduty operators will start the engine and 

leave it running for an entire day or, in 

some cases, even longer. As such, we 

are proposing that any period of 

continuous engine-on operation of four 

hours be considered a complete driving 

cycle. A new driving cycle would begin 

following such a four hour period, 

regardless of whether or not the engine 

had been shut down. Thus, the ‘‘clock’’

for monitors that are required to run 

once per driving cycle would be reset to 

run again (in the same key-on engine 

start or trip) once the engine has been 

operated beyond four hours 

continuously. This would avoid an 

unnecessary delay in detection of 

malfunctions simply because the heavyduty vehicle operator has elected to 

leave the vehicle running continuously 

for an entire day or days at a time. 

Manufacturers may request 

Administrator approval to define 

monitoring conditions that are not 

encountered during the FTP cycle. In 

evaluating the manufacturer’s request, 

the Administrator will consider the 

degree to which the requirement to run 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3211 

17See proposed § 86.010–18(f). 

during the FTP cycle restricts in-use 

monitoring, the technical necessity for 

defining monitoring conditions that are 

not encountered during the FTP cycle, 

data and/or an engineering evaluation 

submitted by the manufacturer which 

demonstrate that the component/system 

does not normally function, or 

monitoring is otherwise not feasible, 

during the FTP cycle, and, where 

applicable, the ability of the 

manufacturer to demonstrate that the 

monitoring conditions will satisfy the 

minimum acceptable in-use monitor 

performance ratio requirement as 

defined below. 

ii. In-Use Performance Tracking 

Monitoring Conditions 

In addition to the general monitoring 

conditions above, we are proposing that 

manufacturers be required to implement 

software algorithms in the OBD system 

to individually track and report in-use 

performance of the following monitors 

in the standardized format specified in 

section II.E: 

• Diesel NMHC converting catalyst(s) 

• Diesel NOX converting catalyst(s) 

• Gasoline catalyst(s) 

• Exhaust gas sensor(s) 

• Gasoline evaporative system 

• Exhaust gas recirculation (EGR) 

system 

• Variable valve timing (VVT) system 

• Gasoline secondary air system 

• Diesel particulate filter system 

• Diesel boost pressure control system 

• Diesel NOX adsorber(s) 

The OBD system is not required to 

track and report in-use performance for 

monitors other than those specifically 

identified above. 

iii. In-Use Performance Ratio 

Requirement 

We are also proposing that, for all 

2013 and subsequent model year 

engines, manufacturers be required to 

define monitoring conditions that, in 

addition to meeting the general 

monitoring conditions, ensure that 

certain monitors yield an in-use 

performance ratio (which monitors and 

the details that define the performance 

ratio are defined in section II.E) that 

meets or exceeds the minimum 

acceptable in-use monitor performance 

ratio for in-use vehicles. We are 

proposing a minimum acceptable in-use 

monitor performance ratio of 0.100 for 

all monitors specifically required to 

track in-use performance. This means 

that the monitors listed in section 

II.A.3.ii above must run and make valid 

diagnostic decisions during 10 percent 

of the vehicle’s trips. We intend to work 

with industry during the initial years of 

implementation to gather data on in-use 

performance ratios and may revise this 

ratio lower as appropriate depending on 

what we learn. 

Note that manufacturers may not use 

the calculated ratio (or any element 

thereof), or any other indication of 

monitor frequency, as a monitoring 

condition for a monitor. For example, 

the manufacturer would not be allowed 

to use a low ratio to enable more 

frequent monitoring through diagnostic 

executive priority or modification of 

other monitoring conditions, or to use a 

high ratio to enable less frequent 

monitoring. 

4. Determining the Proper OBD 

Malfunction Criteria 

For determining the malfunction 

criteria for diesel engine monitors 

associated with an emissions threshold 

(see sections II.B and II.C for more on 

emissions thresholds), we are proposing 

that manufacturers be required to 

determine the appropriate emissions 

test cycle such that the most stringent 

monitor would result. In general, we 

believe that manufacturers can make 

this determination based on engineering 

judgement, but there may be situations 

where testing would be required to 

make the determination. We do not 

necessarily anticipate challenging a 

manufacturer’s determination of which 

test cycle to use. Nonetheless, the 

manufacturer should be prepared, 

perhaps with test data, to justify their 

determination. 

We are also proposing that, for 

engines equipped with emission 

controls that experience infrequent 

regeneration events (e.g., a DPF and/or 

a NOX adsorber), a manufacturer must 

adjust the emission test results for 

monitors that are required to indicate a 

malfunction before emissions exceed a 

certain emission threshold.17 For each 

such monitor, the manufacturer would 

have to adjust the emission result as 

done in accordance with the provisions 

of section 86.004–28(i) with the 

component for which the malfunction 

criteria are being established having 

been deteriorated to the malfunction 

threshold. As proposed, the adjusted 

emission value must be used for 

purposes of determining whether or not 

the applicable emission threshold is 

exceeded. 

While we believe that this adjustment 

process for monitors of systems that 

experience infrequent regeneration 

events makes sense and would result in 

robust monitors, we also believe that it 

could prove to be overly burdensome for 

manufacturers. For example, a NOX

adsorber threshold being evaluated by 

running an FTP using a ‘‘threshold’’ part 

(i.e., a NOX adsorber deteriorated such 

that tailpipe emissions are at the 

applicable thresholds) may be 

considered acceptable provided the 

NOX adsorber does not regenerate 

during the test, but it may be considered 

unacceptable if the NOX adsorber does 

happen to regenerate during the test. 

This could happen because emissions 

would be expected to increase slightly 

during the regeneration event thereby 

causing emissions to be slightly above 

the applicable threshold. This would 

require the manufacturer to recalibrate 

the NOX adsorber monitor to detect at a 

lower level of deterioration to ensure 

that a regeneration event would not 

cause an exceedance of the threshold 

during an emissions test. After such a 

recalibration, the emissions occurring 

during the regeneration event would be 

lower than before because the new 

‘‘threshold’’ NOX adsorber would have a 

slightly higher conversion efficiency. 

We are concerned that manufacturers 

may find themselves in a difficult 

iterative process calibrating such 

monitors that, in the end, will not be 

correspondingly more effective. 

For this reason, we request comment 

regarding the burden associated with 

the need to consider regeneration events 

in determining compliance with 

emissions thresholds. We also request 

comment on how to address any 

environmental concern versus the 

burden. Would it perhaps be best to 

simply use the emissions adjustments 

that are determined in accordance with 

section 86.004–28(i)? Is it necessary to 

even consider regeneration emissions 

when determining emission threshold 

compliance or is it perhaps best to 

ignore regeneration events in 

determining threshold calibrations? 

B. Monitoring Requirements and 

Timelines for Diesel-Fueled/ 

Compression-Ignition Engines 

Table II.B–1 summarizes the proposed 

diesel fueled compression ignition 

emissions thresholds at which point a 

component or system has failed to the 

point of requiring an illuminated MIL 

and a stored DTC. More detail regarding 

the specific monitoring requirements, 

implementation schedules, and 

liabilities can be found in the sections 

that follow. 


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3212 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

TABLE II.B–1.—PROPOSED EMISSIONS THRESHOLDS FOR DIESEL FUELED CI ENGINES OVER 14,000 POUNDS

Component/monitor MY NMHC CO NOX PM 

NMHC catalyst system .................................................................................................. 2010–2012 2.5x ............ ............ ....................

2013+ 2x ............ ............ ....................

NOX catalyst system ...................................................................................................... 2010+ ............ ............ +0.3 ....................

DPF system ................................................................................................................... 2010–2012 2.5x ............ ............ 0.05/+0.04 

2013+ 2x ............ ............ 0.05/+0.04 

Air-fuel ratio sensors upstream ...................................................................................... 2010–2012 2.5x 2.5x +0.3 0.03/+0.02 

2013+ 2x 2x +0.3 0.03/+0.02 

Air-fuel ratio sensors downstream ................................................................................. 2010–2012 2.5x ............ +0.3 0.05/+0.04 

2013+ 2x ............ +0.3 0.05/+0.04 

NOX sensors .................................................................................................................. 2010+ ............ ............ +0.3 0.05/+0.04 

‘‘Other monitors’’ with emissions thresholds (see section II.B) ..................................... 2010–2012 2.5x 2.5x +0.3 0.03/+0.02 

2013+ 2x 2x +0.3 0.03/+0.02 

Notes: MY=Model Year; 2.5x means a multiple of 2.5 times the applicable emissions standard or family emissions limit (FEL); +0.3 means the 

standard or FEL plus 0.3; 0.05/+0.04 means an absolute level of 0.05 or an additive level of the standard or FEL plus 0.04, whichever level is 

higher; not all proposed monitors have emissions thresholds but instead rely on functionality and rationality checks as described in section II.D.4. 

There are exceptions to the emissions 

thresholds shown in Table II.B–1 

whereby a manufacturer can 

demonstrate that emissions do not 

exceed the threshold even when the 

component or system is non-functional 

at which point a functional check would 

be allowed. 

Note that, in general, the monitoring 

strategies designed to meet the 

requirements discussed below should 

not involve the alteration of the engine 

control system or the emissions control 

system such that tailpipe emissions 

would increase. We do not want 

emissions to increase, even for short 

durations, for the sole purpose of 

monitoring the systems intended to 

control emissions. The Administrator 

would consider such monitoring 

strategies on a case-by-case basis taking 

into consideration the emissions impact 

and duration of the monitoring event. 

However, much effort has been 

expended in recent years to minimize 

engine operation that results in 

increased emissions and we encourage 

manufacturers to develop monitoring 

strategies that do not require alteration 

of the basic control system. 

1. Fuel System Monitoring 

a. Background 

The fuel system of a diesel engine is 

an essential component of the engine’s 

emissions control system. Proper 

delivery of fuel—quantity, pressure, and 

timing—can play a crucial role in 

maintaining low engine-out emissions. 

The performance of the fuel system is 

also critical for aftertreatment device 

control strategies. As such, thorough 

monitoring of the fuel system is an 

essential element in an OBD system. 

The fuel system is primarily comprised 

of a fuel pump, fuel pressure control 

device, and fuel injectors. Additionally, 

the fuel system generally has 

sophisticated control strategies that 

utilize one or more feedback sensors to 

ensure the proper amount of fuel is 

being delivered to the cylinders. While 

gasoline engines have undergone 

relatively minor hardware changes (but 

substantial fine-tuning in the control 

strategy and feedback inputs), diesel 

engines have more recently undergone 

substantial changes to the fuel system 

hardware and now incorporate more 

refined control strategies and feedback 

inputs. 

For diesel engines, a substantial 

change has occurred in recent years as 

manufacturers have transitioned to new 

high-pressure fuel systems. One of the 

most widely used is a high-pressure 

common-rail fuel injection system, 

which is generally comprised of a highpressure fuel pump, a fuel rail pressure 

sensor, a common fuel rail that feeds all 

injectors, individual fuel injectors that 

directly control fuel injection quantity 

and timing for each cylinder, and a 

closed-loop feedback system that uses 

the fuel rail pressure sensor to achieve 

the commanded fuel rail pressure. 

Unlike older style fuel systems where 

fuel pressure was mechanically linked 

to engine speed (and thus, varied from 

low to high as engine speed increased), 

common-rail systems are capable of 

controlling fuel pressure independent of 

engine speed. This increase in fuel 

pressure control allows greater 

flexibility in optimizing the 

performance and emission 

characteristics of the engine. The ability 

of the system to generate high pressure 

independent of engine speed also 

improves fuel delivery at low engine 

speeds. 

Precise control of the fuel injection 

timing is crucial for optimal engine and 

emission performance. As injection 

timing is advanced (i.e., fuel injection 

occurs earlier), hydrocarbon (HC) 

emissions and fuel consumption are 

decreased but oxides of nitrogen (NOX) 

emissions are increased. As injection 

timing is retarded (i.e., fuel injection 

occurs later), NOX emissions can be 

reduced but HC emissions, particulate 

matter (PM) emissions, and fuel 

consumption increase. Most modern 

diesel fuel systems even provide engine 

manufacturers with the ability to 

separate a single fuel injection event 

into discrete events such as pilot (or 

pre) injection, main injection, and post 

injection. 

Given the important role that modern 

diesel fuel systems play in emissions 

control, malfunctions or deterioration 

that would affect the fuel pressure 

control, injection timing, pilot/main/ 

post injection timing or quantity, or 

ability to accurately perform rateshaping could lead to substantial 

increases in emissions (primarily NOX

or PM), often times with an associated 

change in fuel consumption. 

b. Fuel System Monitoring 

Requirements 

We are proposing that the OBD 

system monitor the fuel delivery system 

to verify that it is functioning properly. 

The fuel system monitor would be 

required to monitor for malfunctions in 

the injection pressure control, injection 

quantity, injection timing, and feedback 

control (if equipped). The individual 

electronic components (e.g., actuators, 

valves, sensors, pumps) that are used in 

the fuel system and not specifically 

addressed in this section shall be 

monitored in accordance with the 

comprehensive component 

requirements in section II.D.4. 

i. Fuel System Pressure Control 

We are proposing that the OBD 

system continuously monitor the fuel 

system’s ability to control to the desired 

fuel pressure. The OBD system would 

have to detect a malfunction of the fuel 

system’s pressure control system when 


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Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3213 

the pressure control system is unable to 

maintain an engine’s emissions at or 

below the emissions thresholds for 

‘‘other monitors’’ as shown in Table 

II.B–1. For engines in which no failure 

or deterioration of the fuel system 

pressure control could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system would be required to detect 

a malfunction when the system has 

reached its control limits such that the 

commanded fuel system pressure 

cannot be delivered. 

ii. Fuel System Injection Quantity 

We are proposing that the OBD 

system detect a malfunction of the fuel 

injection system when the system is 

unable to deliver the commanded 

quantity of fuel necessary to maintain 

an engine’s emissions at or below the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.B–1. For 

engines in which no failure or 

deterioration of the fuel injection 

quantity could result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the OBD system 

would be required to detect a 

malfunction when the system has 

reached its control limits such that the 

commanded fuel quantity cannot be 

delivered. 

iii. Fuel System Injection Timing 

We are proposing that the OBD 

system detect a malfunction of the fuel 

injection system when the system is 

unable to deliver fuel at the proper 

crank angle/timing (e.g., injection 

timing too advanced or too retarded) 

necessary to maintain an engine’s 

emissions at or below the emissions 

thresholds for ‘‘other monitors’’ as 

shown in Table II.B–1. For engines in 

which no failure or deterioration of the 

fuel injection timing could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system would be required to detect 

a malfunction when the system has 

reached its control limits such that the 

commanded fuel injection timing 

cannot be achieved. 

iv. Fuel System Feedback Control 

If the engine is equipped with 

feedback control of the fuel system (e.g., 

feedback control of pressure or pilot 

injection quantity), we are proposing 

that the OBD system detect a 

malfunction when and if: 

• The system fails to begin feedback 

control within a manufacturer specified 

time interval; 

• A failure or deterioration causes 

open loop or default operation; or 

• Feedback control has used up all of 

the adjustment allowed by the 

manufacturer. 

A manufacturer may temporarily 

disable monitoring for malfunctions 

where the feedback control has used up 

all of the adjustment allowed by the 

manufacturer during conditions that the 

monitor cannot distinguish robustly 

between a malfunctioning system and a 

properly operating system. To do so, the 

manufacturer would be required to 

submit data and/or engineering analyses 

demonstrating that the control system, 

when operating as designed on an 

engine with all emission controls 

working properly, routinely operates 

during these conditions with all of the 

adjustment allowed by the manufacturer 

used up. In lieu of detecting, with a fuel 

system specific monitor, when the 

system fails to begin feedback control 

within a manufacturer specified time 

interval and/or when a failure or 

deterioration causes open loop or 

default operation, the OBD system may 

monitor the individual parameters or 

components that are used as inputs for 

fuel system feedback control provided 

that the monitors detect all 

malfunctions related to feedback 

control. 

c. Fuel System Monitoring Conditions 

The OBD system would be required to 

monitor continuously for malfunctions 

of the fuel pressure control and 

feedback control. Manufacturers would 

be required to define the monitoring 

conditions for malfunctions of the 

injection quantity and injection timing 

such that the minimum performance 

ratio requirements discussed in section 

II.E would be met. 

d. Fuel System MIL Illumination and 

DTC Storage 

We are proposing the general MIL 

illumination and DTC storage 

requirements as discussed in section 

II.A.2. 

2. Engine Misfire Monitoring 

a. Background 

Misfire, the lack of combustion in the 

cylinder, causes increased engine-out 

hydrocarbon emissions. On gasoline 

engines, misfire results from the absence 

of spark, poor fuel metering, and poor 

compression. Further, misfire can be 

intermittent on gasoline engines (e.g., 

the misfire only occurs under certain 

engine speeds or loads). Consequently, 

our existing under 14,000 pound OBD 

regulation requires continuous 

monitoring for misfire malfunctions on 

gasoline engines. 

In contrast, manufacturers have 

historically maintained that a diesel 

engine with traditional diesel 

technology misfires only due to poor 

compression (e.g., worn valves or piston 

rings, improper injector or glow plug 

seating). They have also maintained 

that, when poor compression results in 

a misfiring cylinder, the cylinder will 

misfire under all operating conditions 

rather than only some operating 

conditions. For that reason, our existing 

under 14,000 pound OBD regulation has 

not required continuous monitoring for 

misfire malfunctions on diesel engines. 

However, with the increased use of 

EGR and its use to varying degrees at 

different speeds and load, and with 

emerging technologies such as 

homogeneous charge compression 

ignition (HCCI), we believe that the 

conventional wisdom regarding diesel 

engines and misfires no longer holds 

true. These newer technologies may 

indeed result in misfires that are 

intermittent, spread out among various 

cylinders, and that only happen at 

certain speeds and loads. 

b. Misfire Monitoring Requirements 

We are proposing that the OBD 

system monitor the engine for misfire 

causing excess emissions. The OBD 

system must be capable of detecting 

misfire occurring in one or more 

cylinders. To the extent possible 

without adding hardware for this 

specific purpose, the OBD system must 

also identify the specific misfiring 

cylinder. If more than one cylinder is 

continuously misfiring, a separate DTC 

must be stored indicating that multiple 

cylinders are misfiring. When 

identifying multiple cylinder misfire, 

the OBD system is not required to also 

identify each of the continuously 

misfiring cylinders individually through 

separate DTCs. 

For 2013 and subsequent model year 

engines, we are proposing a more 

stringent requirement that the OBD 

system detect a misfire malfunction 

causing emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.B–1. 

This requirement to detect engine 

misfire prior to exceeding an emissions 

threshold would apply only to those 

engines equipped with sensors capable 

of detecting combustion or combustion 

quality (e.g., cylinder pressure sensors 

used in homogeneous charge 

compression ignition (HCCI) control 

systems). Engines without such sensors 

would have to detect only when one or 

more cylinders are continually 

misfiring. 

To determine what level of misfire 

would cause emissions to exceed the 

applicable emissions thresholds, we are 

proposing that manufacturers determine 


sroberts on PROD1PC70 with PROPOSALS
3214 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

18 ‘‘Similar conditions,’’ as used in conjunction 

with misfire and fuel system monitoring, means 

engine conditions having an engine speed within 

375 rpm, load conditions within 20 percent, and the 

same warm up status (i.e., cold or hot) as existing 

during the applicable previous problem detection. 

The Administrator may approve other definitions of 

similar conditions based on comparable timeliness 

and reliability in detecting similar engine operation. 

the percentage of misfire evaluated in 

1000 revolution increments that would 

cause emissions from an emission 

durability demonstration engine to 

exceed the emissions thresholds if the 

percentage of misfire were present from 

the beginning of the test. To establish 

this percentage of misfire, the 

manufacturer would utilize misfire 

events occurring at equally spaced, 

complete engine cycle intervals, across 

randomly selected cylinders throughout 

each 1000-revolution increment. If this 

percentage of misfire is determined to 

be lower than one percent, the 

manufacturer may set the malfunction 

criteria at one percent. Any malfunction 

should be detected if the percentage of 

misfire established via this testing is 

exceeded regardless of the pattern of 

misfire events (e.g., random, equally 

spaced, continuous). 

The manufacturer may employ other 

revolution increments besides the 1000 

revolution increment being proposed. 

To do so, the manufacturer would need 

to demonstrate that the strategy would 

be equally effective and timely in 

detecting misfire. 

c. Engine Misfire Monitoring Conditions 

For engines without combustion 

sensors, we are proposing that the OBD 

system monitor for misfire during 

engine idle conditions at least once per 

drive cycle in which the monitoring 

conditions for misfire are met. The 

manufacturer would be required to 

define monitoring conditions, supported 

by manufacturer-submitted data and/or 

engineering analyses, that demonstrate 

that the monitoring conditions: are 

technically necessary to ensure robust 

detection of malfunctions (e.g., avoid 

false passes and false detection of 

malfunctions); require no more than 

1000 cumulative engine revolutions; 

and, do not require any single 

continuous idle operation of more than 

15 seconds to make a determination that 

a malfunction is present (e.g., a decision 

can be made with data gathered during 

several idle operations of 15 seconds or 

less). 

For 2013 and subsequent model year 

engines with combustion sensors, we 

are proposing that the OBD system 

continuously monitor for misfire under 

all positive torque engine speeds and 

load conditions. If a monitoring system 

cannot detect all misfire patterns under 

all positive torque engine speeds and 

load conditions, the manufacturer may 

request that the Administrator approve 

the monitoring system nonetheless. In 

evaluating the manufacturer’s request, 

the Administrator would consider the 

following factors: the magnitude of the 

region(s) in which misfire detection is 

limited; the degree to which misfire 

detection is limited in the region(s) (i.e., 

the probability of detection of misfire 

events); the frequency with which said 

region(s) are expected to be encountered 

in-use; the type of misfire patterns for 

which misfire detection is troublesome; 

and demonstration that the monitoring 

technology employed is not inherently 

incapable of detecting misfire under 

required conditions (i.e., compliance 

can be achieved on other engines). The 

evaluation would be based on the 

following misfire patterns: equally 

spaced misfire occurring on randomly 

selected cylinders; single cylinder 

continuous misfire; and, paired cylinder 

(cylinders firing at the same crank 

angle) continuous misfire. 

d. Engine Misfire MIL Illumination and 

DTC Storage 

For engines without combustion 

sensors, we are proposing the general 

MIL illumination and DTC storage 

requirements as discussed in section 

II.A.2. 

For 2013 and subsequent model year 

engines with combustion sensors, we 

are proposing that, after four detections 

of the percentage of misfire that would 

cause emissions to exceed the 

applicable emissions thresholds during 

a single driving cycle, a pending DTC 

would be stored. If a pending DTC is 

stored, the OBD system would be 

required to illuminate the MIL and store 

a MIL—on DTC if the percentage of 

misfire is again exceeded four times 

during either: the driving cycle 

immediately following the storage of the 

pending DTC, regardless of the 

conditions encountered during the 

driving cycle; or, the next driving cycle 

in which similar conditions are 

encountered to the engine conditions 

that occurred when the pending DTC 

was stored.18 For erasure of the pending 

DTC, we are proposing if, by the end of 

the next driving cycle in which similar 

conditions have been encountered to the 

engine conditions that occurred when 

the pending DTC was stored without an 

exceedance of the specified percentage 

of misfire, the pending DTC may be 

erased. The pending DTC may also be 

erased if similar conditions are not 

encountered during the next 80 driving 

cycles immediately following initial 

detection of the malfunction. 

We are proposing some specific items 

with respect to freeze frame storage 

associated with engine misfire. The 

OBD system shall store and erase freeze 

frame conditions either in conjunction 

with storing and erasing a pending DTC 

or in conjunction with storing a MIL—

on DTC and erasing a MIL—on DTC. In 

addition to those proposed requirements 

discussed in section II.A.2, we are 

proposing that, if freeze frame 

conditions are stored for a malfunction 

other than a misfire malfunction when 

a DTC is stored, the previously stored 

freeze frame information shall be 

replaced with freeze frame information 

regarding the misfire malfunction (i.e., 

the misfire’s freeze frame information 

should take precedence over freeze 

frames for other malfunctions). Further, 

we are proposing that, upon detection of 

misfire, the OBD system store the 

following engine conditions: engine 

speed, load, and warm up status of the 

first misfire event that resulted in the 

storage of the pending DTC. 

Lastly, we are proposing that the MIL 

may be extinguished after three 

sequential driving cycles in which 

similar conditions have been 

encountered without an exceedance of 

the specified percentage of misfire. 

3. Exhaust Gas Recirculation (EGR) 

System Monitoring 

a. Background 

Exhaust gas recirculation (EGR) 

systems are currently being used by 

many heavy-duty engine manufacturers 

to meet the 2.5 g/bhp-hr NOX+NMHC 

standard for 2004 and later model year 

engines. (65 FR 59896) EGR reduces 

NOX emissions in several ways. First, 

the recirculated exhaust gases dilute the 

intake air—i.e., oxygen in the fresh air 

is displaced with relatively non-reactive 

exhaust gases—which, in turn, results in 

less oxygen to form NOX. Second, EGR 

absorbs heat from the combustion 

process which reduces combustion 

chamber temperatures which, in turn, 

reduces NOX formation. The amount of 

heat absorbed from the combustion 

process is a function of EGR flow rate 

and recirculated gas temperature, both 

of which are controlled to minimize 

NOX emissions. An EGR cooler can be 

added to the EGR system to lower the 

recirculated gas temperature which 

further enhances NOX control. We fully 

expect that 2007 and later model year 

engines will continue to make use of 

cooled EGR systems. 

While in theory the EGR system 

simply routes some exhaust gas back to 

the intake, production systems can be 

complex and involve many components 

to ensure accurate control of EGR flow 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3215 

19For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

to maintain acceptable PM and NOX

emissions while minimizing effects on 

fuel economy. To control EGR flow 

rates, EGR systems normally use the 

following components: an EGR valve, 

valve position sensor, boost pressure 

sensor, intake temperature sensor, 

intake (fresh) airflow sensor, and tubing 

or piping to connect the various 

components of the system. EGR 

temperature sensors and exhaust 

backpressure sensors can also be used. 

Additionally, some systems use a 

variable geometry turbocharger to 

provide the backpressure necessary to 

drive the EGR flow. Therefore, EGR is 

not a stand alone emission control 

device. Rather, it is carefully integrated 

with the air handling system 

(turbocharging and intake cooling) to 

control NOX while not adversely 

affecting PM emissions and fuel 

economy. 

b. EGR System Monitoring 

Requirements 

We are proposing that the OBD 

system monitor the EGR system on 

engines so equipped for low EGR flow 

rate, high EGR flow rate, and slow EGR 

flow response malfunctions. For engines 

so equipped, we are proposing that the 

EGR feedback control be monitored. 

Also, for engines equipped with EGR 

coolers (e.g., heat exchangers), the OBD 

system would have to monitor the 

cooler for malfunctions associated with 

insufficient EGR cooling. The individual 

electronic components (e.g., actuators, 

valves, sensors) that are used in the EGR 

system would be monitored in 

accordance with the comprehensive 

component requirements presented in 

section II.D.4. 

i. EGR Low Flow Malfunctions 

We are proposing that the OBD 

system detect a malfunction prior to a 

decrease from the manufacturer’s 

specified EGR flow rate that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.B–1. For 

engines in which no failure or 

deterioration of the EGR system that 

causes a decrease in flow could result in 

an engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system would have to detect a 

malfunction when the system has 

reached its control limits such that it 

cannot increase EGR flow to achieve the 

commanded flow rate. 

ii. EGR High Flow Malfunctions 

We are proposing that the OBD 

system detect a malfunction of the EGR 

system, including a leaking EGR valve—

i.e., exhaust gas flowing through the 

valve when the valve is commanded 

closed—prior to an increase from the 

manufacturer’s specified EGR flow rate 

that would cause an engine’s emissions 

to exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 

II.B–1. For engines in which no failure 

or deterioration of the EGR system that 

causes an increase in flow could result 

in an engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system would have to detect a 

malfunction when the system has 

reached its control limits such that it 

cannot reduce EGR flow to achieve the 

commanded flow rate. 

iii. EGR Slow Response Malfunctions 

We are proposing that the OBD 

system detect a malfunction of the EGR 

system prior to any failure or 

deterioration in the capability of the 

EGR system to achieve the commanded 

flow rate within a manufacturerspecified time that would cause an 

engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.B–1. The 

OBD system would have to monitor 

both the capability of the EGR system to 

respond to a commanded increase in 

flow and the capability of the EGR 

system to respond to a commanded 

decrease in flow. 

iv. EGR Feedback Control 

We are proposing that the OBD 

system on any engine equipped with 

feedback control of the EGR system (e.g., 

feedback control of flow, valve position, 

pressure differential across the valve via 

intake throttle or exhaust backpressure), 

detect a malfunction when and if: 

• The system fails to begin feedback 

control within a manufacturer specified 

time interval; 

• A failure or deterioration causes 

open loop or default operation; or 

• Feedback control has used up all of 

the adjustment allowed by the 

manufacturer. 

v. EGR Cooler Performance 

We are proposing that the OBD 

system detect a malfunction of the EGR 

cooler prior to a reduction from the 

manufacturer’s specified cooling 

performance that would cause an 

engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.B–1. For 

engines in which no failure or 

deterioration of the EGR cooler could 

result in an engine’s emissions 

exceeding the applicable emissions 

thresholds, the OBD system would have 

to detect a malfunction when the system 

has no detectable amount of EGR 

cooling. 

c. EGR System Monitoring Conditions 

We are proposing that the OBD 

system monitor continuously for low 

EGR flow, high EGR flow, and feedback 

control malfunctions. Manufacturers 

would be required to define the 

monitoring conditions for EGR slow 

response malfunctions such that the 

minimum performance ratio 

requirements discussed in section II.E 

would be met with the exception that 

monitoring must occur every time the 

monitoring conditions are met during 

the driving cycle in lieu of once per 

driving cycle as required for most 

monitors. For purposes of tracking and 

reporting as required in section II.E, all 

monitors used to detect EGR slow 

response malfunctions must be tracked 

separately but reported as a single set of 

values as specified in section II.E.19

Manufacturersmay temporarily 

disable the EGR system check under 

specific conditions (e.g., when freezing 

may affect performance of the system). 

To do so, the manufacturer would be 

required to submit data and/or 

engineering analyses that demonstrate 

that a reliable check cannot be made 

when these specific conditions exist. 

d. EGR System MIL Illumination and 

DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

4. Turbo Boost Control System 

Monitoring 

a. Background 

Turbochargers are used on internal 

combustion engines to enhance 

performance by increasing the density 

of the intake air. Some of the benefits of 

turbocharging include increased 

horsepower, improved fuel economy, 

and decreased exhaust smoke. Most 

modern diesel engines take advantage of 

these benefits and are equipped with 

turbocharging systems. Moreover, 

smaller turbocharged diesel engines can 

be used in place of larger nonturbocharged engines to achieve the 

desired engine performance 

characteristics. 


sroberts on PROD1PC70 with PROPOSALS
3216 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

Exhaust gases passing through the 

turbine cause it to spin which, in turn, 

causes an adjacent centrifugal pump on 

the same rotating shaft to spin. The 

spinning pump serves to compress the 

intake air thereby increasing its density. 

Typically, a boost pressure sensor is 

located in the intake manifold to 

provide a feedback signal of the current 

intake manifold pressure. As turbo 

speed (boost) increases, the pressure in 

the intake manifold also increases. 

Proper boost control is essential to 

optimize emission levels. Even short 

periods of over-or under-boost can 

result in undesired air-fuel ratio 

excursions and corresponding emission 

increases. Additionally, the boost 

control system directly affects exhaust 

and intake manifold pressures. Another 

critical emission control system, EGR, is 

very dependent on these two pressures 

and generally uses the differential 

between them to force exhaust gas into 

the intake manifold. If the boost control 

system is not operating correctly, the 

exhaust or intake pressures may not be 

as expected and the EGR system may 

not function as designed. In highpressure EGR systems, higher exhaust 

pressures will generate more EGR flow 

and, conversely, lower pressures will 

reduce EGR flow. A malfunction that 

causes excessive exhaust pressures (e.g., 

wastegate stuck closed at high engine 

speed) can produce higher EGR 

flowrates at high load conditions and 

have a negative impact on emissions. 

Manufacturers commonly use charge 

air coolers to maximize the benefits of 

turbocharging and to control NOX

emissions. As the turbocharger 

compresses the intake air, the 

temperature of that intake air increases. 

This increasing air temperature causes 

the air to expand, which conflicts with 

one of the goals of turbocharging which 

is to increase charge air density. Charge 

air coolers are used to exchange heat 

between the compressed air and 

ambient air (or coolant) and cool the 

compressed air. Accordingly, a decrease 

in charge air cooler performance can 

affect emissions by causing higher 

intake air temperatures that can lead to 

higher combustion temperatures and 

higher NOX emissions. 

One drawback of turbocharging is 

known as turbo lag. Turbo lag occurs 

when the driver attempts to accelerate 

quickly from a low engine speed. Since 

the turbocharger is a mechanical device, 

a delay exists from the driver demand 

for more boost until the exhaust flow 

can physically speed up the 

turbocharger enough to deliver that 

boost. In addition to a negative effect on 

driveability and performance, improper 

fueling (e.g., over-fueling) during this 

lag can cause emission increases 

(typically PM). 

To decrease the effects of turbo lag, 

manufacturers design turbos that spool 

up quickly at low engine speeds and 

low exhaust flowrates. However, 

designing a turbo that will accelerate 

quickly from a low engine speed but 

will not result in an over-speed/overboost condition at higher engine speeds 

is challenging. That is, as the engine 

speed and exhaust flowrates near their 

maximum, the turbo speed increases to 

levels that cause excessive boost 

pressures and heat that could lead to 

engine or turbo damage. To prevent 

excessive turbine speeds and boost 

pressures at higher engine speeds, a 

wastegate is often used to bypass part of 

the exhaust stream around the 

turbocharger. The wastegate valve is 

typically closed at lower engine speeds 

so that all exhaust is directed through 

the turbocharger, thus providing quick 

response from the turbocharger when 

the driver accelerates quickly from low 

engine speeds. The wastegate is then 

opened at higher engine speeds to 

prevent engine or turbo damage from an 

over-speed condition. 

An alternative to a wastegate is the 

variable geometry turborcharger (VGT). 

To prevent over-boost conditions and to 

decrease turbo lag, VGTs are designed 

such that the geometry of the 

turbocharger changes with engine 

speed. While various physical 

mechanisms are used to achieve the 

variable geometry, the overall result is 

essentially the same. At low engine 

speeds, the exhaust gas into the turbo is 

restricted in a manner that maximizes 

the use of the available energy to spin 

the turbo. This allows the turbo to spool 

up quickly and provide good 

acceleration response. At higher engine 

speeds, the turbo geometry changes 

such that exhaust gas flow into the turbo 

is not as restricted. In this configuration, 

more exhaust can flow through the 

turbocharger without causing an overspeed condition. The advantage that 

VGTs offer compared to a waste-gated 

turbocharger is that all exhaust flow is 

directed through the turbocharger under 

all operating conditions. This can be 

viewed as maximizing the use of the 

available exhaust energy. 

b. Turbo Boost Control System 

Monitoring Requirements 

We are proposing that the OBD 

system monitor the boost pressure 

control system on engines so equipped 

for under and over boost malfunctions. 

For engines equipped with variable 

geometry turbochargers (VGT), the OBD 

system would have to monitor the VGT 

system for slow response malfunctions. 

For engines equipped with charge air 

cooler systems, the OBD system would 

have to monitor the charge air cooler 

system for cooling system performance 

malfunctions. The individual electronic 

components (e.g., actuators, valves, 

sensors) that are used in the boost 

pressure control system shall be 

monitored in accordance with the 

comprehensive component 

requirements in section II.D.4. 

i. Turbo Underboost Malfunctions 

We are proposing that the OBD 

system detect a malfunction of the boost 

pressure control system prior to a 

decrease from the manufacturer’s 

commanded boost pressure that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.B–1. For 

engines in which no failure or 

deterioration of the boost pressure 

control system that causes a decrease in 

boost could result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the OBD system 

must detect a malfunction when the 

system has reached its control limits 

such that it cannot increase boost to 

achieve the commanded boost pressure. 

ii. Turbo Overboost Malfunctions 

We are proposing that the OBD 

system detect a malfunction of the boost 

pressure control system prior to an 

increase from the manufacturer’s 

commanded boost pressure that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.B–1. For 

engines in which no failure or 

deterioration of the boost pressure 

control system that causes an increase 

in boost could result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the OBD system 

must detect a malfunction when the 

system has reached its control limits 

such that it cannot decrease boost to 

achieve the commanded boost pressure. 

iii. VGT Slow Response Malfunctions 

We are proposing that the OBD 

system detect a malfunction prior to any 

failure or deterioration in the capability 

of the VGT system to achieve the 

commanded turbocharger geometry 

within a manufacturer-specified time 

that would cause an engine’s emissions 

to exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 

II.B–1. For engines in which no failure 

or deterioration of the VGT system 

response could result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the OBD system 

must detect a malfunction of the VGT 

system when proper functional response 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3217 

20For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

21For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

22For gasoline catalyst monitoring, manufacturers 

generally use what is called an exponentially 

Continued 

of the system to computer commands 

does not occur. 

iv. Turbo Boost Feedback Control 

Malfunctions 

We are proposing that, for engines 

equipped with feedback control of the 

boost pressure system—e.g., control of 

VGT position, turbine speed, manifold 

pressure—the OBD system shall detect a 

malfunction when and if: 

• The system fails to begin feedback 

control within a manufacturer specified 

time interval; 

• A failure or deterioration causes 

open loop or default operation; or 

• Feedback control has used up all of 

the adjustment allowed by the 

manufacturer. 

v. Charge Air Undercooling 

Malfunctions 

We are proposing that the OBD 

system detect a malfunction of the 

charge air cooling system prior to a 

decrease from the manufacturer’s 

specified cooling rate that would cause 

an engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.B–1. For 

engines in which no failure or 

deterioration of the charge air cooling 

system that causes a decrease in cooling 

performance could result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the OBD system 

must detect a malfunction when the 

system has no detectable amount of 

charge air cooling. 

c. Turbo Boost Control System 

Monitoring Conditions 

We are proposing that the OBD 

system monitor continuously for 

underboost and overboost malfunctions 

and for boost feedback control 

malfunctions. Manufacturers would be 

required to define the monitoring 

conditions for VGT slow response 

malfunctions such that the minimum 

performance ratio requirements 

discussed in section II.E would be met 

with the exception that monitoring must 

occur every time the monitoring 

conditions are met during the driving 

cycle in lieu of once per driving cycle 

as required for most monitors. For 

purposes of tracking and reporting as 

required in section II.E, all monitors 

used to detect VGT slow response 

malfunctions malfunctions must be 

tracked separately but reported as a 

single set of values as discussed in 

section II.E.20

d. Turbo Boost MIL Illumination and 

DTC Storage 

We are proposing the general MIL 

illumination and DTC storage 

requirements as discussed in section 

II.A.2. 

5. Non-Methane Hydrocarbon (NMHC) 

Converting Catalyst Monitoring 

a. Background 

Diesel oxidation catalysts (DOCs) 

have been used on some nonroad diesel 

engines since the 1960s and on some 

diesel trucks and buses in the U.S. since 

the early 1990s. DOCs are generally 

used for converting HC and carbon 

monoxide (CO) emissions to water and 

CO2 via an oxidation process. Current 

DOCs can also be used to convert PM 

emissions. DOCs may also be used in 

conjunction with other aftertreatment 

emission controls—such as NOX

adsorber systems, selective catalytic 

reduction (SCR) systems, and PM 

filters—to improve their performance 

and/or clean up certain reducing agents 

that might slip through the system (e.g., 

the urea used in urea SCR systems). 

b. NMHC Converting Catalyst 

Monitoring Requirements 

We are proposing that the OBD 

system monitor the NMHC converting 

catalyst(s) for proper NMHC conversion 

capability. We are also proposing that 

each catalyst that converts NMHC be 

monitored either individually or in 

combination with others. For engines 

equipped with catalyzed diesel 

particulate filters (CDPFs) that convert 

NMHC emissions, the catalyst function 

of the CDPF must be monitored in 

accordance with the CDPF monitoring 

requirements in section II.B.8. 

i. NMHC Converting Catalyst 

Conversion Efficiency 

We are proposing that the OBD 

system detect an NMHC catalyst 

malfunction when the catalyst 

conversion capability decreases to the 

point that NMHC emissions exceed the 

emissions thresholds for ‘‘NMHC 

catalysts’’ as shown in Table II.B–1. If 

no failure or deterioration of the catalyst 

NMHC conversion capability could 

result in an engine’s NMHC emissions 

exceeding the applicable emissions 

thresholds, the OBD system would have 

to detect a malfunction when the 

catalyst has no detectable amount of 

NMHC conversion capability. 

ii. Other Aftertreatment Assistance 

Functions 

For catalysts used to generate an 

exotherm to assist CDPF regeneration, 

we are proposing that the OBD system 

detect a malfunction when the catalyst 

is unable to generate a sufficient 

exotherm to achieve that regeneration. 

For catalysts used to generate a feedgas 

constituency to assist SCR systems (e.g., 

to increase NO2 concentration upstream 

of an SCR system), the OBD system 

would have to detect a malfunction 

when the catalyst is unable to generate 

the necessary feedgas constituents for 

proper SCR system operation. For 

catalysts located downstream of a CDPF 

and used to convert NMHC emissions 

during a CDPF regeneration event, the 

OBD system would be required to detect 

a malfunction when the catalyst has no 

detectable amount of NMHC conversion 

capability. 

c. NMHC Converting Catalyst 

Monitoring Conditions 

Manufacturers would be required to 

define the monitoring conditions for 

NMHC converting catalyst malfunctions 

such that the minimum performance 

ratio requirements discussed in section 

II.E would be met. For purposes of 

tracking and reporting as discussed in 

section II.E, all monitors used to detect 

NMHC converting catalyst malfunctions 

must be tracked separately but reported 

as a single set of values as discussed in 

section II.E.21

d. NMHC Converting Catalyst MIL 

Illumination and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage discussed in section II.A.2. 

Note that the monitoring method for the 

catalyst(s) must be capable of detecting 

all instances, except diagnostic selfclearing, when a catalyst DTC has been 

cleared but the catalyst has not been 

replaced (e.g., catalyst over temperature 

histogram approaches are not 

acceptable).22


sroberts on PROD1PC70 with PROPOSALS
3218 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

weighted moving average (EWMA) approach to 

making decisions about the catalyst’s pass/fail 

status. This approach monitors the catalyst and 

‘‘saves’’ that information. The next time it monitors 

the catalyst, it saves that information along with the 

previous information, placing a higher weighting on 

the most recent information. This is done every 

time the OBD system monitors the catalyst and the 

EWMA saves six or seven monitoring events before 

making a decision. Importantly, once there exists 

six or seven pieces of information, every monitoring 

event can result in a decision because the EWMA 

is always using the previous six or seven events. 

Unfortunately, if a service technician clears the data 

with a scan tool, it is going to take six or seven 

monitoring events before the catalyst monitor can 

make a decision on the pass/fail status of the 

catalyst. So, we want to be sure that, in addition 

to the EWMA aspect of the catalyst monitor, there 

exists a way of determining quickly that someone 

has cleared the data but perhaps did not actually 

repair the catalyst. This is required to help prevent 

against DTC clearing without fixing a failed catalyst 

as a means of passing an inspection & maintenance 

test. 

23 Draft Technical Support Document, HDOBD 

NPRM, EPA420–D–06–006, Docket ID# EPA–HQ–

OAR–2005–0047–0008. 

24Schaer, C. M., Onder, C. H., Geering, H. P., and 

Elsener, M., ‘‘Control of a Urea SCR Catalytic 

Converter System for a Mobile Heavy-Duty Diesel 

Engine,’’ SAE Paper 2003–01–0776 which may be 

obtained from Society of Automotive Engineers 

International, 400 Commonwealth Dr., Warrendale, 

PA, 15096–0001. 

25Walker, A. P., Chandler, G. R., Cooper, B. J., et 

al., ‘‘An Integrated SCR and Continuously 

Regenerating Trap System to Meet Future NOX and 

PM Legislation,’’ SAE Paper 2000–01–0188 which 

may be obtained from Society of Automotive 

Engineers International, 400 Commonwealth Dr., 

Warrendale, PA, 15096–0001. 

6. Selective Catalytic Reduction (SCR) 

and Lean NOX Catalyst Monitoring 

a. Background 

Selective Catalytic Reduction (SCR) 

catalysts that use ammonia as a NOX

reductant have been used for stationary 

source NOX control for a number of 

years. Frequently, urea is used as the 

source of ammonia for SCR catalysts, 

and such systems are commonly 

referred to as Urea SCR systems. In 

recent years, considerable effort has 

been invested in developing urea SCR 

systems that could be applied to heavyduty diesel vehicles with low sulfur 

diesel fuel. We now expect that urea 

SCR systems will be introduced in 

Europe to comply with the EURO IV 

heavy-duty diesel emission standards. 

Such systems have been introduced in 

the past year by some heavy-duty diesel 

engine manufacturers both in Europe 

and in Japan. 

SCR catalyst systems require an 

accurate urea control system to inject 

precise amounts of reductant. An 

injection rate that is too low may result 

in lower NOX conversions while an 

injection that is too high may release 

unwanted ammonia emissions—referred 

to as ammonia slip—to the atmosphere. 

In general, ammonia to NOX ratios of 

around 1:1 are used to provide the 

highest NOX conversion rates with 

minimal ammonia slip. Therefore, 

injecting just the right amount of 

ammonia appropriate for the amount of 

NOX in the exhaust is very important. 

This can be challenging in a highway 

application because on-road diesel 

engines operate over a variety of speeds 

and loads. This makes the use of closedloop feedback systems for reductant 

metering very attractive. This can be 

achieved, for example, with a dedicated 

NOX sensor in the exhaust so that the 

NOX concentration can be accurately 

known. With an accurate fast response 

NOX sensor, closed-loop control of the 

ammonia injection can be used to 

achieve and maintain the desired 

ammonia/NOX ratios in the SCR catalyst 

for the high NOX conversion efficiencies 

necessary to achieve the 2010 emission 

standards under various engine 

operating conditions. 

Some have estimated that achieving 

the 2010 NOX emission standards with 

SCR systems will require NOX sensors 

that can measure NOX levels accurately 

in the 20 to 40 ppm range with little 

cross sensitivity to ammonia. Some in 

industry have even stated a desire for 

accuracy in the two to three ppm range. 

Suppliers have been developing NOX

sensors capable of measuring NOX in 

the 0 to 100 ppm range with +/¥5 ppm 

accuracy which we believe will be 

available by 2010.23 Regarding crosssensitivity to ammonia, work has been 

done that indicates ammonia and NOX

measurements can be independently 

measured by conditioning the output 

signal.24 This signal conditioning 

method resulted in a linear output for 

both ammonia and NOX from the NOX

sensor downstream of the catalyst. 

For SCR systems, closed-loop control 

of the reductant injection may require 

the use of two NOX sensors. The first 

NOX sensor would be located upstream 

of the catalyst and the reductant 

injection point would be used for 

measuring the engine-out NOX

emissions and determining the amount 

of reductant injection needed to reduce 

emissions. The second NOX sensor 

located downstream of the catalyst 

would be used for measuring the 

amount of ammonia and NOX emissions 

exiting the catalyst and providing 

feedback to the reductant injection 

control system. If the downstream NOX

sensor detects too much NOX emissions 

exiting the catalyst, the control system 

can inject higher quantities of reductant. 

Conversely, if the downstream NOX

sensor detects too much ammonia slip 

exiting the catalyst, the control system 

can decrease the amount of reductant 

injection. 

In addition to exhaust NOX levels, 

another important parameter for 

achieving high NOX conversion rates 

with minimum ammonia slip is catalyst 

temperature. SCR catalysts have a 

defined temperature range where they 

are most effective. For example, 

platinum catalysts are effective between 

175 and 250 degrees Celsius, vanadium 

catalysts are effective between 300 and 

450 degrees Celsius, and zeolite 

catalysts are most effective between 350 

and 600 degrees Celsius. To determine 

exhaust catalyst temperature for 

reductant control purposes, 

manufacturers are likely to use 

temperature sensors placed in the 

exhaust system. We project that only 

one temperature sensor positioned just 

downstream of the SCR system will be 

utilized for reductant injection control 

purposes. 

Production SCR catalyst systems may 

also contain auxiliary catalysts to 

improve the overall emissions control 

capability of the system. An oxidation 

catalyst is often positioned downstream 

of the SCR catalyst to help control 

ammonia slip on systems without 

closed-loop control of ammonia 

injection. The use of a ‘‘guard’’ catalyst 

could allow higher ammonia injection 

levels, thereby increasing the NOX

conversion efficiency without releasing 

un-reacted ammonia into the exhaust. 

The guard catalyst can also reduce HC 

and CO emission levels and diesel 

odors. However, increased N2O 

emissions may occur and NOX emission 

levels may actually increase if too much 

ammonia is oxidized in the catalyst. 

Some SCR systems may also include an 

oxidation catalyst upstream of the SCR 

catalyst and urea injection point to 

generate NO2 for lowering the effective 

operating temperature and/or volume of 

the SCR catalyst. Studies have indicated 

that increasing the NO2 content in the 

exhaust stream can reduce the SCR 

temperature requirements by about 100 

degrees Celsius.25 This ‘‘pre-oxidation’’

catalyst also has the added benefit of 

reducing HC emissions. 

b. SCR and Lean NOX Catalyst 

Monitoring Requirements 

We are proposing that the OBD 

system monitor SCR catalysts and lean 

NOX catalysts for proper conversion 

capability. We are also proposing that 

each catalyst that converts NOX be 

monitored either individually or in 

combination with others. For engines 

equipped with SCR systems or other 

catalyst systems that utilize an active/ 

intrusive reductant injection (e.g., active 

lean NOX catalysts utilizing diesel fuel 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3219 

26For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

injection), the OBD system would be 

required to monitor the active/intrusive 

reductant injection system for proper 

performance. The individual electronic 

components (e.g., actuators, valves, 

sensors, heaters, pumps) in the active/ 

intrusive reductant injection system 

must be monitored in accordance with 

the comprehensive component 

requirements in section II.D.4. 

i. Catalyst Conversion Efficiency 

Malfunctions 

We are proposing that the OBD 

system detect a catalyst malfunction 

when the catalyst conversion capability 

decreases to the point that would cause 

an engine’s NOX emissions to exceed 

any of the applicable emissions 

thresholds for ‘‘NOX Catalyst Systems’’

as shown in Table II.B–1. If no failure 

or deterioration of the catalyst NOX

conversion capability could result in an 

engine’s NOX emissions exceeding any 

of the applicable emissions thresholds, 

the OBD system would have to detect a 

malfunction when the catalyst has no 

detectable amount of NOX conversion 

capability. 

ii. Active/Intrusive Reductant Injection 

System Malfunctions 

Specific to SCR and other active/ 

intrusive reductant injection system 

performance, we are proposing that the 

OBD system detect a malfunction prior 

to any failure or deterioration of the 

system to regulate reductant delivery 

properly (e.g., urea injection, separate 

injector fuel injection, post injection of 

fuel, air assisted injection/mixing) that 

would cause an engine’s NOX emissions 

to exceed any of the applicable 

emissions thresholds for ‘‘NOX Catalyst 

Systems’’ as shown in Table II.B–1. As 

above, if no failure or deterioration of 

the reductant delivery system could 

result in an engine’s NOX emissions 

exceeding the applicable emissions 

thresholds, the OBD system would have 

to detect a malfunction when the system 

has reached its control limits such that 

it is no longer able to deliver the desired 

quantity of reductant. 

If the system uses a reductant other 

than the fuel used for the engine or uses 

a reservoir/tank for the reductant that is 

separate from the fuel tank used for the 

engine, the OBD system must detect a 

malfunction when there is no longer 

sufficient reductant available (e.g., the 

reductant tank is empty). If the system 

uses a reservoir/tank for the reductant 

that is separate from the fuel tank used 

for the engine, the OBD system must 

detect a malfunction when an improper 

reductant is used in the reductant 

reservoir/tank (e.g., the reductant tank is 

filled with something other than the 

proper reductant). 

iii. SCR and Lean NOX Catalyst 

Feedback Control System Malfunctions 

If the engine is equipped with 

feedback control of the reductant 

injection, we are proposing that the 

OBD system detect a malfunction when 

and if: 

• The system fails to begin feedback 

control within a manufacturer specified 

time interval; 

• A failure or deterioration causes 

open loop or default operation; or 

• Feedback control has used up all of 

the adjustment allowed by the 

manufacturer. 

c. SCR and Lean NOX Catalyst 

Monitoring Conditions 

Manufacturers would be required to 

define the monitoring conditions for 

catalyst conversion efficiency 

malfunctions such that the minimum 

performance ratio requirements 

discussed in section II.E would be met. 

For purposes of tracking and reporting 

as required in section II.E, all monitors 

used to detect catalyst conversion 

efficiency malfunctions must be tracked 

separately but reported as a single set of 

values as specified in section II.E.26 We 

are also proposing that the OBD system 

monitor continuously for active/ 

intrusive reductant injection system 

malfunctions. Manufacturers would be 

required to monitor continuously the 

active/intrusive reductant delivery 

system. 

d. SCR and Lean NOX Catalyst MIL 

Illumination and DTC Storage 

We are proposing the general MIL 

illumination and DTC storage 

requirements presented in section II.A.2 

with the exception of active/intrusive 

reductant injection related 

malfunctions. If the OBD system is 

capable of discerning that a system 

malfunction is being caused by an 

empty reductant tank, the manufacturer 

may delay illumination of the MIL if the 

vehicle is equipped with an alternative 

indicator for notifying the vehicle 

operator of the malfunction. The 

manufacturer would be required to 

demonstrate that: The alternative 

indicator is of sufficient illumination 

and location to be readily visible to the 

operator under all lighting conditions; 

and the alternative indicator provides 

equivalent assurance that a vehicle 

operator will be promptly notified; and, 

that corrective action would be 

undertaken. If the vehicle is not 

equipped with an alternative indicator 

and the MIL illuminates, the MIL may 

be immediately extinguished and the 

corresponding DTC erased once the 

OBD system has verified that the 

reductant tank has been properly 

refilled and the MIL has not been 

illuminated for any other type of 

malfunction. The Administrator may 

approve other strategies that provide 

equivalent assurance that a vehicle 

operator will be promptly notified and 

that corrective action will be 

undertaken. 

The monitoring method for the 

catalyst(s) would have to be capable of 

detecting all instances, except 

diagnostic self-clearing, when a catalyst 

DTC has been cleared but the catalyst 

has not been replaced (e.g., catalyst over 

temperature histogram approaches are 

not acceptable). 

7. NOX Adsorber System Monitoring 

a. Background 

NOX adsorbers, or lean NOX traps 

(LNT), work to control NOX emissions 

by storing NOX on the surface of the 

catalyst during the lean engine 

operation typical of diesel engines and 

then by undergoing subsequent brief 

rich regeneration events where the NOX

is released and reduced across a 

precious metal catalyst. 

NOX adsorber systems generally 

consist of a conventional three-way 

catalyst function (e.g., platinum) with 

NOX storage components (i.e., 

adsorbents) incorporated into the 

washcoat. Three-way catalysts convert 

NOX emissions as well as HC and CO 

emissions (hence the name three-way) 

by promoting oxidation of HC and CO 

to H2O and CO2 using the oxidation 

potential of the NOX pollutant and, in 

the process, reducing the NOX

emissions to nitrogen, N2. Said another 

way, three-way catalysts work with 

exhaust conditions where the net 

oxidizing and reducing chemistry of the 

exhaust is approximately equal, 

allowing the catalyst to promote 

complete oxidation/reduction reactions 

to the desired exhaust components of 

CO2, H2O, and N2. The oxidizing 

potential in the exhaust comes from 

NOX emissions and any feedgas oxygen 

(O2) not consumed during combustion. 

The reducing potential in the exhaust 


sroberts on PROD1PC70 with PROPOSALS
3220 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

27For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

comes from HC and CO emissions, 

which represent products of incomplete 

combustion. Operation of the engine to 

ensure that the oxidizing and reducing 

potential of the combustion and exhaust 

conditions is precisely balanced is 

referred to as stoichiometric engine 

operation. 

Because diesel engines run lean of 

stoichiometric operation, the NOX

emissions are stored, or absorbed—via 

chemical reaction with alkaline earth 

metals such as barium nitrate in the 

washcoat—and then released during 

rich operation for conversion to N2. This 

NOX release during rich operation is 

referred to as a regeneration event. The 

rich operating conditions required for 

NOX regeneration, which generally last 

for several seconds, are typically 

achieved using a combination of intake 

air throttling (to reduce the amount of 

intake air), exhaust gas recirculation, 

and post-combustion fuel injection. 

NOX adsorber systems have 

demonstrated NOX reduction 

efficiencies from 50 percent to in excess 

of 90 percent. This efficiency has been 

found to be highly dependent on the 

fuel sulfur content because NOX

adsorbers are extremely sensitive to 

sulfur. The NOX adsorption material has 

an even greater affinity for sulfur 

compounds than NOX. Thus, sulfur 

compounds can saturate the adsorber 

and limit the number of active sites for 

NOX adsorption, thereby lowering the 

NOX reduction efficiency. Accordingly, 

low sulfur fuel is required to achieve the 

greatest NOX reduction efficiencies. 

Although new adsorber washcoat 

materials are being developed with a 

higher resistance to sulfur poisoning 

and ultra-low sulfur fuel will be the 

norm by 2010, NOX adsorber systems 

will still need to purge the stored sulfur 

from the storage bed by a process 

referred to as desulfation. Because the 

desulfation process takes longer (e.g., 

several minutes) and requires more fuel 

and heat than the NOX regeneration 

step, permanent thermal degradation of 

the NOX adsorber and fuel economy 

penalties may result from desulfation 

events happening with excessive 

frequency. However, if desulfation is 

not done frequently enough, NOX

storage capacity would be compromised 

and fuel economy penalties would be 

incurred from excessive attempts at 

NOX regeneration. 

In order to achieve and maintain high 

NOX conversion efficiencies while 

limiting negative impacts on fuel 

economy and driveability, vehicles with 

NOX adsorber systems will require 

precise air/fuel control in the engine 

and in the exhaust stream. Diesel 

manufacturers are expected to utilize 

NOX sensors and temperature sensors to 

provide the most precise closed-loop 

control for the NOX adsorber system. If 

NOX sensors are not used to control the 

NOX adsorber system, manufacturers 

could use wide-range air-fuel (A/F) 

sensors located upstream and 

downstream of the adsorber as a 

substitute. However, A/F sensors cannot 

provide an instantaneous indication of 

tailpipe NOX levels, which would allow 

the control system to precisely 

determine when the adsorber system is 

filled to capacity and regeneration 

should be initiated. If A/F sensors are 

used in lieu of NOX sensors, an 

estimation of engine-out NOX emissions 

and their subsequent storage in the NOX

adsorber can be achieved indirectly 

through modeling. 

b. NOX Adsorber System Monitoring 

Requirements 

We are proposing that the OBD 

system monitor the NOX adsorber on 

engines so equipped for proper 

performance. For engines equipped with 

active/intrusive injection (e.g., inexhaust fuel and/or air injection) to 

achieve NOX regeneration, the OBD 

system would have to monitor the 

active/intrusive injection system for 

proper performance. The individual 

electronic components (e.g., injectors, 

valves, sensors) that are used in the 

active/intrusive injection system would 

have to be monitored in accordance 

with the comprehensive component 

requirements in section II.D.4. 

i. NOX Adsorber Capability 

Malfunctions 

We are proposing that the OBD 

system detect a NOX adsorber 

malfunction when its capability—i.e., 

its combined adsorption and conversion 

capability—decreases to the point that 

would cause an engine’s NOX emissions 

to exceed the applicable emissions 

thresholds for ‘‘NOX Catalyst Systems’’

as shown in Table II.B–1. If no failure 

or deterioration of the NOX adsorber 

capability could result in an engine’s 

NOX emissions exceeding the applicable 

emissions thresholds, the OBD system 

would have to detect a malfunction 

when the system has no detectable 

amount of NOX adsorber capability. 

ii. Active/Intrusive Reductant Injection 

System Malfunctions 

For NOX adsorber systems that use 

active/intrusive injection (e.g., incylinder post fuel injection, in-exhaust 

air-assisted fuel injection) to achieve 

desorption of the NOX adsorber, the 

OBD system would have to detect a 

malfunction if any failure or 

deterioration of the injection system’s 

ability to properly regulate injection 

causes the system to be unable to 

achieve desorption of the NOX adsorber. 

iii. NOX Adsorber Feedback Control 

System Malfunctions 

If the engine is equipped with 

feedback control of the reductant 

injection (e.g., feedback control of 

injection quantity, time), we are 

proposing that the OBD system detect a 

malfunction when and if: 

• The system fails to begin feedback 

control within a manufacturer specified 

time interval; 

• A failure or deterioration causes 

open loop or default operation; or 

• Feedback control has used up all of 

the adjustment allowed by the 

manufacturer. 

c. NOX Adsorber System Monitoring 

Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 

NOX adsorber capability malfunctions 

such that the minimum performance 

ratio requirements discussed in section 

II.E would be met. For purposes of 

tracking and reporting as required in 

section II.E, all monitors used to detect 

NOX adsorber capability malfunctions 

must be tracked separately but reported 

as a single set of values as specified in 

section II.E.27 We are also proposing 

that the OBD system monitor 

continuously for active/intrusive 

reductant injection and feedback control 

system malfunctions. 

d. NOX Adsorber System MIL 

Illumination and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage discussed in section II.A.2. 

8. Diesel Particulate Filter (DPF) System 

Monitoring 

a. Background 

Diesel particulate filters control diesel 

PM by capturing the soot (solid carbon) 

portion of PM in a filter media, typically 

a ceramic wall flow substrate, and then 

by oxidizing (burning) it in the oxygenrich atmosphere of diesel exhaust.28 In 

aggregate over a driving cycle, the PM 

must be burned at a rate equal to or 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3221 

28See ‘‘Regulatory Impact Analysis: Heavy-Duty 

Engine and Vehicle Standards and Highway Diesel 

Fuel Sulfur Control Requirements;’’ EPA420–R–00–

026; December 2000 at Chapter III for a more 

complete description of DPFs. 

29Salvat, O., Marez, P., and Belot, G., ‘‘Passenger 

Car Serial Application of a Particulate Filter System 

on a Common Rail Direct Injection Diesel Engine,’’

SAE Paper 2000–01–0473 which may be obtained 

from Society of Automotive Engineers International, 

400 Commonwealth Dr., Warrendale, PA, 15096–

0001. 

30Note that these requirements would also apply 

to a catalyzed diesel particulate filter (CDPF). We 

use the more common term DPF throughout this 

discussion. 

greater than its accumulation rate, or the 

DPF will clog. Given low sulfur diesel 

fuel (diesel fuel with a sulfur content of 

15 ppm or lower), highly active catalytic 

metals (e.g., platinum) can be used to 

promote soot oxidation. This method of 

PM filter regeneration, called passive 

regeneration, is the primary means of 

soot oxidation that we project industry 

will use in 2007/2010. 

The DPF technology has proven itself 

in tens of thousands of retrofit 

applications where low sulfur diesel 

fuel is already available. More than a 

million light-duty passenger cars in 

Europe now have diesel particulate 

filters. DPFs are considered the most 

effective control technology for the 

reduction of particulate emissions and 

can typically achieve PM reductions in 

excess of 90 percent. 

In order to maintain the performance 

of the DPF and the engine, the trapped 

PM must be periodically removed before 

too much particulate is accumulated 

and exhaust backpressure reaches 

unacceptable levels. The process of 

periodically removing accumulated PM 

from the DPF is known as 

‘‘regeneration’’ and is very important for 

maintaining low PM emission levels. 

DPF regeneration can be passive (i.e., 

occur continuously during regular 

operation of the filter), active (i.e., occur 

on a controlled, periodic basis after a 

predetermined quantity of particulates 

have been accumulated), or a 

combination of the two. With passive 

regeneration, the oxidizing catalyst 

material on the DPF substrate serves to 

lower the temperature for oxidizing PM. 

This allows the DPF to continuously 

oxidize trapped PM material during 

normal driving. In contrast, active 

systems utilize an external heat 

source—such as an electric heater or 

fuel burner—to facilitate DPF 

regeneration. We are projecting that 

virtually all DPF systems will have 

some sort of active regeneration 

mechanism as a backup mechanism 

should operating conditions not be 

conducive for passive regeneration. 

One of the key considerations for a 

DPF regeneration control system is the 

amount of soot quantity that is stored in 

the DPF (often called soot loading). If 

too much soot is stored when 

regeneration is activated, the soot can 

burn uncontrollably and DPF substrate 

could be damaged via melting or 

cracking. Conversely, activating 

regeneration when there is too little 

trapped soot will not ensure good 

combustion propagation which would 

effectively waste the energy (fuel) used 

to initiate the regeneration. Another 

important consideration in the control 

system design is the fuel economy 

penalty involved with DPF regeneration. 

Prolonged operation with high 

backpressures in the exhaust and 

regenerations occurring too frequently 

are both detrimental to fuel economy 

and DPF durability. Therefore, DPF 

system designers will need to carefully 

balance the regeneration frequency with 

various conflicting factors. To optimize 

the trap regeneration for these design 

factors, the DPF regeneration control 

system is projected to incorporate both 

pressure sensors and temperature 

sensors to model soot loading and other 

phenomena.29 Through the information 

provided by these sensors, designers can 

optimize the DPF for high effectiveness 

and maximum durability while 

minimizing fuel economy and 

performance penalties. 

b. DPF System Monitoring 

Requirements 

We are proposing that the OBD 

system monitor the DPF on engines soequipped for proper performance.30 For 

engines equipped with active 

regeneration systems that utilize an 

active/intrusive injection (e.g., inexhaust fuel injection, in-exhaust fuel/ 

air burner), the OBD system would have 

to monitor the active/intrusive injection 

system for proper performance. The 

individual electronic components (e.g., 

injectors, valves, sensors) that are used 

in the active/intrusive injection system 

must be monitored in accordance with 

the comprehensive component 

requirements in section II.D.4. 

i. PM Filtering Performance 

We are proposing that the OBD 

system detect a malfunction prior to a 

decrease in the filtering capability of the 

DPF (e.g., cracking, melting, etc.) that 

would cause an engine’s PM emissions 

to exceed the applicable emissions 

thresholds for ‘‘DPF Systems’’ as shown 

in Table II.B–1. If no failure or 

deterioration of the PM filtering 

performance could result in an engine’s 

PM emissions exceeding the applicable 

emissions thresholds, the OBD system 

would have to detect a malfunction 

when no detectable amount of PM 

filtering occurs. 

ii. DPF Regeneration Frequency 

Malfunctions—Too Frequent 

We are proposing that the OBD 

system detect a malfunction when the 

DPF regeneration frequency increases 

from—i.e., occurs more often than—the 

manufacturer’s specified regeneration 

frequency to a level such that it would 

cause an engine’s NMHC emissions to 

exceed the applicable emissions 

threshold for ‘‘DPF Systems’’ as shown 

in Table II.B–1. If no such regeneration 

frequency exists that could cause NMHC 

emissions to exceed the applicable 

emission threshold, the OBD system 

would have to detect a malfunction 

when the PM filter regeneration 

frequency exceeds the manufacturer’s 

specified design limits for allowable 

regeneration frequency. 

iii. DPF Incomplete Regeneration 

Malfunctions 

We are proposing that the OBD 

system detect a regeneration 

malfunction when the DPF does not 

properly regenerate under 

manufacturer-defined conditions where 

regeneration is designed to occur. 

iv. DPF NMHC Conversion Efficiency 

Malfunctions 

We are proposing that, for any DPF 

that serves to convert NMHC emissions, 

the OBD system must monitor the 

NMHC converting function of the DPF 

and detect a malfunction when the 

NMHC conversion capability decreases 

to the point that NMHC emissions 

exceed the NMHC threshold for ‘‘DPF 

Systems’’ as shown in Table II.B–1. If no 

failure or deterioration of the NMHC 

conversion capability could result in 

NMHC emissions exceeding the 

applicable NMHC threshold, the OBD 

system would have to detect a 

malfunction when the system has no 

detectable amount of NMHC conversion 

capability. 

v. DPF Missing Substrate Malfunctions 

We are proposing that the OBD 

system detect a malfunction if either the 

DPF substrate is completely destroyed, 

removed, or missing, or if the DPF 

assembly has been replaced with a 

muffler or straight pipe. 

vi. DPF Active/Intrusive Injection 

System Malfunctions 

We are proposing that, for systems 

that utilize active/intrusive injection 

(e.g., in-cylinder post fuel injection, inexhaust air-assisted fuel injection) to 

achieve DPF regeneration, the OBD 

system detect a malfunction if any 


sroberts on PROD1PC70 with PROPOSALS
3222 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

31For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

failure or deterioration of the injection 

system’s ability to properly regulate 

injection causes the system to be unable 

to achieve DPF regeneration. 

vii. DPF Regeneration Feedback Control 

System Malfunctions 

We are proposing that, if the engine 

is equipped with feedback control of the 

DPF regeneration (e.g., feedback control 

of oxidation catalyst inlet temperature, 

PM filter inlet or outlet temperature, incylinder or in-exhaust fuel injection), 

the OBD system must detect a 

malfunction when and if: 

• The system fails to begin feedback 

control within a manufacturer specified 

time interval; 

• A failure or deterioration causes 

open loop or default operation; or 

• Feedback control has used up all of 

the adjustment allowed by the 

manufacturer. 

c. DPF System Monitoring Conditions 

We are proposing that manufacturers 

define the monitoring conditions for all 

DPF related malfunctions such that the 

minimum performance ratio 

requirements discussed in section II.E 

would be met with the exception that 

monitoring must occur every time the 

monitoring conditions are met during 

the driving cycle rather than once per 

driving cycle as required for most 

monitors. For purposes of tracking and 

reporting as required in section II.E, all 

monitors used to detect all DPF related 

malfunctions would have to be tracked 

separately but reported as a single set of 

values as specified in section II.E.31

d. DPF System MIL Illumination and 

DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

9. Exhaust Gas Sensor Monitoring 

a. Background 

Exhaust gas sensors (e.g., oxygen 

sensors, wide-range air-fuel (A/F) 

sensors, NOX sensors) are important to 

the emission control system of vehicles. 

These sensors are used for enhancing 

the performance of several emission 

control technologies (e.g., catalysts, EGR 

systems). We expect that both oxygen 

sensors and wide range A/F sensors may 

be used by heavy-duty manufacturers to 

optimize their emission control 

technologies. We would expect that, in 

addition to their emissions control 

functions, these sensors will also be 

used to satisfy many of the proposed 

HDOBD monitoring requirements, such 

as fuel system monitoring, catalyst 

monitoring, and EGR system 

monitoring. NOX sensors may also be 

used for optimization of several diesel 

emission control technologies, such as 

NOX adsorbers and selective catalytic 

reduction (SCR) systems. Since an 

exhaust gas sensor can be a critical 

component of a vehicle’s fuel and 

emission control system, the proper 

performance of this component needs to 

be assured to maintain low emissions. 

The reliance on these sensors for 

emissions control and OBD monitoring 

makes it important that any malfunction 

that adversely affects the performance of 

any of these sensors be detected by the 

OBD system. 

b. Exhaust Gas Sensor Monitoring 

Requirements 

We are proposing that the OBD 

system monitor all exhaust gas sensors 

(e.g., oxygen, air-fuel ratio, NOX) used 

either for emission control system 

feedback (e.g., EGR control/feedback, 

SCR control/feedback, NOX adsorber 

control/feedback), or as a monitoring 

device, for proper output signal, 

activity, response rate, and any other 

parameter that can affect emissions. For 

engines equipped with heated exhaust 

gas sensors, the OBD system would have 

to monitor the heater for proper 

performance. 

i. Air/Fuel Ratio Sensor Malfunctions 

For all air/fuel ratio sensors, we are 

proposing the following: 

• Circuit malfunctions: The OBD 

system must detect malfunctions of the 

sensor caused by either a lack of circuit 

continuity or out-of-range values. 

• Feedback malfunctions: The OBD 

system must detect a malfunction of the 

sensor when a sensor failure or 

deterioration causes an emissions 

control system—e.g., the EGR, SCR, or 

NOX adsorber systems—to stop using 

that sensor as a feedback input (e.g., 

causes default or open-loop operation). 

• Monitoring capability: To the extent 

feasible, the OBD system must detect a 

malfunction of the sensor when the 

sensor output voltage, resistance, 

impedance, current, amplitude, activity, 

offset, or other characteristics are no 

longer sufficient for use as an OBD 

system monitoring device (e.g., for 

catalyst, EGR, SCR, or NOX adsorber 

monitoring). 

Specifically for sensors located 

upstream of an aftertreatment device, 

we are proposing the following: 

• Sensor performance malfunctions: 

The OBD system must detect a 

malfunction prior to any failure or 

deterioration of the sensor voltage, 

resistance, impedance, current, response 

rate, amplitude, offset, or other 

characteristic(s) that would cause an 

engine’s emissions to exceed the 

applicable emissions thresholds for 

‘‘Other Monitors’’ as shown in Table 

II.B–1. 

Specifically for sensors located 

downstream of an aftertreatment device, 

we are proposing the following: 

• Sensor performance malfunctions: 

The OBD system must detect a 

malfunction prior to any failure or 

deterioration of the sensor voltage, 

resistance, impedance, current, response 

rate, amplitude, offset, or other 

characteristic(s) that would cause an 

engine’s emissions to exceed the 

applicable emissions thresholds for 

‘‘Air-fuel ratio sensors downstream of 

aftertreatment devices’’ as shown in 

Table II.B–1. 

ii. NOX Sensor Malfunctions 

For NOX sensors, we are proposing 

the following: 

• Sensor performance malfunctions: 

The OBD system must detect a 

malfunction prior to any failure or 

deterioration of the sensor voltage, 

resistance, impedance, current, response 

rate, amplitude, offset, or other 

characteristic(s) that would cause an 

engine’s emissions to exceed the 

applicable emissions thresholds for 

‘‘NOX sensors’’ as shown in Table II.B–

1. 

• Circuit malfunctions: The OBD 

system must detect malfunctions of the 

sensor caused by either a lack of circuit 

continuity or out-of-range values. 

• Feedback malfunctions: The OBD 

system shall detect a malfunction of the 

sensor when a sensor failure or 

deterioration causes an emission 

control—e.g., the EGR, SCR, or NOX

adsorber systems—to stop using that 

sensor as a feedback input (e.g., causes 

default or open-loop operation). 

• Monitoring capability: To the extent 

feasible, the OBD system must detect a 

malfunction of the sensor when the 

sensor output voltage, resistance, 

impedance, current, amplitude, activity, 

offset, or other characteristics are no 

longer sufficient for use as an OBD 

system monitoring device (e.g., for 

catalyst, EGR, SCR, or NOX adsorber 

monitoring). 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3223 

32For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

33This is true according to our certification 

database for both he 2004 and 2005 model years. 

Other manufacturers certify engines that use the 

Otto cycle, but those engines do not burn gasoline 

and instead burn various alternative fuels. 

34 ‘‘EMA Comments on Proposed HDOBD 

Requirements for HDGE,’’ bullet items 3 and 4; 

April 28, 2005, Docket ID# EPA–HQ–OAR–2005–

0047–0003. 

iii. Other Exhaust Gas Sensor 

Malfunctions 

For other exhaust gas sensors, we are 

proposing that the manufacturer submit 

a monitoring plan to the Administrator 

for approval. The Administrator would 

approve the request upon determining 

that the manufacturer has submitted 

data and an engineering evaluation that 

demonstrate that the monitoring plan is 

as reliable and effective as the 

monitoring plan required for air/fuel 

ratio sensors and NOX sensors. 

iv. Exhaust Gas Sensor Heater 

Malfunctions 

We are proposing that the OBD 

system detect a malfunction of the 

heater performance when the current or 

voltage drop in the heater circuit is no 

longer within the manufacturer’s 

specified limits for normal operation 

(i.e., within the criteria required to be 

met by the component vendor for heater 

circuit performance at high mileage). 

The manufacturer may use other 

malfunction criteria for heater 

performance malfunctions. To do so, the 

manufacturer would be required to 

submit data and/or engineering analyses 

that demonstrate that the monitoring 

reliability and timeliness would be 

equivalent to the criteria stated here. 

Further, the OBD system would be 

required to detect malfunctions of the 

heater circuit including open or short 

circuits that conflict with the 

commanded state of the heater (e.g., 

shorted to 12 Volts when commanded to 

0 Volts (ground)). 

c. Exhaust Gas Sensor Monitoring 

Conditions 

For exhaust gas sensor performance 

malfunctions, we are proposing that 

manufacturers define the monitoring 

conditions such that the minimum 

performance ratio requirements 

discussed in section II.E would be met. 

For purposes of tracking and reporting 

as required in section II.E, all monitors 

used to detect sensor performance 

malfunctions would have to be tracked 

separately but reported as a single set of 

values as specified in section II.E.32

For exhaust gas sensor monitoring 

capability malfunctions, manufacturers 

would have to define the monitoring 

conditions such that the minimum 

performance ratio requirements 

discussed in section II.E would be met 

with the exception that monitoring must 

occur every time the monitoring 

conditions are met during the driving 

cycle rather than once per driving cycle 

as required for most monitors. 

For exhaust gas sensor circuit 

malfunctions and feedback 

malfunctions, monitoring must be 

conducted continuously. 

The manufacturer may disable 

continuous exhaust gas sensor 

monitoring when an exhaust gas sensor 

malfunction cannot be distinguished 

from other effects (e.g., disable ‘‘out-ofrange low’’ monitoring during fuel cut 

conditions). To do so, the manufacturer 

would be required to submit test data 

and/or engineering analyses that 

demonstrate that a properly functioning 

sensor cannot be distinguished from a 

malfunctioning sensor and that the 

disablement interval is limited only to 

that necessary for avoiding a false 

detection. 

For exhaust gas sensor heater 

malfunctions, manufacturers must 

define monitoring conditions such that 

the minimum performance ratio 

requirements discussed in section II.E 

would be met. Monitoring for sensor 

heater circuit malfunctions must be 

conducted continuously. 

d. Exhaust Gas Sensor MIL Illumination 

and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

C. Monitoring Requirements and 

Timelines for Gasoline/Spark-Ignition 

Engines 

Table II.C–1 summarizes the proposed 

gasoline fueled spark ignition emissions 

thresholds at which point a component 

or system has failed to the point of 

requiring an illuminated MIL and a 

stored DTC. Table II.C–2 summarizes 

the proposed implementation schedule 

for these thresholds—i.e., the proposed 

certification requirements and in-use 

liabilities. More detail regarding the 

specific monitoring requirements, 

implementation schedules, and 

liabilities can be found in the sections 

that follow. 

TABLE II.C–1.—PROPOSED EMISSIONS THRESHOLDS FOR GASOLINE FUELED SI ENGINES OVER 14,000 POUNDS

Component/Monitor MY NMHC CO NOX

Catalytic converter system ....................................................................................................... 2010+ ...... 1.75x ........ ............. 1.75x 

‘‘Other monitors’’ with emissions thresholds (see section II.C) ............................................... 2010+ ...... 1.5x .......... 1.5x .......... 1.5x 

Evaporative emissions control system .................................................................................... 2010+ ...... 0.150 inch 

leak.

Notes: MY=Model Year; 1.75x means a multiple of 1.75 times the applicable emissions standard; not all proposed monitors have emissions

thresholds but instead rely on functionality and rationality checks as described in section II.D.4. The evaporative emissions control system threshold is not, technically, an emissions threshold but rather a leak size that must be detected; nonetheless, for ease we refer to this as the 

threshold. 

There are exceptions to the emissions 

thresholds shown in Table II.C–1 

whereby a manufacturer can 

demonstrate that emissions do not 

exceed the threshold even when the 

component or system is non-functional 

at which point a functional check would 

be allowed. 

The monitoring requirements 

described below for gasoline engines 

mirror those that are already in place for 

gasoline engines used in vehicles under 

14,000 pounds. The HD gasoline 

industry—General Motors and Ford, as 

of today 33—have told us that their 

preference is to use essentially the same 

OBD system on their engines used in 

both under and over 14,000 pound 

vehicles.34 In general, we agree with the 


sroberts on PROD1PC70 with PROPOSALS
3224 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

35 ‘‘Similar conditions,’’ as used in conjunction 

with misfire and fuel system monitoring, means 

engine conditions having an engine speed within 

375 rpm, load conditions within 20 percent, and the 

same warm up status (i.e., cold or hot) as existing 

during the applicable previous problem detection. 

The Administrator may approve other definitions of 

similar conditions based on comparable timeliness 

and reliability in detecting similar engine operation. 

HD gasoline industry on this issue for 

three reasons: 

• The engines used in vehicles above 

and below 14,000 pounds are the same 

which makes it easy for industry to use 

the same OBD monitors. 

• The existing OBD requirements for 

engines used in vehicles below 14,000 

pounds have proven effective; and, 

• The industry members have more 

than 10 years experience complying 

with the OBD requirements for engines 

used in vehicles below 14,000 pounds. 

As a result, we are proposing 

requirements that should allow for OBD 

system consistency in vehicles under 

and over 14,000 pounds rather than 

proposing requirements that mirror the 

proposed HD diesel requirements 

discussed in section II.B. Nonetheless, 

the requirements proposed below are for 

engine-based OBD monitors only rather 

than monitors for the entire powertrain 

(which would include the 

transmission). We are doing this for the 

same reasons as done for the proposed 

diesel OBD requirements in that 

certification of gasoline applications 

over 14,000 pounds, like their diesel 

counterparts, is done on an engine basis 

and not a vehicle basis. 

1. Fuel System Monitoring 

a. Background 

As with diesel engines, the fuel 

system of a gasoline engine is an 

essential component of the engine’s 

emissions control system. Proper 

delivery of fuel is essential to maintain 

stoichiometric operation and minimize 

engine out emissions. Proper 

stoichiometric control is also critical to 

maximize catalyst conversion efficiency 

and reach low tailpipe emission levels. 

As such, thorough monitoring of the 

fuel system is an essential element in an 

OBD system. 

For gasoline engines, the fuel system 

generally includes a fuel pump, fuel 

pressure regulator, fuel rail, individual 

injectors for each cylinder, and a closedloop feedback control system using 

oxygen sensor(s) or air-fuel ratio (A/F) 

sensor(s). The feedback sensors are 

located in the exhaust system and are 

used to regulate the fuel injection 

quantity to achieve a stoichiometric 

mixture in the exhaust. If the sensor 

indicates a rich (or lean) mixture, the 

system reduces (or increases) the 

amount of fuel being injected by 

applying a short term correction to the 

fuel injection quantity calculated for the 

current engine operating condition. To 

account for aging or deterioration in the 

system such as reduced injector flow, 

more permanent long term corrections 

are also learned and applied to the fuel 

injection quantity for more precise 

fueling. 

For gasoline engines, fuel system 

monitoring has been implemented on 

light-duty vehicles since the 1996 model 

year and on heavy-duty vehicles less 

than 14,000 pounds and the engines 

used in those vehicles since the 2004/ 

2005 model year. For heavy-duty 

gasoline engines used in vehicles over 

14,000 pounds (many of which are the 

same engine as is used in vehicles less 

than 14,000 pounds), the system 

components and control strategies are 

identical to those used in the light-duty 

and under 14,000 pound categories. As 

such, the monitoring requirements 

established for engines used in vehicles 

less than 14,000 pounds can be directly 

applied to engines used in vehicles over 

14,000 pounds. 

b. Fuel System Monitoring 

Requirements 

We are proposing that the fuel system 

be continuously monitored for its ability 

to maintain engine emissions below the 

applicable emissions thresholds. 

Manufacturers would also be required to 

verify that the fuel system is in closedloop operation—e.g., that it is using the 

oxygen sensor for feedback control. The 

individual components of the fuel 

system would also be covered by 

separate monitoring requirements for 

oxygen sensors, misfire (for the fuel 

injectors), and comprehensive 

components (in systems such as those 

with electronically-controlled variable 

speed fuel pumps or electronicallycontrolled fuel pressure regulators). 

i. Fuel System Performance 

We are proposing that the OBD 

system be required to detect a 

malfunction of the fuel delivery system 

(including feedback control based on a 

secondary oxygen sensor) when the fuel 

delivery system is unable to maintain 

the engine’s emissions at or below the 

applicable emissions thresholds for 

‘‘Other monitors’’ as shown in Table 

II.C–1. 

ii. Fuel System Feedback Control 

If the engine is equipped with 

adaptive feedback control, we are 

proposing that the OBD system be 

required to detect a malfunction when 

the adaptive feedback control has used 

up all of the adjustment allowed by the 

manufacturer. However, if the engine is 

equipped with feedback control that is 

based on a secondary oxygen (or 

equivalent) sensor, the OBD system 

would not be required to detect a 

malfunction of the fuel system solely 

when the feedback control based on that 

secondary oxygen sensor has used up all 

of the adjustment allowed by the 

manufacturer. For such systems, the 

OBD system would be required to meet 

the fuel system performance 

requirements presented above. 

Additionally, we are proposing that 

the OBD system be required to detect a 

malfunction whenever the fuel control 

system fails to enter closed loop 

operation within a time interval after 

engine startup. The manufacturer would 

be required to submit data and/or 

engineering analyses that support their 

chosen time interval. 

Lastly, manufacturers would be 

allowed to adjust the malfunction 

criteria and/or monitoring conditions to 

compensate for changes in altitude, 

temporary introduction of large amounts 

of purge vapor, or for other similar 

identifiable operating conditions when 

they occur. 

c. Fuel System Monitoring Conditions 

We are proposing that the OBD 

system monitor continuously for 

malfunctions of the fuel system. 

d. Fuel System MIL Illumination and 

DTC Storage 

We are proposing that a pending DTC 

be stored immediately upon detecting a 

malfunction according to the fuel 

system monitoring requirements 

presented in section II.C.1.b (i.e., rather 

than waiting until the end of the drive 

cycle to store the pending DTC). Once 

a pending DTC is stored, the OBD 

system would be required to illuminate 

the MIL immediately and store a MILon DTC if a malfunction is again 

detected during either of the following 

two events: (1) The drive cycle 

immediately following the drive cycle 

during which the pending DTC was 

stored, regardless of the conditions 

encountered during the drive cycle; or, 

(2) on the next drive cycle during which 

similar conditions are encountered to 

those that occurred when the pending 

DTC was stored.35

We are also proposing that the 

pending DTC may be erased at the end 

of the next drive cycle in which similar 

conditions have been encountered 

without detecting a malfunction 

according to the fuel system monitoring 

requirements. The pending DTC may 

also be erased if similar conditions are 

not encountered during the 80 drive 

cycles immediately after the initial 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3225 

36 ‘‘Redline engine speed’’ is actually defined by 

the manufacturer as either the recommended 

maximum engine speed as normally displayed on 

instrument panel tachometers or the engine speed 

at which fuel shutoff occurs. 

detection of a malfunction for which the 

pending DTC was set. 

We are proposing some specific 

requirements with respect to storage of 

freeze frame information associated 

with fuel system malfunctions. First, the 

OBD system must store and erase freeze 

frame information either in conjunction 

with storing and erasing a pending DTC 

or in conjunction with storing and 

erasing a MIL-on DTC. Second, if freeze 

frame information is already stored for 

a malfunction other than an engine 

misfire or fuel system malfunction at the 

time that a fuel system DTC is stored, 

the preexisting freeze frame information 

must be replaced with freeze frame 

information regarding the fuel system 

malfunction. 

The OBD system would also be 

required to store the engine speed, load, 

and warm up status present when the 

first fuel system malfunction is detected 

that resulted in the storage of the 

pending DTC. The MIL may be 

extinguished after three sequential drive 

cycles in which similar conditions have 

been encountered without detecting a 

malfunction of the fuel system. 

2. Engine Misfire Monitoring 

a. Background 

Detecting engine misfire on a gasoline 

spark ignition engine is important for 

two reasons: Its impact on the emissions 

performance of the engine and its 

impact on the durability of the catalytic 

converter. Engine misfire has two 

primary causes: Lack of spark and poor 

fuel metering (delivery). When misfire 

occurs, unburned fuel and air are 

pumped out of the engine and into the 

exhaust system and into the catalyst. 

This can increase dramatically the 

operating temperature of the catalyst 

where temperatures can soar to above 

900 degrees Celsius. This problem is 

usually most severe under high load/ 

high speed engine operating conditions 

and can cause irreversible damage to the 

catalyst. Though the durability of 

catalysts has been improving, most are 

unable to sustain continuous operation 

at such high temperatures. Engine 

misfire also contributes to poor 

emissions performance, especially when 

the misfire occurs during engine warmup and the catalyst itself has not yet 

reached its operating temperature. 

b. Engine Misfire Monitoring 

Requirements 

We are proposing that the OBD 

system detect both engine misfire 

capable of causing catalyst damage and 

engine misfire capable of causing poor 

emissions performance. Additionally, 

the OBD system would be required to 

identify the specific cylinder in which 

misfire is occurring and/or if there 

exists a condition in which more than 

one cylinder is misfiring; when 

identifying a multiple cylinder misfire 

condition, the OBD system would not be 

required to identify individually each of 

the misfiring cylinders. We are 

proposing an exception to this whereby 

if more than 90 percent of the detected 

misfires are occurring in a single 

cylinder, the manufacturer may elect to 

consider it a single cylinder misfire 

condition rather than a multiple 

cylinder misfire condition. However, we 

are proposing that, if two or more 

cylinders individually have more than 

10 percent of the total number of 

detected misfires, the manufacturer 

must consider it a multiple cylinder 

misfire condition. 

i. Engine Misfire Capable of Causing 

Catalyst Damage 

We are proposing that the 

manufacturer be required to detect the 

percentage of misfire—evaluated in 200 

revolution increments—for each engine 

speed and load condition that would 

result in a temperature capable of 

damaging the catalyst. For every engine 

speed and load condition at which this 

percentage is determined to be less than 

five percent, the manufacturer may set 

the malfunction criteria at five percent. 

The manufacturer may use a longer 

interval than a 200 revolution increment 

but only for determining, on a given 

drive cycle, the first misfire exceedance; 

upon detecting the first such 

exceedance, the 200 revolution 

increment must be used. The 

manufacturer may use a longer initial 

interval by submitting data and/or 

engineering analyses that demonstrate 

that catalyst damage would not occur 

due to unacceptably high catalyst 

temperatures before the interval has 

elapsed. 

Further, we are proposing that, for the 

purpose of establishing the temperature 

at which catalyst damage would occur, 

manufacturers not be allowed to define 

the catalyst damaging temperature at a 

temperature more severe than what the 

catalyst system could be operated at for 

10 consecutive hours and still meet the 

applicable standards. 

ii. Engine Misfire Causing Poor 

Emissions Performance 

We are proposing that the 

manufacturer be required to detect the 

percentage of misfire—evaluated in 

1000 revolution increments—that would 

cause emissions to exceed the emissions 

thresholds for ‘‘Other monitors’’ as 

shown in Table II.C–1 if that percentage 

of misfire were present from the 

beginning of the test procedure. To 

establish this percentage of misfire, the 

manufacturer would be required to use 

misfire events occurring at equally 

spaced, complete engine cycle intervals, 

across randomly selected cylinders 

throughout each 1000 revolution 

increment. If this percentage of misfire 

is determined to be lower than one 

percent, the manufacturer may set the 

malfunction criteria at one percent. The 

manufacturer may use a different 

interval than a 1000 revolution 

increment. To do so, the manufacturer 

would be required to submit data and/ 

or engineering analyses demonstrating 

that the strategy would be equally 

effective and timely at detecting misfire. 

A malfunction must be detected if the 

percentage of misfire is exceeded 

regardless of the pattern of misfire 

events (e.g., random, equally spaced, 

continuous). 

c. Engine Misfire Monitoring Conditions 

We are proposing that the OBD 

system monitor continuously to detect 

engine misfire under all of the following 

conditions: 

• From no later than the end of the 

second crankshaft revolution after 

engine start; 

• During the rise time and settling 

time as the engine reaches the desired 

idle speed immediately following 

engine start-up (i.e., ‘‘flare-up’’ and 

‘‘flare-down’’); and, 

• Under all positive torque conditions 

except within the engine operating 

region bound by lines connecting the 

following three points: An engine speed 

of 3000 rpm with the engine load at the 

positive torque line (i.e., engine load 

with the transmission in neutral), an 

engine speed at the redline rpm with the 

engine load at the positive torque line, 

and an engine speed at the redline rpm 

with an engine load at which intake 

manifold vacuum is four inches of 

mercury lower than that at the positive 

torque line (this would be an engine 

load somewhat greater than the engine 

load at the positive torque line).36

If a monitoring system cannot detect 

all misfire patterns under the required 

engine speed and load conditions, the 

manufacturer may request approval of 

the system nonetheless. In evaluating 

the manufacturer’s request, the 

Administrator would consider: 

• The magnitude of the region(s) in 

which misfire detection is limited; 

• The degree to which misfire 

detection is limited in those region(s) 


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3226 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

(i.e., the probability of detection of 

misfire events); 

• The frequency with which said 

region(s) are expected to be encountered 

in-use; 

• The type of misfire patterns for 

which misfire detection is troublesome; 

and, 

• Demonstration that the monitoring 

technology being used is not inherently 

incapable of detecting misfire under the 

required conditions (i.e., compliance 

can be achieved by other manufacturers 

on their engines). 

The Administrator’s evaluation would 

be based on the following misfire 

patterns: 

• Equally spaced misfire occurring on 

randomly selected cylinders; 

• Single cylinder continuous misfire; 

and, 

• Paired cylinder (cylinders firing at 

the same crank angle) continuous 

misfire. 

Further, a manufacturer may use a 

monitoring system that has reduced 

misfire detection capability during the 

portion of the first 1000 revolutions 

after engine start during which a cold 

start emission reduction strategy is 

active that reduces engine torque (e.g., 

spark retard strategies). To do so, the 

manufacturer would be required to 

submit data and/or engineering analyses 

demonstrating that the probability of 

detection is greater than or equal to 75 

percent during the worst case condition 

(i.e., lowest generated torque) for a 

vehicle operated continuously at idle 

(park/neutral idle) on a cold start 

between 50 and 86 degrees Fahrenheit 

and that the technology cannot reliably 

detect a higher percentage of the misfire 

events during these conditions. 

A manufacturer may disable misfire 

monitoring or use an alternative 

malfunction criterion when misfire 

cannot be distinguished from other 

effects. To do so, the manufacturer 

would be required to submit data and/ 

or engineering analyses demonstrating 

that the disablement interval or period 

of use of an alternative malfunction 

criterion is limited only to that 

necessary for avoiding a false detection 

(errors of commission). Such 

disablements would be allowed for 

conditions involving: 

• Rough road; 

• Fuel cut; 

• Gear changes for manual 

transmission vehicles; 

• Traction control or other vehicle 

stability control activation such as antilock braking or other engine torque 

modifications to enhance vehicle 

stability; 

• Off-board control or intrusive 

activation of vehicle components or 

diagnostics during service or assembly 

plant testing; 

• Portions of intrusive evaporative 

system or EGR diagnostics that can 

significantly affect engine stability (i.e., 

while the purge valve is open during the 

vacuum pull-down of a evaporative 

system leak check but not while the 

purge valve is closed and the 

evaporative system is sealed or while an 

EGR diagnostic causes the EGR valve to 

be intrusively cycled on and off during 

positive torque conditions); or, 

• Engine speed, load, or torque 

transients due to throttle movements 

more rapid than occurs over the FTP 

cycle for the worst case engine within 

each engine family. 

Additionally, the manufacturer may 

disable misfire monitoring when the 

fuel level is 15 percent or less of the 

nominal capacity of the fuel tank, when 

PTO units are active, or while engine 

coolant temperature is below 20 degrees 

Fahrenheit. For the latter case, the 

manufacturer may continue the misfire 

monitoring disablement until engine 

coolant temperature exceeds 70 degrees 

Fahrenheit provided the manufacturer 

can demonstrate that it is necessary. 

In general, the Administrator would 

not approve misfire monitoring 

disablement for conditions involving 

normal air conditioning compressor 

cycling from on-to-off or off-to-on, 

automatic transmission gear shifts 

(except for shifts occurring during wide 

open throttle operation), transitions 

from idle to off-idle, normal engine 

speed or load changes that occur during 

the engine speed rise time and settling 

time (i.e., ‘‘flare-up’’ and ‘‘flare-down’’) 

immediately after engine starting 

without any vehicle operator-induced 

actions (e.g., throttle stabs), or excess 

acceleration (except for acceleration 

rates that exceed the maximum 

acceleration rate obtainable at wide 

open throttle while the vehicle is in gear 

due to abnormal conditions such as 

slipping of a clutch). 

Further, the manufacturer may 

request approval of other misfire 

monitoring disablements or use of 

alternative malfunction criteria for any 

other condition. The Administrator 

would consider such requests on a case 

by case basis and will consider whether 

or not the manufacturer has 

demonstrated that the request is based 

on an unusual or unforeseen 

circumstance and that it is applying the 

best available computer and monitoring 

technology. 

For engines with more than eight 

cylinders that cannot meet the 

continuous monitoring and detection 

requirements listed above, a 

manufacturer may use alternative 

misfire monitoring conditions. Any 

manufacturer wishing to use alternative 

misfire monitoring conditions must 

submit data and/or an engineering 

evaluation that demonstrate that misfire 

detection throughout the required 

operating region cannot be achieved 

when using proven monitoring 

technology (i.e., a technology that 

provides for compliance with these 

requirements on other engines) and 

provided misfire is detected to the 

fullest extent permitted by the 

technology. However, the misfire 

detection system would still be required 

to monitor during all positive torque 

operating conditions encountered 

during an FTP transient cycle. 

d. Engine Misfire MIL Illumination and 

DTC Storage 

Manufacturers may store a general 

misfire DTC instead of a cylinder 

specific DTC under certain operating 

conditions. Do so shall depend on the 

manufacturer submitting data and/or an 

engineering evaluation that demonstrate 

that the specific misfiring cylinder 

cannot be reliably identified when the 

certain operating conditions occur. 

i. Engine Misfire Capable of Causing 

Catalyst Damage 

We are proposing that a pending DTC 

shall be stored immediately if, during a 

single drive cycle, the percentage of 

misfire determined by the manufacturer 

as being capable of causing catalyst 

damage is exceeded three times when 

operating in the positive torque region 

encountered during an FTP transient 

cycle or is exceeded on a single 

occasion when operating at any other 

engine speed and load condition in the 

positive torque region defined above. 

Immediately after a pending DTC is 

stored, the MIL shall blink once per 

second at all times while misfire is 

occurring during the drive cycle (i.e., 

the MIL may be extinguished during 

those times when misfire is not 

occurring during the drive cycle). If, at 

the time such a catalyst damaging 

engine misfire is occurring, the MIL is 

already illuminated for a malfunction 

other than engine misfire, the MIL shall 

blink similarly while the engine misfire 

is occurring and, if the misfire ceases, 

the MIL shall stop blinking but shall 

remain illuminated as commanded by 

the other malfunction. 

If a pending DTC is stored as 

described above, the OBD system shall 

immediately store a MIL-on DTC if the 

percentage of misfire determined by the 

manufacturer as being capable of 

causing catalyst damage is again 

exceeded one or more times during 

either: (a) the drive cycle immediately 


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following the storage of the pending 

DTC, regardless of the conditions 

encountered during the drive cycle; or, 

(b) on the next drive cycle in which 

similar conditions are encountered to 

those that existed when the pending 

DTC was stored. 

If, during a previous drive cycle, a 

pending DTC has been stored associated 

with detection of an engine misfire 

capable of causing poor emissions 

performance, the OBD system shall 

immediately store a MIL-on DTC if the 

percentage of misfire determined by the 

manufacturer as capable of causing 

catalyst damage is exceeded, regardless 

of the conditions encountered. 

Upon storage of a MIL-on DTC 

associated with engine misfire capable 

of causing catalyst damage, the MIL 

shall blink as described above while the 

engine misfire is occurring and then 

shall remain continuously illuminated if 

the engine misfire ceases. This MIL 

illumination logic shall continue until 

the requirements for extinguishing the 

MIL are met, as described below. 

If the engine misfire is not again 

detected by the end of the next drive 

cycle in which similar conditions are 

encountered to those that existed when 

the pending DTC was stored then the 

pending DTC shall be erased. The 

pending DTC may also be erased if 

similar conditions are not encountered 

during the 80 drive cycles subsequent to 

the initial malfunction detection. 

We are also proposing that engines 

with fuel shutoff and default fuel 

control—that are used to prevent 

catalyst damage should engine misfire 

capable of causing catalyst damage be 

detected—shall have some exemptions 

from these MIL illumination 

requirements. Most notably, the MIL is 

not required to blink while the catalyst 

damaging misfire is occurring. Instead, 

the MIL may simply illuminate in a 

steady fashion while the misfire is 

occurring provided that the fuel shutoff 

and default fuel control are activated as 

soon as the misfire is detected. Fuel 

shutoff and default fuel control may be 

deactivated only to permit fueling 

outside of the misfire range. 

Manufacturers may also periodically, 

but not more than once every 30 

seconds, deactivate fuel shutoff and 

default fuel control to determine if the 

catalyst damaging misfire is still 

occurring. Normal fueling and fuel 

control may be resumed if the catalyst 

damaging misfire is no longer being 

detected. 

Manufacturers may also use a MIL 

illumination strategy that continuously 

illuminates the MIL in lieu of blinking 

the MIL during extreme misfire 

conditions capable of causing catalyst 

damage (i.e., misfire capable of causing 

catalyst damage that is occurring at all 

engine speeds and loads). 

Manufacturers would be allowed to use 

such a strategy only when catalyst 

damaging misfire levels cannot be 

avoided during reasonable driving 

conditions and the manufacturer can 

demonstrate that the strategy will 

encourage operation of the vehicle in 

conditions that will minimize catalyst 

damage (e.g., at low engine speeds and 

loads). 

ii. Engine Misfire Causing Poor 

Emissions Performance 

We are proposing that, for a misfire 

detected within the first 1000 

revolutions after engine start during 

which misfire detection is active, a 

pending DTC shall be stored after the 

first exceedance of the percentage of 

misfire determined by the manufacturer 

as capable of causing poor emissions 

performance. If a pending DTC is stored, 

the OBD system shall illuminate the 

MIL and store a MIL-on DTC within 10 

seconds if an exceedance of the 

percentage of misfire is again detected 

in the first 1000 revolutions during any 

subsequent drive cycle, regardless of the 

conditions encountered during the 

driving cycle. The pending DTC shall be 

erased at the end of the next drive cycle 

in which similar conditions are 

encountered to those that existed when 

the pending DTC was stored provided 

the specified percentage of misfire is not 

again detected. The pending DTC may 

also be erased if similar conditions are 

not encountered during the 80 drive 

cycles subsequent to the initial 

malfunction detection. 

For a misfire detected after the first 

1000 revolutions following engine start, 

a pending DTC shall be stored no later 

than after the fourth exceedance—

during a single drive cycle—of the 

percentage of misfire determined by the 

manufacturer as being capable of 

causing poor emissions performance. If 

a pending DTC is stored, the OBD 

system shall illuminate the MIL and 

store a MIL-on DTC within 10 seconds 

if an exceedance of the percentage of 

misfire is again detected four times 

during: (a) the drive cycle immediately 

following the storage of the pending 

DTC, regardless of the conditions 

encountered during the drive cycle; or, 

(b) on the next drive cycle in which 

similar conditions are encountered to 

those that existed when the pending 

DTC was stored. The pending DTC shall 

be erased at the end of the next drive 

cycle in which similar conditions are 

encountered to those that existed when 

the pending DTC was stored provided 

the specified percentage of misfire is not 

again detected. The pending DTC may 

also be erased if similar conditions are 

not encountered during the 80 drive 

cycles subsequent to the initial 

malfunction detection. 

We are proposing some specific items 

with respect to freeze frame storage 

associated with engine misfire. The 

OBD system shall store and erase freeze 

frame conditions either in conjunction 

with storing and erasing a pending DTC 

or in conjunction with storing a MIL-on 

DTC and erasing a MIL-on DTC. In 

addition to those proposed requirements 

discussed in section II.A.2, we are 

proposing that, if freeze frame 

conditions are stored for a malfunction 

other than a misfire malfunction when 

a DTC is stored, the previously stored 

freeze frame information shall be 

replaced with freeze frame information 

regarding the misfire malfunction (i.e., 

the misfire’s freeze frame information 

should take precedence over freeze 

frames for other malfunctions). Further, 

we are proposing that, upon detection of 

misfire, the OBD system store the 

following engine conditions: engine 

speed, load, and warm up status of the 

first misfire event that resulted in the 

storage of the pending DTC. 

Lastly, we are proposing that the MIL 

may be extinguished after three 

sequential driving cycles in which 

similar conditions have been 

encountered without an exceedance of 

the specified percentage of misfire. 

3. Exhaust Gas Recirculation (EGR) 

Monitoring 

a. Background 

EGR works to reduce NOX emissions 

the same way in gasoline engines as 

described earlier for diesel engines. 

First, the recirculated exhaust gases 

dilute the intake air—i.e., oxygen in the 

fresh air is displaced with relatively 

non-reactive exhaust gases—which, in 

turn, results in less oxygen to form NOX. 

Second, EGR absorbs heat from the 

combustion process which reduces 

combustion chamber temperatures 

which, in turn, reduces NOX formation. 

The amount of heat absorbed from the 

combustion process is a function of EGR 

flow rate and recirculated gas 

temperature, both of which are 

controlled to minimize NOX emissions. 

EGR systems can involve many 

components to ensure accurate control 

of EGR flow, including valves, valve 

position sensors, and actuators. 

b. EGR System Monitoring 

Requirements 

We are proposing that the OBD 

system monitor the EGR system on 

engines so equipped for low and high 


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3228 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

37For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

flow rate malfunctions. The individual 

electronic components (e.g., actuators, 

valves, sensors) that are used in the EGR 

system must be monitored in 

accordance with the comprehensive 

component requirements in section 

II.D.4. 

i. EGR Low Flow Malfunctions 

We are proposing that the OBD 

system detect a malfunction prior to a 

decrease from the manufacturer’s 

specified EGR flow rate that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.C–1. For 

engines in which no failure or 

deterioration of the EGR system that 

causes a decrease in flow could result in 

an engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system would have to detect a 

malfunction when the system has 

reached its control limits such that it 

cannot increase EGR flow to achieve the 

commanded flow rate. 

ii. EGR High Flow Malfunctions 

We are proposing that the OBD 

system detect a malfunction of the EGR 

system, including a leaking EGR valve—

i.e., exhaust gas flowing through the 

valve when the valve is commanded 

closed—prior to an increase from the 

manufacturer’s specified EGR flow rate 

that would cause an engine’s emissions 

to exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 

II.C–1. For engines in which no failure 

or deterioration of the EGR system that 

causes an increase in flow could result 

in an engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system would have to detect a 

malfunction when the system has 

reached its control limits such that it 

cannot reduce EGR flow to achieve the 

commanded flow rate. 

c. EGR System Monitoring Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 

EGR system malfunctions such that the 

minimum performance ratio 

requirements discussed in section II.E 

would be met. For purposes of tracking 

and reporting as required in section II.E, 

all monitors used to detect EGR low 

flow and high flow malfunctions must 

be tracked separately but reported as a 

single set of values as specified in 

section II.E.37

Manufacturers may temporarily 

disable the EGR system monitor under 

conditions when monitoring may not be 

reliable (e.g., when freezing may affect 

performance of the system). Such 

temporary disablement would be 

allowed provided the manufacturer has 

submitted data and/or an engineering 

evaluation that demonstrate that the 

EGR monitor cannot be done reliably 

when these specific conditions exist. 

d. EGR System MIL Illumination and 

DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

4. Cold Start Emission Reduction 

Strategy Monitoring 

a. Background 

The largest portion of exhaust 

emissions from gasoline engines is 

generated during the brief period 

following startup before the engine and 

catalyst have warmed up to their normal 

operating temperatures. To meet 

increasingly stringent emissions 

standards, manufacturers are developing 

hardware and associated control 

strategies to reduce these ‘‘cold start’’

emissions. Most efforts center on 

reducing catalyst warm-up time. 

A cold catalyst is heated mainly by 

two mechanisms: heat transferred from 

the exhaust gases to the catalyst; and, 

heat generated in the catalyst as a result 

of the exothermic catalytic reactions. 

Most manufacturers use substantial 

spark retard and/or increased idle speed 

following a cold engine start, both of 

which maximize the heat available in 

the exhaust gases which, in turn, 

increases the heat transfer to the 

catalyst. Vehicle drivability and engine 

idle quality concerns tend to limit the 

amount of spark retard and/or increased 

idle speed that a manufacturer can use 

to accelerate catalyst warm up. These 

strategies or, more correctly, the systems 

used to employ these strategies—the 

ignition system for spark retard and the 

idle control system for control of engine 

speed—are normally monitored only 

after engine warm-up. Therefore, any 

malfunctions that might occur during 

the cold start event may not be detected 

by the OBD system. This could have 

significant emissions consequences due 

to the unknown loss of emissions 

control during the time following engine 

startup. 

This concern is exacerbated by the 

high cost of precious metals—the 

platinum group metals (PGM) platinum, 

palladium, and rhodium—which 

motivates industry to minimize their 

use in catalysts. To compensate for the 

resultant reduction in overall catalyst 

performance, manufacturers will likely 

use increasingly more aggressive cold 

start emission reduction strategies in an 

attempt to further reduce cold start 

emissions. These strategies must be 

successful—and be properly 

monitored—to meet the more stringent 

2008 emissions standards and to 

maintain low emissions in-use. 

b. Cold Start Emission Reduction 

Strategy Monitoring Requirements 

We are proposing that, if an engine 

incorporates an engine control strategy 

specifically to reduce cold start 

emissions, the OBD system must 

monitor the key components (e.g., idle 

air control valve), other than the 

secondary air system, while the control 

strategy is active to ensure that the 

control strategy is operating properly. 

Secondary air systems would have to be 

monitored separately as discussed in 

section II.C.5. 

The OBD system would be required to 

detect a malfunction prior to any failure 

or deterioration of the individual 

components associated with the cold 

start emissions reduction control 

strategy that would cause an engine’s 

emissions to exceed the emissions 

thresholds for ‘‘other monitors’’ as 

shown in Table II.C–1. For components 

where no failure or deterioration of the 

component used by the cold start 

emission reduction strategy could result 

in an engine’s emissions exceeding the 

applicable emissions thresholds, the 

individual components would have to 

be monitored for proper functional 

response as described in section II.D.4 

while the control strategy is active. 

Manufacturers would be required to 

establish the appropriate malfunction 

criteria based on data from one or more 

representative engine(s). Further, 

manufacturers would be required to 

provide an engineering evaluation for 

establishing the malfunction criteria for 

the remainder of the manufacturer’s 

product line. An annual evaluation of 

these criteria by the Administrator may 

not be necessary provided the 

manufacturer can demonstrate that any 

technological changes from one year to 

the next do not affect the previously 

approved malfunction criteria. 

c. Cold Start Emission Reduction 

Strategy Monitoring Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 


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Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3229 

38For purposes of secondary air system 

malfunctions, ‘‘air flow’’ is defined as the air flow 

delivered by the secondary air system to the 

exhaust system. For engines using secondary air 

systems with multiple air flow paths/distribution 

points, the air flow to each bank (i.e., a group of 

cylinders that share a common exhaust manifold, 

catalyst, and control sensor) must be monitored in 

accordance with these malfunction criteria. Also, 

‘‘normal operation’’ is defined as the condition 

where the secondary air system is activated during 

catalyst and/or engine warm-up following engine 

start. ‘‘Normal operation’’ does not include the 

condition where the secondary air system is 

intrusively turned on solely for the purpose of 

monitoring. 

39 Ibid. 

malfunctions of the cold start emissions 

reduction strategy such that the 

minimum performance ratio 

requirements discussed in section II.E 

would be met. 

d. Cold Start Emission Reduction 

Strategy MIL Illumination and DTC 

Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

5. Secondary Air System Monitoring 

a. Background 

Secondary air systems—expected to 

be used on gasoline engines only—are 

used to reduce cold start emissions of 

hydrocarbons and carbon monoxide. 

Many of today’s engines operate near 

stoichiometry after a cold engine start. 

However, the future more stringent 

emission standards may require the 

addition of a secondary air system in 

combination with a richer than 

stoichiometric cold start mixture. Such 

an approach could quickly warm up the 

catalyst for improved cold start 

emissions performance. 

Secondary air systems typically 

consist of an electric air pump, various 

hoses, and check valves to deliver 

outside air to the exhaust system 

upstream of the catalytic converter(s). 

This system usually operates only after 

a cold engine start and usually for only 

a brief period of time. When the electric 

air pump is operating, fresh air is 

delivered into the exhaust where it 

mixes with and ignites any unburned 

fuel. This serves to warm up the catalyst 

far more rapidly than would otherwise 

occur. Any problems that might occur in 

the field—corroded check valves, 

damaged tubing and hoses, 

malfunctioning air switching valves—

could cause cold start emissions 

performance to suffer. Therefore, 

monitoring is needed given the 

importance of a properly functioning 

secondary air system to emissions 

performance. 

b. Secondary Air System Monitoring 

Requirements 

We are proposing that the OBD 

system on engines equipped with any 

form of secondary air delivery system be 

required to monitor the proper 

functioning of the secondary air 

delivery system, including all air 

switching valve(s). The individual 

electronic components (e.g., actuators, 

valves, sensors) in the secondary air 

system would have to be monitored in 

accordance with the comprehensive 

component requirements discussed in 

section II.D.4. 

i. Secondary Air System Low Flow 

Malfunctions 

We are proposing that the OBD 

system detect a secondary air system 

malfunction prior to a decrease from the 

manufacturer’s specified air flow during 

normal operation that would cause an 

engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.C–1.38

For engines in which no deterioration or 

failure of the secondary air system 

would result in an engine’s emissions 

exceeding any of the applicable 

emissions thresholds, the OBD system 

would have to detect a malfunction 

when no detectable amount of air flow 

is delivered during normal operation of 

the secondary air system. 

ii. Secondary Air System High Flow 

Malfunctions 

We are proposing that the OBD 

system detect a secondary air system 

malfunction prior to an increase from 

the manufacturer’s specified air flow 

during normal operation that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.C–1.39

For engines in which no deterioration or 

failure of the secondary air system 

would result in an engine’s emissions 

exceeding any of the applicable 

emissions thresholds, the OBD system 

would have to detect a malfunction 

when no detectable amount of air flow 

is delivered during normal operation of 

the secondary air system. 

c. Secondary Air System Monitoring 

Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 

malfunctions of the secondary air 

system such that the minimum 

performance ratio requirements 

discussed in section II.E would be met. 

For purposes of tracking and reporting 

as required in section II.E, all monitors 

used to detect malfunctions of the 

secondary air system during its normal 

operation must be tracked separately but 

reported as a single set of values as 

specified in section II.E 

d. Secondary Air System MIL 

Illumination and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

6. Catalytic Converter Monitoring 

a. Background 

Three-way catalysts are one of the 

most important emission-control 

components on gasoline engines. They 

consist of ceramic or metal substrates 

coated with the one or more of the 

platinum group metals (PGM) platinum, 

palladium, and rhodium. These PGMs 

are dispersed within an alumina 

washcoat containing ceria, and the 

substrates are mounted in a stainless 

steel container in the vehicle exhaust 

system. Three-way catalysts are capable 

of oxidizing HC emissions, oxidizing CO 

emissions, and reducing NOX emissions, 

hence the term three-way. 

While continuous improvements to 

catalysts have increased their durability, 

their performance still deteriorates, 

especially when subjected to very high 

temperatures. Such high temperatures 

can be caused by, among other factors, 

engine misfire which results in 

unburned fuel and air entering and 

igniting in the catalyst. Exposure to 

such high temperatures will result in 

reduced catalyst conversion efficiency. 

Catalyst efficiency can also deteriorate 

via poisoning if exposed to lead, 

phosphorus, or high sulfur levels. 

Catalysts can also fail by mechanical 

means such as excessive vibration. 

Given its importance to emissions 

control and the many factors that can 

reduce its effectiveness, the catalyst is 

one of the most important components 

to be monitored. 

b. Catalytic Converter Monitoring 

Requirements 

We are proposing that the OBD 

system monitor the catalyst system for 

proper conversion capability. 

Specifically, the OBD system would be 

required to detect a catalyst system 

malfunction when the catalyst system’s 

conversion capability decreases to the 

point that any of the following occurs: 

• NMHC and/or NOX emissions 

exceed the emissions thresholds for the 

‘‘catalytic converter system’’ as shown 

in Table II.C–1. 

For purposes of determining the 

catalyst system malfunction criteria the 

manufacturer would be required to use 

a catalyst system deteriorated to the 

malfunction criteria using methods 

established by the manufacturer to 


sroberts on PROD1PC70 with PROPOSALS
3230 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

40The unmonitored portion of the catalyst system 

would be that portion downstream of the sensor(s) 

used for catalyst monitoring. 

41 In their HDOBD regulation, 13 CCR 1971.1, 

CARB defines ‘‘orifice’’ as an O’Keefe Controls Co. 

precision metal ‘‘Type B’’ orifice with NPT 

connections with a diameter of the specified 

dimension (e.g., part number B–31–SS for a 

stainless steel 0.031 inch diameter orifice). 

represent real world catalyst 

deterioration under normal and 

malfunctioning operating conditions. 

The malfunction criteria must be 

established by using a catalyst system 

with all monitored and unmonitored 

catalysts simultaneously deteriorated to 

the malfunction criteria.40 For engines 

using fuel shutoff to prevent overfueling during misfire conditions (see 

section II.C.2), the malfunction criteria 

could be established using a catalyst 

system with all monitored catalysts 

simultaneously deteriorated to the 

malfunction criteria and all 

unmonitored catalysts deteriorated to 

the end of the engine’s useful life. 

c. Catalytic Converter Monitoring 

Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 

malfunctions of the catalytic converter 

system such that the minimum 

performance ratio requirements 

discussed in section II.E would be met. 

For purposes of tracking and reporting 

as required in section II.E, all monitors 

used to detect malfunctions of the 

catalytic converter system during its 

normal operation must be tracked 

separately but reported as a single set of 

values as specified in section II.E. 

d. Catalytic Converter MIL Illumination 

and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. Note that the monitoring method 

for the catalyst(s) would have to be 

capable of detecting all instances, 

except diagnostic self-clearing, when a 

catalyst DTC has been cleared but the 

catalyst has not been replaced (e.g., 

catalyst over temperature histogram 

approaches are not acceptable). 

7. Evaporative Emission Control System 

Monitoring 

a. Background 

The evaporative emission control 

system controls HC emissions that 

would otherwise evaporate from the 

vehicle’s fuel tank and fuel lines. 

Should any leak develop in the 

evaporative emission control system—

e.g., a disconnected hose—the HC 

emissions can be quite high and well 

over the evaporative emissions 

standards. Additionally, evaporative 

purge system defects—e.g., deteriorated 

vacuum lines, damaged canisters, nonfunctioning purge control valves—may 

occur which could also result in very 

high evaporative emissions. 

b. Evaporative System Monitoring 

Requirements 

We are proposing that the OBD 

system verify purge flow from the 

evaporative system and detect any vapor 

leaks from the complete evaporative 

system, excluding the tubing and 

connections between the purge valve 

and the intake manifold. Individual 

components of the evaporative system 

(e.g. valves, sensors) must be monitored 

in accordance with the comprehensive 

components requirements discussed in 

section II.D.4. 

The OBD system would be required to 

detect an evaporative system 

malfunction when any of the following 

conditions exist: 

• No purge flow from the evaporative 

system to the engine can be detected by 

the OBD system (i.e., the ‘‘purge flow’’

requirement); or 

• For the 2010 and later model years, 

the complete evaporative system 

contains a leak or leaks that 

cumulatively are greater than or equal to 

a leak caused by a 0.150 inch diameter 

orifice (i.e., the ‘‘system leak’’

requirement).41

If the most reliable monitoring 

method available cannot reliably detect 

a system leak as specified above, a 

manufacturer may design their system 

to detect a larger leak. The manufacturer 

would be required to provide data and/ 

or engineering analyses that 

demonstrate the inability of the monitor 

to reliably detect the required leak and 

their justification for detecting at their 

proposed orifice size. Further, if the 

manufacturer can demonstrate that leaks 

of the required size cannot cause 

evaporative or running loss emissions to 

exceed 1.5 times the applicable 

evaporative emissions standards, the 

Administrator would revise upward the 

required leak size to the size 

demonstrated by the manufacturer that 

would result in emissions exceeding 1.5 

times the standards. 

c. Evaporative System Monitoring 

Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 

both purge flow and system leak 

malfunctions such that the minimum 

performance ratio requirements 

discussed in section II.E would be met. 

For purposes of tracking and reporting 

as required in section II.E, all monitors 

used to detect system leak malfunctions 

must be tracked separately but reported 

as a single set of values as specified in 

section II.E. 

Manufacturers may disable or abort an 

evaporative emission control system 

monitor when the fuel tank level is over 

85 percent of nominal tank capacity or 

during a refueling event. Manufacturers 

may design their evaporative emission 

control system monitor such that it 

executes only during drive cycles 

determined by the manufacturer to be 

cold starts if such a condition is needed 

to ensure reliable monitoring. The 

manufacturer would have to provide 

data and/or an engineering evaluation 

demonstrating that a reliable check can 

only be made on drive cycles when the 

cold start criteria are satisfied. However, 

the manufacturer may not determine a 

cold start solely on the basis that 

ambient temperature is higher than 

engine coolant temperature at engine 

start. Lastly, manufacturers would be 

allowed to disable temporarily the 

evaporative purge system to perform an 

evaporative system leak check. 

d. Evaporative System MIL Illumination 

and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2, with an exception for leaks 

associated with the fuel filler cap. If the 

OBD system is capable of discerning 

that a system leak is being caused by a 

missing or improperly secured fuel filler 

cap, the manufacturer is not required to 

illuminate the MIL or store a DTC 

provided the vehicle is equipped with 

an alternative indicator for notifying the 

vehicle operator of the fuel filler cap 

‘‘malfunction.’’ The alternative indicator 

would have to be of sufficient 

illumination and location to be readily 

visible to the vehicle operator under all 

lighting conditions. However, if the 

vehicle is not equipped with an 

alternative indicator and, instead, the 

MIL is illuminated to inform the 

operator of the ‘‘malfunction,’’ the MIL 

may be extinguished and the 

corresponding DTC(s) erased once the 

OBD system has verified that the fuel 

filler cap has been securely fastened and 

the MIL has not been commanded ON 

for any other type of malfunction. The 

Administrator may approve other 

strategies provided the manufacturer 

was able to demonstrate that the vehicle 

operator would be promptly notified of 

the missing or improperly secured fuel 

filler cap and that the notification 

would reasonably result in corrective 

action being undertaken. 


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Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3231 

8. Exhaust Gas Sensor Monitoring 

a. Background 

Exhaust gas sensors (e.g., oxygen 

sensors, air-fuel ratio (A/F) sensors) are 

a critical element of the emissions 

control system on gasoline engines. In 

addition to maintaining a stoichiometric 

air-fuel mixture and, thus, helping to 

achieve the lowest possible emissions, 

these sensors are also used for 

enhancing the performance of several 

emission control technologies—e.g., 

catalysts, EGR systems). Many modern 

vehicles control the fuel supply with an 

oxygen sensor feedback system to 

maintain stoichiometry. Oxygen sensors 

are located typically in the exhaust 

system upstream and downstream of the 

catalytic converters. The front, or 

upstream, oxygen sensor is used 

generally for fuel control. The rear, or 

downstream, oxygen sensor is used 

generally for adjusting the front oxygen 

sensor signal as it drifts slightly with 

age related deterioration—often referred 

to as fuel trimming—and for onboard 

monitoring the catalyst system. Many 

vehicles use A/F sensors in lieu of the 

more conventional oxygen sensors since 

A/F sensors provide a precise reading of 

the actual air-fuel ratio. 

We expect that heavy-duty gasoline 

manufacturers will use both of these 

types of sensors to optimize their 

emissions control strategies and to 

satisfy many of the proposed heavy-duty 

OBD monitoring requirements—fuel 

system monitoring, catalyst monitoring, 

EGR system monitoring. Since exhaust 

gas sensors can be a critical component 

of an engine’s fuel and emissions 

control system, their proper 

performance needs to be assured to 

maintain low emissions. Thus, any 

malfunction that adversely affects the 

performance of any of these exhaust gas 

sensors should be detected by the OBD 

system. 

b. Exhaust Gas Sensor Monitoring 

Requirements 

We are proposing that the OBD 

system monitor the output signal, 

response rate, and any other parameter 

that could affect emissions of all 

primary (i.e., fuel control) exhaust gas 

sensors for malfunction. Both the lean to 

rich and rich to lean response rates must 

be monitored. In addition, we are 

proposing that the OBD system monitor 

all secondary exhaust gas sensors (i.e., 

those used for fuel trimming or as a 

monitoring device for another system) 

for proper output signal, activity, and 

response rate. For engines equipped 

with heated exhaust gas sensors, the 

OBD system would be required to 

monitor the sensor heater for proper 

performance. 

i. Primary Exhaust Gas Sensors 

We are proposing that the OBD 

system detect a malfunction prior to any 

failure or deterioration of the exhaust 

gas sensor output voltage, resistance, 

impedance, current, response rate, 

amplitude, offset, or other 

characteristic(s) (including drift or bias 

corrected for by secondary sensors) that 

would cause an engine’s emissions to 

exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 

II.C–1. The OBD system would also be 

required to detect the following exhaust 

gas sensor malfunctions: 

• Those caused by either a lack of 

circuit continuity or out-of-range values. 

• Those where a sensor failure or 

deterioration causes the fuel system to 

stop using that sensor as a feedback 

input (e.g., causes default or open-loop 

operation). 

• Those where the sensor output 

voltage, resistance, impedance, current, 

amplitude, activity, or other 

characteristics are no longer sufficient 

for use as an OBD system monitoring 

device (e.g., for catalyst monitoring). 

ii. Secondary Exhaust Gas Sensors 

We are proposing that the OBD 

system detect a malfunction prior to any 

failure or deterioration of the exhaust 

gas sensor voltage, resistance, 

impedance, current, response rate, 

amplitude, offset, or other 

characteristic(s) that would cause an 

engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table II.C–1. The 

OBD system would also be required to 

detect the following exhaust gas sensor 

malfunctions: 

• Those caused by either a lack of 

circuit continuity or out-of-range values. 

• Those where a sensor failure or 

deterioration causes the fuel system to 

stop using that sensor as a feedback 

input (e.g., causes default or open-loop 

operation). 

• Those where the sensor output 

voltage, resistance, impedance, current, 

amplitude, activity, or other 

characteristics are no longer sufficient 

for use as an OBD system monitoring 

device (e.g., for catalyst monitoring). 

iii. Exhaust Gas Sensor Heaters 

We are proposing that the OBD 

system detect a malfunction of the 

sensor heater performance when the 

current or voltage drop in the heater 

circuit is no longer within the 

manufacturer’s specified limits for 

normal operation (i.e., within the 

criteria required by the component 

vendor for heater circuit performance at 

high mileage). The manufacturer may 

use other malfunction criteria for heater 

performance malfunctions. To do so, the 

manufacturer would be required to 

submit data and/or engineering analyses 

that demonstrate that the monitoring 

reliability and timeliness would be 

equivalent to the criteria stated here. 

In addition, the OBD system would be 

required to detect malfunctions of the 

heater circuit including open or short 

circuits that conflict with the 

commanded state of the heater (e.g., 

shorted to 12 Volts when commanded to 

0 Volts (ground)). 

c. Exhaust Gas Sensor Monitoring 

Conditions 

i. Primary Exhaust Gas Sensors 

We are proposing that manufacturers 

define the monitoring conditions for 

primary exhaust gas sensor 

malfunctions causing exceedance of the 

applicable thresholds and/or inability to 

perform as an OBD monitoring device 

such that the minimum performance 

ratio requirements discussed in section 

II.E would be met. For purposes of 

tracking and reporting as required in 

section II.E, all such monitors must be 

tracked separately but reported as a 

single set of values as specified in 

section II.E. 

Monitoring for primary exhaust gas 

sensor malfunctions related to circuit 

continuity, out-of-range, and open-loop 

operation must be done continuously 

with the exception that manufacturers 

may disable continuous exhaust gas 

sensor monitoring when an exhaust gas 

sensor malfunction cannot be 

distinguished from other effects. As an 

example, a manufacturer may disable 

monitoring for out-of-range on the low 

side during conditions where fuel has 

been cut (i.e., shut off temporarily). To 

do so, the manufacturer would have to 

submit data and/or engineering analyses 

that demonstrate that a properly 

functioning sensor cannot be 

distinguished from a malfunctioning 

sensor and that the disablement interval 

is limited only to that necessary for 

avoiding a false detection. 

ii. Secondary Exhaust Gas Sensors 

We are proposing that manufacturers 

define the monitoring conditions for 

secondary exhaust gas sensor 

malfunctions causing exceedance of the 

applicable emissions thresholds, lack of 

circuit continuity, and/or inability to 

perform as an OBD monitoring device 

such that the minimum performance 

ratio requirements discussed in section 

II.E would be met. 

Monitoring for secondary exhaust gas 

sensor malfunctions related to out-ofVerDate Aug<31>2005 19:18 Jan 23, 2007 Jkt 211001 PO 00000 Frm 00033 Fmt 4701 Sfmt 4702 E:\FR\FM\24JAP2.SGM 24JAP2

sroberts on PROD1PC70 with PROPOSALS
3232 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

42For specific components or systems that have 

multiple monitors that are required to be reported 

(e.g., exhaust gas sensor bank 1 may have multiple 

monitors for sensor response or other sensor 

characteristics), the OBD system must separately 

track numerators and denominators for each of the 

specific monitors and report only the corresponding 

numerator and denominator for the specific monitor 

that has the lowest numerical ratio. If two or more 

specific monitors have identical ratios, the 

corresponding numerator and denominator for the 

specific monitor that has the highest denominator 

shall be reported for the specific component. 

range and open loop operation must be 

done continuously with the exception 

that manufacturers may disable 

continuous exhaust gas sensor 

monitoring when an exhaust gas sensor 

malfunction cannot be distinguished 

from other effects. As an example, a 

manufacturer may disable monitoring 

for out-of-range on the low side during 

conditions where fuel has been cut (i.e., 

shut off temporarily). To do so, the 

manufacturer would have to submit data 

and/or engineering analyses that 

demonstrate that a properly functioning 

sensor cannot be distinguished from a 

malfunctioning sensor and that the 

disablement interval is limited only to 

that necessary for avoiding a false 

detection. 

iii. Sensor Heaters 

We are proposing that manufacturers 

define monitoring conditions for sensor 

heater performance malfunctions such 

that the minimum performance ratio 

requirements discussed in section II.E 

would be met. Monitoring for sensor 

heater circuit malfunctions must be 

done continuously. 

d. Exhaust Gas Sensor MIL Illumination 

and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

D. Monitoring Requirements and 

Timelines for Other Diesel and Gasoline 

Systems 

1. Variable Valve Timing and/or Control 

(VVT) System Monitoring 

a. Background 

Variable valve timing (VVT) and/or 

control systems are used primarily to 

optimize engine performance and have 

many advantages over conventional 

valve control. Instead of opening and 

closing the valves by fixed amounts and 

at fixed times, VVT controls can vary 

the timing of valve opening/closing and 

vary the effective size of the valve 

opening itself (in some systems) 

depending on the driving conditions 

(e.g., high engine speed and load). This 

feature permits a better compromise 

between performance, driveability, and 

emissions than conventional systems. 

With more stringent NOX emission 

standards being phased in, more 

vehicles are anticipated to use VVT. By 

doing so, some exhaust gas can be 

retained in the combustion chamber 

thereby reducing peak combustion 

temperatures and, hence, NOX

emissions (known as ‘‘internal EGR’’). 

b. VVT and/or Control System 

Monitoring Requirements 

We are proposing that the OBD 

system monitor the VVT system on 

engines so equipped for target error and 

slow response malfunctions. The 

individual electronic components (e.g., 

actuators, valves, sensors) that are used 

in the VVT system must be monitored 

in accordance with the comprehensive 

components requirements in section 

II.D.4. 

i. VVT Target Error Malfunctions 

We are proposing that the OBD 

system detect a malfunction prior to any 

failure or deterioration in the capability 

of the VVT system to achieve the 

commanded valve timing and/or control 

within a crank angle and/or lift 

tolerance that would cause an engine’s 

emissions to exceed the emissions 

thresholds for ‘‘other monitors’’ as 

shown in Table II.B–1 for diesel engines 

or Table II.C–1 for gasoline engines. For 

engines in which no failure or 

deterioration of the VVT system could 

result in an engine’s emissions 

exceeding the applicable emissions 

thresholds, the OBD system would have 

to detect a malfunction of the VVT 

system when proper functional response 

of the system to computer commands 

does not occur. 

ii. VVT Slow Response Malfunctions 

We are proposing that the OBD 

system detect a malfunction prior to any 

failure or deterioration in the capability 

of the VVT system to achieve the 

commanded valve timing and/or control 

within a manufacturer-specified time 

that would cause an engine’s emissions 

to exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 

II.B–1 for diesel engines or Table II.C–

1 for gasoline engines. For engines in 

which no failure or deterioration of the 

VVT system could result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the OBD system 

would have to detect a malfunction of 

the VVT system when proper functional 

response of the system to computer 

commands does not occur. 

c. VVT and/or Control System 

Monitoring Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 

VVT target error or slow response 

malfunctions such that the minimum 

performance ratio requirements 

discussed in section II.E would be met 

with the exception that monitoring shall 

occur every time the monitoring 

conditions are met during the driving 

cycle rather than once per driving cycle 

as required for most monitors. For 

purposes of tracking and reporting as 

required in section II.E, all monitors 

used to detect all VVT related 

malfunctions would have to be tracked 

separately but reported as a single set of 

values as specified in section II.E.42

d. VVT and/or Control System MIL 

Illumination and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

2. Engine Cooling System Monitoring 

a. Background 

We are concerned about two elements 

of the engine cooling system. These 

elements are the thermostat and the 

engine coolant temperature sensor. 

Manufacturers typically use a 

thermostat to control the flow of coolant 

through the radiator and around the 

engine. During a cold engine start, the 

thermostat is closed typically which 

prevents the flow of coolant and serves 

to promote more rapid warm-up of the 

engine. As the coolant approaches a 

specific temperature, the thermostat 

begins to open allowing circulation of 

coolant through the radiator and around 

the engine. The thermostat then acts to 

regulate the coolant to the specified 

temperature. If the temperature rises 

above the regulated temperature, the 

thermostat opens further to allow more 

coolant to circulate, thus reducing the 

temperature. If the temperature drops 

below the regulated temperature, the 

thermostat partially closes to reduce the 

amount of coolant circulating, thereby 

increasing the temperature. If a 

thermostat malfunctions in such a 

manner that it does not adequately 

restrict coolant flow during vehicle 

warm-up, an increase in emissions 

could occur due to prolonged operation 

of the vehicle at temperatures below the 

stabilized, warmed-up value. This is 

particularly true at lower ambient 

temperatures—50 degrees Fahrenheit 

and below—but not so low that they are 

rare in the U.S. Equally important is that 

the engine coolant temperature is often 

used as an enable criterion for many 

OBD monitors. If the engine’s coolant 

temperature does not reach the 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3233 

manufacturer-specified warmed-up 

value, such monitors would be 

effectively disabled, perhaps 

indefinitely, and would, therefore, never 

detect malfunctions. 

Closely linked with the thermostat is 

the engine coolant temperature (ECT) 

sensor. Manufacturers typically use an 

ECT sensor as an input for many of the 

emission-related engine control systems. 

For gasoline engines, the ECT sensor is 

often one of the most important factors 

in determining when to begin closedloop fuel control. If the engine coolant 

does not warm-up sufficiently, closedloop fuel control is usually not engaged 

and the vehicle remains in open-loop 

fuel control. Since open-loop fuel 

control does not provide the precision 

of closed-loop control, the result is 

increased emissions levels. For diesel 

engines, the ECT sensor is often used to 

engage closed-loop control of the EGR 

system. Similar to closed-loop fuel 

control on gasoline engines, if the 

coolant temperature does not warm up, 

closed-loop control of the EGR system 

would not engage which would result in 

increased emissions levels. In addition, 

for both gasoline and diesel engines, the 

ECT sensor may be used to enable many 

of the monitors that are being proposed. 

Such monitors would be effectively 

disabled and incapable of detecting 

malfunctions should the ECT sensor 

itself malfunction. 

b. Engine Cooling System Monitoring 

Requirements 

We are proposing that the OBD 

system monitor the thermostat on 

engines so equipped for proper 

operation. We are also proposing that 

the OBD system monitor the ECT sensor 

for circuit continuity, out-of-range 

values, and rationality faults. For 

engines that use an approach other than 

the cooling system and ECT sensor—

e.g., oil temperature, cylinder head 

temperature—for an indication of 

engine operating temperature for 

emission control purposes (e.g., to 

modify spark or fuel injection timing or 

quantity), the manufacturer may forego 

cooling system monitoring in favor of 

monitoring the components or systems 

used in their approach. To do so, the 

manufacturer would be required to 

submit data and/or engineering analyses 

that demonstrate that their monitoring 

plan is as reliable and effective as the 

monitoring required for the engine 

cooling system. 

i. Thermostat Monitoring Requirements 

We are proposing that the OBD 

system detect a thermostat malfunction 

if, within the manufacturer specified 

time interval following engine start, any 

of the following conditions occur: 

• The coolant temperature does not 

reach the highest temperature required 

by the OBD system to enable other 

diagnostics; 

• The coolant temperature does not 

reach a warmed-up temperature within 

20 degrees Fahrenheit of the 

manufacturer’s nominal thermostat 

regulating temperature. The 

manufacturer may use a lower 

temperature for this criterion provided 

the manufacturer can demonstrate that 

the fuel, spark timing, and/or other 

coolant temperature-based modification 

to the engine control strategies would 

not cause an emissions increase greater 

than or equal to 50 percent of any of the 

applicable emissions standards. 

The time interval specified by the 

manufacturer would have to be 

supported by the manufacturer via data 

and/or engineering analyses 

demonstrating that it provides robust 

monitoring and minimizes the 

likelihood of other OBD monitors being 

disabled. The manufacturer may use 

alternative malfunction criteria that are 

a function of temperature at engine start 

on engines that do not reach the 

temperatures specified in the 

malfunction criteria when the 

thermostat is functioning properly. To 

do so, the manufacturer would be 

required to submit data and/or 

engineering analyses that demonstrate 

that a properly operating system does 

not reach the specified temperatures 

and that the possibility is minimized for 

cooling system malfunctions to go 

undetected and disable other OBD 

monitors. In some cases, a manufacturer 

may forgo thermostat monitoring if the 

manufacturer can demonstrate that a 

malfunctioning thermostat cannot cause 

a measurable increase in emissions 

during any reasonable driving condition 

nor cause any disablement of other OBD 

monitors. 

ii. Engine Coolant Temperature Sensor 

Monitoring Requirements 

We are proposing that the OBD 

system detect an ECT sensor 

malfunction when a lack of circuit 

continuity or an out-of-range value 

occurs. We are also proposing that the 

OBD system detect if, within the 

manufacturer specified time interval 

following engine start, the ECT sensor 

does not achieve the highest stabilized 

minimum temperature that is needed to 

initiate closed-loop/feedback control of 

all affected emission control systems 

(e.g., fuel system, EGR system). The 

manufacturer specified time interval 

would have to be a function of the 

engine coolant temperature and/or 

intake air temperature at startup. The 

manufacturer time interval would also 

have to be supported by the 

manufacturer via data and/or 

engineering analyses demonstrating that 

it provides robust monitoring and 

minimizes the likelihood of other OBD 

monitors being disabled. Manufacturers 

may forego the requirement to detect the 

‘‘time to closed loop/feedback enable 

temperature’’ malfunction if the 

manufacturer does not use engine 

coolant temperature or the ECT sensor 

to enable closed-loop/feedback control 

of any emission control systems. 

We are also proposing that, to the 

extent feasible when using all available 

information, the OBD system must 

detect a malfunction if the ECT sensor 

inappropriately indicates a temperature 

below the highest minimum enable 

temperature required by the OBD 

system to enable other monitors. For 

example, an OBD system that requires 

an engine coolant temperature greater 

than 140 degrees Fahrenheit prior to 

enabling an OBD monitor must detect 

malfunctions that cause the ECT sensor 

to indicate inappropriately a 

temperature below 140 degrees 

Fahrenheit. Manufacturers may forego 

such monitoring within temperature 

regions in which the thermostat monitor 

or the ECT sensor ‘‘time to reach closedloop/feedback enable temperature’’

monitor would detect this ‘‘stuck in a 

range below the highest minimum 

enable temperature’’ ECT sensor 

malfunction. 

Lastly, we are proposing that, to the 

extent feasible when using all available 

information, the OBD system must 

detect a malfunction if the ECT sensor 

inappropriately indicates a temperature 

above the lowest maximum enable 

temperature required by the OBD 

system to enable other monitors. For 

example, an OBD system that requires 

an engine coolant temperature less than 

90 degrees Fahrenheit at startup prior to 

enabling an OBD monitor must detect 

malfunctions that cause the ECT sensor 

to indicate inappropriately a 

temperature above 90 degrees 

Fahrenheit. Manufacturers may forego 

such monitoring within temperature 

regions in which the thermostat 

monitor, the ECT sensor ‘‘time to reach 

closed-loop/feedback enable 

temperature’’ monitor, or the ECT 

sensor ‘‘stuck in a range below the 

highest minimum enable temperature’’

monitor would detect this ECT sensor 

‘‘stuck in a range above the lowest 

maximum enable temperature’’ ECT 

sensor malfunction. The manufacturer 

may also forego such monitoring if the 

MIL would be illuminated for entering 

a ‘‘limp home’’ or default mode of 


sroberts on PROD1PC70 with PROPOSALS
3234 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

operation—e.g., for an over temperature 

protection strategy—as discussed in 

section II.A.2. Manufacturers may also 

forego this monitoring within 

temperature regions where the 

temperature gauge indicates a 

temperature in the engine overheating 

‘‘red zone’’ should the vehicle have a 

temperature gauge on the instrument 

panel that displays the same 

temperature information as used by the 

OBD system (note that a temperature 

gauge would be required, not a 

temperature warning light). 

c. Engine Cooling System Monitoring 

Conditions 

i. Thermostat Monitoring Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 

thermostat malfunctions in accordance 

with the general monitoring conditions 

for all engines described in section 

II.A.3. Additionally, monitoring for 

thermostat malfunctions would have to 

be done once per drive cycle on every 

drive cycle in which the ECT sensor 

indicates, at engine start, a temperature 

lower than the temperature established 

as the malfunction criteria in section 

II.D.2.b.i. Manufacturers would be 

allowed to disable thermostat 

monitoring at ambient engine start 

temperatures below 20 degrees 

Fahrenheit. Manufacturers may suspend 

or disable thermostat monitoring if the 

engine is subjected to conditions that 

could lead to false diagnosis (e.g., 

engine operation at idle for more than 

50 percent of the warm-up time and/or 

hot restart conditions). To do so, the 

manufacturer must submit data and/or 

engineering analyses that demonstrate 

that the suspension or disablement is 

necessary. In general, the manufacturer 

would not be allowed to suspend or 

disable the thermostat monitor on 

engine starts where the engine coolant 

temperature at engine start is more than 

35 degrees Fahrenheit lower than the 

thermostat malfunction threshold 

temperature. 

ii. Engine Coolant Temperature Sensor 

Monitoring Conditions 

We are proposing that monitoring for 

ECT sensor circuit continuity and outof-range malfunctions be done 

continuously. Manufacturers would be 

allowed to disable continuous ECT 

sensor monitoring when an ECT sensor 

malfunction cannot be distinguished 

from other effects. To do so, the 

manufacturer would have to submit test 

data and/or engineering evaluation that 

demonstrate that a properly functioning 

sensor cannot be distinguished from a 

malfunctioning sensor and that the 

disablement interval is limited only to 

that necessary for avoiding false 

detection. 

We are also proposing that 

manufacturers define the monitoring 

conditions for ‘‘time to reach closedloop/feedback enable temperature’’

malfunctions in accordance with the 

general monitoring conditions for all 

engines described in section II.A.3. 

Additionally, monitoring for ‘‘time to 

reach closed-loop/feedback enable 

temperature’’ malfunctions would have 

to be conducted once per drive cycle on 

every drive cycle in which the ECT 

sensor at engine start indicates a 

temperature lower than the closed-loop 

enable temperature (i.e., all engine start 

temperatures greater than the ECT 

sensor out-of-range low temperature and 

less than the closed-loop enable 

temperature). Manufacturers would be 

allowed to suspend or delay the ‘‘time 

to reach closed-loop/feedback enable 

temperature’’ monitor if the engine is 

subjected to conditions that could lead 

to false diagnosis (e.g., vehicle operation 

at idle for more than 50 to 75 percent 

of the warm-up time). 

We are also proposing that 

manufacturers define the monitoring 

conditions for ECT sensor ‘‘stuck in a 

range below the highest minimum 

enable temperature’’ and ‘‘stuck in a 

range above the lowest maximum enable 

temperature’’ malfunctions in 

accordance with the general monitoring 

conditions for all engines described in 

section II.A.3 and in accordance with 

the minimum performance ratio 

requirements discussed in section II.E. 

d. Engine Cooling System MIL 

Illumination and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. 

3. Crankcase Ventilation System 

Monitoring 

a. Background 

Crankcase emissions are the 

pollutants emitted in the gases that are 

vented from an engine’s crankcase. 

These gases are also referred to as 

‘‘blowby gases’’ because they result from 

engine exhaust from the combustion 

chamber ‘‘blowing by’’ the piston rings 

into the crankcase. These gases are 

vented to prevent high pressures from 

occurring in the crankcase. Our 

emission standards have historically 

prohibited crankcase emissions from all 

highway engines except turbocharged 

heavy-duty diesel engines. The most 

common way to eliminate crankcase 

emissions has been to vent the blowby 

gases into the engine air intake system, 

so that the gases can be recombusted. 

We made the exception for turbocharged 

heavy-duty diesel engines in the past 

because of concerns about fouling that 

could occur by routing the diesel 

particulates (including engine oil) into 

the turbocharger and aftercooler. Newly 

developed closed crankcase filtration 

systems specifically designed for 

turbocharged heavy-duty diesel engines 

now allow the crankcase gases to be 

captured. 

In general, the crankcase ventilation 

system consists of a fresh air inlet hose, 

a crankcase vapor outlet hose, and a 

crankcase ventilation valve to control 

the flow through the system. Fresh air 

is introduced to the crankcase via the 

inlet (typically a connection from the 

intake air cleaner assembly). On the 

opposite side of the crankcase, vapors 

are vented from the crankcase through 

the valve by way of the outlet hose and 

then to the intake manifold. On gasoline 

engines, the intake manifold provides 

the vacuum that is needed to 

accomplish the circulation while the 

engine is running. 

For gasoline engines, the valve is used 

to regulate the amount of flow based on 

engine speed. During low engine load 

operation (e.g., idle), the valve is nearly 

closed allowing only a small portion of 

air to flow through the system. With 

open throttle conditions, the valve 

opens to allow more air into the system. 

At high engine load operation (i.e., hard 

accelerations), the valve begins to close 

again, limiting air flow to a small 

amount. For most systems, a mechanical 

valve is all that is necessary to 

adequately regulate crankcase 

ventilation system air flow. The 

crankcase ventilation system on diesel 

engines, while slightly different than 

that for gasoline engines, has essentially 

the same purpose and function. 

We do not believe that failures 

involving cracked or deteriorated hoses 

have a significant impact on crankcase 

emissions because vapors are drawn 

into the engine by intake manifold 

vacuum which suggests that fresh air 

would be drawn into the cracked hose 

rather than dirty exhaust being blown 

out of the cracked hose. The more likely 

cause of crankcase ventilation system 

malfunctions and excess emissions is 

improper service or tampering of the 

system. Such failures include misrouted 

or disconnected hoses and missing 

valves. Of these failures, hose 

disconnections on the vapor vent side of 

the system and/or missing valves can 

cause harmful crankcase emissions to be 

vented directly to the atmosphere. 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3235 

43When referring to ‘‘comprehensive 

components’’ and their monitors, ‘‘electronic engine 

components/systems’’ is not meant to include 

components/systems that are driven by the engine 

yet are not related to the control of the fueling, air 

handling, or emissions of the engine (e.g., PTO 

components, air conditioning system components, 

and power steering components are not included). 

b. Crankcase Ventilation System 

Monitoring Requirements 

We are proposing that the OBD 

system monitor the crankcase 

ventilation system on engines so 

equipped for system integrity. Engines 

not equipped with crankcase ventilation 

systems would be exempt from 

monitoring the crankcase ventilation 

system. 

Specifically for diesel engines, the 

manufacturer would be required to 

submit a plan for the monitoring 

strategy, malfunction criteria, and 

monitoring conditions prior to OBD 

certification. The plan would have to 

demonstrate the effectiveness of the 

strategy to monitor the performance of 

the crankcase ventilation system to the 

extent feasible with respect to the 

malfunction criteria below and the 

monitoring conditions required by the 

monitor. 

We are proposing that the OBD 

system detect a malfunction of the 

crankcase ventilation system when a 

disconnection of the system occurs 

between either the crankcase and the 

crankcase ventilation valve, or between 

the crankcase ventilation valve and the 

intake manifold. Manufacturers may 

forego detecting a disconnection 

between the crankcase and the 

crankcase ventilation valve provided the 

manufacturer can demonstrate that the 

crankcase ventilation system is designed 

such that the crankcase ventilation 

valve is fastened directly to the 

crankcase in a manner that makes it 

significantly more difficult to remove 

the valve from the crankcase than to 

disconnect the line between the valve 

and the intake manifold (aging effects 

must be taken into consideration). 

Manufacturers may also forego detecting 

a disconnection between the crankcase 

and the crankcase ventilation valve for 

system designs that use tubing between 

the valve and the crankcase provided 

the manufacturer can demonstrate that 

the connections between the valve and 

the crankcase are: (1) Resistant to 

deterioration or accidental 

disconnection; (2) significantly more 

difficult to disconnect than the line 

between the valve and the intake 

manifold; and, (3) not subject to 

disconnection per the manufacturer’s 

repair procedures for non-crankcase 

ventilation system repair work. Lastly, 

manufacturers may forego detecting a 

disconnection between the crankcase 

ventilation valve and the intake 

manifold upon determining that the 

disconnection: (1) Causes the vehicle to 

stall immediately during idle operation; 

or, (2) is unlikely to occur due to a 

crankcase ventilation system design that 

is integral to the induction system (e.g., 

machined passages rather than tubing or 

hoses). 

c. Crankcase Ventilation System 

Monitoring Conditions 

We are proposing that manufacturers 

define the monitoring conditions for 

crankcase ventilation system 

malfunctions in accordance with the 

general monitoring conditions for all 

engines described in section II.A.3, and 

the minimum performance ratio 

requirements discussed in section II.E. 

d. Crankcase Ventilation System MIL 

Illumination and DTC Storage 

We are proposing the general 

requirements for MIL illumination and 

DTC storage as discussed in section 

II.A.2. The stored DTC need not 

specifically identify the crankcase 

ventilation system (e.g., a DTC for idle 

speed control or fuel system monitoring 

can be stored) if the manufacturer can 

demonstrate that additional monitoring 

hardware would be necessary to make 

this identification, and provided the 

manufacturer’s diagnostic and repair 

procedures for the detected malfunction 

include directions to check the integrity 

of the crankcase ventilation system. 

4. Comprehensive Component Monitors 

a. Background 

Comprehensive components is a term 

meant to capture essentially every other 

emissions related component not 

discussed above. Specifically, it covers 

all other electronic engine components 

or systems not mentioned above that 

either can affect vehicle emissions or are 

used as part of the OBD diagnostic 

strategy for another monitored 

component or system. Comprehensive 

components are generally identified as 

input components—i.e., those that 

provide input directly or indirectly to 

the onboard computer—or as output 

components and/or systems—i.e., those 

that receive commands from the 

onboard computer. Typical examples of 

input components include temperature 

sensors and pressure sensors, while 

examples of output components and/or 

systems include the idle control system, 

glow plugs, and wait-to-start lamps. 

While a malfunctioning 

comprehensive component may not 

have as much impact on emissions as a 

malfunctioning major emissions-related 

component, it still could result in a 

measurable increase in emissions. The 

proper performance of these 

components can be critical to both the 

proper functioning of major emissionsrelated components, and to the accurate 

monitoring of those components or 

systems. Malfunctions of 

comprehensive components that go 

undetected by the OBD system may 

disable or adversely affect the 

robustness of other OBD monitors 

without any awareness by the operator 

that a problem exists. Due to the vital 

role these components play, monitoring 

them properly is extremely important. 

b. Comprehensive Component 

Monitoring Requirements 

We are proposing that the OBD 

system monitor for malfunction any 

electronic engine components/systems 

not otherwise described in sections 

above that either provides input to 

(directly or indirectly) or receives 

commands from the onboard 

computer(s), and: (1) Can affect 

emissions during any reasonable in-use 

driving condition; or, (2) is used as part 

of the diagnostic strategy for any other 

monitored system or component.43

Input components required to be 

monitored may include the crank angle 

sensor, knock sensor, throttle position 

sensor, cam position sensor, intake air 

temperature sensor, boost pressure 

sensor, manifold pressure sensor, mass 

air flow sensor, exhaust temperature 

sensor, exhaust pressure sensor, fuel 

pressure sensor, and fuel composition 

sensor (e.g., flexible fuel vehicles). 

Output components/systems required to 

be monitored may include the idle 

speed control system, glow plug system, 

variable length intake manifold runner 

systems, supercharger or turbocharger 

electronic components, heated fuel 

preparation systems, the wait-to-start 

lamp on diesel applications, and the 

MIL. The manufacturer would be 

responsible for determining which input 

and output components/systems could 

affect emissions during any reasonable 

in-use driving condition. The 

manufacturer would be allowed to make 

this determination based on data or 

engineering judgment. However, if the 

Administrator reasonably believes that a 

manufacturer has incorrectly 

determined that a component/system 

cannot affect emissions, the 

manufacturer may be required to 

provide emissions data showing that the 

component/system, when 

malfunctioning and installed in a 

suitable test engine, does not have an 

emissions effect. Such emissions data 

may be requested for any reasonable 

driving condition. 


sroberts on PROD1PC70 with PROPOSALS
3236 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

i. Input Components 

We are proposing that the OBD 

system detect malfunctions of input 

components caused by a lack of circuit 

continuity, out-of-range values, and, 

where feasible, improper rationality. To 

the extent feasible, the rationality 

diagnostics should verify that a sensor’s 

input to the onboard computer is 

neither inappropriately high nor 

inappropriately low (i.e., ‘‘two-sided’’

diagnostics should be used). Also to the 

extent feasible, the OBD system should 

detect and store different DTCs that 

distinguish rationality malfunctions 

from lack of circuit continuity 

malfunctions and out-of-range values. 

For lack of circuit continuity 

malfunctions and out-of-range values, 

the OBD system should detect and store 

different DTCs for each distinct 

malfunction (e.g., out-of-range low, outof-range high, open circuit). The OBD 

system is not required to store separate 

DTCs for lack of circuit continuity 

malfunctions that cannot be 

distinguished from malfunctions 

associated with out-of-range values. 

For input components that are used to 

activate alternative strategies that can 

affect emissions (e.g., AECDs, engine 

shutdown systems), the OBD system 

would be required to detect rationality 

malfunctions that cause the system to 

erroneously activate or deactivate the 

alternative strategy. To the extent 

feasible when using all available 

information, the rationality diagnostics 

should detect a malfunction if the input 

component inappropriately indicates a 

value that activates or deactivates the 

alternative strategy. For example, if an 

alternative strategy requires an intake 

air temperature greater than 120 degrees 

Fahrenheit prior to activating, the OBD 

system should detect malfunctions that 

cause the intake air temperature sensor 

to inappropriately indicate a 

temperature above 120 degrees 

Fahrenheit. 

For engines that require precise 

alignment between the camshaft and the 

crankshaft, the OBD system would be 

required to monitor the crankshaft 

position sensor(s) and camshaft position 

sensor(s) to verify proper alignment 

between the camshaft and crankshaft. 

The OBD system would also have to 

monitor the sensors for circuit 

continuity and rationality malfunctions. 

Such monitoring for proper alignment 

between a camshaft and a crankshaft 

would only be required in cases where 

both are equipped with position 

sensors. 

For engines equipped with VVT 

systems and a timing belt or chain, the 

OBD system must detect a malfunction 

if the alignment between the camshaft 

and crankshaft is off by one or more 

cam/crank sprocket cogs (e.g., the 

timing belt/chain has slipped by one or 

more teeth/cogs). If a manufacturer 

demonstrates that a single tooth/cog 

misalignment cannot cause a 

measurable increase in emissions during 

any reasonable driving condition, the 

OBD system would be required to detect 

a malfunction when the minimum 

number of teeth/cogs misalignment 

needed to cause a measurable emission 

increase has occurred. 

ii. Output Components/Systems 

We are proposing that the OBD 

system detect a malfunction of an 

output component/system when proper 

functional response of the component/ 

system to computer commands does not 

occur. If a functional check is not 

feasible, the OBD system would be 

required to detect malfunctions caused 

by a lack of circuit continuity (e.g., short 

to ground or high voltage). For output 

component malfunctions associated 

with the lack of circuit continuity, the 

OBD system is not required to store 

different DTCs for each distinct 

malfunction (e.g., open circuit, shorted 

low). Further, manufacturers would not 

be required to activate an output 

component/system when it would not 

normally be active for the exclusive 

purpose of performing functional 

monitoring of output components/ 

systems. 

Additionally, the idle control system 

would have to be monitored for proper 

functional response to computer 

commands. For gasoline engines that 

use monitoring strategies based on 

deviation from target idle speed, a 

malfunction would have to be detected 

when either of the following conditions 

occur: (a) The idle speed control system 

cannot achieve the target idle speed 

within 200 revolutions per minute (rpm) 

above the target speed or 100 rpm below 

the target speed—the OBD system could 

use larger engine speed tolerances 

provided the manufacturer is able to 

demonstrate via data and/or engineering 

analyses that the tolerances can be 

exceeded without a malfunction being 

present; or, (b) the idle speed control 

system cannot achieve the target idle 

speed within the smallest engine speed 

tolerance range required by the OBD 

system to enable any other OBD 

monitors. For diesel engines, a 

malfunction would have to be detected 

when either of the following conditions 

occur: (a) The idle fuel control system 

cannot achieve the target idle speed or 

fuel injection quantity within +/¥50 

percent of the manufacturer-specified 

fuel quantity and engine speed 

tolerances; or, (b) the idle fuel control 

system cannot achieve the target idle 

speed or fueling quantity within the 

smallest engine speed or fueling 

quantity tolerance range required by the 

OBD system to enable any other OBD 

monitors. 

Glow plugs and intake air heater 

systems would also have to be 

monitored for proper functional 

response to computer commands and 

for malfunctions associated with circuit 

continuity. The glow plug and intake air 

heater circuit(s) would have to be 

monitored for proper current and 

voltage drop. The manufacturer may use 

other monitoring strategies by 

submitting data and/or engineering 

analyses that demonstrate that the 

strategy provides equally reliable and 

timely detection of malfunctions. In 

general, the OBD system would have to 

detect a malfunction when a single glow 

plug no longer operates within the 

manufacturer’s specified limits for 

normal operation. If a manufacturer 

demonstrates that a single glow plug 

malfunction cannot cause a measurable 

increase in emissions during any 

reasonable driving condition, the OBD 

system must detect a malfunction for 

the minimum number of glow plugs 

needed to cause an emissions increase. 

Further, to the extent feasible without 

adding additional hardware for this 

purpose, the stored DTC must identify 

the specific malfunctioning glow 

plug(s). 

Lastly, the wait-to-start lamp circuit 

and the MIL circuit would have to be 

monitored for malfunctions that cause 

either lamp to fail to illuminate when 

commanded on (e.g., burned out bulb). 

c. Comprehensive Component 

Monitoring Conditions 

i. Input Components 

We are proposing that input 

components be monitored continuously 

for circuit continuity and for providing 

values within the proper range. For 

rationality monitoring, where 

applicable, manufacturers would define 

the monitoring conditions for detecting 

malfunctions in accordance with the 

general monitoring conditions for all 

engines described in section II.A.3 and 

the minimum performance ratio 

requirements described in section II.E 

except that rationality monitoring 

would have to occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in section II.A.3. 

A manufacturer may disable 

continuous monitoring for circuit 

continuity, and for providing values 

within the proper range, when a 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3237 

malfunction cannot be distinguished 

from other effects. To do so, the 

manufacturer would have to submit data 

and/or engineering analyses that 

demonstrate that a properly functioning 

input component cannot be 

distinguished from a malfunctioning 

input component and that the 

disablement interval is limited only to 

that necessary for avoiding false 

detection. 

ii. Output Components/Systems 

We are proposing that output 

components/systems be monitored 

continuously for circuit continuity. For 

functional monitoring, manufacturers 

would define the monitoring conditions 

for detecting malfunctions in 

accordance with the general monitoring 

conditions for all engines described in 

section II.A.3 and the minimum 

performance ratio requirements 

described in section II.E. 

For the idle control system, we are 

proposing that manufacturers define the 

monitoring conditions for functional 

monitoring in accordance with the 

general monitoring conditions for all 

engines described in section II.A.3 and 

the minimum performance ratio 

requirements described in section II.E 

except that functional monitoring would 

have to occur every time the monitoring 

conditions are met during the drive 

cycle rather than once per drive cycle as 

required in section II.A.3. 

A manufacturer may disable 

continuous monitoring for circuit 

continuity when a malfunction cannot 

be distinguished from other effects. To 

do so, the manufacturer would have to 

submit data and/or engineering analyses 

that demonstrate that a properly 

functioning output component cannot 

be distinguished from a malfunctioning 

output component and that the 

disablement interval is limited only to 

that necessary for avoiding false 

detection. 

d. Comprehensive Component MIL 

Illumination and DTC Storage 

With a couple of exceptions, we are 

proposing the general requirements for 

MIL illumination and DTC storage as 

discussed in section II.A.2. The 

exceptions to this being that MIL 

illumination would not be required in 

conjunction with storing a MIL-on DTC 

for any comprehensive component if: (a) 

The component or system, when 

malfunctioning, could not cause engine 

emissions to increase by 15 percent or 

more of the FTP standard during any 

reasonable driving condition; and, (b) 

the component or system is not used as 

part of the diagnostic strategy for any 

other monitored system or component. 

MIL illumination is also not required if 

a malfunction has been detected in the 

MIL circuit that prevents the MIL from 

illuminating (e.g., burned out bulb or 

light emitting diode (LED)). However, 

the electronic MIL status must be 

reported as ‘‘commanded on’’ and a 

MIL-on DTC would have to be stored. 

5. Other Emissions Control System 

Monitoring 

a. Background 

As noted above, the primary purpose 

of OBD is to detect malfunctions in the 

engine and/or emissions control system. 

Therefore, we are proposing that 

manufacturers be required to submit to 

the Administrator a monitoring plan for 

any new engine and/or emissions 

control technology not otherwise 

described above. Such technology might 

include hydrocarbon traps or 

homogeneous charge compression 

ignition (HCCI) systems. This would 

allow manufacturers and EPA to 

evaluate the new technology and 

determine an appropriate level of 

monitoring that would be both 

technologically feasible and consistent 

with the monitoring requirements for 

the other emissions control devices 

described above. 

As proposed, the Administrator 

would provide guidance as to what type 

of components would fall under the 

‘‘other emissions control system’’

requirements and which would fall 

under the comprehensive component 

requirements. Specifically, we are 

concerned that uncertainty may arise for 

those emission control components or 

systems that also meet the definition of 

electronic engine components. As such, 

the proposal would delineate the two by 

requiring components/systems that fit 

both definitions but are not corrected or 

compensated for by the adaptive fuel 

control system to be monitored as 

‘‘other emissions control devices’’ rather 

than as comprehensive components. A 

typical device that would fall under this 

category instead of the comprehensive 

components category because of this 

delineation would be a swirl control 

valve system. Such delineation is 

necessary because such emissions 

control components generally require 

more thorough monitoring than 

comprehensive components to ensure 

low emissions levels throughout an 

engine’s life. Further, emissions control 

components that are not compensated 

for by the fuel control system as they 

age or deteriorate can have a larger 

impact on tailpipe emissions than is 

typical of comprehensive components 

that are corrected for by the fuel control 

system as they deteriorate. 

Note that the Administrator does not 

foresee any outcome where a promising 

new emissions control technology 

would be prohibited based solely on the 

lack of an OBD monitoring strategy for 

it. Instead, we want to instill in 

manufacturers the need to consider OBD 

monitoring when developing any new 

emissions control technology. Further, 

we want to instill in manufacturers the 

sense that an OBD monitoring strategy 

will, one day, be necessary so a plan for 

such should exist prior to introducing 

the technology on new products. 

b. Other Emissions Control System 

Monitoring Requirements/Conditions 

We are proposing that, for other 

emission control systems that are: (1) 

Not identified or addressed in sections 

II.B through II.D.4—e.g., hydrocarbon 

traps, HCCI control systems; or, (2) 

identified or addressed in section II.D.4 

but not corrected or compensated for by 

an adaptive control system—e.g., swirl 

control valves, manufacturers would be 

required to submit a plan for 

Administrator approval of the 

monitoring strategy, the malfunction 

criteria, and the monitoring conditions 

prior to introduction on a production 

engine. Administrator approval of the 

plan would be based on the 

effectiveness of the monitoring strategy, 

the robustness of the malfunction 

criteria, and the frequency of meeting 

the necessary monitoring conditions. 

We are also proposing that, for 

engines that use emissions control 

systems that alter intake air flow or 

cylinder charge characteristics by 

actuating valve(s), flap(s), etc., in the 

intake air delivery system (e.g., swirl 

control valve systems), the 

manufacturers, in addition to meeting 

the requirements above, may elect to 

have the OBD system monitor the shaft 

to which all valves in one intake bank 

are physically attached rather than 

monitoring the intake air flow, cylinder 

charge, or individual valve(s)/flap(s) for 

proper functional response. For nonmetal shafts or segmented shafts, the 

monitor must verify all shaft segments 

for proper functional response (e.g., by 

verifying the segment or portion of the 

shaft furthest from the actuator 

functions properly). For systems that 

have more than one shaft to operate 

valves in multiple intake banks, 

manufacturers are not required to add 

more than one set of detection hardware 

(e.g., sensor, switch) per intake bank to 

meet this requirement. 


sroberts on PROD1PC70 with PROPOSALS
3238 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

6. Exceptions to Monitoring 

Requirements 

a. Background 

Under some conditions, the reliability 

of specific monitors may be diminished 

significantly. Therefore, we are 

proposing to allow manufacturers to 

disable the affected monitors when 

these conditions are encountered in-use. 

These include situations of extreme 

conditions (e.g., very low ambient 

temperatures, high altitudes) and of 

periods where default modes of 

operation are active (e.g., when a tire 

pressure problem is detected). In some 

of these cases, we may allow 

manufacturers to revise the emission 

malfunction threshold to ensure the 

most reliable monitoring performance. 

b. Requirements for Exceptions to 

Monitoring 

The Administrator may revise the 

emission threshold for any monitor, or 

revise the PM filtering performance 

malfunction criteria for DPFs to exclude 

detection of specific failure modes such 

as partially melted substrates, if the 

most reliable monitoring method 

developed requires a higher threshold 

or, in the case of PM filtering 

performance, the exclusion of specific 

failure modes, to prevent significant 

errors of commission in detecting a 

malfunction. The Administrator would 

notify the industry of any such revisions 

to ensure that all manufacturers would 

be able to implement OBD on an equal 

basis. In other words, we would not 

allow one manufacturer to revise a 

specific monitoring threshold upwards 

while insisting that another meet the 

proposed threshold. 

Manufacturers may disable an OBD 

system monitor at ambient engine start 

temperatures below 20 degrees 

Fahrenheit (low ambient temperature 

conditions may be determined based on 

intake air or engine coolant temperature 

at engine start) or at elevations higher 

than 8000 feet above sea level. To do so, 

the manufacturer would have to submit 

data and/or engineering analyses that 

demonstrate that monitoring would be 

unreliable during the disable 

conditions. A manufacturer may request 

that an OBD system monitor be disabled 

at other ambient engine start 

temperatures by submitting data and/or 

engineering analyses demonstrating that 

misdiagnosis would occur at the given 

ambient temperatures due to their effect 

on the component itself (e.g., 

component freezing). 

Manufacturers may disable an OBD 

system monitor when the fuel level is 15 

percent or less of the nominal fuel tank 

capacity for those monitors that can be 

affected by low fuel level or running out 

of fuel (e.g., misfire detection). To do so, 

the manufacturer would have to submit 

data and/or engineering analyses that 

demonstrate that both monitoring at the 

given fuel levels would be unreliable, 

and the OBD system is still able to 

detect a malfunction if the component(s) 

used to determine fuel level indicates 

erroneously a fuel level that causes the 

disablement. 

Manufacturers may disable OBD 

monitors that can be affected by vehicle 

battery or system voltage levels. For an 

OBD monitor affected by low vehicle 

battery or system voltages, 

manufacturers may disable monitoring 

when the battery or system voltage is 

below 11.0 Volts. Manufacturers may 

use a voltage threshold higher than 11.0 

Volts to disable monitors but would 

have to submit data and/or engineering 

analyses that demonstrate that 

monitoring at those voltages would be 

unreliable and that either operation of a 

vehicle below the disablement criteria 

for extended periods of time is unlikely 

or the OBD system monitors the battery 

or system voltage and would detect a 

malfunction at the voltage used to 

disable other monitors. 

For monitoring systems affected by 

high vehicle battery or system voltages, 

manufacturers may disable monitoring 

when the battery or system voltage 

exceeds a manufacturer-defined voltage. 

To do so, the manufacturer would have 

to submit data and/or engineering 

analyses that demonstrate that 

monitoring above the manufacturerdefined voltage would be unreliable and 

that either the electrical charging 

system/alternator warning light would 

be illuminated (or voltage gauge would 

be in the ‘‘red zone’’) or the OBD system 

monitors the battery or system voltage 

and would detect a malfunction at the 

voltage used to disable other monitors. 

A manufacturer may also disable 

affected OBD monitors in vehicles 

designed to accommodate the 

installation of power take off (PTO) 

units provided disablement occurs only 

while the PTO unit is active and the 

OBD readiness status is cleared by the 

onboard computer (i.e., all monitors set 

to indicate ‘‘not complete’’) while the 

PTO unit is activated (see section II.F.4 

below). If the disablement occurs, the 

readiness status may be restored, when 

the disablement ends, to its state prior 

to PTO activation. 

E. A Standardized Method To Measure 

Real World Monitoring Performance 

As was noted in section II.A.3, 

manufacturers determine the most 

appropriate times to run the noncontinuous OBD monitors. This way, 

they are able to make their OBD 

evaluation either at the operating 

condition when an emissions control 

system is active and its operational 

status can best be evaluated, and/or at 

the operating condition when the most 

accurate evaluation can be made (e.g., 

highly transient conditions or extreme 

conditions can make evaluation 

difficult). Importantly, manufacturers 

are prohibited from using a monitoring 

strategy that is so restrictive such that it 

rarely or never runs. To help protect 

against monitors that rarely run, we are 

proposing an ‘‘in-use monitor 

performance ratio’’ requirement as 

described here. 

The set of operating conditions that 

must be met so that an OBD monitor can 

run are called the ‘‘enable criteria’’ for 

that given monitor. These enable criteria 

are often different for different monitors 

and may well be different for different 

types of engines. A large diesel engine 

intended for use in a Class 8 truck 

would be expected to see long periods 

of relatively steady-state operation 

while a smaller engine intended for use 

in an urban delivery truck would be 

expected to see a lot of transient 

operation. Manufacturers will need to 

balance between a rather loose set of 

enable criteria for their engines and 

vehicles given the very broad range of 

operation HD highway engines see and 

a tight set of enable criteria given the 

desire for greater monitor accuracy. 

Manufacturers would be required to 

design these enable criteria so that the 

monitor: 

• Is robust (i.e., accurate at making 

pass/fail decisions); 

• Runs frequently in the real world; 

and, 

• In general, also runs during the FTP 

heavy-duty transient cycle. 

If designed incorrectly, these enable 

criteria may be either too broad and 

result in inaccurate monitors, or overly 

restrictive thereby preventing the 

monitor from executing frequently in 

the real world. 

Since the primary purpose of an OBD 

system is to monitor for and detect 

emission-related malfunctions while the 

engine is operating in the real world, a 

standardized methodology for 

quantifying real world performance 

would be beneficial to both EPA and 

manufacturers. Generally, in 

determining whether a manufacturer’s 

monitoring conditions are sufficient, a 

manufacturer would discuss the 

proposed monitoring conditions with 

EPA staff. The finalized conditions 

would be included in the certification 

applications and submitted to EPA staff 

who would review the conditions and 

make determinations on a case-by-case 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3239 

basis based on the engineering judgment 

of the staff. In cases where we are 

concerned that the documented 

conditions may not be met during 

reasonable in-use driving conditions, we 

would most likely ask the manufacturer 

for data or other engineering analyses 

used by the manufacturer to determine 

that the conditions would occur in-use. 

In proposing a standardized 

methodology for quantifying real world 

performance, we believe this review 

process can be done more efficiently 

than would occur otherwise. 

Furthermore, it would serve to ensure 

that all manufacturers are held to the 

same standard for real world 

performance. Lastly, we want review 

procedures that will ensure that 

monitors operate properly and 

frequently in the field. 

Therefore, we are proposing that all 

manufacturers be required to use a 

standardized method for determining 

real world monitoring performance and 

to hold manufacturers liable if 

monitoring occurs less frequently than a 

minimum acceptable level, expressed as 

minimum acceptable in-use 

performance ratio. We are also 

proposing that manufacturers be 

required to implement software in the 

onboard computer to track how often 

several of the major monitors (e.g., 

catalyst, EGR, CDPF, other diesel 

aftertreatment devices) execute during 

real world driving. The onboard 

computer would keep track of how 

many times each of these monitors has 

executed and how much the engine has 

been operated. By measuring both of 

these values, the ratio of monitor 

operation relative to engine operation 

can be calculated to determine 

monitoring frequency. 

The proposed minimum acceptable 

frequency requirement would apply to 

many but not all of the OBD monitors. 

We are proposing that monitors be 

required to operate either continuously, 

once per drive cycle, or, in a few cases, 

multiple times per drive cycle (i.e., 

whenever the proper monitoring 

conditions are present). For components 

or systems that are more likely to 

experience intermittent failures or 

failures that can routinely happen in 

distinct portions of an engine’s 

operating range (e.g., only at high engine 

speed and load, only when the engine 

is cold or hot), monitors would be 

required to operate continuously. 

Examples of continuous monitors 

include the fuel system monitor and 

most electrical/circuit continuity 

monitors. For components or systems 

that are less likely to experience 

intermittent failures or failures that only 

occur in specific vehicle operating 

regions or for components or systems 

where accurate monitoring can only be 

performed under limited operating 

conditions, monitors would be required 

to run once per drive cycle. Examples of 

once per drive cycle monitors typically 

include gasoline catalyst monitors, 

evaporative system leak detection 

monitors, and output comprehensive 

component functional monitors. For 

components or systems that are 

routinely used to perform functions that 

are crucial to maintaining low emissions 

but may still require monitoring under 

fairly limited conditions, monitors 

would be required to run each and every 

time the manufacturer-defined enable 

conditions are present. Examples of 

multiple times per drive cycle monitors 

typically include input comprehensive 

component rationality monitors and 

some exhaust aftertreatment monitors. 

Monitors required to run 

continuously, by definition, would 

always be running, thereby making a 

minimum frequency requirement moot. 

The new frequency requirement would 

essentially apply only to those monitors 

that are designated as once per drive 

cycle or multiple times per drive cycle 

monitors. For all of these monitors, 

manufacturers would be required to 

define monitoring conditions that 

ensure adequate frequency in-use. 

Specifically, the monitors would need 

to run often enough so that the 

measured monitor frequency on in-use 

engines would exceed the minimum 

acceptable frequency. However, even 

though the minimum frequency 

requirement would apply to nearly all 

once per drive cycle and multiple times 

per drive cycle monitors, manufacturers 

would only be required to implement 

software to track and report the in-use 

frequency for a few of the major 

monitors. These few monitors generally 

represent the major emissions control 

components and the ones with the most 

limited enable criteria. 

We believe that OBD monitors should 

run frequently to ensure early detection 

of emissions-related malfunctions and, 

consequently, to maintain low 

emissions. Allowing malfunctions to 

continue undetected and unrepaired for 

long periods of time allows emissions to 

increase unnecessarily. Frequent 

monitoring can also help to ensure 

detection of intermittent emissionsrelated malfunctions (i.e., those that are 

not continuously present but occur 

sporadically for days and even weeks at 

a time). The nature of mechanical and 

electrical systems is that intermittent 

malfunctions can and do occur. The less 

frequent the monitoring, the less likely 

these malfunctions will be detected and 

repaired. Additionally, for both 

intermittent and continuous 

malfunctions, earlier detection is 

equivalent to preventative maintenance 

in that the original malfunction can be 

detected and repaired prior to it causing 

subsequent damage to other 

components. This can help vehicle 

operators avoid more costly repairs that 

could have resulted had the first 

malfunction gone undetected. 

Infrequent monitoring can also have 

an impact on the service and repair 

industry. Specifically, monitors that 

have unreasonable or overly restrictive 

enable conditions could hinder vehicle 

repair services. In general, upon 

completing an OBD-related repair to an 

engine, a technician will attempt to 

verify that the repair has indeed fixed 

the problem. Ideally, a technician will 

operate the vehicle in a manner that will 

exercise the appropriate OBD monitor 

and allow the OBD system to confirm 

that the malfunction is no longer 

present. This affords a technician the 

highest level of assurance that the repair 

was indeed successful. However, OBD 

monitors that operate infrequently are 

difficult to exercise and, therefore, 

technicians may not be able (or may not 

be likely) to perform such post-repair 

evaluations. Despite the service 

information availability requirements 

we are proposing—requirements that 

manufacturers make all of their service 

and repair information available to all 

technicians, including the information 

necessary to exercise OBD monitors—

technicians would still find it difficult 

to exercise monitors that require 

infrequently encountered engine 

operating conditions (e.g., abnormally 

steady constant speed operation for an 

extended period of time). Additionally, 

to execute OBD monitors in an 

expeditious manner or to execute 

monitors that would require unusual or 

infrequently encountered conditions, 

technicians may be required to operate 

the vehicle in an unsafe manner (e.g., at 

freeway speeds on residential streets or 

during heavy traffic). If unsuccessful in 

executing these monitors, technicians 

may even take shortcuts in attempting to 

validate the repair while maintaining a 

reasonable cost for customers. These 

shortcuts would likely not be as 

thorough in verifying repairs and could 

increase the chance that improperly 

repaired engines would be returned to 

the vehicle owner or additional repairs 

would be performed just to ensure the 

problem is fixed. In the end, monitors 

that operate less frequently can result in 

unnecessary costs and inconvenience to 

both vehicle owners and technicians. 


sroberts on PROD1PC70 with PROPOSALS
3240 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

1. Description of Software Counters to 

Track Real World Performance 

As stated above, manufacturers would 

be required to track monitor peformance 

by comparing the number of monitoring 

events (i.e., how often each monitor has 

run) to the number of driving events 

(i.e., how often has the vehicle been 

operated). The ratio of these two 

numbers would give an indication of 

how often the monitor is operating 

relative to vehicle operation. In equation 

form, this can be stated as: 

In-Use Performance (Ratio) = Number of Monitoring Events (Numerator)

Number of Driving Events (Denominator)

To ensure that all manufacturers are 

tracking in-use performance in the same 

manner, we are proposing very detailed 

requirements for defining and 

incrementing both the numerator and 

denominator of this ratio. Manufacturers 

would be required to keep track of 

separate numerators and denominators 

for each of the major monitors, and to 

ensure that the data are saved every 

time the engine is shut off. The 

numerators and denominators would be 

reset to zero only in extreme 

circumstances when the non-volatile 

memory has been cleared (e.g., when the 

onboard computer has been 

reprogrammed in the field or when the 

onboard computer memory has been 

corrupted). The values would not be 

reset to zero during normal occurrences 

such as clearing of stored DTCs or 

performing routine service or 

maintenance. 

Further, the numerator and 

denominator would be structured such 

that their maximum values would be 

65,535 which is the maximum number 

that can be stored in a 2-byte location. 

This would ensure that manufacturers 

allocate sufficient and consistent 

memory space in the onboard computer. 

If either the numerator or denominator 

for a particular monitor reaches the 

maximum value, both values for that 

particular monitor would be divided by 

two before counting resumes. In general, 

the numerator and denominator would 

only be allowed to increment a 

maximum of once per drive cycle 

because most of the major monitors are 

designed to operate only once per drive 

cycle. Additionally, incrementing of 

both the numerator and denominator for 

a particular monitor would be disabled 

(i.e., paused but the stored values would 

not be erased or reset) only when a 

problem has been detected (i.e., a 

pending or MIL-on DTC has been 

stored) that prevents the monitor from 

executing. Once the problem is no 

longer detected and any stored DTCs 

associated with the problem have been 

erased, either through the allowable 

self-clearing process or upon command 

by a technician via a scan tool, 

incrementing of both the numerator and 

denominator would resume. 

SAE has developed standards for 

storing and reporting the data to a 

generic scan tool. This would help 

ensure that all manufacturers report the 

data in an identical manner which 

should ease data collection in the field. 

a. Number of Monitoring Events 

(‘‘Numerator’’) 

For the numerator, manufacturers 

would be required to keep a separate 

numeric count of how often each of the 

particular monitors has operated. More 

specifically, manufacturers would have 

to implement a software counter that 

increments by one every time the 

particular monitor meets all of the 

enable/monitoring conditions for a long 

enough period of time such that a 

malfunctioning component would have 

been detected. For example, if a 

manufacturer requires a vehicle to be 

warmed-up and at idle for 20 seconds 

continuously to detect a malfunctioning 

catalyst, the catalyst monitor numerator 

could only be incremented if the vehicle 

actually operates simultaneously in all 

of those conditions. If the vehicle is 

operated in some but not all of the 

conditions (e.g., at idle but not warmedup), the numerator would not be 

allowed to increment because the 

monitor would not have been able to 

detect a malfunctioning catalyst since 

all of the conditions were not satisfied 

simultaneously. 

Another complication is the 

difference between a monitor reaching a 

‘‘pass’’ or ‘‘fail’’ decision. At first glance, 

it would appear that a manufacturer 

should simply increment the numerator 

anytime the particular monitor reaches 

a decision, be it ‘‘pass’’ or ‘‘fail’’. 

However, monitoring strategies may 

have a different set of criteria that must 

be met to reach a ‘‘pass’’ decision versus 

a ‘‘fail’’ decision. As a simple example, 

a manufacturer may appropriately 

require only 10 seconds of operation at 

idle to reach a ‘‘pass’’ decision but 

require 30 seconds of operation at idle 

to reach a ‘‘fail’’ decision. 

Manufacturers would not be allowed to 

increment the numerator if the vehicle 

had idled for 10 seconds and reached a 

‘‘pass’’ decision since insufficient time 

had passed to allow for a possible ‘‘fail’’

decision. This is necessary because the 

primary function of OBD systems is to 

detect malfunctions (i.e., to correctly 

reach ‘‘fail’’ decisions, not ‘‘pass’’

decisions) and, thus, the real world 

ability of the monitors to detect 

malfunctions is the parameter we want 

most to measure. Therefore, monitors 

with different criteria to reach a ‘‘pass’’

decision versus a ‘‘fail’’ decision would 

not be allowed to increment the 

numerator solely upon satisfying the 

‘‘pass’’ criteria. 

The correct implementation of the 

numerator counters by manufacturers is 

imperative to ensure a reliable measure 

for determining real world performance. 

‘‘Overcounting’’ would falsely indicate 

the monitor is executing more often 

than it really is, while ‘‘undercounting’’

would make it appear as if the monitor 

is not running as often as it really is. 

Manufacturers would be required to 

describe their numerator incrementing 

strategy in their certification 

documentation and to verify the proper 

performance of their strategy during 

production vehicle evaluation testing. 

b. Number of Driving Events 

(‘‘Denominator’’) 

We are also proposing that 

manufacturers separately track how 

often the engine is operated. Basically, 

the denominator would be a counter 

that increments by one each time the 

engine is operated. We are proposing 

that the denominator counter be 

incremented by one only if several 

criteria are satisfied during a single 

drive cycle. This allows very short trips 

or trips during extreme conditions such 

as very cold temperatures or very high 

altitude to be filtered out and excluded 

from the count. This is appropriate 

because these are also conditions where 

most OBD monitors are neither expected 

nor required to operate. 

Specifically, the denominator would 

be incremented if, on a single key start, 

the following criteria were satisfied 

while ambient temperature remained 

above 20 degrees Fahrenheit and 

altitude remained below 8,000 feet: 

• Minimum engine run time of 10 

minutes; 


sroberts on PROD1PC70 with PROPOSALSEP24JA07.004</MATH>
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3241 

44These monitors, as presented in section II.A.3, 

are, for diesel engines: the NMHC catalyst, the 

CDPF system, the NOX adsorber system, the NOX

converting catalyst system, and the boost system; 

and, for gasoline engines: the catalyst, the 

evaporative system, and the secondary air system; 

and, for all engines, the exhaust gas sensors, the 

EGR system, and the VVT system. 

• Minimum of 5 minutes, 

cumulatively, of operation at vehicle 

speeds greater than 25 miles-per-hour 

for gasoline engines or calculated load 

greater than 15 percent for diesel 

engines; and 

• At least one continuous idle for a 

minimum of 30 seconds encountered. 

We intend to work with industry to 

collect data during the first few years of 

implementation and make any 

adjustments, if necessary, to the criteria 

used to increment the denominator to 

ensure that the in-use performance ratio 

provides a meaningful measure of in-use 

monitoring performance. 

2. Proposed Performance Tracking 

Requirements 

a. In-use Monitoring Performance Ratio 

Definition 

For monitors required to meet the inuse performance tracking 

requirements,44 we are proposing that 

the incrementing of numerators and 

denominators and the calculation of the 

in-use performance ratio be done in 

accordance with the following 

specifications. 

The numerator(s) would be defined as 

a measure of the number of times a 

vehicle has been operated such that all 

monitoring conditions necessary for a 

specific monitor to detect a malfunction 

have been encountered. Except for 

systems using alternative statistical MIL 

illumination protocols, the numerator is 

to be incremented by an integer of one. 

The numerator(s) may not be 

incremented more than once per drive 

cycle. The numerator(s) for a specific 

monitor would be incremented within 

10 seconds if and only if the following 

criteria are satisfied on a single drive 

cycle: 

• Every monitoring condition 

necessary for the monitor of the specific 

component to detect a malfunction and 

store a pending DTC has been satisfied, 

including enable criteria, presence or 

absence of related DTCs, sufficient 

length of monitoring time, and 

diagnostic executive priority 

assignments (e.g., diagnostic ‘‘A’’ must 

execute prior to diagnostic ‘‘B’’). For the 

purpose of incrementing the numerator, 

satisfying all the monitoring conditions 

necessary for a monitor to determine 

that the component is passing may not, 

by itself, be sufficient to meet this 

criteria. 

• For monitors that require multiple 

stages or events in a single drive cycle 

to detect a malfunction, every 

monitoring condition necessary for all 

events to have completed must be 

satisfied. 

• For monitors that require intrusive 

operation of components to detect a 

malfunction, a manufacturer would be 

required to request Administrator 

approval of the strategy used to 

determine that, had a malfunction been 

present, the monitor would have 

detected the malfunction. Administrator 

approval of the request would be based 

on the equivalence of the strategy to 

actual intrusive operation and the 

ability of the strategy to determine 

accurately if every monitoring condition 

was satisfied as necessary for the 

intrusive event to occur. 

• For the secondary air system 

monitor, the three criteria above are 

satisfied during normal operation of the 

secondary air system. Monitoring during 

intrusive operation of the secondary air 

system later in the same drive cycle 

solely for the purpose of monitoring 

may not, by itself, be sufficient to meet 

these criteria. 

The third bullet item above requires 

explanation. There may be monitors, 

and there have been monitors in lightduty, designed to use what could be 

termed a two stage or two step process. 

The first step is usually a passive and/ 

or short evaluation that can be used to 

‘‘pass’’ a properly working component 

where ‘‘pass’’ refers to evaluating the 

component and determining that it is 

not malfunctioning. The second step is 

usually an intrusive and/or longer 

evaluation that is necessary to ‘‘fail’’ a 

malfunctioning component or ‘‘pass’’ a 

component nearing the point of failure. 

An example of such an approach might 

be an evaporative leak detection 

monitor that uses an intrusive vacuum 

pull-down/bleed-up evaluation during 

highway cruise conditions. If the 

evaporative system is sealed tight, the 

monitor ‘‘passes’’ and is done with 

testing for the given drive cycle. If the 

monitor senses a leak close to the 

required detection limit, the monitor 

does not ‘‘pass’’ and an internal flag is 

stored that will trigger the second stage 

of the test during the next cold start 

when a more accurate evaluation can be 

conducted. On the next cold start, 

provided the internal flag is set, an 

intrusive vacuum pull-down/bleed up 

monitor might be conducted during 

engine idle a very short time after the 

cold start. This second evaluation stage, 

being at idle and cold, gives a more 

accurate indication of the evaporative 

system’s integrity and provides for a 

more accurate decision regarding the 

presence and size of a leak. 

In this example, the second stage of 

this monitor would run less frequently 

in real use than the first stage since it 

is activated only on those occasions 

where the first stage suggests that a leak 

may be present (which most cars will 

not have). The rate-based tracking 

requirements are meant to give a 

measure of how often a monitor could 

detect a malfunction. To know the right 

answer, we need to know how often the 

first stage is running and could ‘‘fail’’, 

thus triggering the second stage, and 

then how often the second stage is 

completing. If we track only the first 

stage, we would get a false indication of 

how often the monitor could really 

detect a leak. But, if we track only the 

second stage, most cars would never 

increment the counter since most cars 

do not have leaks and would not trigger 

stage two. 

In considering this, we see two 

possible solutions: (1) Always activate 

the second stage evaluation in which 

case there would be an intrusive 

monitor being performed that does not 

really need to be performed; or, (2) 

implement a ‘‘ghost’’ monitor that 

pretends that the first stage evaluation 

triggers the second stage evaluation and 

then also looks for when the second 

stage evaluation could have completed 

had it been necessary. The third bullet 

item in the list above requires that, if a 

manufacturer intends to implement a 

two stage monitor and intends to 

implement such a ‘‘ghost’’ monitor as 

described here for rate based tracking, 

approval must be sought for doing so to 

make sure we agree that you are doing 

it correctly and properly. 

For monitors that can generate results 

in a ‘‘gray zone’’ or ‘‘non-detection 

zone’’ (i.e., results that indicate neither 

a passing system nor a malfunctioning 

system) or in a ‘‘non-decision zone’’

(e.g., monitors that increment and 

decrement counters until a pass or fail 

threshold is reached), the manufacturer 

would be responsible for incrementing 

the numerator appropriately. In general, 

the numerator should not be 

incremented when the monitor 

indicates a result in the ‘‘non-detection 

zone’’ or prior to the monitor reaching 

a decision. When necessary, the 

Administrator would consider data and/ 

or engineering analyses submitted by 

the manufacturer demonstrating the 

expected frequency of results in the 

‘‘non-detection zone’’ and the ability of 

the monitor to determine accurately, 

had an actual malfunction been present, 

whether or not the monitor would have 

detected a malfunction instead of a 

result in the ‘‘non-detection zone.’’


sroberts on PROD1PC70 with PROPOSALS
3242 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

45These monitors, as presented in section II.A.3, 

are, for diesel engines: the NMHC catalyst, the 

CDPF system, the NOX adsorber system, the NOX

converting catalyst system, and the boost system; 

and, for gasoline engines: the catalyst, the 

evaporative system, and the secondary air system; 

and, for all engines, the exhaust gas sensors, the 

EGR system, and the VVT system. 

For monitors that run or complete 

their evaluation with the engine off, the 

numerator must be incremented either 

within 10 seconds of the monitor 

completing its evaluation in the engine 

off state, or during the first 10 seconds 

of engine start on the subsequent drive 

cycle. 

Manufacturers using alternative 

statistical MIL illumination protocols 

for any of the monitors that require a 

numerator would be required to 

increment the numerator(s) 

appropriately. The manufacturer may be 

required to provide supporting data 

and/or engineering analyses 

demonstrating both the equivalence of 

their incrementing approach to the 

incrementing specified above for 

monitors using the standard MIL 

illumination protocol, and the overall 

equivalence of their incrementing 

approach in determining that the 

minimum acceptable in-use 

performance ratio has been satisfied. 

Regarding the denominator(s), defined 

as a measure of the number of times a 

vehicle has been operated, we are 

proposing that it also be incremented by 

an integer of one. The denominator(s) 

may not be incremented more than once 

per drive cycle. The general 

denominator and the denominators for 

each monitor would be incremented 

within 10 seconds if and only if the 

following criteria are satisfied on a 

single drive cycle during which ambient 

temperature remained at or above 20 

degrees Fahrenheit and altitude 

remained below 8,000 feet: 

• Cumulative time since the start of 

the drive cycle is greater than or equal 

to 600 seconds (10 minutes); 

• Cumulative gasoline engine 

operation at or above 25 miles per hour 

or diesel engine operation at or above 15 

percent calculated load, either of which 

occurs for greater than or equal to 300 

seconds (5 minutes); and 

• Continuous engine operation at idle 

(e.g., accelerator pedal released by 

driver and vehicle speed less than or 

equal to one mile per hour) for greater 

than or equal to 30 seconds. 

In addition to the requirements above, 

the evaporative system monitor 

denominator(s) must be incremented if 

and only if: 

• Cumulative time since the start of 

the drive cycle is greater than or equal 

to 600 seconds (10 minutes) while at an 

ambient temperature of greater than or 

equal to 40 degrees Fahrenheit but less 

than or equal to 95 degrees Fahrenheit; 

and 

• Engine cold start occurs with 

engine coolant temperature at engine 

start greater than or equal to 40 degrees 

Fahrenheit but less than or equal to 95 

degrees Fahrenheit and less than or 

equal to 12 degrees Fahrenheit higher 

than ambient temperature at engine 

start. 

In addition to the requirements above, 

the denominator(s) for the following 

monitors must be incremented if and 

only if the component or strategy is 

commanded ‘‘on’’ for a time greater than 

or equal to 10 seconds: 

• Gasoline secondary air system; 

• Cold start emission reduction 

strategy; 

• Components or systems that operate 

only at engine start-up (e.g., glow plugs, 

intake air heaters) and are subject to 

monitoring under ‘‘other emission 

control systems’’ (section II.D.5) or 

comprehensive component output 

components (see section II.D.4). 

For purposes of determining this 

commanded ‘‘on’’ time, the OBD system 

may not include time during intrusive 

operation of any of the components or 

strategies later in the same drive cycle 

solely for the purposes of monitoring. 

In addition to the requirements above, 

the denominator(s) for the monitors of 

the following output components 

(except those operated only at engine 

start-up as outlined above) must be 

incremented if and only if the 

component is commanded to function 

(e.g., commanded ‘‘on’’, ‘‘open’’, 

‘‘closed’’, ‘‘locked’’) two or more times 

during the drive cycle or for a time 

greater than or equal to 10 seconds, 

whichever occurs first: 

• Variable valve timing and/or 

control system 

• ‘‘Other emission control systems’’

• Comprehensive component (output 

component only, e.g., turbocharger 

waste-gates, variable length manifold 

runners) 

For monitors of the following 

components, the manufacturer may use 

alternative or additional criteria to that 

set forth above for incrementing the 

denominator. To do so, the 

manufacturer would need to be able to 

demonstrate that the criteria would be 

equivalent to the criteria outlined above 

at measuring the frequency of monitor 

operation relative to the amount of 

engine operation: 

• Engine cooling system input 

components (section II.D.2) 

• ‘‘Other emission control systems’’

(section II.D.5) 

• Comprehensive component input 

components that require extended 

monitoring evaluation (section II.D.4, 

e.g., stuck fuel level sensor rationality) 

For monitors of the following 

components or other emission controls 

that experience infrequent regeneration 

events, the manufacturer may use 

alternative or additional criteria to that 

set forth above for incrementing the 

denominator. To do so, the 

manufacturer would need to 

demonstrate that the criteria would be 

equivalent to the criteria outlined above 

at measuring the frequency of monitor 

operation relative to the amount of 

engine operation: 

• Oxidation catalysts 

• Diesel particulate filters 

For hybrid engine systems, engines 

that employ alternative engine start 

hardware or strategies (e.g., integrated 

starter and generators), or alternative 

fueled engines (e.g., dedicated, bi-fuel, 

or dual-fuel applications), the 

manufacturer may request 

Administrator approval to use 

alternative criteria to that set forth above 

for incrementing the denominator. In 

general, approval would not be given for 

alternative criteria that only employ 

engine shut off at or near idle/vehicle 

stationary conditions. Approval of the 

alternative criteria would be based on 

the equivalence of the alternative 

criteria at determining the amount of 

engine operation relative to the measure 

of conventional engine operation in 

accordance with the criteria above. 

The numerators and denominators 

may need to be disabled at some times. 

To do this, within 10 seconds of a 

malfunction being detected (i.e., a 

pending, MIL-on, or active DTC being 

stored) that disables a monitor required 

to meet the performance tracking 

requirements,45 the OBD system must 

disable further incrementing of the 

corresponding numerator and 

denominator for each monitor that is 

disabled. When the malfunction is no 

longer detected (e.g., the pending DTC 

is erased through self-clearing or 

through a scan tool command), 

incrementing of all corresponding 

numerators and denominators should 

resume within 10 seconds. Also, within 

10 seconds of the start of a power 

takeoff unit (PTO) that disables a 

monitor required to meet the 

performance tracking requirements, the 

OBD system should disable further 

incrementing of the corresponding 

numerator and denominator for each 

monitor that is disabled. When the PTO 

operation ends, incrementing of all 

corresponding numerators and 

denominators should resume within 10 

seconds. The OBD system must disable 

further incrementing of all numerators 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3243 

and denominators within 10 seconds if 

a malfunction has been detected in any 

component used to determine if: vehicle 

speed/calculated load; ambient 

temperature; elevation; idle operation; 

engine cold start; or, time of operation 

has been satisfied, and the 

corresponding pending DTC has been 

stored. Incrementing of all numerators 

and denominators should resume 

within 10 seconds when the 

malfunction is no longer present (e.g., 

pending DTC erased through selfclearing or by a scan tool command). 

The in-use performance monitoring 

ratio itself is defined as the numerator 

for the given monitor divided by the 

denominator for that monitor. 

b. Standardized Tracking and Reporting 

of Monitor Performance 

We are proposing that the OBD 

system separately report an in-use 

monitor performance numerator and 

denominator for each of the following 

components: 

• For diesel engines: NMHC catalyst 

bank 1, NMHC catalyst bank 2, NOX

catalyst bank 1, NOX catalyst bank 2, 

exhaust gas sensor bank 1, exhaust gas 

sensor bank 2, EGR/VVT system, DPF 

system, turbo boost control system, and 

the NOX adsorber. The OBD system 

must also report a general denominator 

and an ignition cycle counter in the 

standardized format discussed below 

and in section II.F.5. 

• For gasoline engines: catalyst bank 

1, catalyst bank 2, oxygen sensor bank 

1, oxygen sensor bank 2, evaporative 

leak detection system, EGR/VVT system, 

and secondary air system. The OBD 

system must also report a general 

denominator and an ignition cycle 

counter in the standardized format 

specified below and in section II.F.5. 

The OBD system would be required to 

report a separate numerator for each of 

the components listed in the above 

bullet lists. For specific components or 

systems that have multiple monitors 

that are required to be reported under 

section II.B—e.g., exhaust gas sensor 

bank 1 may have multiple monitors for 

sensor response or other sensor 

characteristics—the OBD system should 

separately track numerators and 

denominators for each of the specific 

monitors and report only the 

corresponding numerator and 

denominator for the specific monitor 

that has the lowest numerical ratio. If 

two or more specific monitors have 

identical ratios, the corresponding 

numerator and denominator for the 

specific monitor that has the highest 

denominator should be reported for the 

specific component. The numerator(s) 

must be reported in accordance with the 

specifications in section II.F.5. 

The OBD system would also be 

required to report a separate 

denominator for each of the components 

listed in the above bullet lists. The 

denominator(s) must be reported in 

accordance with the specifications in 

section II.F.5. 

Similarly, for the in-use performance 

ratio, determining which corresponding 

numerator and denominator to report as 

required for specific components or 

systems that have multiple monitors 

that are required to be reported—e.g., 

exhaust gas sensor bank 1 may have 

multiple monitors for sensor response or 

other sensor characteristics’the ratio 

should be calculated in accordance with 

the specifications in section II.F.5. 

The ignition cycle counter is defined 

as a counter that indicates the number 

of ignition cycles a vehicle has 

experienced. The ignition cycle counter 

must also be reported in accordance 

with the specifications in section II.F.5. 

The ignition cycle counter, when 

incremented, should be incremented by 

an integer of one. The ignition cycle 

counter may not be incremented more 

than once per ignition cycle. The 

ignition cycle counter should be 

incremented within 10 seconds if and 

only if the engine exceeds an engine 

speed of 50 to 150 rpm below the 

normal, warmed-up idle speed (as 

determined in the drive position for 

vehicles equipped with an automatic 

transmission) for at least two seconds 

plus or minus one second. The OBD 

system should disable further 

incrementing of the ignition cycle 

counter within 10 seconds if a 

malfunction has been detected in any 

component used to determine if engine 

speed or time of operation has been 

satisfied and the corresponding pending 

DTC has been stored. The ignition cycle 

counter may not be disabled from 

incrementing for any other condition. 

Incrementing of the ignition cycle 

counter should resume within 10 

seconds after the malfunction is no 

longer present (e.g., pending DTC erased 

through self-clearing or by a scan tool 

command). 

F. Standardization Requirements 

The heavy-duty OBD regulation 

would include requirements for 

manufacturers to standardize certain 

features of the OBD system. Effective 

standardization assists all repair 

technicians in diagnosing and repairing 

malfunctions by providing equal access 

to essential repair information, and 

requires structuring the information in a 

common format from manufacturer to 

manufacturer. Additionally, the 

standardization would help to facilitate 

the potential use of OBD checks in 

heavy-duty inspection and maintenance 

programs. 

Among the features that would be 

standardized under the proposed heavyduty OBD regulation include: 

• The diagnostic connector, the 

computer communication protocol; 

• The hardware and software 

specifications for tools used by service 

technicians; 

• The information communicated by 

the onboard computer and the methods 

for accessing that information; 

• The numeric designation of the 

DTCs stored when a malfunction is 

detected; and, 

• The terminology used by 

manufacturers in their service manuals. 

Our proposal would require that only 

a certain minimum set of emissionsrelated information be made available 

through the standardized format, 

protocol, and connector. We are not 

limiting engine manufacturers as to 

what protocol they use for engine 

control, communication between 

onboard computers, or communication 

to manufacturer-specific scan tools or 

test equipment. Further, we are not 

prohibiting engine manufacturers from 

equipping the vehicle with additional 

diagnostic connectors or protocols as 

required by other suppliers or 

purchasers. For example, fleets that use 

data logging or other equipment that 

requires the use of SAE J1587 

communication and connectors could 

still be installed and supported by the 

engine and vehicle manufacturers. The 

OBD rules would only require that 

engine manufacturers also equip their 

vehicles with a specific connector and 

communication protocol that meet the 

standardized requirements to 

communicate a minimum set of 

emissions-related diagnostic, service 

and, potentially, inspection information. 

Additionally, our proposal includes a 

phase-in of one engine family meeting 

the requirements of OBD in the model 

years 2010 through 2012. Because noncompliant engines would not require 

the proposed standardization features, 

truck and coach builders could be faced 

with several integration issues when 

building product in 2010 through 2012. 

Specifically, they could be faced with 

designing their vehicles to 

accommodate a standardized MIL, 

diagnostic connector, and 

communication protocol when using a 

compliant engine yet to not 

accommodate those features when using 

a non-compliant engine. This outcome 

could easily arise since only one enginefamily per manufacturer would be 

compliant and, therefore, a given truck 


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designed to accommodate several 

engines from several engine 

manufacturers would very likely need to 

accommodate a compliant engine from 

manufacturer A and a non-compliant 

engine from manufacturer B. It should 

be noted that engine choices are 

typically driven by the end user—the 

truck buyer—and not by the truck or 

coach builder. For that reason, the truck 

builder must accommodate all possible 

engines for the truck size and cannot 

necessarily demand from the engine 

manufacturer a compliant versus a noncompliant engine. 

As a result, rather than force truck 

and coach builders to accommodate two 

different systems and risk 

incompatibilities, we are proposing to 

exempt the 2010 through 2012 model 

year engines from meeting certain 

standardization requirements of OBD. 

This should allow truck and coach 

builders to integrate engines in the same 

manner as done currently and then to 

switch over to integrating a single 

system in 2013 when all engines are 

required to meet all of the 

standardization requirements of OBD. 

The proposed implementation schedule 

for standardization features is shown in 

Table II.G–2. 

1. Reference Documents 

We are proposing that OBD systems 

comply with the following provisions 

laid out in the following Society of 

Automotive Engineers (SAE) and/or 

International Organization of Standards 

(ISO) documents that are or would be 

incorporated by reference (IBR) into 

federal regulation: 

TABLE II.F—1. REFERENCE DOCUMENTS FOR OVER 14,000 POUND OBD 

Document No. Document title Date Comment 

SAE J1962 ......... ‘‘Diagnostic Connector—Equivalent to ISO/DIS 15031–3: December 14, 

2001’’.

April 2002 ........................ Updated IBR. 

SAE J1930 ......... ‘‘Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, 

and Acronyms—Equivalent to ISO/TR 15031–2: April 30, 2002’’.

April 2002 ........................ Updated IBR. 

SAE J1978 ......... ‘‘OBD II Scan Tool—Equivalent to ISO/DIS 15031–4: December 14, 2001’’ .... April 2002 ........................ Updated IBR. 

SAE J1979 ......... ‘‘E/E Diagnostic Test Modes—Equivalent to ISO/DIS 15031–5: April 30, 

2002’’.

April 2002 ........................ Updated IBR. 

SAE J2012 ......... ‘‘Diagnostic Trouble Code Definitions—Equivalent to ISO/DIS 15031–6: April 

30, 2002’’.

April 2002 ........................ Updated IBR. 

SAE J1939 ......... ‘‘Recommended Practice for a Serial Control and Communications Vehicle 

Network,’’ and the associated subparts included in SAE HS–1939, ‘‘Truck 

and Bus Control and Communications Network Standards Manual’’.

2005 Edition, March 2005 Updated IBR. 

SAE J2403 ......... ‘‘Medium/Heavy-Duty E/E Systems Diagnosis Nomenclature’’ .......................... August 2004 .................... New IBR. 

SAE J2534 ......... ‘‘Recommended Practice for Pass-Thru Vehicle Reprogramming’’ ................... February 2002 ................. New IBR. 

ISO 15765–

4:2001.

‘‘Road Vehicles—Diagnostics on Controller Area Network (CAN)—Part 4: Requirements for emission-related systems’’.December 2001 ............... New IBR. 

Copies of these SAE materials may be 

obtained from Society of Automotive 

Engineers International, 400 

Commonwealth Dr., Warrendale, PA, 

15096–0001. Copies of these ISO 

materials may be obtained from the 

International Organization for 

Standardization, Case Postale 56, CH–

1211 Geneva 20, Switzerland. 

2. Diagnostic Connector Requirements 

We are proposing that a standard data 

link connector conforming to either SAE 

J1962 or SAE J1939–13 specifications 

(except as noted below) would have to 

be included in each vehicle. The 

connector would have to be located in 

the driver’s side foot-well region of the 

vehicle interior in the area bound by the 

driver’s side of the vehicle and the 

driver’s side edge of the center console 

(or the vehicle centerline if the vehicle 

does not have a center console) and at 

a location no higher than the bottom of 

the steering wheel when in the lowest 

adjustable position. The Administrator 

would not allow the connector to be 

located on or in the center console (i.e., 

neither on the horizontal faces near the 

floor-mounted gear selector, parking 

brake lever, or cup-holders, nor on the 

vertical faces near the car stereo, climate 

system, or navigation system controls). 

The location of the connector must be 

easily identifiable and accessed (e.g., to 

connect an off-board tool). For vehicles 

equipped with a driver’s side door, the 

connector would have to be easily 

identified and accessed by someone 

standing (or ‘‘crouched’’) on the ground 

outside the driver’s side of the vehicle 

with the driver’s side door open. 

If a manufacturer wants to cover the 

connector, the cover must be removable 

by hand without the use of any tools 

and be labeled ‘‘OBD’’ to aid technicians 

in identifying the location of the 

connector. Access to the diagnostic 

connector could not require opening or 

removing any storage accessory (e.g., 

ashtray, coinbox). The label would have 

to clearly identify that the connector is 

located behind the cover and is 

consistent with language and/or 

symbols commonly used in the 

automobile and/or heavy truck industry. 

If the ISO 15765–4 protocol (see 

section II.F.3) is used for the required 

OBD standardized functions, the 

connector would have to meet the 

‘‘Type A’’ specifications of SAE J1962. 

Any pins in the connector that provide 

electrical power must be properly fused 

to protect the integrity and usefulness of 

the connector for diagnostic purposes 

and may not exceed 20.0 Volts DC 

regardless of the nominal vehicle system 

or battery voltage (e.g., 12V, 24V, 42V). 

If the SAE J1939 protocol (see section 

II.F.3)) is used for the required OBD 

standardized functions, the connector 

must meet the specifications of SAE 

J1939–13. Any pins in the connector 

that provide electrical power must be 

properly fused to protect the integrity 

and usefulness of the connector for 

diagnostic purposes. 

Manufacturers would be allowed to 

equip engines/vehicles with additional 

diagnostic connectors for manufacturerspecific purposes (i.e., purposes other 

than the required OBD functions). 

However, if the additional connector 

conforms to the ‘‘Type A’’ specifications 

of SAE J1962 or the specifications of 

SAE J1939–13 and is located in the 

vehicle interior near the required 

connector as described above, the 

connector(s) must be clearly labeled to 

identify which connector is used to 

access the standardized OBD 

information proposed below. 


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Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3245 

3. Communications to a Scan Tool 

a. Background 

In light-duty OBD, manufacturers are 

allowed to use one of four protocols for 

communication between a generic scan 

tool and the vehicle’s onboard 

computer. A generic scan tool 

automatically cycles through each of the 

allowable protocols until it hits upon 

the proper one with which to establish 

communication with the particular 

onboard computer. While this has 

generally worked successfully in the 

field, some communication problems 

have arisen. 

In an effort to address these problems, 

CARB has made recent changes to their 

light-duty OBD II regulation that require 

all light-duty vehicle manufacturers to 

use only one communication protocol 

by the 2008 model year. In making these 

changes, CARB staff argued that their 

experience with standardization under 

the OBD II regulation showed that 

having a single set of standards used by 

all vehicles would be desirable. CARB 

staff argued that a single protocol offers 

a tremendous benefit to both scan tool 

designers and service technicians. Scan 

tool designers could focus on added 

feature content and could expend much 

less time and money validating basic 

functionality of their product on all the 

various permutations of protocol 

interpretations that are implemented. In 

turn, technicians would likely get a scan 

tool that works properly on all vehicles 

without the need for repeated software 

updates that incorporate ‘‘workarounds’’ or other patches to fix bugs or 

adapt the tool to accommodate slight 

variances in how the multiple protocols 

interact with each other or are 

implemented by various manufacturers. 

Further, a single protocol should also be 

beneficial to fleet operators that use 

add-on equipment such as data loggers, 

and for vehicle manufacturers that 

integrate parts from various engine and 

component suppliers all of which must 

work together. 

Based on our similar experiences at 

the federal level with communication 

protocols giving rise to service and 

inspection/maintenance program issues, 

we initially wanted to propose a single 

communication protocol for engines 

used in over 14,000 pound vehicles. 

However, the affected industry has been 

divided over which single protocol 

should be required and has strongly 

argued for more than one protocol to be 

allowed. Therefore, for vehicles with 

diesel engines, we are proposing that 

manufacturers be required to use either 

the standards set forth in SAE J1939, or 

those set forth in the 500 kbps baud rate 

version of ISO 15765. For vehicles with 

gasoline engines, we are proposing that 

manufacturers be required to use the 

500 kbps baud rate version of ISO 

15765. Manufacturers would be 

required to use only one standard to 

meet all the standardization 

requirements on a single vehicle; that is, 

a vehicle must use only one protocol for 

all OBD modules on the vehicle. 

Several in the heavy-duty industry 

have argued for options that would 

allow the use of more than these two 

protocols on heavy-duty engines. Some 

have even argued for combinations of 

these protocols—e.g., diagnostic 

connector and messages of ISO 15765 

on an SAE J1939 physical layer 

network. However, as described above, 

experience from multiple protocols and 

multiple variants within the protocols 

has unnecessarily caused a significant 

number of problems with engine and 

vehicle related computer 

communications. 

b. Requirements for Communications to 

a Scan Tool 

We are proposing that all OBD control 

modules—e.g., engine, auxiliary 

emission control module—on a single 

vehicle be required to use the same 

protocol for communication of required 

emissions-related messages from 

onboard to off-board network 

communications to a scan tool meeting 

SAE J1978 specifications or designed to 

communicate with a SAE J1939 

network. Engine manufacturers would 

not be allowed to alter normal operation 

of the engine emissions control system 

due to the presence of off-board test 

equipment accessing the OBD 

information proposed below. The OBD 

system would be required to use one of 

the following standardized protocols: 

• ISO 15765–4 and all required 

emission-related messages using this 

protocol would have to use a 500 kbps 

baud rate. 

• SAE J1939 which may only be used 

on vehicles with diesel engines. 

4. Required Emissions Related 

Functions 

Most of the proposed emissions 

related functions are elements that exist 

in our light-duty OBD requirements. We 

are proposing several required 

functions, these are: 

• Readiness status 

• Distance and number of warm-up 

cycles since DTC clear 

• Permanent DTC storage 

• Real time indication of monitor 

status 

• Communicating readiness status to 

the vehicle operator 

• Diagnostic trouble codes (DTC) 

• Data stream 

• Freeze frame 

• Test results 

• Software calibration identification 

• Software calibration verification 

number 

• Vehicle identification number (VIN) 

i. Readiness Status 

The main intent of readiness status is 

to ensure that a vehicle is ready for an 

OBD-based inspection—by indicating 

that monitors have run and operational 

status of the emissions-control system 

has been fully evaluated—and to 

prevent fraudulent testing in inspection 

programs. In general, for OBD-based 

inspections, technicians ‘‘fail’’ a vehicle 

with an illuminated MIL since this 

would indicate the presence of an 

emissions control system malfunction. 

Without the readiness status indicators, 

technicians would not have a clear 

indication from the OBD system that it 

had sufficiently evaluated the emissions 

control system prior to the inspection. 

Since the potential exists for OBD 

checks to be used as part of a heavy 

truck inspection program, we believe 

that having readiness status indicators 

as part of this proposal is important—

waiting for a subsequent OBD–I/M 

rulemaking to require such indicators 

would unnecessarily delay 

implementation of such OBD–I/M 

programs. 

Absent such OBD–I/M programs, we 

still believe that readiness indicators are 

an important OBD tool. Technicians 

would be expected to use the readiness 

status to verify OBD-related repairs. 

Specifically, technicians would clear 

the computer memory after repairing an 

OBD-detected fault in order to erase the 

DTC, extinguish the MIL, and reset the 

readiness status to ‘‘incomplete.’’ Then 

the vehicle could be operated in such a 

manner that the monitor of the repaired 

component would run (i.e., the 

readiness status of the monitor would be 

set to ‘‘complete’’). The absence of any 

DTCs or MIL illumination upon 

readiness status indicating ‘‘complete’’

would indicate a successful repair. 

Therefore, we are proposing that 

manufacturers be required to indicate 

the readiness status of the OBD 

monitors. This would serve to indicate 

whether or not engine operation has 

been sufficient to allow certain OBD 

monitors to perform their system 

evaluations. The OBD system would be 

required to report a readiness status of 

either ‘‘complete’’ if the monitor has run 

a sufficient number of times to detect a 

malfunction since computer memory 

was last cleared, ‘‘incomplete’’ if the 

monitor has not yet run a sufficient 

number of times since the memory was 

last cleared, or ‘‘not applicable’’ if the 


sroberts on PROD1PC70 with PROPOSALS
3246 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

46The fault memory being any DTCs, readiness 

status indicators, freeze frame information, etc. 

monitor is not present or if the specific 

monitored component is not equipped 

on the vehicle. The readiness status of 

monitors that are required to run 

continuously would always indicate 

‘‘complete.’’ The details of the proposal 

discussed below clarify that the 

readiness status would be set to 

‘‘incomplete’’ whenever memory is 

cleared either by a battery disconnect or 

by a scan tool but not after a normal 

vehicle shutdown (i.e., key-off). 

ii. Distance Traveled and Number of 

Warm-Up Cycles Since DTC Clear 

As originally envisioned in our OBD–

I/M rulemaking (61 FR 40940), we 

intended to require that all readiness 

status indicators be set to ‘‘complete’’

prior to accepting a vehicle for I/M 

inspection. However, it became clear 

that some vehicles were being rejected 

from inspection for reasons beyond the 

driver’s control. For example, a vehicle 

driven in extreme ambient conditions 

would prohibit monitors from running 

and setting readiness status indicators to 

‘‘complete.’’ Also, a vehicle repaired 

just prior to arriving at the inspection 

station may not have been operated 

sufficiently to set the readiness status of 

the monitor for the recently repaired 

component to ‘‘complete.’’ The driver of 

such a vehicle would, in essence, be 

punished unintentionally for having 

taken the time and expense to repair the 

vehicle just prior to the inspection. As 

a result, we issued guidance (cite) to 

state inspectors recommending that 

vehicles be accepted for I/M inspection 

provided two or fewer readiness status 

indicators are ‘‘incomplete.’’ Note that 

most light-duty gasoline vehicles—the 

bulk of the vehicle fleet facing 

OBD–I/M checks—have only four 

monitors for which the readiness status 

indicator is meaningful (all of their 

other monitors being continuous 

monitors). However, there exists 

evidence that this policy is perhaps 

accepting vehicles for I/M inspection 

that should not be accepted due to 

unscrupulous clearing of DTCs and 

readiness status by people that 

understand how to do so and then 

operate their vehicles just enough to set 

the required minimum number of 

readiness indicators to ‘‘complete.’’

As a result, we are proposing some 

additional features that should better 

differentiate between vehicles that have 

been repaired recently or have 

‘‘incomplete’’ readiness indicators 

through circumstances outside the 

driver’s control, and those vehicles 

operated by drivers that are attempting 

to fraudulently get through an OBDbased inspection. We are proposing that 

the OBD system make available data 

that would report the distance traveled 

or engine run time for those engines that 

do not use vehicle speed information, 

and the number of warm-up cycles since 

the fault memory was last cleared.46 By 

combining these data with the readiness 

data, technicians or inspectors would 

better be able to determine if 

‘‘incomplete’’ readiness status 

indicators or an extinguished MIL are 

due to unscrupulous memory clearing 

or circumstances beyond the driver’s 

control. For example, a vehicle with 

several ‘‘incomplete’’ readiness 

indicators but with a high distance 

traveled/engine run time and a high 

number of warm-up cycles since the last 

clearing of fault memory would be 

unlikely to have undergone a recent 

fault memory clearing for the purpose of 

extinguishing the MIL prior to 

inspection. On the other hand, a vehicle 

with only one or two ‘‘incomplete’’

readiness indicators and a very low 

distance traveled/engine run time and a 

low number of warm-up cycles since 

fault memory clearing should probably 

be rejected or failed at an inspection. 

This would better allow an inspection 

program to be set up to reject only those 

vehicles with recently cleared memories 

while minimizing the chances of 

rejecting vehicles that driven such that 

monitors rarely run whether by unique 

driver behaviors or extreme ambient 

conditions. 

iii. Permanent Diagnostic Trouble Code 

Storage 

Consistent with the proposal for 

distance traveled/engine run time and 

number of warm-up cycles, we are 

proposing a requirement to make it 

much more difficult for a vehicle owner 

or technician to clear the fault memory 

and erase all traces of a previously 

detected malfunction. Current OBD 

systems on under 14,000 pound 

vehicles allow a technician or vehicle 

owner to erase all DTCs and extinguish 

the MIL by issuing a command from a 

generic scan tool or, in many cases, 

simply by disconnecting the vehicle 

battery. This would set to ‘‘incomplete’’

the readiness status indicators for all 

monitors and would remove all record 

of the malfunction that had been 

detected. 

We are proposing that manufacturers 

be required to store in non-volatile 

memory random access memory 

(NVRAM) a minimum of four MIL-on 

DTCs that are, at present, commanding 

the MIL-on. These ‘‘permanent’’ DTCs 

would have to be stored in NVRAM at 

the end of every key cycle. By requiring 

these permanent DTCs to be stored in 

NVRAM, one would not be able to erase 

them simply by disconnecting the 

battery. Further, manufacturers would 

not be allowed to design their OBD 

systems such that these permanent 

DTCs could be erased by any generic or 

manufacturer-specific scan tool 

command. Instead, the permanent DTCs 

could be erased only via an OBD system 

self-clearing—i.e., upon evaluating the 

component or system for which the 

permanent DTC has been stored and 

detecting on sufficient drive cycles that 

the malfunction is no longer present, the 

OBD system would erase the fault 

memory as discussed in section II.A.2. 

Once this has occurred, the permanent 

DTC stored in NVRAM would be erased 

also. 

The permanent DTCs should help if 

states choose to implement OBD-based 

I/M programs for heavy trucks. A truck 

with readiness status indicators for EGR 

and boost control set to ‘‘incomplete’’

and with permanent DTCs stored for 

both EGR and boost control would quite 

probably be a truck that should be 

rejected from inspection. The OBD 

system on such a truck has almost 

certainly had its fault memory cleared—

via scan tool command or battery 

disconnect—which would set the 

readiness indicators to ‘‘incomplete’’

and erase all MIL-on DTCs but would 

still have permanent DTCs stored (only 

the OBD system itself can erase 

permanent DTCs). Likewise, a truck 

with the same readiness indicators set to 

‘‘incomplete’’ and no permanent DTCs 

for those monitors should almost 

certainly be accepted for inspection 

since the lack of readiness is almost 

certainly due to circumstances outside 

the driver’s control. 

We believe that the permanent DTCs 

also provide advantages to technicians 

attempting to repair a malfunction and 

prepare it for subsequent inspection or 

proof of correction. The permanent DTC 

would identify the specific monitor that 

would need to be exercised after repair 

and prior to inspection to be sure that 

the malfunction has been repaired. By 

combining this information with the 

vehicle manufacturer’s service 

information, technicians could identify 

the exact conditions necessary to 

exercise the particular monitor. As such, 

technicians could more effectively 

verify that the specific monitor (that 

monitor having illuminated the MIL for 

which the repair has been done) has run 

and confirmed that the malfunction no 

longer exists and the repair has been 

made correctly. This should also reduce 

vehicle owner ‘‘come-backs’’ for 

incomplete or ineffective repairs. 


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iv. Real Time Indication of Monitor 

Status 

We are also proposing provisions to 

make it easier for technicians to prepare 

a vehicle for an inspection following a 

repair. These provisions would require 

that the OBD system provide real time 

data that indicate whether the necessary 

conditions are present currently to set 

all of the readiness indicators to 

‘‘complete.’’ These data would indicate 

whether a particular monitor may still 

have an opportunity to run on the 

current drive cycle or whether a 

condition has been encountered that has 

disabled the monitor for the rest of the 

drive cycle regardless of the driving 

conditions that might be encountered. 

While these data would not provide 

technicians with the exact conditions 

necessary to exercise the monitors (only 

service information would provide such 

information), the date in combination 

with the service information should 

assist technicians in verifying repairs 

and/or preparing a vehicle for 

inspection. Technicians would be able 

to use this information to identify when 

specific monitors have indeed 

completed or to identify situations 

where they have overlooked one or 

more of the enable criteria and need to 

check the service information and try 

again. 

v. Communicating Readiness Status to 

the Vehicle Operator 

As mentioned above, substantial 

feedback has been received from OBDbased I/M programs throughout the U.S. 

Much of this feedback pertains to the 

effect on vehicle owners caused by 

being rejected from I/M inspection due 

to ‘‘incomplete’’ readiness status 

indicators. To address this, some lightduty vehicle manufacturers requested 

that they be allowed to communicate 

the vehicle’s readiness status to the 

vehicle owner directly without need of 

a scan tool. This would provide 

assurance to the vehicle owner that their 

vehicle is ready for inspection prior to 

taking the vehicle to the I/M station. We 

are proposing that heavy-duty engine 

manufacturers be allowed to do the 

same thing (this is a proposed option, 

not a proposed requirement). If a 

manufacturer chooses to implement this 

option, though, they would be required 

to do so in a standardized manner. On 

engines equipped with this option, the 

owner would be able to initiate a selfcheck of the readiness status, thereby 

greatly reducing the possibility of being 

rejected at a roadside inspection. 

vi. Diagnostic Trouble Codes (DTC) 

Malfunctions are reported by the OBD 

system and displayed on a scan tool for 

service technicians in the form of 

diagnostic trouble codes (DTCs). We are 

proposing that manufacturers be 

required to report all emissions-related 

DTCs using a standardized format and 

to make them accessible to all service 

technicians, including the independent 

service industry. The reference 

document standards selected by the 

manufacturer would define many 

generic DTCs to be used by all 

manufacturers. In the rare 

circumstances that a manufacturer 

cannot find within the reference 

documents a suitable DTC, a unique 

‘‘manufacturer-specific’’ DTC could be 

used. However, such manufacturerspecific DTCs are not as easily 

interpreted by the independent service 

industry. Excessive use of manufacturerspecific DTCs may increase the time and 

cost for vehicle repairs. Thus, we are 

proposing to restrict the use of 

manufacturer-specific DTCs. If a generic 

DTC suitable for a given malfunction 

cannot be found, the manufacturer 

would be expected to pursue approval 

and addition of appropriate generic 

DTCs into the reference documents; the 

intent being to standardize as much 

information as possible. 

Additionally, we are proposing that 

the OBD system store DTCs that are as 

specific as possible to identify the 

nature of the malfunction. The intent 

being to provide service technicians 

with as detailed information as possible 

to diagnose and repair vehicles in an 

efficient manner. In other words, 

manufacturers should use separate 

DTCs for every monitor where the 

monitor and repair procedure, or likely 

cause of the failure, is different. 

Generally, a manufacturer would design 

an OBD monitor that detects different 

root causes (e.g., sensor shorted to 

ground or battery) for a malfunctioning 

component or system. We would expect 

manufacturers to store a specific DTC 

such as ‘‘sensor circuit high input’’ or 

‘‘sensor circuit low input’’ rather than a 

general code such as ‘‘sensor circuit 

malfunction.’’ Further, we expect 

manufacturers to store different DTCs 

that distinguish circuit malfunctions 

from rationality and functional 

malfunctions since the root cause for 

each is different and, thus, the repair 

procedures may be different. 

We are also proposing specific 

provisions for storage of pending and 

MIL-on DTCs. These proposed 

provisions were discussed in section 

II.A.2. 

We are also proposing requirements 

that would help to distinguish between 

DTCs stored for malfunctions that are 

currently present and for malfunctions 

that are no longer present. These 

requirements would apply only to those 

engines using ISO 15765–4 as the 

communication protocol. As described 

in section II.A.2, the OBD system would 

generally extinguish the MIL if the 

malfunction responsible for the MIL 

illumination has not been detected (i.e., 

the monitor runs and determines that 

the malfunction no longer exists) on 

three subsequent sequential drive 

cycles. However, a manufacturer would 

not be allowed to erase the associated 

MIL-on DTC until 40 engine warm-up 

cycles have occurred without again 

detecting the malfunction. So even 

though the malfunction is no longer 

present and a MIL-on is not being 

commanded, the DTC would still 

remain (termed a ‘‘history’’ code in the 

ISO standard). Consequently, if another 

unrelated malfunction occurs and 

results in a MIL-on, a new DTC would 

be stored along with the history DTC. 

When trying to diagnose the OBD 

problem, technicians accessing DTC 

information may have trouble 

distinguishing which DTC is 

responsible for illuminating the MIL 

(i.e., which malfunction is present 

currently), and thus could have trouble 

determining what exactly must be 

repaired. Therefore, we are proposing 

this requirement for ISO engines to help 

distinguish between DTCs stored for 

malfunctions that are present and those 

that were present. Note that, for engines 

using SAE J1939 as the communication 

protocol, such a distinction is already 

provided for. 

Permanent DTCs would also need to 

be separately identified from the other 

types of DTCs. Additionally, as 

described above, manufacturers would 

be required to develop additional 

software routines to store and erase 

permanent DTCs in NVRAM and to 

prevent erasure from any battery 

disconnect or scan tool command. 

vii. Data Stream/Freeze Frame/Test 

Results 

An important aspect of OBD is the 

ability of technicians to access critical 

information from the onboard computer 

to diagnose and repair emissions-related 

malfunctions. We believe that having 

access through the diagnostic connector 

to real-time electronic information 

regarding certain emissions critical 

components and systems would provide 

valuable assistance for repairing 

vehicles properly. The availability of 

real-time information would also 

provide assistance to technicians 


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47Note that, for purposes of the calculated load 

and torque parameters for diesel engines, 

manufacturers would be required to report the most 

accurate values that are calculated within the 

applicable electronic control unit (e.g., the engine 

control computer). ‘‘Most accurate values,’’ in this 

context, would be those of sufficient accuracy, 

resolution, and filtering that they could be used for 

the purpose of in-use emissions testing with the 

engine still in a vehicle (e.g., using portable 

emissions measurement equipment). 

responding to drivability complaints 

since the vehicle could be operated 

within the necessary operating 

conditions and the technician could see 

how various sensors and systems were 

acting. Similarly, fuel economy 

complaints, loss of performance 

complaints, intermittent problems, and 

others issues could also be addressed. 

We are proposing a number of data 

parameters that the OBD system would 

be required to report to a generic scan 

tool. These parameters, which would 

include information such as engine 

speed and exhaust gas sensor readings, 

would allow technicians to understand 

how the vehicle engine control system 

is functioning, either as the vehicle 

operates in a service bay or during 

actual driving. They would also help 

technicians diagnose and repair 

emission-related malfunctions by 

allowing them to watch instantaneous 

changes in the values while operating 

the vehicle. 

Some of the data parameters we are 

proposing are intended to assist us in 

performing in-use testing of heavy-duty 

engines for compliance with emissions 

standards. One of the parameters that 

manufacturers would be required to 

report is the real-time status of the NOX

and PM ‘‘not-to-exceed’’ (NTE) control 

areas. The NTE standards define a wide 

range of engine operating points where 

a manufacturer must design the engine 

to be below a maximum emission level. 

In theory, whenever the engine is 

operated within the speed and load 

region defined as the NTE zone, 

emissions will be below the required 

standards. However, within the NTE 

zone, manufacturers are allowed, if 

justified on a case-by-case basis, to 

either modify the time frame in which 

the standard must be met, and in the 

second case to be exempted from the 

emission standards under specific 

conditions (e.g., an NTE deficiency). 

Manufacturers can request two types of 

modifications: first, a five percent 

limited testing region within which no 

more than five percent of in-use 

operation is expected to occur and, thus, 

no more than five percent of NTE 

emissions sampling within that region 

can be compared to the NTE standard 

for a given sampling event; and second, 

NTE deficiencies which are precisely 

defined exemption conditions where 

compliance cannot be met due to 

technical reasons or for engine 

protection. These regions and 

conditions can be defined by directly 

measured signals or, in some cases, by 

complicated modeled values calculated 

internally in the engine computer. 

When conducting emissions testing of 

these engines, knowing if the engine is 

inside the NTE zone—and subject to the 

NTE standards—or is outside of the NTE 

zone or, perhaps, in an NTE limited 

testing region or covered by an NTE 

deficiency is imperative. As our in-use 

testing program requirements are 

written currently, we must post process 

data to determine which data points 

were generated within a compliance 

zone and which were generated within 

an exempted zone. Such post 

processing, while possible, is 

inefficient, time consuming, and 

resource intensive. Having the NTE 

zone data broadcast in real-time over the 

engine’s network would allow for a 

much more efficient use of our 

resources. 

The specific parameters we are 

proposing for inclusion in the data 

stream are, for gasoline engines: 

calculated load value, engine coolant 

temperature, engine speed, vehicle 

speed, time elapsed since engine start, 

absolute load, fuel level (if used to 

enable or disable any other monitors), 

barometric pressure (directly measured 

or estimated), engine control module 

system voltage, commanded 

equivalence ratio, number of stored 

MIL-on DTCs, catalyst temperature (if 

directly measured or estimated for 

purposes of enabling the catalyst 

monitor(s)), monitor status (i.e., 

disabled for the rest of this drive cycle, 

complete this drive cycle, or not 

complete this drive cycle) since last 

engine shut-off for each monitor used 

for readiness status, distance traveled/ 

engine run time with a commanded 

MIL-on, distance traveled/engine run 

time since fault memory last cleared, 

number of warm-up cycles since fault 

memory last cleared, OBD requirements 

to which the engine is certified (e.g., 

California OBD, EPA OBD, non-OBD) 

and MIL status (i.e., commanded-on or 

commanded-off). And, for diesel 

engines: calculated load (engine torque 

as a percentage of maximum torque 

available at the current engine speed),47

driver’s demand engine torque (as a 

percentage of maximum engine torque), 

actual engine torque (as a percentage of 

maximum engine torque), reference 

engine maximum torque, reference 

maximum engine torque as a function of 

engine speed (suspect parameter 

numbers (SPN) 539 through 543 defined 

in SAE J1939 within parameter group 

number (PGN) 65251 for engine 

configuration), engine coolant 

temperature, engine oil temperature (if 

used for emission control or any OBD 

monitors), engine speed, time elapsed 

since engine start, fuel level (if used to 

enable or disable any other diagnostics), 

vehicle speed (if used for emission 

control or any OBD monitors), 

barometric pressure (directly measured 

or estimated), engine control module 

system voltage, number of stored MILon DTCs, monitor status (i.e., disabled 

for the rest of this drive cycle, complete 

this drive cycle, or not complete this 

drive cycle) since last engine shut-off for 

each monitor used for readiness status, 

distance traveled/engine run time with 

a commanded MIL-on, distance 

traveled/engine run time since fault 

memory last cleared, number of warmup cycles since DTC memory last 

cleared, OBD requirements to which the 

engine is certified (e.g., EPA OBD parent 

rating, EPA OBD child rating, nonOBD), and MIL status (i.e., commandedon or commanded-off). Also for diesel 

engines, as discussed above, separate 

NOX and PM NTE control area status 

(i.e., inside control area, outside control 

area, inside manufacturer-specific NTE 

carve-out area, or deficiency active 

area). Also, for all engines so equipped 

(and only those so equipped): absolute 

throttle position, relative throttle 

position, fuel control system status (e.g., 

open loop, closed loop), fuel trim, fuel 

pressure, ignition timing advance, fuel 

injection timing, intake air/manifold 

temperature, engine intercooler 

(aftercooler) temperature, manifold 

absolute pressure, air flow rate from 

mass air flow sensor, secondary air 

status (upstream, downstream, or 

atmosphere), ambient air temperature, 

commanded purge valve duty cycle/ 

position, commanded EGR valve duty 

cycle/position, actual EGR valve duty 

cycle/position, EGR error between 

actual and commanded, PTO status 

(active or not active), redundant 

absolute throttle position (for electronic 

throttle or other systems that utilize two 

or more sensors), absolute pedal 

position, redundant absolute pedal 

position, commanded throttle motor 

position, fuel rate, boost pressure, 

commanded/target boost pressure, turbo 

inlet air temperature, fuel rail pressure, 

commanded fuel rail pressure, DPF inlet 

pressure, DPF inlet temperature, DPF 

outlet pressure, DPF outlet temperature, 

DPF delta pressure, exhaust pressure 

sensor output, exhaust gas temperature 

sensor output, injection control 

pressure, commanded injection control 

pressure, turbocharger/turbine speed, 


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variable geometry turbo position, 

commanded variable geometry turbo 

position, turbocharger compressor inlet 

temperature, turbocharger compressor 

inlet pressure, turbocharger turbine inlet 

temperature, turbocharger turbine outlet 

temperature, wastegate valve position, 

glow plug lamp status, oxygen sensor 

output, air/fuel ratio sensor output, NOX

sensor output, and evaporative system 

vapor pressure. 

We are also proposing requirements 

for storage of ‘‘freeze frame’’ information 

at the time a malfunction is detected 

and a DTC is stored. The freeze frame 

provides the operating conditions of the 

vehicle at the time of malfunction 

detection and the DTC associated with 

the data. The parameters we are 

proposing for inclusion in the freeze 

frame are a subset of the parameters 

listed above for the data stream. Note 

that storage of only one freeze frame 

would be required. Manufacturers may 

choose to store additional frames, 

provided that the required frame can be 

read using a scan tool meeting SAE 

J1978 specifications or designed to 

communicate with an SAE J1939 

network. 

We are also proposing that the OBD 

system store the most recent monitoring 

results for most of the major monitors. 

Manufacturers would be required to 

store and make available to the scan tool 

certain test information—i.e., the 

minimum and maximum values that 

should occur during proper operation 

along with the actual test value—of the 

most recent monitoring event. ‘‘Passing’’

systems would store test results that are 

within the test limits, while ‘‘failing’’

systems would store test results that are 

outside the test limits. The storage of 

test results would assist technicians in 

diagnosing and repairing malfunctions 

and would help distinguish between 

components that are performing well 

below the malfunction thresholds from 

those that are passing the malfunction 

thresholds marginally. 

viii. Identification Numbers 

We are also proposing that 

manufacturers be required to report two 

identification numbers related to the 

software and specific calibration values 

in the onboard computer. The first item, 

Calibration Identification Number (CAL 

ID), would identify the software version 

installed in the onboard computer. 

Software is often changed following 

production of the engine. These 

software changes often make changes to 

the emissions control system or the OBD 

system. We are proposing that these 

changes include a new CAL ID and that 

it be communicated via the diagnostic 

connector to the scan tool. The second 

item, Calibration Verification Number 

(CVN), would help to ensure that the 

current software has not been corrupted, 

modified inappropriately, or otherwise 

tampered with. Both CAL ID and CVN 

help ensure the integrity of the OBD 

system. The CVN proposal would 

require manufacturers to develop 

sophisticated software algorithms that 

would essentially be a self-check 

calculation of all of the emissionsrelated software and calibration values 

in the onboard computer and would 

return the result of the calculation to a 

scan tool. If the calculated result did not 

equal the expected result for that CAL 

ID, one would know that the software 

had been corrupted or otherwise 

modified. The CVN result would have to 

be made available at all times to a 

generic scan tool. 

We are also proposing that the 

Vehicle Identification Number (VIN) be 

communicated via the diagnostic 

connector to a generic scan tool in a 

standardized format. The VIN would be 

a unique number assigned by the 

vehicle manufacturer to every vehicle 

built. The VIN is commonly used for 

purposes of ownership and registration 

to uniquely identify every vehicle. By 

requiring the VIN to be stored in the 

onboard computer and available 

electronically to a generic scan tool, the 

possibility of a fraudulent inspection 

(e.g., by plugging into a different vehicle 

than an inspection citation was issued 

originally to generate a proof of 

correction) would be minimized. 

Electronic access to this number would 

also simplify the inspection process and 

reduce transcription errors from manual 

data entry. 

We are proposing that the VIN be 

electronically stored in a control 

module on the vehicle, but not that it 

necessarily be stored in the engine 

control module. As long as the VIN is 

reported correctly and according to the 

selected reference document standards, 

we consider it irrelevant as to which 

control module (e.g., engine controller, 

instrument cluster controller) contains 

the information. Further, we are 

proposing that the ultimate 

responsibility would lie with the engine 

manufacturer to ensure that every 

vehicle manufactured with one of its 

engines satisfies this requirement. 

However, we would expect that the 

physical task of implementing this 

requirement would likely be passed 

from the engine manufacturer to the 

vehicle manufacturer via an additional 

build specification. Thus, analogous to 

how the engine manufacturer currently 

provides engine purchasers with 

detailed specifications regarding engine 

cooling requirements, additional sensor 

inputs, physical mounting 

specifications, weight limitations, etc., 

the engine manufacturer would likely 

include an additional specification 

dictating the need for the VIN to be 

made available electronically. It would 

be left to each engine manufacturer to 

determine the most effective method to 

achieve this, as long as the VIN 

requirement is met. Some manufacturers 

may find it most effective to provide the 

capability in the engine control module 

delivered with the engine coupled with 

a mechanism for the vehicle 

manufacturer to program the module 

with the VIN upon installation of the 

engine into an actual vehicle. Others 

may find it more effective to require the 

vehicle manufacturer to have the 

capability built into other modules 

installed on the vehicle such as 

instrument cluster modules, etc. We are 

aware of several current vehicles with 

engines from three different engine 

manufacturers that already have the VIN 

available through engine-manufacturer 

specific scan tools; this indicates that 

such arrangements already exist in one 

form or another and that they are 

working. 

5. In-Use Performance Ratio Tracking 

Requirements 

To separately report an in-use 

performance ratio for each applicable 

monitor as discussed in sections II.B 

through II.D, we are proposing that 

manufacturers be required to implement 

software algorithms to report a 

numerator and denominator in the 

standardized format specified below 

and in accordance with the 

specifications of the reference 

documents listed in section II.F.1. 

For the numerator, denominator, 

general denominator, and ignition cycle 

counter: 

• Each number must have a minimum 

value of zero and a maximum value of 

65,535 with a resolution of one. 

• Each number must be reset to zero 

only when a non-volatile random access 

memory (NVRAM) reset occurs (e.g., 

reprogramming event) or, if the numbers 

are stored in keep-alive memory (KAM), 

when KAM is lost due to an 

interruption in electrical power to the 

control module (e.g., battery 

disconnect). Numbers may not be reset 

to zero under any other circumstances 

including when commanded to do so 

via a scan tool command to clear DTCs 

or reset KAM. 

• If either the numerator or 

denominator for a specific component 

reaches the maximum value of 65,535 

±2, both numbers should be divided by 

two before either is incremented again 

to avoid overflow problems. 


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• If the ignition cycle counter reaches 

the maximum value of 65,535 ±2, the 

ignition cycle counter should rollover 

and increment to zero on the next 

ignition cycle to avoid overflow 

problems. 

• If the general denominator reaches 

the maximum value of 65,535 ±2, the 

general denominator should rollover 

and increment to zero on the next drive 

cycle that meets the general 

denominator definition to avoid 

overflow problems. 

• If an engine is not equipped with a 

component (e.g., oxygen sensor bank 2, 

secondary air system), the 

corresponding numerator and 

denominator for that specific 

component should always be reported 

as zero. 

For the in-use performance ratio: 

• The ratio should have a minimum 

value of zero and a maximum value of 

7.99527 with a resolution of 0.000122. 

• A ratio for a specific component 

should be considered to be zero 

whenever the corresponding numerator 

is equal to zero and the corresponding 

denominator is not zero. 

• A ratio for a specific component 

should be considered to be the 

maximum value of 7.99527 if the 

corresponding denominator is zero or if 

the actual value of the numerator 

divided by the denominator exceeds the 

maximum value of 7.99527. 

For engine run time tracking on all 

gasoline and diesel engines, 

manufacturers would be required to 

implement software algorithms to 

individually track and report in a 

standardized format the engine run time 

while being operated in the following 

conditions: 

• Total engine run time 

• Total idle run time (with ‘‘idle’’

defined as accelerator pedal released by 

driver, vehicle speed less than or equal 

to one mile per hour, and PTO not 

active); 

• Total run time with PTO active. 

Each of the above engine run time 

counters would have the following 

numerical value specifications: 

• Each numerical counter must be a 

four-byte value with a minimum value 

of zero at a resolution of one minute per 

bit. 

• Each numerical counter must be 

reset to zero only when a nonvolatile 

memory reset occurs (e.g., a 

reprogramming event). Numerical 

counters cannot be reset to zero under 

any other circumstances including a 

scan tool (generic or enhanced) 

command to clear DTCs or reset KAM. 

• When any of the individual 

numerical counters reaches its 

maximum value, all counters must be 

divided by two before any are 

incremented again. This is meant to 

avoid overflow problems. 

6. Exceptions to Standardization 

Requirements 

For alternative-fueled engines derived 

from a diesel-cycle engine, we are 

proposing that the manufacturer be 

allowed to meet the standardized 

requirements discussed in this section 

that are applicable to diesel engines 

rather than meeting the requirements 

applicable to gasoline engines. 

G. Implementation Schedule, In-Use 

Liability, and In-Use Enforcement 

1. Implementation Schedule and In-Use 

Liability Provisions 

Table II.G–1 summarizes the proposed 

implementation schedule for the OBD 

monitoring requirements—i.e., the 

proposed certification requirements and 

in-use liabilities. More detail regarding 

the implementation schedule and 

liabilities can be found in the sections 

that follow. 

TABLE II.G–1.—OBD CERTIFICATION REQUIREMENTS AND IN-USE LIABILITY FOR DIESEL FUELED AND GASOLINE FUELED

ENGINES OVER 14,000 POUNDS: MONITORING REQUIREMENTS

Model year Applicability Certification requirement In-use liability 

2010–2012 .... Parent rating within 1 compliant engine 

family. a

Full liability to thresholds according to 

certification demonstration procedures. b

Full liability to 2x thresholds. c

Child ratings within the compliant engine 

family.

Certification documentation only (i.e., no 

certification demonstration); no liability 

to thresholds.

Liability to monitor and detect as noted 

in certification documentation. 

All other engine families and ratings ....... None ........................................................ None. 

2013–2015 .... Parent rating from 2010–2012 and parent rating within 1–2 additional engine 

families.

Full liability to thresholds according to 

certification demonstration procedures.

Full liability to 2x thresholds. 

Child ratings from 2010–2012 and parent 

ratings from any remaining engine 

families or OBD groups.d

Full liability to thresholds but certification 

documentation only.

Full liability to 2x thresholds. 

Additional engine ratings ......................... Certification documentation only; no liability to thresholds.Liability to monitor and detect as noted 

in certification demonstration. 

2016–2018 .... One rating from 1–3 engine families and/ 

or OBD groups.

Full liability to thresholds according to 

certification demonstration procedures.

Full liability to thresholds. 

Remaining ratings .................................... Full liability to thresholds but certification 

documentation only.

Full liability to 2x thresholds. 

2019+ ............ One rating from 1–3 engine families and/ 

or OBD groups.

Full liability to thresholds according to 

certification demonstration procedures.

Full liability to thresholds. 

Remaining ratings .................................... Full liability to thresholds but certification 

documentation only.

Full liability to thresholds. 

Notes: (a) Parent and child ratings are defined in section II.G; which rating(s) serves as the parent rating and which engine families must comply is not left to the manufacturer, as discussed in section II.G. (b) The certification demonstration procedures and the certification documentation 

requirements are discussed in section VIII.B. (c) Where in-use liability to thresholds and 2x thresholds is noted, manufacturer liability to monitor 

and detect as noted in their certification documentation is implied. (d) OBD groups are groupings of engine families that use similar OBD strategies and/or similar emissions control systems, as described in the text. 

For the 2010 through 2012 model 

years, manufacturers would be required 

to implement OBD on one engine 

family. All other 2010 through 2012 

engine families would not be subject to 

any OBD requirements unless otherwise 

required to do so (e.g., to demonstrate 

that SCR equipped vehicles will not be 

operated without urea). For 2013, 


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manufacturers would be required to 

implement OBD on all engine families. 

We are proposing this implementation 

schedule for several reasons. First, 

industry has made credible arguments 

that their resources are stretched to the 

limit developing and testing strategies 

for compliance with the 2007/2010 

heavy-duty highway emissions 

standards. We do not want to jeopardize 

their success toward that goal by being 

too aggressive with our OBD program. 

Second, OBD is a complex and difficult 

regulation with which to comply. We 

believe that our implementation 

schedule would give industry the 

opportunity to introduce OBD systems 

on a limited number of engines giving 

them and us very valuable learning 

experience. Should mistakes or errors in 

regulatory interpretation occur, the 

ramifications would be limited to only 

a subset of the new vehicle fleet rather 

than the entire new vehicle fleet. Lastly, 

the proposed OBD requirements 

outlined above, and the production 

vehicle evaluation provisions discussed 

in Section VIII, reflect 10 to 20 years of 

learning by EPA, CARB, and industry 

(primarily the light-duty gasoline 

industry) as to what works and what 

does not work. This is, perhaps, 

especially true for those OBD elements 

that involve the interface between the 

OBD system and service and I/M 

inspection personnel. Gasoline 

manufacturers have had the ability to 

evolve their OBD systems along with 

this learning process. However, diesel 

engine manufacturers have not really 

been involved in this learning process 

and, as a result, 100 percent 

implementation in 2010 would be 

analogous to implementing 10 to 20 

years of OBD learning in one 

implementation step. We believe that 

implementing in two or three gradual 

steps rather than one big step will 

benefit everyone involved. 

Table II.G–1 makes reference to 

‘‘parent’’ and ‘‘child’’ ratings. In general, 

engine manufacturers certify an engine 

family that consists of several ratings 

having slightly different horsepower 

and/or torque characteristics but no 

differences large enough to require a 

different engine family designation. For 

emissions certification, the parent 

rating—i.e., the rating for which 

emissions data are submitted to EPA for 

the purpose of demonstrating emissions 

compliance—is defined as the ‘‘worst 

case’’ rating. This worst case rating is 

the rating considered as having the 

worst emissions performance and, 

therefore, its compliance demonstrates 

that all other ratings within the family 

must comply. For OBD purposes, we 

wanted to limit the burden on 

industry—hence the proposal for only 

one compliant engine family in 2010—

yet maximize the impact of the OBD 

system. Therefore, for model years 2010 

through 2012, we are defining the OBD 

parent rating as the rating having the 

highest weighted projected sales within 

the engine family having the highest 

weighted projected sales, with sales 

being weighted by the useful life of the 

engine rating. Table II.G–2 presents a 

hypothetical example for how this 

would work. Using this approach, the 

OBD compliant engine family in 2010 

would be the engine family projected to 

produce the most in-use emissions 

(based on sales weighted by expected 

miles driven). Likewise, the fully liable 

parent OBD rating would be the rating 

within that family projected to produce 

the most in-use emissions. 

TABLE II.G–2.—HYPOTHETICAL EXAMPLE OF HOW THE OBD PARENT AND CHILD RATINGS WOULD BE DETERMINED

OBD group Engine family Rating Projected 

sales 

Certified useful 

life 

OBD 

weighting—engine rating a

(billions) 

OBD 

weighting—engine family b

(billions) 

I .............................................. A 1 10,000 285,000 2 .85 14.25 

2 40,000 285,000 11 .4 ........................

B 1 10,000 435,000 4 .35 21.60 

2 20,000 435,000 8 .70 ........................

3 30,000 285,000 8 .55 ........................

II ............................................. C 1 20,000 110,000 2 .20 7.70 

2 50,000 110,000 5 .50 ........................

Notes: (a) For engine family A, rating 1, 10,000 × 285,000 / 1 billion = 2.85. 

(b) For engine family A, 2.85 + 11.4 = 14.25. 

In the example shown in Table II.G–

2, the compliant engine family in 2010 

would be engine family B and the 

parent OBD rating within that family 

would be rating 2. The other OBD 

compliant ratings within engine family 

B would be dubbed the ‘‘child’’ ratings. 

For model years 2013 through 2015, the 

parent ratings would be those ratings 

having the highest weighted projected 

sales within each of the one to three 

engine families having the highest 

weighted projected sales, with sales 

being weighted by the useful life of the 

engine rating. In the example shown in 

Table II.G–2, the parent ratings would 

be rating 2 of engine family A, rating 2 

of engine family B, and rating 2 of 

engine family C (Note that this is only 

for illustration purposes since our 

proposal would not require that a 

manufacturer with only three engine 

families have three parent ratings and 

instead would require only one). 

The manufacturer would not need to 

submit test data demonstrating 

compliance with the emissions 

thresholds for the child ratings. We 

would fully expect these child ratings to 

use OBD calibrations—i.e., malfunction 

trigger points—that are identical or 

nearly so to those used on the parent 

rating. However, we would allow 

manufacturers to revise the calibrations 

on their child ratings where necessary 

so as to avoid unnecessary or 

inappropriate MIL illumination. Such 

revisions to OBD calibrations have been 

termed ‘‘extrapolated’’ OBD calibrations 

and/or systems. The revisions to the 

calibrations on child ratings and the 

rationale for them would need to be 

very clearly described in the 

certification documentation. 

For the 2013 and later model years, 

we are proposing that manufacturers 

certify one to three parent ratings. The 

actual number of parent ratings would 

depend upon the manufacturer’s fleet 

and would be based on both the 

emissions control system architectures 

present in their fleet and the 

similarities/differences of the engine 

families in their fleet. For example, a 

manufacturer that uses a DPF with NOX

adsorber on each of the engines would 

have only one system architecture. 

Another manufacturer that uses a DPF 

with NOX adsorber on some engines and 

a DPF with SCR on others would have 

at least two architectures. We would 

expect that manufacturers would group 

similar architectures and similar engine 


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families into so called ‘‘OBD groups.’’

These OBD groups would consist of a 

combination of engines, engine families, 

or engine ratings that use the same OBD 

strategies and similar calibrations. The 

manufacturer would be required to 

submit details regarding their OBD 

groups as part of their certification 

documentation that shows the engine 

families and engine ratings within each 

OBD group for the coming model year. 

While a manufacturer may end up with 

more than three OBD groups, we do not 

intend to require a parent rating for 

more than three OBD groups. Therefore, 

in the example shown in Table II.G–2, 

rather than submitting test data for the 

three parent ratings as suggested above, 

the OBD grouping would result in the 

parent ratings being rating 2 of engine 

family B and rating 2 of engine family 

C. These parents would represent OBD 

groups I and II, and the manufacturer’s 

product line. For 2013 through 2015, we 

intend to allow the 2010 parent to again 

act as a parent rating and, provided no 

significant changes had been made to 

the engine or its emissions control 

system, complete carryover would be 

possible. However, for model years 2016 

and beyond, we would work closely 

with CARB staff and the manufacturer 

to determine the parent ratings so that 

the same ratings are not acting as the 

parents every year. In other words, our 

definitions for the OBD parent ratings as 

discussed here apply only during the 

years 2010 through 2012 and again for 

the years 2013 through 2015. We request 

comment on this approach. 

In addition to this gradual 

certification implementation schedule, 

we are proposing some relaxations for 

in-use liability during the 2010 through 

2018 model years. The first such 

relaxation is higher interim in-use 

compliance standards for those OBD 

monitors calibrated to specific 

emissions thresholds. For the 2010 

through 2015 model years, an OBD 

monitor on an in-use engine would not 

be considered non-compliant (i.e., 

subject to enforcement action) unless 

emissions exceeded twice the OBD 

threshold without detection of a 

malfunction. For example, for an EGR 

monitor on an engine with a NOX FEL 

of 0.2 g/bhp-hr and an OBD threshold of 

0.5 g/bhp-hr (i.e., the NOX FEL+0.3), a 

manufacturer would not be subject to 

enforcement action unless emissions 

exceeded 1.0 g/bhp-hr NOX without a 

malfunction being detected. For the 

model years 2016 through 2018, parent 

ratings would be liable to the 

certification emissions thresholds, but 

child ratings and other ratings would 

remain liable to twice the certification 

thresholds. Beginning in the 2019 model 

year, all families and all ratings would 

be liable to the certification thresholds. 

The second in-use relaxation is a 

limitation in the number of engines that 

would be liable for in-use compliance 

with the OBD emissions thresholds. For 

2010 through 2012, we are proposing 

that manufacturers be fully liable in-use 

to twice the thresholds for only the OBD 

parent rating. The child ratings within 

the compliant engine family would have 

liability for monitoring in the manner 

described in the certification 

documentation, but would not have 

liability for detecting a malfunction at 

the specified emissions thresholds. For 

example, a child rating’s DPF monitor 

designed to operate under conditions X, 

Y, and Z and calibrated to detect a 

backpressure within the range A to B 

would be expected to do exactly that 

during in-use operation. However, if the 

tailpipe emissions of the child engine 

were to exceed the applicable OBD inuse thresholds (i.e., 2x the certification 

thresholds during 2010–2015), despite 

having a backpressure within range A to 

B under conditions X, Y, and Z, there 

would be no in-use OBD failure nor 

cause for enforcement action. In fact, we 

would expect the OBD monitor to 

determine that the DPF was functioning 

properly since its backpressure was in 

the acceptable range. For model years 

2013 through 2015, this same in-use 

relaxation would apply to those engine 

families that do not lie within an engine 

family for which a parent rating has 

been certified. For 2016 and later model 

years, all engines would have some inuse liability to thresholds, either the 

certification thresholds or twice those 

thresholds. 

These in-use relaxations are meant to 

provide ample time for manufacturers to 

gain experience without an excessive 

level of risk for mistakes. They would 

also allow manufacturers to fine-tune 

their calibration techniques over a six to 

ten year period. 

We are also proposing some a specific 

implementation schedule for the 

standardization requirements discussed 

in section II.F. We initially intended to 

require that any compliant OBD engine 

family would be required to implement 

all of the standardization requirements. 

However, we became concerned that, 

during model years 2010 through 2012, 

we could have a situation where OBD 

compliant engines from manufacturer A 

might be competing against non-OBD 

engines from manufacturer B for sales in 

the same truck. In such a case, the truck 

builder would be placed in a difficult 

position of needing to design their truck 

to accommodate OBD compliant 

engines—along with a standardized 

MIL, a specific diagnostic connector 

location specification, etc.—and nonOBD engines. After consideration of this 

almost certain outcome, we have 

decided to limit the standardization 

requirements that must be met during 

the 2010 through 2012 model years. 

Beginning in 2013, all engines will be 

OBD compliant and this would become 

a moot issue. Table II.G–3 shows the 

proposed implementation schedule for 

standardization requirements. 

TABLE II.G–3.—OBD STANDARDIZATION REQUIREMENTS FOR DIESEL FUELED AND GASOLINE FUELED ENGINES OVER

14,000 POUNDS

Model year Applicability Required standardization features Waived standardization features 

2010–2012 .... Parent and Child ratings within 1 compliant engine family. aEmissions related (II.F.4) except for the 

requirement to make the data available in a standardized format or in accordance with SAE J1979/1939 specifications). MIL activation and deactivation.b Performance tracking—calculation of numerators, denominators, ratios.

Standardized connector (II.F.2). Dedicated (i.e., regulated OBD-only) MIL. 

Communication protocols (II.F.3). 

Emissions related functions (II.F.4) 

with respect to the requirement to 

make the data available in a standardized format or in accordance with SAE 

J1979/1939 specifications) 

Other engine families ............................... None ........................................................ All. 

2013+ ............ All engine families and ratings ................ All ............................................................. None. 

Notes: (a) Parent and child ratings are defined in section II.G; which rating serves as the parent rating and which engine families must comply 

is not left to the manufacturer, as discussed in section II.G. (b) There would be no requirement for a dedicated MIL and no requirement to use a 

specific MIL symbol, only that a MIL be used and that it use the proposed activation/deactivation logic. 


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Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3253 

2. In-Use Enforcement 

When conducting our in-use 

enforcement investigations into OBD 

systems, we intend to use all tools we 

have available to analyze the 

effectiveness and compliance of the 

system. These tools may include onvehicle emission testing systems such as 

the portable emissions measurement 

systems (PEMS). We would also use 

scan tools and data loggers to analyze 

the data stream information to compare 

real world operation to the 

documentation provided at certification. 

Importantly, we would not intend to 

pursue enforcement action against a 

manufacturer for not detecting a failure 

mode that could not have been 

reasonably predicted or otherwise 

detected using monitoring methods 

known at the time of certification. For 

example, we are proposing a 

challenging set of requirements for 

monitoring of DPF systems. As of today, 

engine manufacturers are reasonably 

confident in their ability to detect 

certain DPF failure modes at or near the 

proposed thresholds—e.g., a leaking 

DPF resulting from a cracked 

substrate—but are not confident in their 

ability to detect some other DPF failure 

modes—e.g., a leaking DPF resulting 

from a partially melted substrate. If a 

partially melted substrate indeed cannot 

be detected and this is known during 

the certification process, we cannot 

expect such a failure to be detected on 

an in-use vehicle. 

We also want to make it clear who 

would be the responsible party should 

we pursue any in-use enforcement 

action with respect to OBD. We are very 

familiar with the heavy-duty industry 

and its tendency toward separate engine 

and component suppliers. This 

contrasts with the light-duty industry 

which tends toward a more vertically 

integrated structure. The non-vertically 

integrated nature of the heavy-duty 

industry can present unique difficulties 

for OBD implementation and for OBD 

enforcement. With the complexity of 

OBD systems, especially those meeting 

the requirements being proposed today, 

we would expect the interactions 

between the various parties involved—

engine manufacturer, transmission 

manufacturer, vehicle manufacturer, 

etc.—to be further complicated. 

Nonetheless, in the end the vast 

majority of the proposed OBD 

requirements would apply directly to 

the engine and its associated emission 

controls, and the engine manufacturer 

would have complete responsibility to 

ensure that the OBD system performs 

properly in-use. Given the central role 

the engine and engine control unit 

would play in the OBD system, we are 

proposing that the party certifying the 

engine and OBD system (typically, the 

engine manufacturer) be the responsible 

party for in-use compliance and 

enforcement actions. In this role, the 

certifying party would be our sole point 

of contact for potential noncompliances 

identified during in-use or enforcement 

testing. We would leave it to the engine 

manufacturer to determine the ultimate 

party responsible for the potential 

noncompliance (e.g., the engine 

manufacturer, the vehicle manufacturer, 

or some other supplier). In cases where 

remedial action such as an engine recall 

would be required, the certifying party 

would take on the responsibility of 

arranging to bring the engines or OBD 

systems back into compliance. Given 

that heavy-duty engines are already 

subject to various emission 

requirements including engine emission 

standards, labels, and certification, 

engine manufacturers currently impose 

restrictions via signed agreements with 

engine purchasers to ensure that their 

engines do not deviate from their 

certified configuration when installed. 

We would expect the OBD system’s 

installation to be part of such 

agreements in the future. 

H. Proposed Changes to the Existing 

8,500 to 14,000 Pound Diesel OBD 

Requirements 

We are also proposing changes to our 

OBD requirements for diesel engines 

used in heavy-duty vehicles under 

14,000 pounds (see 40 CFR 86.005–17 

for engine-based requirements and 40 

CFR 86.1806–05 for vehicle or chassisbased requirements). Table II.H–1 

summarizes the proposed changes to 

under 14,000 pound heavy-duty diesel 

emissions thresholds at which point a 

component or system has failed to the 

point of requiring an illuminated MIL 

and a stored DTC. Table II.H–2 

summarizes the proposed changes for 

diesel engines used in heavy-duty 

applications under 14,000 pounds. The 

proposed changes are meant to maintain 

consistency with the diesel OBD 

requirements we are proposing for over 

14,000 pound applications. 

TABLE II.H–1.—PROPOSED NEW, OR PROPOSED CHANGES TO EXISTING, EMISSIONS THRESHOLDS FOR DIESEL FUELED

CI HEAVY-DUTY VEHICLES UNDER 14,000 POUNDS (G/MI) 

Component/monitor MY NMHC CO NOX PM 

NMHC catalyst system .................................................................................. 2010–2012 2.5x. 

2013+ ...... 2x. 

NOX catalyst system ..................................................................................... 2007–2009 .................. .................. 3x..

2010+ ...... .................. .................. +0.3. 

DPF system ................................................................................................... 2010–2012 2.5x .......... .................. .................. 4x. 

2013+ ...... 2x ............. .................. .................. +0.04. 

Air-fuel ratio sensors upstream ..................................................................... 2007–2009 2.5x .......... 2.5x .......... 3x ............. 4x. 

2010–2012 2.5x .......... 2.5x .......... +0.3 ......... +0.02. 

2013+ ...... 2x ............. 2x ............. +0.3 ......... +0.02. 

Air-fuel ratio sensors downstream ................................................................ 2007–2009 2.5x .......... .................. 3x ............. 4x. 

2010–2012 2.5x .......... .................. +0.3 ......... 4x. 

2013+ ...... 2x ............. .................. +0.3 ......... +0.04. 

NOX sensors ................................................................................................. 2007–2009 .................. .................. 4x ............. 5x. 

2010–2012 .................. .................. +0.3 ......... 4x. 

2013+ ...... .................. .................. +0.3 ......... +0.04. 

‘‘Other monitors’’ with emissions thresholds ................................................. 2007–2009 2.5x .......... 2.5x .......... 3x ............. 4x. 

2010–2012 2.5x .......... 2.5x .......... +0.3 ......... 4x. 

2013+ ...... 2x ............. 2x ............. +0.3 ......... +0.02. 

Notes: MY=Model Year; 2.5x means a multiple of 2.5 times the applicable emissions standard; +0.3 means the standard plus 0.3; not all proposed monitors have emissions thresholds but instead rely on functionality and rationality checks as described in section II.D.4. 


sroberts on PROD1PC70 with PROPOSALS
3254 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

TABLE II.H–2.—PROPOSED NEW, OR PROPOSED CHANGES TO EXISTING, EMISSIONS THRESHOLDS FOR DIESEL FUELED

CI ENGINES USED IN HEAVY-DUTY VEHICLES UNDER 14,000 POUNDS (G/BHP-HR) 

Component/Monitor MY Std/FEL NMHC CO NOX PM 

NMHC catalyst system ............................................................ 2010–2012 All ............. 2.5x. 

2013+ ...... All ............. 2x. 

NOX catalyst system ............................................................... 2007–2009 >0.5 NOX .................. .................. 1.75x. 

2007–2009 <=0.5 NOX .................. .................. +0.5. 

2010+ ...... All ............. .................. .................. +0.3. 

DPF system ............................................................................. 2010–2012 All ............ 2.5x .......... .................. .................. 0.05/+0.04. 

2013+ ...... All ............. 2x ............. .................. .................. 0.05/+0.04. 

Air-fuel ratio sensors upstream ............................................... 2007–2009 >0.5 NOX 2.5x .......... 2.5x .......... 1.75x ........ 0.05/+0.04. 

2007–2009 <=0.5 NOX 2.5x .......... 2.5x .......... +0.5 ......... 0.05/+0.04. 

2010–2012 All ............ 2.5x .......... 2.5x .......... +0.3 ......... 0.03/+0.02. 

2013+ ...... All ............. 2x ............. 2x ............. +0.3 ......... 0.03/+0.02. 

Air-fuel ratio sensors downstream ........................................... 2007–2009 >0.5 NOX 2.5x .......... .................. 1.75x ........ 0.05/+0.04. 

2007–2009 <=0.5 NOX 2.5x .......... .................. +0.5 ......... 0.05/+0.04. 

2010–2012 All ............ 2.5x .......... .................. +0.3 ......... 0.05/+0.04. 

2013+ ...... All ............. 2x ............. .................. +0.3 ......... 0.05/+0.04. 

NOX sensors ............................................................................ 2007–2009 >0.5 NOX .................. .................. 1.75x ........ 0.05/+0.04. 

2007–2009 <=0.5 NOX .................. .................. +0.5 ......... 0.05/+0.04. 

2010+ ...... All ............. .................. .................. +0.3 ......... 0.05/+0.04. 

‘‘Other monitors’’ with emissions thresholds ........................... 2007–2009 >0.5 NOX 2.5x .......... 2.5x .......... 1.75x ........ 0.05/+0.04. 

2007–2009 <=0.5 NOX 2.5x .......... 2.5x .......... +0.5 ......... 0.05/+0.04. 

2010–2012 All ............ 2.5x .......... 2.5x .......... +0.3 ......... 0.03/+0.02. 

2013+ ...... All ............. 2x ............. 2x ............. +0.3 ......... 0.03/+0.02. 

Notes: MY=Model Year; 2.5x means a multiple of 2.5 times the applicable emissions standard or family emissions limit (FEL); +0.3 means the 

standard or FEL plus 0.3; 0.05/+0.04 means an absolute level of 0.05 or an additive level of the standard or FEL plus 0.04, whichever level is 

higher; not all proposed monitors have emissions thresholds but instead rely on functionality and rationality checks as described in section II.D.4. 

1. Selective Catalytic Reduction and 

Lean NOX Catalyst Monitoring 

We are proposing that the 8,500 to 

14,000 pound SCR and lean NOX

catalyst monitoring requirements mirror 

those discussed in section II.B.6. The 

current regulations require detection of 

a NOX catalyst malfunction before 

emissions exceed 1.5x the emissions 

standards. We no longer believe that 

such a tight threshold level is 

appropriate for diesel SCR and lean 

NOX catalyst systems. We believe that 

such a tight threshold could result in 

too many false failure indications. The 

required monitoring conditions with 

respect to performance tracking 

(discussed in section II.B.6.c) would not 

apply for under 14,000 pound heavyduty applications since we do not have 

performance tracking requirements for 

under 14,000 pound applications. We 

are proposing this change for the 2007 

model year. 

2. NOX Adsorber System Monitoring 

We are proposing that the 8,500 to 

14,000 pound NOX adsorber monitoring 

requirements mirror those discussed in 

section II.B.7. The current regulations 

require detection of a NOX adsorber 

malfunction before emissions exceed 

1.5x the emissions standards. We no 

longer believe that such a tight 

threshold level is appropriate for diesel 

NOX adsorber systems. We believe that 

such a tight threshold could result in 

too many false failure indications. The 

required monitoring conditions with 

respect to performance tracking 

(discussed in section II.B.7.c) would not 

apply for under 14,000 pound heavyduty applications since we do not have 

performance tracking requirements for 

under 14,000 pound applications. We 

are proposing this change for the 2007 

model year. 

3. Diesel Particulate Filter System 

Monitoring 

We are proposing that the 8,500 to 

14,000 pound DPF monitoring 

requirements mirror those discussed in 

section II.B.8. Our current regulations 

require detection of a catastrophic 

failure only. The proposed monitoring 

requirements discussed in section II.B.8 

would be far more comprehensive and 

protective of the environment than 

would a catastrophic failure monitor. 

The required monitoring conditions 

with respect to performance tracking 

(discussed in section II.B.8.c) would not 

apply for under 14,000 pound heavyduty applications since we do not have 

performance tracking requirements for 

under 14,000 pound applications. We 

are proposing no changes to the DPF 

monitoring requirements in the 2007 to 

2009 model years because there is not 

sufficient lead time for manufacturers to 

develop a new monitor. The new, more 

stringent monitoring requirements 

would begin in the 2010 model year, 

with a further tightening of the DPF 

NMHC threshold in the 2013 model year 

as is also proposed for over 14,000 

pound applications. 

4. NMHC Converting Catalyst 

Monitoring 

We are proposing that the 8,500 to 

14,000 pound NMHC converting 

catalyst monitoring requirements mirror 

those discussed in section II.B.5. Our 

current regulations do not require the 

monitoring of NMHC catalysts on diesel 

applications. The proposed monitoring 

requirements discussed in section II.B.5 

would be far more comprehensive and 

protective of the environment than the 

current lack of any requirement. The 

required monitoring conditions with 

respect to performance tracking 

(discussed in section II.B.8.c) would not 

apply for under 14,000 pound heavyduty applications since we do not have 

performance tracking requirements for 

under 14,000 pound applications. We 

are not proposing this new threshold for 

the 2007 to 2009 model years because 

there is not sufficient lead time for 

manufacturers to develop a new 

monitor. The new, more stringent 

monitoring requirements would begin in 

the 2010 model year, with a further 

tightening of the NMHC threshold in the 

2013 model year as is also proposed for 

over 14,000 pound applications. 

5. Other Monitors 

We are also proposing changes to the 

emissions thresholds for all other diesel 

monitors in the 8,500 to 14,000 pound 

range (e.g., NOX sensors, air fuel ratio 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3255 

48See 13 CCR 1968.2, released August 11, 2006, 

Docket ID# EPA–HQ–OAR–2005–0047–0005. 

49 13 CCR 1971.1, Docket ID# EPA–HQ–OAR–

2005–0047–0006. 

50 ‘‘Memorandum of Agreement: On-road Heavyduty Diagnostic Regulation Development,’’ signed 

by Chet France, U.S. EPA, and Tom Cackette, 

California ARB, August 11, 2004, Docket ID# EPA–

HQ–OAR–2005–0047–0002. 

51Note that, by idle emission control strategies 

we mean strategies that, for example, shut down the 

engine after 10 minutes of constant idle. We do not 

mean strategies that control emissions during 

engine idles that occur at stop lights or in congested 

traffic. 

52See also proposed § 86.010–18(n). 

53See 13 CCR 1968.2, released August 11, 2006, 

Docket ID# EPA–HQ–OAR–2005–0047–0005. 

54See 13 CCR 1971.1(f)(6.2.1)(B) and compare to 

proposed § 86.010–18(h)(6)(ii). 

sensors, etc.). These proposed changes 

are meant to maintain consistency with 

the proposed changes for over 14,000 

pound applications. We believe that 

these proposed thresholds are far more 

appropriate for diesel applications than 

the thresholds we have in our current 

OBD requirements which are, generally, 

1.5 times the applicable standards. None 

of the proposed thresholds represents a 

new threshold where none currently 

exists. Instead, they represent different 

thresholds that would require, in most 

cases, malfunction detection at different 

emissions levels than would be required 

by our current OBD requirements. 

6. CARB OBDII Compliance Option and 

Deficiencies 

We are also proposing some changes 

to our deficiency provisions for vehicles 

and engines meant for vehicles under 

14,000 pounds. We have included 

specific mention of air-fuel ratio sensors 

and NOX sensors where we had long 

referred only to oxygen sensors. We 

have also updated the referenced CARB 

OBDII document that can be used to 

satisfy the federal OBD requirements.48

I. How Do the Proposed Requirements 

Compare to California’s? 

The California Air Resources Board 

(CARB) has its own OBD regulations for 

engines used in vehicles over 14,000 

pounds GVWR.49 (13 CCR 1971.1) In 

August of 2004, EPA and CARB signed 

a memorandum of agreement to work 

together to develop a single, nationwide 

OBD program for engines used in 

vehicles over 14,000 pounds.50 We 

believe that, for the most part, we have 

been successful in doing so at least for 

the early years of implementation. 

Nonetheless, there are differences in 

some of the details contained within 

each regulation. These differences are 

summarized here and we request 

comment on all of these differences. 

The first difference is that the CARB 

regulation contains some more stringent 

thresholds beginning in the 2013 

timeframe for some engines and 2016 

for all engines. Specifically, CARB’s PM 

threshold for diesel particulate filters 

(DPF) and exhaust gas sensors 

downstream of aftertreatment devices, 

and their NOX threshold for NOX

aftertreatment devices and exhaust gas 

sensors downstream of aftertreatment 

devices, become more stringent in 2013 

for some engines and 2016 for all. We 

are not proposing these more stringent 

thresholds—our proposed thresholds 

are shown in Table II.B–1. At this time, 

EPA is not in a position to propose these 

more stringent OBD thresholds for the 

national program. The industry believes 

that CARB’s more stringent NOX and 

PM thresholds for 2013 and 2016 are not 

technically feasible. EPA is reviewing 

these longer term OBD thresholds, but at 

this time we have not made a decision 

regarding the feasibility and the 

appropriateness of these longer term 

thresholds. Because these thresholds do 

not take effect until model year 2013 at 

the earliest, we do not believe it is 

necessary to make such a determination 

in this rulemaking. It would be our 

intention to monitor the progress made 

towards complying with the 2010 

thresholds contained in today’s 

proposal and potentially revisit the 

appropriateness of more stringent OBD 

thresholds for model year 2013 and later 

in the future. CARB has made 

commitments to review their HD OBD 

program every two years and they can 

consider making changes to their longterm program during this biennial 

review process. EPA’s regulatory 

development process does not lend 

itself to making updates every two years 

because the Federal rulemaking process 

tends to be lengthier than CARB’s. As 

mentioned above, we intend to monitor 

the CARB long-term thresholds during 

the coming years, and if we determine 

that more stringent thresholds are 

appropriate, we would consider 

changing our thresholds to include the 

more stringent thresholds through a 

notice and comment rulemaking 

process. 

CARB also has some slightly different 

certification demonstration 

requirements in the 2011 and 2012 

model years. They are requiring 

demonstration testing of the child 

ratings from the 2010 model year 

certified engine family for 2011 and 

2012 model year certification. As Table 

II.B–1 shows, we are not requiring such 

demonstration testing in the 2011 and 

2012 model years provided the child 

ratings meet the requirements of 

certification carry-over. Further, CARB 

is requiring that one engine rating from 

one to three engine families undergo full 

certification demonstration testing in 

the 2013 model year and every model 

year thereafter. In contrast, EPA is 

requiring that one to three engine 

ratings be fully demonstrated in the 

2013 model year and then carry-over 

through the 2015 model year (again, 

provided the engine ratings meet the 

requirements of certification carry-over). 

In 2016 and subsequent model years, 

EPA would require that one to three 

engine ratings be fully demonstrated on 

an ‘‘as needed’’ basis. In the same vein, 

our evaluation protocol associated with 

certification demonstration testing, as 

discussed in section VIII.C, requires less 

testing than is required in CARB’s 

regulation. 

Our OBD requirements for over 

14,000 pounds do not contain any 

provisions to monitor control strategies 

associated with idle emission control 

strategies because EPA does not have 

currently any regulatory requirements 

that specifically target idle emissions 

control strategies.51 We are not 

proposing a provision to charge fees 

associated with OBD deficiencies as 

CARB does. We are also not proposing 

provisions for ‘‘retroactive deficiencies’’

as CARB has. Our deficiency provisions 

along with our misbuild and other inuse enforcement programs accomplish 

the same thing. Deficiencies are 

discussed in section VIII.D.52

For diesel engines used in heavy-duty 

vehicles under 14,000 pounds, our 

proposed OBD requirements are in line 

with those recently proposed by 

CARB.53 Our proposed requirements are 

also in line—both the technical aspects 

and the implementation timing 

aspects—with our proposed 

requirements for over 14,000 pound 

diesel applications. We are also 

proposing diesel vehicle-based OBD 

requirements in line with the proposed 

diesel engine-based requirements. In 

contrast, CARB does not have diesel 

thresholds in terms of ‘‘grams per mile’’

specified in their regulation for the 

8,500 to 14,000 pound range. 

Specifically for gasoline engines 

meant for applications over 14,000 

pounds, our proposal differs from 

CARB’s in that we are not requiring 

detection of catalysts that are less than 

50 percent effective at converting 

emissions.54 We are not requiring this 

because we are relying on the emissions 

threshold of 1.75 times the applicable 

standard as a means of defining a 

catalyst system malfunction. We are also 

proposing some differences with respect 

to misfire monitoring. Most notably, we 

are not proposing a provision analogous 


sroberts on PROD1PC70 with PROPOSALS
3256 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

55See 13 CCR 1971.1(f)(2.3.4)(D) and compare to 

proposed § 86.010–18(h)(2)(iii)(D). 56See 13 CCR 1971.1(f)(7.2.3) and compare to 

proposed § 86.010–18(h)(7)(ii)(B) and (C). 

57 ‘‘Spotlight on Technology: Smart glowplugs 

may make Clean Diesels cost-effective Pressuresensing units could let designers cut NOX

aftertreatment,’’ Tony Lewin, Automotive News, 

February 6, 2006. 

to CARB’s provision that allows the 

Executive Officer to approve misfire 

monitor disablement or alternative 

malfunction criteria on a case by case 

basis.55 In general, we prefer to avoid 

having regulatory provisions that are 

implemented on a case by case basis. 

For similar reasons, we are also not 

proposing a provision analogous to 

CARB’s provision that allows the 

Executive Officer to revise the orifice for 

evaporative leak detection if the most 

reliable monitoring strategy cannot 

detect the required orifice.56

III. Are the Proposed Monitoring 

Requirements Feasible? 

Some of the OBD monitoring 

strategies discussed here would be 

intrusive monitors that would result in 

very brief emissions increases, or spikes, 

for the sake of determining if certain 

emissions control components/systems 

are working properly during the 

remaining 99 percent or more of the 

engine’s operation. While these 

emissions spikes are brief, and their 

levels cannot be meaningfully predicted 

or estimated, we are concerned about 

strategies that might give little concern 

to emissions during such spikes in favor 

of an easier monitor. We request 

comment on this issue—should such 

strategies be allowed or should such 

strategies be prohibited? If a commenter 

has the latter opinion, then suggestions 

should be provided for how the 

monitoring requirements should be 

changed to allow for a non-intrusive 

monitor—i.e., one that could run during 

normal operation or operation ‘‘on the 

cycle’’—that may not provide the 

monitoring capability nor the control 

expected by the requirements we are 

proposing. 

A. Feasibility of the Monitoring 

Requirements for Diesel/CompressionIgnition Engines 

1. Fuel System Monitoring 

a. Fuel Pressure Monitoring 

Manufacturers control fuel pressure 

by using a closed-loop feedback 

algorithm that allows them to increase 

or decrease fuel pressure until the fuel 

pressure sensor indicates they have 

achieved the desired fuel pressure. For 

the common-rail OBD systems certified 

in the under 14,000 pound category, the 

manufacturers are monitoring the actual 

fuel system pressure sensed by a fuel 

rail pressure sensor, comparing it to the 

target fuel system pressure stored in a 

software table or calculated by an 

algorithm inside the onboard computer, 

and indicating a malfunction if the 

magnitude of the difference between 

these two exceeds an acceptable level. 

The error limits are established by 

engine dynamometer emission tests to 

ensure that a malfunction would be 

detected before emissions exceed the 

applicable thresholds. 

In cases where no fuel pressure error 

can generate a large enough emission 

increase to exceed the applicable 

thresholds, manufacturers are required 

to set the malfunction trigger at their 

fuel pressure control limits (e.g., when 

they reach a point where they can no 

longer increase or decrease fuel pressure 

to achieve the desired fuel pressure). 

This monitoring requirement has been 

demonstrated as technically feasible 

given that several under 14,000 pound 

diesels already meet this requirement. 

Further, the nature of a closed-loop 

algorithm is that such a system is 

inherently capable of being monitored 

because it simply requires analysis of 

the same closed-loop feedback 

parameter being used by the system for 

control purposes. 

Another promising technology is a 

pressure sensing glow plug. The glow 

plug is an electronic device in the 

cylinder of most diesel engines used to 

facilitate combustion during cold engine 

starting conditions. Glow plugs are 

being developed that incorporate a 

pressure sensor capable of detecting the 

quality of combustion within the 

cylinder.57 Pressure-sensing glow plugs 

provide feedback to the enginemanagement system that controls the 

timing and quantity of fuel injected into 

the cylinder. This feedback allows the 

engine electronics to adjust the injection 

characteristics so the engine avoids fuelmixture combinations that generate high 

levels of NOX. In this sense, a feedback 

loop is available that works like the 

oxygen sensor in a gasoline engine 

exhaust system. By measuring the 

quality of combustion, a determination 

can also be made about the quality of 

the fuel injection event—the pressure of 

fuel delivered, quantity of fuel 

delivered, timing of fuel delivered. 

b. Fuel Injection Quantity Monitoring 

Absent combustion sensors and/or 

pressure sensing glow plugs mentioned 

above, there is currently no feedback 

sensor indicating that the proper 

quantity of fuel has been injected. 

Therefore, injection quantity monitoring 

will be more difficult than pressure 

monitoring. Nonetheless, a 

manufacturer has identified a strategy 

currently being used that verifies the 

injection quantity under very specific 

engine operating conditions and appears 

to be capable of determining that the 

system is accurately delivering the 

desired fuel quantity. This strategy 

entails intrusive operation of the fuel 

injection system during a deceleration 

event where fuel injection is normally 

shut off (e.g., coasting or braking from 

a higher vehicle speed down to a low 

speed or a stop). During the 

deceleration, fuel injection to a single 

cylinder is turned back on to deliver a 

very small amount of fuel. Typically, 

the amount of fuel would be smaller 

than, or perhaps comparable to, the 

amount of fuel injected during a pilot or 

pre-injection. If the fuel injection system 

is working correctly, that known 

injected fuel quantity will generate a 

known increase in fluctuations 

(accelerations) of the crankshaft that can 

be measured by the crankshaft position 

sensor. If too little fuel is delivered, the 

measured crankshaft acceleration will 

be smaller than expected. If too much 

fuel is delivered, the measured 

crankshaft acceleration will be larger 

than expected. This process can even be 

used to ‘‘balance’’ out each cylinder or 

correct for system tolerances or 

deterioration by modifying the 

commanded injection quantity until it 

produces the desired crankshaft 

acceleration and applying a correction 

or adaptive term to that cylinder’s future 

injections. Each cylinder can, in turn, be 

cycled through this process and a 

separate analysis can be made for the 

performance of the fuel injection system 

for each cylinder. Even if this procedure 

would require only one cylinder be 

tested per revolution (to eliminate any 

change in engine operation or output 

that would be noticeable to the driver) 

and require each cylinder to be tested 

on four separate revolutions, this 

process would only take two seconds for 

a six cylinder engine decelerating 

through 1500 rpm. 

The crankshaft position sensor is 

commonly used to identify the precise 

position of the piston relative to the 

intake and exhaust valves to allow for 

very accurate fuel injection timing 

control and, as such, there exists 

sufficient resolution and data sampling 

within the onboard computer to enable 

such measurement of crankshaft 

accelerations. Further, in addition to the 

current use of this strategy in an under 

14,000 pound diesel application, a 

nearly identical crankshaft fluctuation 

technique has been used since 1997 on 

under 14,000 pound diesel engines 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3257 

58 Draft Technical Support Document, HDOBD 

NPRM, EPA420–D–06–006, Docket ID# EPA–HQ–

OAR–2005–0047–0008. 

59Technically, the EPA OBD diesel misfire 

monitoring requirement for under 14,000 pound 

applications is to detect a lack of combustion 

whereas the California OBDII diesel misfire 

monitoring requirement is identical to what we are 

proposing for over 14,000 pounds. Since all 

manufacturers to date are designing to the OBDII 

requirements, this statement is, for practical 

purposes, true. 

during idle conditions to determine if 

individual cylinders are misfiring. 

Another technique that may be used 

to achieve the same monitoring 

capability is some variation on the 

current cylinder balance tests used by 

many manufacturers to improve idle 

quality. In such strategies, fueling to 

individual cylinders is increased, 

decreased, or shut off to determine if the 

cylinder is contributing an equal share 

to the output of the engine. This strategy 

again relies on changes in crankshaft/ 

engine speed to measure the individual 

cylinder’s contribution relative to 

known good values and/or the other 

cylinders. Such an approach seems 

viable to determine whether the fuel 

injection quantity is correct for each 

cylinder, but it has the disadvantage of 

not necessarily being able to verify 

whether the system is able to deliver 

small amounts of fuel precisely (such as 

those commanded during a pilot 

injection). 

One other approach that has been 

mentioned but not investigated 

thoroughly is the use of a wide-range 

air-fuel (A/F) sensor in the exhaust to 

confirm fuel injection quantity. The A/ 

F sensor output could be compared to 

the measured air going into the engine 

and calculated fuel quantity injected to 

see if the two agree. Differences in the 

comparison may allow for the 

identification of incorrect fuel injection 

quantity. 

c. Fuel Injection Timing Monitoring 

In the same manner as described for 

quantity monitoring, we believe that 

fuel injection timing could be verified. 

By monitoring the crankshaft speed 

fluctuation and, most notably, the time 

at which such fluctuation begins, ends, 

or reaches a peak, the OBD system could 

compare the time to the commanded 

fuel injection timing point and verify 

that the crankcase fluctuation occurred 

within an acceptable time delay relative 

to the commanded fuel injection. If the 

system was working improperly and 

actual fuel injection was delayed 

relative to when it was commanded, the 

corresponding crankshaft speed 

fluctuation would also be delayed and 

would result in a longer than acceptable 

time period between commanded fuel 

injection timing and crankshaft speed 

fluctuation. A more detailed discussion 

of this possible monitoring method is 

presented in the technical support 

document contained in the docket.58

Another possible monitoring method 

that has been mentioned but not 

investigated thoroughly would be to 

look for an electrical feedback signal 

from the injector to the computer to 

confirm when the injection occurred. 

Such a technique would likely use an 

inductive signature to identify exactly 

when an injector opened or closed and 

verify that it was at the expected timing. 

We expect that further investigation 

would be needed to confirm that such 

a monitoring technique would be 

sufficient to verify fuel injection timing. 

d. Fuel System Feedback Control 

Monitoring 

The conditions necessary for feedback 

control (i.e., the feedback enable 

criteria) are defined as part of the 

control strategy in the engine computer. 

The feedback enable criteria are 

typically based on minimum conditions 

necessary for reliable and stable 

feedback control. When the 

manufacturer is designing and 

calibrating the OBD system, the 

manufacturer would determine, for the 

range of in-use operating conditions, the 

time needed to satisfy these feedback 

enable criteria on a properly functioning 

engine. In-use, the OBD system would 

evaluate the time needed for these 

conditions to be satisfied following an 

engine start, compare that to normal 

behavior for the system, and indicate a 

malfunction when the time exceeds a 

specified value (i.e., the malfunction 

criterion). For example, fuel pressure 

feedback control may be calibrated to 

begin once fuel system pressure has 

reached a minimum specified value. In 

a properly functioning system, pressure 

builds in the system during engine 

cranking and shortly after starting and 

the pressure enable criterion are reached 

within a few seconds. However, in a 

malfunctioning system (e.g., due to a 

faulty low-pressure fuel pump), it may 

take a significantly longer time to reach 

the feedback enable pressure. A 

malfunction would be indicated when 

the actual time to reach feedback enable 

pressure exceeds the malfunction 

criterion. 

Malfunctions that cause open-loop or 

default operation can be readily 

detected as well. As discussed above, 

the feedback enable criteria are clearly 

defined in the computer and are based 

on what is necessary for reliable control. 

After feedback control has begun, the 

OBD system can detect these criteria 

and indicate a malfunction when they 

are no longer being satisfied. For 

example, one enable criterion could be 

a pressure sensor reading within a 

certain range where the upper pressure 

limit would be based on the maximum 

pressure that could be generated in a 

properly functioning system. A 

malfunction would be indicated if the 

pressure sensor reading exceeded the 

upper limit which would cause the fuel 

system to go open loop. 

The feedback control system adjusts 

the base fuel strategy such that actual 

engine operating characteristics meet 

driver demand. But, the feedback 

control system has limits on how much 

adjustment can be made based, 

presumably, on the ability to maintain 

acceptable control. Like the feedback 

enable criteria, these control limits are 

defined in the computer. The OBD 

system would track the actual 

adjustments made by the control system 

and continuously compare them with 

the control limits. A malfunction would 

be indicated if the limits were reached. 

2. Engine Misfire Monitoring 

Diesel engines certified to the under 

14,000 pound OBD requirements have 

been monitoring for misfire since the 

1998 model year. The monitoring 

requirements we are proposing for over 

14,000 pound applications are identical 

to the existing requirements for under 

14,000 pound applications for those 

engines that do not use combustion 

sensors.59 Therefore, technological 

feasibility has been demonstrated for 

these applications. 

For engines that use combustion 

sensors, the misfire monitoring 

requirements are more stringent since 

the requirement calls for detection of 

malfunctions causing emissions to 

exceed the emissions thresholds. 

Nonetheless, detection on these engines 

should be straight forward since the 

combustion sensors would provide a 

direct measurement of combustion. 

Therefore, lack of combustion (i.e., 

misfire) could be measured directly. The 

combustion sensors are intended to 

measure various characteristics of a 

combustion event for feedback control. 

Such feedback is needed for engines 

that require very precise air and fuel 

metering controls such as would be 

required for homogeneous charge 

compression ignition (HCCI) engine. 

Accordingly, the resolution of sensors 

having that capability is well beyond 

what would be needed to detect a 

complete lack of combustion. 


sroberts on PROD1PC70 with PROPOSALS
3258 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

3. Exhaust Gas Recirculation (EGR) 

Monitoring 

a. EGR Low Flow/High Flow Monitoring 

Typically, the EGR control system 

determines a desired EGR flow rate 

based on the engine operating 

conditions such as engine speed and 

engine load. The desired EGR flow rates, 

and the corresponding EGR valve 

positions needed to achieve the desired 

flow rates, are established when the 

manufacturer designs and calibrates the 

EGR system. Once established, 

manufacturers store the desired EGR 

flow rate/valve position in a lookup 

table in the onboard computer. During 

operation, the onboard computer 

commands the EGR valve to the position 

necessary to achieve the desired flow—

i.e., the commanded EGR flow. The 

onboard computer then calculates or 

directly measures both the fresh air 

charge (fresh air intake) and total intake 

charge. The difference between the total 

intake charge and fresh air intake is the 

actual EGR flow. The closed-loop 

control system continuously adjusts the 

EGR valve position until the actual EGR 

flow equals the desired EGR flow. 

Such closed-loop control strategies 

and their associated OBD monitoring 

strategies are used on many existing 

gasoline and diesel vehicles under 

14,000 pounds. The OBD system 

evaluates the difference (i.e., error) 

between the look-up value—i.e., the 

desired flow rate—and the final 

commanded value needed to achieve 

the desired flow rate. Typically, as the 

feedback parameter or learned offset 

increases, there is an attendant increase 

in emissions. A correlation can be made 

between feedback adjustment and 

emissions. When the error exceeds a 

specific threshold, a malfunction would 

be indicated. This type of monitoring 

strategy could be used to detect both 

high and low flow malfunctions. 

While the closed-loop control strategy 

described above is effective in 

measuring and controlling EGR flow, 

some manufacturers are currently 

investigating the use of a second control 

loop based on an air-fuel ratio (A/F) 

sensor (also known as wide-range 

oxygen sensors or linear oxygen sensors) 

to further improve EGR control and 

emissions. With this second control 

loop, the desired air-fuel ratio is 

calculated based on engine operating 

conditions (i.e., intake airflow, 

commanded EGR flow and commanded 

fuel). The calculated air-fuel ratio is 

compared to the air-fuel ratio from the 

A/F sensor and refinements can be 

made to the EGR and airflow rates—i.e., 

the control can be ‘‘trimmed’’—to 

achieve the desired rates. On systems 

that use the second control loop, flow 

rate malfunctions could also be detected 

using the feedback information from the 

A/F sensor and by applying a similar 

monitoring strategy as discussed above 

for the primary EGR control loop. 

We are also proposing that two 

leaking EGR valve failure modes be 

detected. One type is the failure of the 

valve to seal when in the closed 

position. For example, if the valve or 

seating surface is eroded, the valve 

could close and seat, yet still allow 

some flow across the valve. A flow 

check is necessary to detect a 

malfunctioning valve that closes 

properly but still leaks. EGR flow—total 

intake charge minus fresh air charge—

could be calculated using the 

monitoring strategy described above for 

high and low flow malfunctions. With 

the valve closed, a malfunction would 

be indicated when flow exceeds 

unacceptable levels. Or, some cooled 

EGR systems will incorporate an EGR 

temperature sensor that could be used to 

detect a leaking EGR valve by reacting 

to the presence of hot exhaust gases 

when none should be present. A leaking 

valve can also be caused by failure of 

the valve to close/seat. For example, 

carbon deposits on the valve or seat 

could prevent the valve from closing 

fully. The flow check described above 

could detect failure of the valve to 

close/seat, but this approach would 

require a repair technician to further 

diagnose whether the problem is a 

sealing or seating problem. Such a 

failure of the valve to close/seat could 

be more specifically monitored by 

closing the valve and checking the zero 

position of the valve with a position 

sensor. If the valve position is out of the 

acceptable range for a closed valve, a 

malfunction would be indicated. This 

type of zero position sensor check is 

commonly used to verify the closed 

position of valves/actuators used in 

gasoline OBD systems (e.g. gasoline EGR 

valves, electronic throttle) and should 

be feasible for diesel EGR valves. 

b. EGR Slow Response Monitoring 

While the flow rate monitor discussed 

above would evaluate the ability of the 

EGR system to achieve a commanded 

flow rate under relatively steady state 

conditions, the EGR slow response 

monitor would evaluate the ability of 

the EGR system to modulate (i.e., 

increase and decrease) EGR flow as 

engine operating conditions and, 

consequently, commanded EGR rates 

change. Specifically, as engine operating 

conditions and commanded EGR flow 

rates change, the monitor would 

evaluate the time it takes for the EGR 

control system to achieve the 

commanded change in EGR flow. This 

monitor could evaluate EGR response 

passively during transient engine 

operating conditions encountered 

during in-use operation. The monitor 

could also evaluate EGR response 

intrusively by commanding a change in 

EGR flow under a steady state engine 

operating condition and measuring the 

time it takes to achieve the new EGR 

flow rate. Similar passive and intrusive 

strategies have been developed for 

variable valve control and/or timing 

(VVT) monitoring on vehicles under 

14,000 pounds. 

c. EGR Feedback Control Monitoring 

Monitoring of EGR feedback control 

could be performed using analogous 

strategies to those discussed in Section 

III.A.1 for monitoring of fuel system 

feedback control. 

d. EGR Cooling System Monitoring 

Some diesel engine manufacturers 

currently use exhaust gas temperature 

sensors as an input to their EGR control 

systems. On such systems—EGR 

temperature—which is measured 

downstream of the EGR cooler—could 

be used to monitor the effectiveness of 

the EGR cooler. For a given engine 

operating condition (e.g., a steady 

speed/load that generates a known 

exhaust mass flow and exhaust 

temperature to the EGR cooler), EGR 

temperature will increase as the 

performance of the EGR cooling system 

decreases. During the OBD calibration 

process, manufacturers could develop a 

correlation between increased EGR 

temperatures and cooling system 

performance (i.e., increased emissions). 

The EGR cooling system monitor would 

use such a correlation and indicate a 

malfunction when the EGR temperature 

increases to the level that would cause 

emissions to exceed the emissions 

thresholds. 

While we anticipate that most, if not 

all, manufacturers will use EGR 

temperature sensors to meet future 

emissions standards, EGR cooling 

system monitoring may be feasible 

without such a temperature sensor. The 

monitor could be done using the intake 

manifold temperature (IMT) sensor by 

looking at the change in IMT (i.e., 

‘‘delta’’ IMT) with EGR turned on and 

EGR turned off (IMT would be higher 

with EGR turned on). If there is 

significant cooling capacity with a 

normally functioning EGR cooling 

system, there would likely be a 

significant difference in IMT with EGR 

turned on versus turned off. Delta IMT 

could be correlated to decreased EGR 

cooling system performance and 

increased emissions. 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3259 

4. Turbo Boost Control System 

Monitoring 

a. Turbo Underboost/Overboost 

Monitoring 

To monitor boost control systems, 

manufacturers are expected to look at 

the difference between the actual 

pressure sensor reading (or calculation 

thereof) and the desired/target boost 

pressure. If the error between the two is 

too large or persists for too long, a 

malfunction would be indicated. 

Manufacturers would need to calibrate 

the size of error and/or error duration to 

ensure robust malfunction detection 

occurs before the emissions thresholds 

are exceeded. Given that the purpose of 

a closed-loop control system with a 

feedback sensor is to measure 

continuously the difference between 

actual and desired boost pressure, the 

control system is already monitoring 

that difference and attempting to 

minimize it. As such, a monitoring 

requirement to indicate a malfunction 

when the difference gets large enough 

such that it can no longer achieve the 

desired boost is essentially an extension 

of the existing control strategy. 

To monitor for malfunction or 

deterioration of the boost pressure 

sensors, manufacturers could validate 

sensor readings against other sensors 

present on the vehicle or against 

ambient conditions. For example, at 

initial key-on before the engine is 

running, the boost pressure sensor 

should read ambient pressure. If the 

vehicle is equipped with a barometric 

pressure sensor, the two sensors could 

be compared and a malfunction 

indicated when the two readings differ 

beyond the specific tolerances. A more 

crude rationality check of the boost 

pressure sensor could be accomplished 

by verifying that the pressure reading is 

within reasonable atmospheric limits for 

the conditions the vehicle will be 

subjected to. 

b. VGT Slow Response Monitoring 

The VGT slow response monitor 

would evaluate the ability of the VGT 

system to modulate (i.e., increase and 

decrease) boost pressure as engine 

operating conditions and, consequently, 

commanded boost pressure changes. 

Specifically, as engine operating 

conditions and commanded boost 

pressures change, the monitor would 

evaluate the time it takes for the VGT 

control system to achieve the 

commanded change in boost pressure. 

This monitor could evaluate VGT 

response passively during transient 

engine operating conditions 

encountered during in-use operation. 

The monitor could also evaluate VGT 

response intrusively by commanding a 

change in boost pressure under a steady 

state engine operating condition and 

measuring the time it takes to achieve 

the new boost pressure. 

Rationality monitoring of VGT 

position sensors could be accomplished 

by comparing the measured sensor 

value to expected values for the given 

engine speed and load conditions. For 

example, at high engine speeds and 

loads, the position sensor should 

indicate that the VGT position is opened 

more than would be expected at low 

engine speeds and loads. Such 

rationality checks would need to be 

two-sided (i.e., position sensors should 

be checked for appropriate readings at 

both high and low engine speed/load 

operating conditions. 

c. Turbo Boost Feedback Control 

Monitoring 

Monitoring of boost pressure feedback 

control could be performed using 

analogous strategies to those discussed 

for fuel system feedback control 

monitoring in Section III.A.1. 

d. Charge Air Undercooling Monitoring 

We expect that most engines will 

make use of a temperature sensor 

downstream of the charge air cooler to 

protect against overcooling conditions 

that could cause excessive 

condensation, and to prevent 

undercooling that could result in loss of 

performance. A comparison of the 

actual charge air temperature to the 

expected, or design, temperature would 

indicate any errors that might be 

occurring. Manufacturers could 

correlate that error to an emissions 

impact and, when the error reached a 

level such that emissions would exceed 

the emissions thresholds, a malfunction 

would be indicated. 

5. Non-Methane Hydrocarbon (NMHC) 

Converting Catalyst Monitoring 

a. NMHC Converting Catalyst 

Conversion Efficiency Monitoring 

Monitoring of the NMHC converting 

catalyst, or diesel oxidation catalyst 

(DOC), could be performed similar to 

three-way catalyst monitoring on 

gasoline engines. Three-way catalyst 

monitoring uses the concept that 

catalyst’s oxygen storage capacity 

correlates well with its hydrocarbon 

conversion efficiency. Oxygen sensors 

located upstream and downstream of 

the catalyst can be used to determine 

when its oxygen storage capacity—and, 

hence, its conversion efficiency—has 

deteriorated below a predetermined 

level. 

Determining the oxygen storage 

capacity would require lean air-fuel 

(A/F) operation followed by rich A/F 

operation or vice-versa during the 

catalyst monitoring event. Since a diesel 

engine normally operates lean of 

stoichiometry, lean A/F operation 

would be normal operation. However, 

rich A/F operation would have to be 

commanded intrusively when the 

catalyst monitor is active. The rich A/ 

F operation could be achieved by 

injecting some fuel late enough in the 

four stroke process (i.e., late injection) 

that the raw fuel would not combust incylinder. Rich A/F operation could also 

be achieved using an in-exhaust fuel 

injector upstream of the catalyst. During 

normal lean operation, the catalyst 

would become saturated with stored 

oxygen. As a result, both the front and 

rear oxygen sensors should be reading 

lean. When rich A/F operation initiates, 

the front oxygen sensor would switch 

immediately to a ‘‘rich’’ indication. For 

a short time, the rear oxygen sensor 

should continue to read ‘‘lean’’ until 

such time as the stored oxygen in the 

catalyst is consumed by the rich fuel 

mixture in the exhaust and the rear 

oxygen sensor would read ‘‘rich.’’ As 

the catalyst deteriorates, the delay time 

between the front and rear oxygen 

sensors switching from their normal 

lean state to a rich state would become 

progressively smaller because the 

deteriorated catalyst would have less 

oxygen storage capacity. Thus, by 

comparing the time difference between 

the responses of the front and rear 

oxygen sensors to the lean-to-rich or 

rich-to-lean A/F changes, the 

performance of the catalyst could be 

estimated. Although this discussion 

suggests the use of conventional oxygen 

sensors, these sensors could be 

substituted with A/F sensors which 

would also provide for additional 

engine control benefits such as EGR 

trimming and fuel trimming. 

If a malfunction of the catalyst cannot 

cause emissions to exceed the emissions 

thresholds, then only a functional 

monitor would be required. A 

functional monitor could be done using 

temperature sensors. A functioning 

oxidation catalyst would be expected to 

provide some level of exotherm when it 

oxidizes HC and CO. The temperature of 

the catalyst could be measured by 

placing one or more temperature sensors 

at or near the catalyst. However, 

depending on the nominal conversion 

efficiency of the catalyst and the duty 

cycle of the vehicle, the exotherm may 

be difficult to discern from the inlet 

exhaust temperatures. To add 

robustness to the monitor, the 

functional monitor would need to be 

conducted during predetermined 


sroberts on PROD1PC70 with PROPOSALS
3260 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

60An active or forced regeneration would be 

those regeneration events that are initiated via a 

driver selectable switch or activator and/or those 

initiated by computer software. 

61Schaer, C.M., Onder, C.H., Geering, H.P., and 

Elsener, M., ‘‘Control of a Urea SCR Catalytic 

Converter System for a Mobile Heavy-Duty Diesel 

Engine,’’ SAE Paper 2003–01–0776 which may be 

obtained from Society of Automotive Engineers 

International, 400 Commonwealth Dr., Warrendale, 

PA, 15096–0001. 

62 Ibid. 

63 Draft Technical Support Document, HDOBD 

NPRM, EPA420–D–06–006, Docket ID# EPA–HQ–

OAR–2005–0047–0008. 

64 Ibid. 

65 Ibid. 

operating conditions where the amount 

of HC and CO entering the catalyst 

could be known. This may require an 

intrusive monitor that actively forces 

the fueling strategy richer (e.g., through 

late or post injection) than normal for a 

short period of time. If the measured 

exotherm does not exceed a 

predetermined amount that only a 

properly-working catalyst could 

achieve, a malfunction would be 

indicated. As noted, such an approach 

would require a brief period of 

commanded rich operation that would 

result in a very brief HC and perhaps a 

PM emissions spike. 

b. Other Aftertreatment Assistance 

Function Monitoring 

A functional monitor should be 

sufficient for monitoring the oxidation 

catalyst’s ability to fulfill aftertreatment 

assistance functions such as generating 

an exotherm for DPF regeneration or 

providing a proper feedgas for SCR or 

NOX adsorbers. We would expect that 

manufacturers would use the exotherm 

approach mentioned above either to 

measure directly for the proper 

exotherm or to correlate indirectly for 

the proper feedgas. For catalysts 

upstream of a DPF, we expect that this 

monitoring would be conducted during 

an active or forced regeneration event.60

For catalysts downstream of the DPF, 

we expect that manufacturers would 

have to add fuel intrusively (either inexhaust or through in-cylinder postinjection) to create a sufficient exotherm 

to distinguish malfunctioning from 

properly operating catalysts. 

6. Selective Catalytic Reduction (SCR) 

and NOX Conversion Catalyst 

Monitoring 

a. SCR and NOX Catalyst Conversion 

Efficiency Monitoring 

We would expect manufacturers to 

use NOX sensors to monitor a lean NOX

catalyst. NOX sensors placed upstream 

and downstream of the lean NOX

catalyst could be used to determine 

directly the NOX conversion efficiency. 

Manufacturers could potentially use a 

single NOX sensor placed downstream 

of the catalyst to measure catalyst-out 

NOX emissions. This would have to be 

done within a tightly controlled engine 

operation window where engine-out 

NOX emissions (i.e., NOX emissions at 

the lean NOX catalyst inlet) performance 

is relatively stable and could be 

estimated reliably. Within this engine 

operation window, catalyst-out 

measurements could be compared to the 

expected engine-out NOX emissions and 

a catalyst conversion efficiency could be 

calculated. Should the calculated 

conversion efficiency be insufficient to 

maintain emissions below the emissions 

thresholds, a malfunctioning or 

deteriorated lean NOX catalyst would be 

indicated. If both an upstream and 

downstream NOX sensor are used for 

monitoring, the upstream sensor could 

be used to improve the overall 

effectiveness of the catalyst by precisely 

controlling the air-fuel ratio in the 

exhaust to the levels where the catalyst 

is most effective. 

For monitoring the SCR catalyst, care 

must be taken to account for the cross 

sensitivity of NOX sensors to ammonia 

(NH3). Current NOX sensor technology 

tends to have such a cross-sensitivity to 

ammonia in that as much as 65 percent 

of ammonia can be read as NOX.61

However, urea SCR feedback control 

studies have shown that the NH3

interference signal is discernable from 

the NOX signal and can, in effect, allow 

the design of a better feedback control 

loop than a NOX sensor that doesn’t 

have any NH3 cross-sensitivity. In one 

study, a signal conditioning method was 

developed that resulted in a linear 

output for both NH3 and NOX from the 

NOX sensor downstream of the 

catalyst.62 Monitoring of the catalyst can 

be done by using the same NOX sensors 

that are used for SCR control. When the 

SCR catalyst is functioning properly, the 

upstream sensor should read ‘‘high’’ for 

high NOX levels while the downstream 

sensor should read ‘‘low’’ for low NOX

and low ammonia levels. With a 

deteriorated SCR catalyst, the 

downstream sensor should read similar 

or higher values as the upstream sensor 

(i.e., high NOX and high ammonia 

levels) since the NOX reduction 

capability of the catalyst has 

diminished. Therefore, a malfunctioning 

SCR catalyst could be detected when the 

downstream sensor output is near to or 

greater than the upstream sensor output. 

A similar monitoring approach could be 

used if a manufacturer models upstream 

NOX emissions instead of using an 

upstream NOX sensor. In this case, the 

comparison would be made between the 

modeled upstream NOX value and the 

downstream sensor value. 

Manufacturers have expressed 

concern over both the sensitivity and 

the durability of NOX sensors. They are 

concerned that NOX sensors will not 

have the necessary sensitivity to detect 

NOX at the low levels that will exist 

downstream of the NOX catalyst. They 

are also concerned that NOX sensors 

will not be durable enough to last the 

full useful life of big diesel trucks. We 

have researched NOX sensors—the 

current state of development and future 

expectations—and summarized our 

findings in the technical support 

document in the docket for this rule.63

Some of our findings are summarized 

here. 

Regarding NOX sensor sensitivity, we 

expect that 2010 and later model year 

engines will have average tailpipe NOX

emissions in the 0 to 50 ppm range. 

Current NOX sensors have an accuracy 

of ±10 ppm in the 0 to 100 ppm range. 

This means that current NOX sensors 

should be able to detect NOX emissions 

that exceed the standard by two to three 

times the 2010 limit.64 This should 

allow for compliance with our proposed 

threshold which is effectively 2.5 times 

the 2010 limit. Further, we expect that 

NOX sensors in the 0 to 100 ppm range 

with ±5 ppm accuracy will be available 

by the middle of 2006. Regarding 

durability, improvements are being 

made and a test program is currently 

underway with the intent of aging 

several NOX sensors placed at various 

exhaust system locations out to 6,000 

hours (roughly equivalent to 360,000 

miles). Results after 2,000 hours of aging 

are promising and results after 4,000 

hours of aging are currently being 

analyzed.65

b. SCR and NOX Catalyst Active/ 

Intrusive Reductant Injection System 

Monitoring 

If an active catalyst system is used—

i.e., one that relies on injection of a 

reductant upstream of the catalyst to 

assist in emissions conversion—

manufacturers would be required to 

monitor the mechanism for adding the 

fuel reductant. In the active catalyst 

system, a temperature sensor is 

expected to be placed near or at the 

catalyst to determine when the catalyst 

temperature is high enough to convert 

emissions. Because NOX catalyst 

systems, especially lean NOX catalyst 

systems, tend to have a narrow 

temperature range where they are most 

effective, adding reductant when the 

catalyst temperature is not sufficiently 

high would waste reductant. If fuel is 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3261 

66Crawford, John M., Mitsui Mining & Smelting 

Co., Ltd., presentation to EPA, October 2006, Docket 

ID# EPA–HQ–OAR–2005–0047–0007. 

67 Ingram, G.A. and Surnilla, G., ‘‘On-Line 

Estimation of Sulfation Levels in a Lean NOX Trap,’’

SAE Paper 2002–01–0731 may be obtained from 

Society of Automotive Engineers International, 400 

Commonwealth Dr., Warrendale, PA 15096–0001. 

68 Draft Technical Support Document, HDOBD 

NPRM, EPA420–D–06–006, Docket ID# EPA–HQ–

OAR–2005–0047–0008. 

used as the reductant, this would 

adversely affect fuel economy without a 

corresponding reduction in emissions 

levels. Therefore, a temperature sensor 

is expected to be placed in the exhaust 

near or at the catalyst to help determine 

when reductant injection should occur. 

This same sensor could be used to 

determine if an exotherm resulted 

following reductant injection. The lack 

of an exotherm would indicate a 

malfunction of the reductant delivery 

system. 

Alternatively, any NOX sensors used 

to monitor conversion efficiency could 

be used to determine if reductant 

injection has occurred. NOX sensors are 

also oxygen sensors so they could be 

used to determine the air-fuel ratio in 

the exhaust stream which would allow 

for verification of reductant injection 

into the exhaust. Further, with a 

properly functioning injector, the 

downstream NOX sensor should see a 

change from high NOX levels to low 

NOX levels. In contrast, a lack of 

reductant injection would result in 

continuously high NOX levels at the 

downstream NOX sensor. Therefore, a 

malfunctioning injector could be 

indicated when the downstream NOX

sensor continues to measure high NOX

after an injection event has been 

commanded. 

Reductant level monitoring could also 

be conducted by using the existing NOX

sensors that are used for control 

purposes. Specifically, the downstream 

NOX sensor can be used to determine if 

the reductant tank no longer has 

sufficient reductant available. Similar to 

the fuel reductant injection 

functionality monitor described above, 

when the reductant tank has a sufficient 

reductant quantity and the injection 

system is working properly, the 

downstream NOX sensor should see a 

change from high NOX levels to low 

NOX levels. If the NOX levels remain 

constant both before and after reductant 

injection, then the reductant was not 

properly delivered and either the 

injection system is malfunctioning or 

there is no longer sufficient reductant 

available in the reductant tank. 

Alternatively, reductant level 

monitoring could be conducted by using 

a dedicated ‘‘float’’ type level sensor 

similar to the ones used in fuel tanks. 

Some manufacturers may prefer using a 

dedicated reductant level sensor in the 

reductant tank to inform the vehicle 

operator of current reductant levels via 

a gauge on the instrument panel. If such 

a sensor is used by the manufacturer for 

operator convenience, it could also be 

used to monitor the reductant level in 

the tank. 

Monitoring the reductant itself—

whether it be the wrong reductant or a 

poor quality reductant—could also be 

conducted using the NOX sensors used 

for control purposes. If an improper 

reductant is injected, the NOX catalyst 

system would not function properly. 

Therefore, NOX emissions downstream 

from the catalyst would remain high 

both before and after injection. The 

downstream NOX sensor would see the 

high NOX levels after injection and a 

malfunction would be indicated. If the 

reductant tank level sensor indicated 

sufficient levels for injection and 

decreasing levels following injections 

(which would mean the injection 

system was working), then the probable 

cause of the malfunction would be the 

reductant itself. For urea SCR systems, 

another possible means of monitoring 

the reductant itself would be to use a 

urea quality sensor in the urea tank. 

First generation sensors show promise 

at verifying that urea is indeed in the 

tank, rather than water or some other 

fluid, and that the urea concentration is 

within the needed range (i.e., not 

diluted with water or some other fluid). 

The sensor could also be used in place 

of a urea level sensor. By 2010, we 

would expect subsequent generation 

sensors to provide even better 

capability.66

c. SCR and NOX Catalyst Feedback 

Control Monitoring 

Monitoring of feedback control could 

be performed using analogous strategies 

to those discussed for fuel system 

feedback control monitoring in Section 

III.A.1. 

7. NOX Adsorber Monitoring 

a. NOX Adsorber Capability Monitoring 

We expect that either NOX sensors or 

A/F sensors along with a temperature 

sensor will be used to provide the 

feedback necessary to control the NOX

adsorber system. These same sensors 

could also be used to monitor the NOX

adsorber system’s capability. The use of 

NOX sensors placed upstream and 

downstream of the adsorber system 

would allow the system’s NOX

reduction performance to be 

continuously monitored. For example, 

the upstream NOX sensor on a properly 

functioning adsorber system operating 

with lean fuel mixtures, will read high 

NOX levels while the downstream NOX

sensor should read low NOX levels. 

With a deteriorated NOX adsorber 

system, the upstream NOX levels will 

continue to be high while the 

downstream NOX levels will also be 

high. Therefore, a malfunction of the 

system can be detected by comparing 

the NOX levels measured by the 

downstream NOX sensor versus the 

upstream sensor. 

The possibility exists that an 

upstream NOX sensor will not be used 

for NOX adsorber control. Manufacturers 

may choose to model engine-out NOX

levels—based on engine operating 

parameters such as engine speed, fuel 

injection quantity and timing, EGR flow 

rate—thereby eliminating the need for 

the upstream NOX sensor. In this case, 

we believe that monitoring of the system 

could be conducted using A/F sensors 

in place of NOX sensors.67 During lean 

engine operation with a properly 

operating NOX adsorber system, both 

the upstream and downstream A/F 

sensors would indicate lean mixtures. 

When the exhaust gas is intrusively 

commanded rich to regenerate the NOX

adsorber, the upstream A/F sensor 

would quickly indicate a rich mixture 

while the downstream sensor should 

continue to see a lean mixture due to 

the chemical reaction of the reducing 

agents with NOX and oxygen stored on 

the adsorber. Once all of the stored NOX

and oxygen has been released, the 

reducing agents in the exhaust would 

cause the downstream A/F sensor to 

indicate a rich reading. The more NOX

that is stored in the adsorber, the longer 

the delay between the rich indications 

from the upstream and downstream 

sensors. Thus, the time differential 

between the rich indications from the 

upstream and downstream A/F sensors 

is a gauge of the NOX storage capacity 

of the adsorber. This delay could be 

correlated to an emissions increase and 

the monitor could be calibrated to 

indicate a malfunction upon detecting 

an unacceptably short delay. In fact, 

Honda currently uses a similar approach 

to monitor the NOX adsorber on a 2003 

model year gasoline vehicle which 

demonstrates the viability of the 

approach in a shorter lived application. 

We have studied A/F sensors and their 

durability with respect to longer lived 

diesel applications and our results are 

summarized in a report placed in the 

docket to this rule.68


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b. NOX Adsorber Active/Intrusive 

Reductant Injection System Monitoring 

The injection system used to achieve 

NOX regeneration of the NOX adsorber 

could also be monitored with A/F 

sensors. When the control system injects 

extra fuel to achieve a rich mixture, the 

upstream A/F sensor would respond to 

the change in fueling and could measure 

directly whether or not the proper 

amount of fuel had been injected. If 

manufacturers employ a NOX adsorber 

system design that uses only a single A/ 

F sensor downstream of the adsorber, 

that downstream sensor could be used 

to monitor the performance of the 

injection system. As discussed above, 

the downstream sensor would switch 

from a lean reading to a rich reading 

when the stored NOX has been 

completely released and reduced. If the 

sensor switches too quickly after rich 

fueling is initiated, then either too much 

fuel has been injected or the adsorber 

itself has poor storage capability. 

Conversely, if the sensor takes too long 

to switch after rich fueling is initiated, 

it may be an indication that the adsorber 

has very good storage capability. 

However, excessive switch times (i.e., 

times that exceed the maximum storage 

capability of the adsorber) could be 

indicative of an injection system 

malfunction (i.e., insufficient fuel has 

been injected) or a sensor malfunction 

(i.e., the sensor has a slow response). 

c. NOX Adsorber Feedback Control 

Monitoring 

Monitoring of feedback control could 

be performed using analogous strategies 

to those discussed for fuel system 

feedback control monitoring in Section 

III.A.1. 

8. Diesel Particulate Filter (DPF) 

Monitoring 

a. PM Filtering Performance Monitoring 

The PM filtering performance monitor 

is perhaps the monitor for which we 

have the most concern with respect to 

feasibility. Part of this concern stems 

from the difficulty in detecting the very 

low PM emissions levels required for 

2007/2010 engines (i.e., 0.01 g/bhp-hr). 

While we have made changes to our test 

procedures that will allow for more 

accurate measurement of PM in the test 

cell, it is still very difficult to do. With 

today’s proposal, we are expecting 

manufacturers to detect failures in the 

filtering performance of only a few 

times the actual standards. Success at 

doing so presents a very difficult 

challenge to manufacturers. Our 

concerns, in part, have led us to propose 

a different 2013 and later emissions 

threshold for this monitor than that 

proposed by ARB. This was discussed 

in more detail in section I.D.2. 

We anticipate that manufacturers can 

meet the proposed PM filtering monitor 

requirements without adding hardware 

other than that used for control 

purposes. We believe that the same 

pressure and temperature sensors that 

are used to control DPF regeneration 

will be used for OBD monitoring. For 

control purposes, manufacturers 

generally use a differential or delta 

pressure sensor placed across the DPF 

and at least one temperature sensor 

located near the DPF. The differential 

pressure sensor is expected to be used 

on DPF systems to prevent damage that 

could be caused by delayed or 

incomplete regeneration. Such 

conditions could lead to excessive 

temperatures and melting of the DPF 

substrate. When the differential pressure 

exceeds a predetermined level, a 

regeneration event would be initiated to 

burn the trapped PM. 

However, engine manufacturers have 

told us that differential pressure alone 

does not provide a robust indication of 

trapped PM in the DPF. For example, 

most if not all DPFs in the 2010 

timeframe will be catalyzed DPFs that 

are designed to regenerate passively 

during most operation. Sometimes, 

conditions will not permit the passive 

regeneration and an active regeneration 

would have to be initiated. Relying 

solely on the differential pressure sensor 

to determine when an active 

regeneration event was necessary would 

not be sufficient. A low differential 

pressure could mean a low PM load and 

could also mean a leaking DPF 

substrate. A high differential pressure 

could mean a high PM load and could 

also mean a melted substrate. In the 

latter case, the system may continually 

attempt to regenerate the DPF despite a 

low PM load which would both waste 

fuel and increase HC emissions. 

As a result, manufacturers will 

probably use some sort of soot-loading 

model to predict the PM load on the 

DPF as part of their regeneration 

strategy. Without a robust prediction, a 

regeneration event could be initiated too 

early (i.e., when too little PM was 

present which would be a waste of fuel 

and would increase HC emissions) or 

too late (i.e., when too much PM has 

been allowed to build and the 

regeneration event could cause a 

meltdown of the substrate). The model 

would estimate the PM load by tracking 

the difference between the modeled 

engine-out PM (i.e., the emissions that 

are being loaded on the DPF) and 

regenerated PM (i.e., the PM that is 

being burned off the DPF due to passive 

and/or active regenerations). 

Given this, we believe that a 

comprehensive and accurate sootloading model is also necessary for 

successful monitoring of DPF filtering 

performance. The model would predict 

the PM load on the DPF based on fuel 

consumption and engine operating 

conditions and would predict passively 

regenerated PM based on temperatures. 

This predicted PM load would be 

compared to the measured PM load 

taken from the differential pressure 

sensors. Differences would correspond 

to either a leaking substrate (i.e., 

predicted load greater than measured 

load) or melting of the substrate 

faceplate (i.e., measured load greater 

than predicted load). 

Nonetheless, much development 

remains to be done and success is not 

guaranteed. Manufacturers have noted 

that a melted substrate through which a 

large channel has opened could have 

differential pressure characteristics 

identical to a good substrate despite 

allowing most of the engine-out PM to 

flow directly through. We agree that this 

is a difficult failure mode and have 

proposed language that would allow 

certification of DPF monitors that are 

unable to detect it. Possibly, a 

temperature sensor in the DPF could 

detect the extreme temperatures capable 

of causing such a severe substrate 

melting. Upon detecting such a 

temperature, a regeneration event could 

be initiated to burn off any trapped PM. 

Following that event, the soot model 

would expect a certain increase in 

differential pressure based on modeled 

engine-out PM and passive regeneration 

characteristics. Presumably, the 

measured differential pressure profile 

would not match the predicted profile 

because most PM would be flowing 

straight through the melted channel. 

This same approach, or perhaps a 

simple temperature sensor, should quite 

easily be able to detect a missing 

substrate. 

Lastly, manufacturers have noted 

their concern that small differences in 

substrate crack size or location may 

generate large differences in tailpipe 

emission levels. They have also noted 

their lack of confidence that they will be 

able to reliably detect all leaks that 

would result in emissions exceeding the 

proposed thresholds. Accordingly, the 

manufacturers have suggested pursuing 

an alternate malfunction criterion 

independent of emission level. They 

have suggested criteria such as a percent 

of exhaust flow leakage or a specific 

leak or hole size that must be detected. 

We believe that pursuit of such alternate 

thresholds would not be appropriate at 

this time. Manufacturers have not yet 

completed work on initial widespread 


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implementation of DPFs for the 2007 

model year. We expect that during the 

year or two following that 

implementation, substantial refinement 

and optimization will occur based on 

field experiences and that correlation of 

sensor readings to emissions levels will 

be possible for at least some DPF failure 

modes by the 2010 model year. 

b. DPF Regeneration Monitoring 

Pressure sensing, in combination with 

the soot model, could also be used to 

determine if regeneration is functioning 

correctly. After a regeneration event, the 

differential pressure should drop 

significantly since the trapped PM has 

been removed. If it does not drop to 

within the soot model’s predicted range 

after the regeneration event, either the 

regeneration did not function correctly 

or the filter could have excessive ash 

loading. Ash loading is a normal 

byproduct of engine operation (the ash 

loading is largely a function of oil 

consumption by the engine and the ash 

content of the engine oil). The ash 

builds up in the DPF and does not 

burnout as does the PM but rather must 

be removed or blown out of the DPF. 

Manufacturers are working with us to 

determine the necessary maintenance 

intervals at which this ash removal will 

occur. The soot model would have to 

account for ash buildup in the DPF with 

miles or hours of operation. Future 

engine oils will have lower ash content 

and have tighter quality control such 

that more accurate predictions of ash 

loading will be possible. By including 

ash loading in the soot model, we 

believe that its effects could be 

accounted for in the predicted 

differential pressure following a 

regeneration event. 

As stated, manufacturers are projected 

to make use of temperature sensors for 

regeneration control. These same 

sensors could also be used to monitor 

active regeneration of the filter. If excess 

temperatures are seen by the 

temperature sensor during active 

regeneration, the regeneration process 

can be stopped or slowed down to 

protect the filter. If an active 

regeneration event is initiated and there 

a temperature rise commensurate with 

the amount of trapped PM is not 

detected, the regeneration system is not 

working and a malfunction would be 

indicated. 

c. DPF NMHC Conversion Efficiency 

Monitoring 

Given the stringency of the 2010 

standards, we believe that manufactures 

may rely somewhat on the DPF to 

convert some of the HC emissions. The 

proposed requirement requires 

monitoring this function only if the 

system serves this function. We believe 

that, provided the filtering performance 

and regeneration system monitors have 

not detected any malfunctions, the 

NMHC conversion is probably working 

fine. Given the level of the threshold, 

and the expectation that the DPF will 

serve to control NMHC only marginally, 

we do not anticipate this monitor 

needing emissions correlation work. 

Instead, we expect that, with the DPF 

temperature sensor, it should be 

possible to infer adequate NMHC 

conversion by verifying an exotherm. 

Nonetheless, if a manufacturer relies so 

heavily on the DPF for NMHC 

conversion that its ability to convert 

could be compromised to the point of 

emissions exceeding the threshold, a 

more robust monitor may be required by 

correlating exotherm levels to NMHC 

impacts. 

d. DPF Regeneration Feedback Control 

Monitoring 

Monitoring of DPF regeneration 

feedback control could be performed 

using analogous strategies to those 

discussed for fuel system feedback 

control monitoring in Section III.A.1. 

9. Exhaust Gas Sensor Monitoring 

The under 14,000 pound OBD 

regulations have required oxygen sensor 

monitoring since the 1996 model year. 

Vehicles have been certified during that 

time meeting the requirements. The 

technological feasibility of monitoring 

oxygen sensors has been demonstrated. 

Additionally, A/F sensor monitoring has 

been required, manufacturers have 

complied, and the feasibility has been 

similarly demonstrated. 

NOX sensors are a recent technology 

and, as such, they are still being 

developed and improved. However, we 

would expect that manufacturers would 

design their upstream NOX sensor 

monitors to be similar the A/F sensor 

monitors used in under 14,000 pound 

applications. Monitoring of downstream 

sensors may require modifications to 

existing A/F sensor strategies and/or 

new strategies. Since NOX sensors are 

projected to be used only for control and 

monitoring of aftertreatment systems 

that reduce NOX emissions (e.g., SCR 

systems), the OBD system would have to 

distinguish between deterioration of the 

aftertreatment system and the NOX

sensor itself. As the aftertreatment 

deteriorates, NOX emissions 

downstream of the aftertreatment device 

will increase and, assuming there is no 

such deterioration in the NOX sensor, 

the NOX sensor will read these 

increasing NOX levels. As discussed in 

sections III.A.6 and III.A.7, the 

increased NOX levels can be the basis 

for monitoring the performance of the 

aftertreatment system. However, if the 

NOX sensor does deteriorate with the 

aftertreatment device (i.e., its response 

rate slows with mileage/operating 

hours), the sensor may not properly read 

the increasing NOX levels from the 

deteriorating aftertreatment system, and 

the aftertreatment monitor might 

conclude that the aftertreatment system 

is functioning properly. Similarly, the 

performance or level of deterioration of 

the NOX aftertreatment device could 

affect the results of the NOX sensor 

monitor. Therefore to achieve robust 

monitoring of aftertreatment and 

sensors, the OBD system has to 

distinguish between deterioration of the 

aftertreatment system and deterioration 

of the NOX sensor. To properly monitor 

the NOX sensor, the sensor monitor has 

to run under conditions where the 

aftertreatment performance can be 

quantified and compensated for or 

eliminated in the monitoring results. 

For example, the effects of the SCR 

performance could be eliminated by 

monitoring the NOX sensor under a 

steady-state operating condition during 

which engine-out NOX emissions were 

stable. Under a relatively steady-state 

condition, reductant injection could be 

‘‘frozen’’ (i.e., the reductant injection 

quantity could be held constant) which 

would also freeze the conversion 

efficiency of the SCR system. With SCR 

performance held constant, engine-out 

NOX emissions could be intrusively 

increased by a known amount (e.g., by 

reducing EGR flow or changing fuel 

injection timing and allowing the 

engine-out NOX model to determine the 

increase in emissions). The resulting 

increase in emissions would pass 

through the SCR catalyst unconverted, 

and the sensor response to the known 

increase in NOX concentrations could be 

measured and evaluated. This strategy 

could be used to detect both response 

malfunctions (i.e., the sensor reads the 

correct NOX concentration levels but the 

sensor reading does not change fast 

enough to keep up with changing 

exhaust NOX concentrations) and 

rationality malfunctions (i.e., the sensor 

reads the wrong NOX level). Rationality 

malfunctions could be detected by 

making sure the sensor reading changes 

by the same amount as the intrusive 

change in emissions. Lastly, the sensor 

response to decreasing NOX

concentrations could also be evaluated 

by measuring the response when the 

intrusive strategy is turned off and 

engine-out NOX emissions are returned 

to normal levels. By correlating sensor 

response rates and the resulting 


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emissions impacts, the malfunction 

criteria could then be determined. 

B. Feasibility of the Monitoring 

Requirements for Gasoline/SparkIgnition Engines 

1. Fuel System Monitoring 

For gasoline vehicles since the 1996 

model year and gasoline engines since 

the 2005 model year, the under 14,000 

pound OBD requirements have required 

fuel system monitoring identical to that 

being proposed. Over 100 million cars 

and light trucks have been built and 

sold in the U.S. to these fuel system 

monitoring requirements including 

some heavy-duty vehicles that use the 

exact same gasoline engines that are 

used in some over 14,000 pound 

applications. This clearly demonstrates 

the technological feasibility of the 

proposed requirements. 

2. Engine Misfire Monitoring 

For gasoline vehicles since the 1996 

model year and gasoline engines since 

the 2005 model year, the under 14,000 

pound OBD requirements have required 

misfire monitoring identical to that 

being proposed. One of the most reliable 

methods for detecting misfire is the use 

of a crankshaft position sensor—which 

measures the fluctuations in engine 

angular velocity to determine the 

presence of misfire—along with a 

camshaft position sensor—which can be 

used to identify the misfiring cylinder. 

This method has been shown to be 

technologically feasible and should 

work equally well on over 14,000 pound 

applications. 

3. Exhaust Gas Recirculation (EGR) 

Monitoring 

For vehicles since the 1996 model 

year and engines since the 2005 model 

year, the under 14,000 pound OBD 

requirements have required EGR system 

monitoring identical to that being 

proposed. The general approach has 

been to detect EGR flow rate 

malfunctions by looking at the change 

in fuel trim or manifold pressure under 

conditions when the EGR system is 

active. This demonstrates the 

technological feasibility of the proposed 

requirements. 

4. Cold Start Emission Reduction 

Strategy Monitoring 

We expect this monitoring to be done 

mainly via computer software. For 

example, if spark retard is used during 

cold starts, the commanded amount of 

spark retard would have to be 

monitored if the amount of spark retard 

can be restricted by external factors 

such as idle quality or driveability. This 

can be done with software algorithms 

that compare the actual overall 

commanded final ignition timing with 

the threshold timing that would result 

in emissions that exceed the emissions 

thresholds. Cold start strategies that 

always command a predetermined 

amount of ignition retard independent 

of all other factors and do not allow idle 

quality or other factors to override the 

desired ignition retard would not 

require monitoring of the commanded 

timing. Other methods that could be 

used to ensure that the actual timing has 

been reached include verifying other 

factors such as corresponding increases 

in mass air flow and idle speed 

indicative of retarded spark combustion. 

Both mass air flow and idle speed are 

used currently by the engine control 

system and the OBD system and, 

therefore, only minor software 

modifications should be required to 

analyze these signals while the cold 

start strategy is invoked. 

5. Secondary Air System Monitoring 

A/F sensors would most likely be 

required to monitor effectively the 

secondary air system when it is 

normally active. These sensors are 

currently installed on many new cars 

and their implementation is projected to 

increase in the future as more stringent 

emission standards are phased in. A/F 

sensors are useful in determining airfuel ratio over a broader range than 

conventional oxygen sensors and are 

especially valuable in engines that 

require very precise fuel control. They 

would be useful for secondary air 

system monitoring because of their 

ability to determine air-fuel ratio with 

high accuracy. This would enable a 

correlation between secondary airflow 

rates and emissions. 

6. Catalytic Converter Monitoring 

A common method used for 

estimating catalyst efficiency is to 

measure the catalyst’s oxygen storage 

capacity. This monitoring method has 

been used by all light-duty gasoline 

vehicles since the 1996 model year and 

most gasoline engines since the 2005 

model year as a result of our under 

14,000 OBD requirements. Generally, as 

the catalyst’s oxygen storage capacity 

decreases, the conversion efficiencies of 

HC and NOX also decrease. With this 

strategy, a catalyst malfunction would 

be detected when its oxygen storage 

capacity has deteriorated to a 

predetermined level. Manufacturers 

determine this by using the information 

from an upstream oxygen sensor and a 

downstream or mid-bed oxygen sensor 

(this second sensor is also used for 

trimming the front sensor to maintain 

more precise fuel control). By 

comparing the level of oxygen measured 

by the second sensor with that 

measured by the upstream sensor, 

manufacturers can determine the 

catalyst’s oxygen storage capacity and 

estimate its conversion efficiency. With 

a properly functioning catalyst, the 

second oxygen sensor signal will be 

fairly steady since the fluctuating 

oxygen concentration (due to fuel 

system cycling around stoichiometry) at 

the inlet of the catalyst is damped by the 

storage and release of oxygen in the 

catalyst. When a catalyst is deteriorated 

it is no longer capable of storing and 

releasing oxygen. This causes the 

frequency and peak-to-peak voltage of 

the second oxygen sensor to simulate 

the signal from the upstream oxygen 

sensor at which time a malfunction 

would be indicated. 

7. Evaporative System Monitoring 

Our OBD requirements have required 

monitoring for evaporative system leaks 

for many years. The EPA OBD 

requirement has been the equivalent of 

a 0.040 inch hole, while the ARB 

requirement has gone as low as a 0.020 

inch hole. These requirements have 

been met on applications such as 

incomplete trucks and engine 

dynamometer certified configurations 

equipped with similar and, in many 

cases, identical configurations as are 

used in over 14,000 pound applications. 

Manufacturers have successfully met 

these requirements by using engine 

vacuum to create a vacuum in both the 

fuel tank and evaporative system and 

then monitoring the system’s ability to 

maintain that vacuum. The ramp down 

in vacuum (or ramp up in pressure) can 

then be correlated to leak size. In 

general, these systems require the 

addition of an evaporative system 

pressure sensor and a canister vent 

valve capable of closing the vent line. 

Manufacturers of over 14,000 pound 

applications have expressed concerns 

with their ability to detect evaporative 

system leaks on these larger vehicles. 

One such concern relates to the 

relatively larger fuel tank sizes on the 

larger applications. These tanks can be 

on the order of 50 to 80 gallons, which 

makes the impact of a small hole, on a 

percentage basis, less severe and less 

easily detected. Another concern is the 

relatively large number of fuel tank and 

evaporative system configurations on 

the larger applications. Confounding 

both of these concerns is that the engine 

manufacturers quite often have no idea 

what tanks and configurations will 

ultimately be matched with their engine 

in the final vehicle product. 

While we agree that these concerns 

are valid, they can also be said of the 


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under 14,000 pound applications 

(except perhaps the tank size concern). 

The over 14,000 pound gasoline 

applications are expected to use near 

identical, if not equivalent, evaporative 

system components and we are not 

aware of any reason why the existing 

monitoring techniques would not 

continue to work on over 14,000 pound 

applications. Nonetheless, we do not 

want false failures in the field. By 

limiting the monitoring requirement to 

leaks of 0.150 inch or larger, we believe 

that manufacturers would be able to 

employ a single monitoring strategy to 

all possible tank sizes and 

configurations without much concern 

for false failures. Nonetheless, it may be 

necessary for manufacturers to impose 

tighter restrictions on their engine 

purchasers than is done currently with 

regards to tank specifications and 

evaporative system components. 

8. Exhaust Gas Sensor Monitoring 

Our light-duty OBD requirements 

since the 1996 model year and our 8,500 

to 14,000 pound OBD requirements 

since the 2005 model year have required 

oxygen sensor monitoring similar to the 

requirements being proposed. Years of 

compliance with those requirements 

demonstrates the technological 

feasibility of the proposed requirements. 

Additionally, A/F sensor monitoring has 

been required and demonstrated on 

these vehicles for many years. 

C. Feasibility of the Monitoring 

Requirements for Other Diesel and 

Gasoline Systems 

1. Variable Valve Timing and/or Control 

(VVT) System Monitoring 

VVT systems are already in general 

use in many under 14,000 pound 

applications. Further, under the 

California OBD II requirements, vehicles 

equipped with VVT systems have been 

monitoring those systems for proper 

function since the 1996 model year. 

More recently, manufacturers have 

employed monitoring strategies to 

detect VVT system malfunctions that 

detect not only proper function but also 

exceedances of emissions thresholds. 

Such strategies include the use of the 

crank angle sensor and camshaft 

position sensor to confirm that the valve 

opening and closing occurs within an 

allowable tolerance of the commanded 

crank angle. By calculating the 

difference between the commanded 

valve opening crank angle and the 

achieved valve opening crank angle, a 

diagnostic algorithm can differentiate 

between a malfunctioning system with 

too large of an error and a properly 

functioning system with very little to no 

error. By calibrating the size of this error 

(or integrating it over time), 

manufacturers can design the system to 

indicate a malfunction prior to the 

required emissions thresholds. In the 

same manner, system response can be 

measured by monitoring the length of 

time necessary to achieve the 

commanded valve timing. To ensure 

adequate resolution between properly 

functioning systems and malfunctioning 

systems, most manufacturers perform 

this type of monitor only when a 

sufficiently large ‘‘step change’’ in 

commanded valve timing occurs. 

2. Engine Cooling System Monitoring 

The existing OBD requirements have 

required identical ECT sensor and 

thermostat monitoring for several years. 

While the technical feasibility of the 

proposed requirements has been 

demonstrated on lighter applications 

which tend to be produced through a 

vertically integrated manufacturing 

process, the manufacturers of big diesel 

engines have expressed concerns that 

monitoring of the cooling system on 

over 14,000 pound applications would 

create unique and possibly 

insurmountable challenges. Generally, 

the cooling system is divided into two 

cooling circuits connected by the 

thermostat. The two circuits are the 

engine circuit and the radiator circuit. 

Since the big diesel engine industry 

tends to be horizontally integrated, the 

manufacturers contend that they do not 

know what types of devices will be 

added to the cooling system when the 

vehicle is manufactured or the vehicle 

is put into service. They are concerned 

that the unknown devices can add/ 

remove unknown quantities of heat to/ 

from the system which would prevent 

them from predicting reliably the proper 

system behavior (e.g., warm up). 

Without the ability to predict system 

behavior reliably, they fear that they 

cannot know when the system is 

malfunctioning (e.g., not warming up as 

expected). 

The industry’s concerns regarding 

unknown devices added on the radiator 

circuit of the system seem unwarranted. 

A properly functioning thermostat does 

not allow flow through the radiator 

during warm-up. Devices added to the 

radiator circuit could only affect coolant 

temperature when there is significant 

coolant flow through the radiator (i.e., 

after the engine is warmed-up and the 

thermostat is open, allowing coolant to 

flow through the radiator). 

We agree that unknown devices 

added on the engine circuit (e.g., 

passenger compartment heaters) can 

affect the warm-up rate of the system. 

Manufacturers of under 14,000 pound 

applications have demonstrated robust 

thermostat monitoring with high 

capacity passenger heaters in the 

cooling system. To do so, they have to 

know the maximum rate of heat loss due 

to the heater. Manufacturers of over 

14,000 pound applications have control 

over this by providing limits on such 

devices in the build specifications that 

they provide to the vehicle 

manufacturers. In some cases, an engine 

manufacturer might need multiple build 

specifications with corresponding 

thermostat monitoring calibrations to 

accommodate the ranges of heater 

capacities that are needed when a given 

engine is used in a range of vehicle 

applications (e.g., a local delivery truck 

having a passenger compartment for two 

people and a small capacity heater 

versus a bus having a passenger 

compartment for 20 people and a large 

capacity heater). The vehicle 

manufacturer would then select the 

appropriate calibration for the engine 

when installing it in the vehicle. 

Nonetheless, engine manufacturers have 

requested limited enable conditions for 

the thermostat monitor (e.g., to disable 

the thermostat monitor below 50 

degrees F). This would help to minimize 

their resource needs to calibrate the 

thermostat monitor. While this may be 

directionally favorable to 

manufacturers, it would result in 

disabled thermostat monitoring during 

cold ambient conditions which occur in 

much of the country and, in some areas, 

during a large portion of the year. In 

such regions, a vehicle could experience 

a thermostat malfunction with no 

indication to the vehicle operator. Since 

many other OBD monitors will operate 

only after reaching a certain engine 

coolant temperature, a malfunctioning 

thermostat without any indication could 

effectively result in disablement of the 

OBD system. 

3. Crankcase Ventilation System 

Monitoring 

Crankcase ventilation system 

monitoring requirements have been met 

for years by manufacturers of under 

14,000 pound gasoline applications. 

Therefore, the technological feasibility 

has been demonstrated for gasoline 

applications. 

Effectively, diesel engine 

manufacturers would be required to 

meet design requirements for the entire 

system in lieu of actually monitoring 

any of the hoses for disconnection. 

Specifically, the proposed requirement 

would allow for an exemption for any 

portion of the system that is resistant to 

deterioration or accidental 

disconnection and not subject to 

disconnection during any of the 


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69Motor and Equipment Manufacturers 

Association, Automotive Industry Status Report, 

1999. 

manufacturer’s repair procedures for 

non-crankcase ventilation system repair 

work. These safeguards would be 

expected to eliminate the chances of 

disconnected or improperly connected 

hoses while still allowing manufacturers 

to meet the requirements without 

adding any additional hardware meant 

solely for the purpose of meeting the 

monitoring requirements. 

4. Comprehensive Component 

Monitoring 

Both ARB and EPA OBD requirements 

have for year contained requirements to 

monitor computer input and output 

components. While these monitors are 

sometimes tricky and are not easy as 

many incorrectly assume, the many 

years of successful implementation and 

compliance with the existing 

requirements demonstrates their 

feasibility. The proposed requirements 

are equivalent to the under 14,000 

pound requirements. 

IV. What Are the Service Information 

Availability Requirements? 

A. What Is the Important Background 

Information for the Proposed Service 

Information Provisions? 

Section 202(m)(5) of the CAA directs 

EPA to promulgate regulations requiring 

OEMs to provide to: 

any person engaged in the repairing or 

servicing of motor vehicles or motor vehicle 

engines, and the Administrator for use by any 

such persons, * * * any and all information 

needed to make use of the [vehicle’s] 

emission control diagnostic system * * * 

and such other information including 

instructions for making emission-related 

diagnoses and repairs. 

Such requirements are subject to the 

requirements of section 208(c) regarding 

protection of trade secrets; however, no 

such information may be withheld 

under section 208(c) if that information 

is provided (directly or indirectly) by 

the manufacturer to its franchised 

dealers or other persons engaged in the 

repair, diagnosing or servicing of motor 

vehicles. 

On June 27, 2003 EPA published a 

final rulemaking (68 FR 38428) which 

set forth the Agency’s service 

information regulations for light- and 

heavy-duty vehicles and engines below 

14,000 pounds GVWR. These 

regulations, in part, required eachcovered Original Equipment 

Manufacturer (OEM) to do the 

following: (1) OEMs must make full text 

emissions-related service information 

available via the World Wide Web. (2) 

OEMs must provide equipment and tool 

companies with information that allows 

them to develop pass-through 

reprogramming tools. (3) OEMs must 

make available enhanced diagnostic 

information to equipment and tool 

manufacturers and to make available 

OEM-specific diagnostic tools for sale. 

These requirements were finalized to 

ensure that aftermarket service and 

repair facilities have access to the same 

emission-related service information, in 

the same or similar manner, as that 

provided by OEMs to their franchised 

dealerships. 

As EPA moves forward proposing 

OBD requirements for the heavy-duty 

over 14,000 pounds sector, EPA is 

similarly moving forward with 

proposals to require the availability of 

service information to heavy-duty 

aftermarket service providers as 

required by section 202(m) of the Clean 

Air Act. 

All of the following proposed 

provisions regarding the availability of 

service information for the heavy-duty 

industry are based on our extensive 

experience and regulatory history with 

the light-duty service industry. 

However, as discussed below, EPA 

understands that there may be 

significant differences between the 

light-duty service industry and the 

heavy-duty service industry. EPA 

welcomes comment on all of the 

proposed provisions and their need 

and/or applicability to the heavy-duty 

service industry. 

B. How Do the Below 14,000 Pound and 

Above 14,000 Pounds Aftermarket 

Service Industry Compare? 

As we consider proposing the 

availability of service information for 

the heavy-duty sector above 14,000 

pounds, EPA recognizes that differences 

do exist between the industries that 

service vehicles above and below 14,000 

pounds. On the below 14,000 pound 

side, estimates indicate that 

independent technicians perform up to 

80% of all vehicle service and repairs 

once a vehicle exceeds the manufacturer 

warranty period.69 On the above 14,000 

pound side, the 1997 U.S. Census 

Bureau Vehicle Inventory and Use 

Survey, estimated that 25 percent of the 

general maintenance and over 30 

percent of the major overhaul on heavyduty vehicles was performed by the 

independent sector. According to the 

Census Bureau, these values represent a 

16.7 percent increase in general 

maintenance and a 6.2 percent increase 

in major overhaul from 1992. Trucks 

and Parts Service Magazine provides the 

following information on the breakdown 

of the independent repair industry for 

vehicles above 14,000 pounds (not 

including any fuel injection shops): 

U.S. independent machine shops for 

above 14,000 pounds—5,820 

U.S. independent engine service shops 

for above 14,000 pounds—12,170 

U.S. independent transmission repair 

shops for above 14,000 pounds—

11,420 

Technicians, independent repair shops 

for above 14,000 pounds—133,700 

Technicians, truck parts distributors for 

vehicles above 14,000 pounds—

41,600 

Thus, the increase in business and the 

large number of independent 

aftermarket shops make it necessary that 

repair information is readily available 

for the aftermarket trucking industry. 

On the light-duty side, vehicle 

manufacturers are entirely integrated in 

that they are responsible for the design 

and production of the entire vehicle 

from the chassis to the body. In 

comparison, the heavy-duty industry is 

mostly non-integrated. In other words, 

different manufacturers separately 

produce the engine, the chassis, and the 

transmission of a vehicle. This nonintegration speaks to the fact that a 

completed vehicle is typically produced 

in response to the customized needs of 

owners/operators. In addition, the lack 

of integration indicates that a given 

engine will ultimately be part of many 

different engine, transmission, and 

chassis configurations. In addition, 

heavy-duty manufacturers have stated 

that diagnostic tool designs differ 

significantly from tools produced for 

light-duty vehicles as a result of this 

non-integration. 

EPA requests comment and also 

additional data on the current state of 

the heavy-duty aftermarket industry. 

C. What Provisions Are Being Proposed 

for Service Information Availability? 

1. What Information Is Proposed To Be 

Made Available by OEMs? 

Today’s action proposes a provision 

that requires OEMs to make available to 

any person engaged in the repairing or 

servicing of heavy-duty motor vehicles 

or motor vehicle engines above 14,000 

pounds all information necessary to 

make use of the OBD systems and any 

information for making emission-related 

repairs, including any emissions-related 

information that is provided by the 

OEM to franchised dealers beginning 

with MY2010. We are proposing that 

this information includes, but is not 

limited to, the following: 

(1) Manuals, technical service 

bulletins (TSBs), diagrams, and charts 

(the provisions for training materials, 


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including videos and other media are 

discussed in Sections II.C.3 and II.C.4 

below. 

(2) A general description of the 

operation of each monitor, including a 

description of the parameter that is 

being monitored. 

(3) A listing of all typical OBD 

diagnostic trouble codes associated with 

each monitor. 

(4) A description of the typical 

enabling conditions for each monitor to 

execute during vehicle operation, 

including, but not limited to, minimum 

and maximum intake air and engine 

coolant temperature, vehicle speed 

range, and time after engine startup. A 

listing and description of all existing 

monitor-specific drive cycle information 

for those vehicles that perform misfire, 

fuel system, and comprehensive 

component monitoring. 

(5) A listing of each monitor 

sequence, execution frequency and 

typical duration. 

(6) A listing of typical malfunction 

thresholds for each monitor. 

(7) For OBD parameters that deviate 

from the typical parameters, the OBD 

description shall indicate the deviation 

for the vehicles it applies to and provide 

a separate listing of the typical values 

for those vehicles. 

(8) Identification and scaling 

information necessary to interpret and 

understand data available to a generic 

scan tool through Diagnostic Message 8 

pursuant to SAE Recommended Practice 

J1939–73, which is incorporated by 

reference in section X. 

(9) For vehicles below 14,000 pounds, 

EPA requires that any information 

related to the service, repair, installation 

or replacement of parts or systems 

developed by third party (Tier 1) 

suppliers for OEMs, to the extent they 

are made available to franchise 

dealerships. EPA believes that Tier 1 

suppliers are an important element of 

the market related to vehicles below 

14,000 pounds and EPA is requesting 

comment on the role that Tier 1 

suppliers play in the heavy-duty market 

above 14,000 pounds and the need to 

extend this provision to the heavy-duty 

industry above 14,000 pounds. 

(10) Any information on other 

systems that can directly effect the 

emission system within a multiplexed 

system (including how information is 

sent between emission-related system 

modules and other modules on a 

multiplexed bus), 

(11) Any information regarding any 

system, component, or part of a vehicle 

monitored by the OBD system that 

could in a failure mode cause the OBD 

system to illuminate the malfunction 

indicator light (MIL). 

(12) Any other information relevant to 

the diagnosis and completion of an 

emissions-related repair. This 

information includes, but is not limited 

to, information needed to start the 

vehicle when the vehicle is equipped 

with an anti-theft or similar system that 

disables the engine described below in 

paragraph (13). This information also 

includes any OEM-specific emissionsrelated diagnostic trouble codes (DTCs) 

and any related service bulletins, 

trouble shooting guides, and/or repair 

procedures associated with these OEMspecific DTCs. 

(13) For vehicles below 14,000 

pounds, EPA requires that OEMs make 

available computer or anti-theft system 

initialization information necessary for 

the proper installation of on-board 

computers on motor vehicles that 

employ integral vehicle security systems 

or the repair or replacement of any other 

emission-related part. We did not 

finalize a provision that would require 

OEMs to make this information 

available on the OEM’s Web site unless 

they chose to do so. However, we did 

finalize a provision requiring that the 

OEM’s Web site contain information on 

alternate means for obtaining the 

information and/or ability to perform 

reintialization. EPA is proposing to 

expand this provision to OEMs for 

vehicles above 14,000 pounds and 

requests comment on the prevalence of 

this type of repair, the means and 

methods for performing this type of 

repair and the need to extend this 

provision to the heavy-duty industry. 

In addition, EPA’s current service 

information rules require that, 

beginning with the 2008 model year, all 

OEM systems will be designed in such 

a way that no special tools or processes 

will be necessary to perform reinitialization. In other words, EPA 

expects that the re-initialization of 

vehicles can be completed with generic 

aftermarket tools, a pass-through device, 

or an inexpensive OEM-specific cable. 

EPA finalized this provision for vehicles 

below 14,000 pounds to prevent the 

need for aftermarket service providers to 

invest in expensive OEM-specific or 

specialty tools to complete an 

emissions-related repair that does not 

occur very frequently, but does in fact 

occur. In the June 2003 final rule, EPA 

gave OEMs a significant amount of lead 

time to either separate the need for 

reinitialization from an emissions 

related repair or otherwise redesign the 

reinitialization process in such a way 

that it does not require the use of special 

tools. EPA requests comment on the 

need for such a provision for the above 

14,000 pound market. To the extent that 

such a provision may be needed for the 

heavy-duty arena, EPA also requests 

comment and what lead-time might be 

needed to meet EPA’s goal of not relying 

on special tools or processes to perform 

reinitialization. 

Information for making emissionrelated repairs does not include 

information used to design and 

manufacture parts, but may include 

OEM changes to internal calibrations, 

and other indirect information, as 

discussed below. 

2. What Are the Proposed Requirements 

for Web-Based Delivery of the Required 

Information? 

a. OEM Web Sites 

Today’s action proposes a provision 

that would require OEMs to make 

available in full-text all of the 

information outlined above, on 

individual OEM Web sites. Today’s 

action further proposes that each OEM 

launch their individual Web sites with 

the required information within 6 

months of publication of the final rule 

for all 2010 and later model year 

vehicles. The only proposed exceptions 

to the full-text requirements are training 

information, anti-theft information, and 

indirect information. 

b. Timeliness and Maintenance of 

Information on OEM Web Sites 

Today’s action proposes a provision 

that would require OEMs to make 

available the required information on 

their Web site within six months of 

model introduction. After this six 

month period, we propose that the 

required information for each model 

must be available and updated on the 

OEM Web site at the same time it is 

available by any means to their dealers. 

For vehicles under 14,000 pounds, 

EPA finalized a provision that OEMs 

maintain the required information in 

full text on their Web sites for at least 

15 years after model introduction. After 

this fifteen-year period, OEMs can 

archive the required service 

information, but it must be made 

available upon request, in a format of 

the OEM’s choice (e.g. CD–ROM). Given 

the significantly longer lifetime of 

heavy-duty vehicles and engines above 

14,000 pounds, EPA requests comment 

on the need to require that the required 

information be required to remain on 

the Web sites for a longer period of time. 

c. Accessibility, Reporting and 

Performance Requirements for OEM 

Web Sites 

Performance reports that adequately 

demonstrate that their individual Web 

sites meets the requirements outlined in 

Section C(1) above will be submitted to 

the Administrator annually or upon 


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request by the Administrator. These 

reports shall also indicate the 

performance and effectiveness of the 

Web sites by using commonly used 

Internet statistics (e.g. successful 

requests, frequency of use, number of 

subscriptions purchased, etc). EPA will 

issue additional direction in the form of 

official manufacturer guidance to 

further specify the process for 

submitting reports to the Administrator. 

In addition, EPA is proposing a 

provision that requires OEMs to launch 

Web sites that meet the following 

performance criteria: 

(1) OEM Web sites shall possess 

sufficient server capacity to allow ready 

access by all users and have sufficient 

downloading capacity to assure that all 

users may obtain needed information 

without undue delay; 

(2) Broken Web links shall be 

corrected or deleted weekly. 

(3) Web site navigation does not 

require a user to return to the OEM 

home page or a search engine in order 

to access a different portion of the site. 

(4) It is also proposed that any 

manufacturer-specific acronym or 

abbreviation shall be defined in a 

glossary webpage which, at a minimum, 

is hyperlinked by each webpage that 

uses such acronyms and abbreviations. 

OEMs may request Administrator 

approval to use alternate methods to 

define such acronyms and 

abbreviations. The Administrator shall 

approve such methods if the motor 

vehicle manufacturer adequately 

demonstrates that the method provides 

equivalent or better ease-of-use to the 

Web site user. 

(5) Indicates the minimum hardware 

and software specifications required for 

satisfactory access to the Web site(s). 

d. Structure and Cost of OEM Web Sites 

In addition to the proposed 

requirements described above, EPA is 

proposing that OEMs establish a threetiered approach for the access to their 

Web-based service information. These 

three tiers are proposed to include, but 

are not limited to short-term, mid-term, 

and long-term access to the required 

information. 

(1) Short-Term Access 

OEMs shall provide short-term access 

for a period of 24–72 hours whereby an 

aftermarket service provider will be able 

to access that OEM’s Web site, search 

for the information they need, and 

purchase and/or print it for a set fee. 

(2) Mid-Term Access 

OEMs shall provide mid-term access 

for a period of 30 days whereby an 

aftermarket service provider will be able 

to access that OEM’s Web site, search 

for the information they need, and 

purchase and/or print it for a set fee. 

(3) Long-Term Access 

OEMs shall provide long-term access 

for a period of 365 days whereby an 

aftermarket service provider will be able 

to access that OEM’s Web site, search 

for the information they need, and 

purchase and/or print it for a set fee. 

In addition, for each of the tiers, we 

propose that OEMs make their entire 

site accessible for the respective period 

of time and price. In other words, we 

propose that an OEM may not limit any 

or all of the tiers to just one make or one 

model. 

EPA finalized the three-tiered 

information access approach in our June 

2003 rulemaking to accommodate the 

wide variety of ways in which EPA 

believes aftermarket service providers 

utilize service information. On the 

under 14,000 side, aftermarket 

technicians approach the service of 

vehicles anywhere from servicing any 

make or model that comes into their 

shops to specializing in one particular 

manufacturer. In addition, EPA believes 

that there are other parties such as ‘‘doit-yourself’’ mechanics or Inspection/ 

Maintenance programs that may be 

interested in accessing such OEM websites. In addition, aftermarket service 

providers for vehicles below 14,000 

pounds also relay on third party 

information consolidation entities such 

as Mitchell or All Data to supplement 

OEM-specific information. These 

factors, in addition to the fact that there 

are approximately 25ish (check this 

number) light-duty vehicle 

manufacturers, led EPA to the 

conclusion that a tiered approach to 

Web site access was necessary to ensure 

maximum availability to the 

aftermarket. EPA requests comment on 

the nature of aftermarket service for the 

heavy-duty above 14,000 pound 

industry and the need for a tiered 

approach to information availability. 

Today’s action also proposes that, 

prior to the official launch of OEM Web 

sites, each OEM will be required to 

present to the Administrator a specific 

outline of what will be charged for 

access to each of the tiers. We are 

further proposing that OEMs must 

justify these charges, and submit to the 

Administrator information on the 

following parameters, which include 

but are not limited to, the following: 

(1) The price the manufacturer 

currently charges their branded dealers 

for service information. At a minimum, 

this must include the direct price 

charged that is identified exclusively as 

being for service information, not 

including any payment that is 

incorporated in other fees paid by a 

dealer, such as franchise fees. In 

addition, we propose that the OEM must 

describe the information that is 

provided to dealers, including the 

nature of the information (e.g., the 

complete service manual), etc.; whether 

dealers have the option of purchasing 

less than all of the available 

information, or if purchase of all 

information is mandatory; the number 

of branded dealers who currently pay 

for this service information; and 

whether this information is made 

available to any persons at a reduced or 

no cost, and if so, identification of these 

persons and the reason they receive the 

information at a reduced cost. 

(2) The price the manufacturer 

currently charges persons other than 

branded dealers for service information. 

The OEM must describe the information 

that is provided, including the nature of 

the information (e.g., the complete 

service manual, emissions control 

service manual), etc.; and the number of 

persons other than branded dealers to 

whom the information is supplied. 

(3) The estimated number of persons 

to whom the manufacturer would be 

expected to provide the service 

information following implementation 

of today’s requirements. If the 

manufacturer is proposing a fee 

structure with different access periods 

(e.g., daily, monthly and annual 

periods), the manufacturer must 

estimate the number of users who 

would be expected to subscribe for the 

different access periods. 

A complete list of the proposed 

criteria for establishing reasonable cost 

can be found in the proposed regulatory 

language for this final rule. We are also 

proposing that, subsequent to the 

launch of the OEM Web sites, OEMs 

would be required to notify the 

Administrator upon the increase in 

price of any one or all of the tiers of 

twenty percent or more accounting for 

inflation or that sets the charge for enduser access over the established price 

guidelines discussed above, including a 

justification based on the criteria for 

reasonable cost as established by this 

regulation. 

Throughout the history of the current 

service information regulations, the 

price of service information and how 

price impacts the availability of service 

information has been a source of 

significant debate and discussion. In 

looking at the legislative history that led 

to the inclusion of the service 

information mandate in the Clean Air 

Act Amendments of 1990, it is clear that 

Congress did not intend for the pricing 

of information to be an artificial barrier 


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to access. Further, Congress did not 

intend for information access charges to 

become a profit center for OEMs. 

However, EPA has interpreted that 

Congress did intend for OEMs to be able 

to recover reasonable costs for making 

information available. Since the initial 

implementation of the service 

information requirements beginning 

with original 1995 final rulemaking, 

EPA has continued to refine the 

provisions regulating the cost of service 

to try to balance the Congressional 

intent while understanding that OEMs 

should be able to recover reasonable 

costs for making the required 

information available to the aftermarket. 

In fact, the relatively prescriptive nature 

of some of the requirements stem 

directly from instances on the light-duty 

side where, in the past, we believe some 

manufacturers deliberately priced 

access to information in such a way that 

effectively made it unavailable to the 

aftermarket. The provisions being 

proposed today regarding the pricing of 

service information reflect many years 

of implementation experience, debate, 

and discussion on the light-duty side 

and EPA specifically requests comment 

from heavy-duty aftermarket service 

providers on current state of pricing of 

OEM heavy-duty service information 

and what else EPA should consider for 

heavy-duty that might be different from 

light-duty. 

e. Hyperlinking to and From OEM Web 

Sites 

Today’s action proposes a provision 

that requires OEMs to allow direct 

simple hyperlinking to their Web sites 

from government Web sites and from all 

automotive-related Web sites, such as 

aftermarket service providers, 

educational institutions, and automotive 

associations. 

f. Administrator Access to OEM Web 

Sites 

Today’s action proposes a provision 

that requires that the Administrator 

shall have access to each OEM Web site 

at no charge to the Agency. The 

Administrator shall have access to the 

site, reports, records and other 

information as provided by sections 114 

and 208 of the Clean Air Act and other 

provisions of law. 

g. Other Media 

We are proposing a provision which 

would require OEMs to make available 

for ordering the required information in 

some format approved by the 

Administrator directly from their Web 

site after the proposed full-text window 

of 15 years has expired. It is proposed 

that each OEM shall index their 

available information with a title that 

adequately describes the contents of the 

document to which it refers. In the 

alternate, OEMs may allow for the 

ordering of information directly from 

their Web site, or from a Web site 

hyperlinked to the OEM Web site. We 

also propose that OEMs be required to 

list a phone number and address where 

aftermarket service providers can call or 

write to obtain the desired information. 

We also propose that OEMs must also 

provide the price of each item listed, as 

well as the price of items ordered on a 

subscription basis. To the extent that 

any additional information is added or 

changed for these model years, OEMs 

shall update the index as appropriate. 

OEMs will be responsible for ensuring 

that their information distributors do so 

within one regular business day of 

received the order. Items are less than 

20 pages (e.g. technical service 

bulletins) shall be faxed to the requestor 

and distributors are required to deliver 

the information overnight if requested 

and paid for by the ordering party. 

h. Small Volume Provisions for OEM 

Web Sites 

In the July 2003 final rulemaking, 

EPA finalized a provision to provide 

flexibility for small volume OEMs. In 

particular, EPA finalized a provision 

that requires OEMs who are issued 

certificates of conformity with total 

annual sales of less than one thousand 

vehicles are be exempt from the full-text 

Internet requirements, provided they 

present to the Administrator and obtain 

approval for an alternative method by 

which emissions-related information 

can be obtained by the aftermarket or 

other interested parties. EPA also 

finalized a provision giving OEMs with 

total annual sales of less than five 

thousand vehicles an additional 12 

months to launch their full-text Web 

sites. 

These small-volume flexibilities are 

limited to the distribution and 

availability of service information via 

the World Wide Web under paragraph 

(4) of the regulations. All OEMs, 

regardless of volume, must comply with 

all other provisions as finalized in this 

rulemaking. EPA is requesting comment 

on the existence of small volume OEMs 

in the heavy-duty arena and the need for 

any provisions relating to small volume 

OEMs. 

3. What Provisions Are Being Proposed 

for Service Information for Third Party 

Information Providers? 

The nature of the light-duty 

aftermarket service industry is such that 

they rely to a great extent on 

consolidated service information that is 

development by third party information 

providers such as Mitchell and All-data. 

Third-party information providers will 

license OEM service information and 

consolidate that information for sale to 

the aftermarket. In the June 2003 final 

rule, EPA finalized a provision that will 

require OEMs who currently have, or in 

the future engage in, licensing or 

business arrangements with third party 

information providers, as defined in the 

regulations, to provide information to 

those parties in an electronic format in 

English that utilizes non-proprietary 

software. Further, EPA required that any 

OEM licensing or business arrangements 

with third party information providers 

are subject to fair and reasonable cost 

requirements. Lastly, we expect that 

OEMs will develop pricing structures 

for access to this information that make 

it affordable to any third party 

information providers with which they 

do business. EPA proposes to extend 

these provisions to the heavy-duty 

vehicle and engine manufacturers 

beginning with the 2010 model year. 

However, EPA is specifically 

requesting comment on what role thirdparty consolidated information plays in 

the heavy-duty aftermarket. Further, 

EPA requests comment on the need for 

these, or additional provisions, related 

to third-party information providers. 

4. What Requirements are Being 

Proposed for the Availability of Training 

Information? 

a. Purchase of Training Materials for 

OEM Web Sites 

In the light-duty service information 

final rule, EPA finalized two provisions 

for access to OEM emissions-related 

training. First, OEMs are required to 

make available for purchase on their 

Web sites the following items: Training 

manuals, training videos, and 

interactive, multimedia CD’s or similar 

training tools available to franchised 

dealerships. Second, we finalized a 

provision that OEMs who transmit 

emissions-related training via satellite 

or the Internet must tape these 

transmissions and make them available 

for purchase on their Web sites within 

30 days after the first transmission to 

franchised dealerships. Further, all of 

the items included in this provision 

must be shipped within 24 hours of the 

order being placed and are to be made 

available at a reasonable price. We also 

finalized a provision that will allow for 

an exception to the 24 hour shipping 

requirement in those circumstances 

where orders exceed supply and 

additional time is needed by the 

distributor to reproduce the item being 

ordered. For subsequent model years, 


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the required information must be made 

available for purchase within three 

months of model introduction, and then 

be made available at the same time it is 

made available to franchised 

dealerships. 

EPA is proposing to extend these 

provisions to the heavy-duty industry 

and requests comment on the need to so 

or to develop other provisions 

pertaining to the availability of training 

information for the heavy-duty 

aftermarket. 

b. Third Party Access to OEM Training 

Material 

In the light-duty final rule, we also 

finalized a provision that requires OEMs 

who utilize Internet and satellite 

transmissions to present emissionsrelated training to their dealerships to 

make these same transmissions 

available to third party training 

providers. In this way, we believe we 

are providing at least one opportunity 

for aftermarket technicians to receive 

similar emissions-related training 

information as provided to dealerships, 

thus furthering the goals and letter of 

section 202(m)(5). This requirement 

only requires OEMs to provide the same 

information to legitimate aftermarket 

training providers as is provided to 

dealerships and aftermarket service 

providers. It is not a requirement to 

license OEM copyrighted materials to 

these entities. 

OEMs may take reasonable steps to 

protect their copyright to the extent 

some or all of this material may be 

copyrighted and may refuse to do 

business with any party that does not 

agree to such steps. However, we do 

expect OEMs to use fair business 

practices in its dealings with these third 

parties, in keeping with the ‘‘fair and 

reasonable price’’ requirements in these 

regulations. OEMs may not charge 

unreasonable up-front fees for access to 

these transmissions, but OEMs may 

require a royalty, percentage or other 

arranged fee based limits of on a per-use 

or enrollment subscription basis. 

EPA requests comment on the need to 

expand the light-duty requirements to 

the heavy-duty sector. EPA also requests 

comments on any additional provisions 

it should consider to ensure that heavyduty aftermarket service providers and 

trainers have sufficient access to OEM 

training information at a fair and 

reasonable price. EPA also requests 

comments on the types of training that 

is currently development by heavy-duty 

OEMs and what processes may already 

be in place for availability to the 

aftermarket. 

5. What Requirements Are Being 

Proposed for Reprogramming of 

Vehicles? 

The 2003 final rule required that 

light-duty OEMs comply with SAE 

J2534, ‘‘Recommended Practice for PassThru Vehicle Programming’’. EPA 

understands that the heavy-duty 

industry has a similar standard in place 

that is similar to SAE J2534 

specification for reprogramming. 

Therefore, today’s action proposes two 

options for pass-thru reprogramming. 

We are proposing that heavy-duty OEMs 

comply with SAE J2534 beginning with 

2010 model year. In the alternate, 

heavy-duty OEMs may comply with the 

Technology and Maintenance Council’s 

Recommended Practice RP1210a, 

‘‘Windows Communication API,’’ July 

1999 beginning in the 2010 model year. 

We will also propose a provision that 

will require that reprogramming 

information be made available within 3 

months of vehicle introduction for new 

models. 

6. What Requirements are Being 

Proposed for the Availability of 

Enhanced Information for Scan Tools 

for Equipment and Tool Companies? 

a. Description of Information That Must 

Be Provided 

Today’s action proposes a provision 

that requires OEMs to make available to 

equipment and tool companies all 

generic and enhanced information, 

including bi-directional control and 

data stream information. In addition, it 

is proposed that OEMs must make 

available the following information. 

(i) The physical hardware 

requirements for data communication 

(e.g. system voltage requirements, cable 

terminals/pins, connections such as 

RS232 or USB, wires, etc.). 

(ii) ECU data communication (e.g. 

serial data protocols, transmission speed 

or baud rate, bit timing requirements, 

etc.). 

(iii) Information on the application 

physical interface (API) or layers. (i.e., 

processing algorithms or software 

design descriptions for procedures such 

as connection, initialization, and 

termination). 

(iv) Vehicle application information 

or any other related service information 

such as special pins and voltages or 

additional vehicle connectors that 

require enablement and specifications 

for the enablement. 

(v) Information that describes which 

interfaces, or combinations of interfaces, 

from each of the categories as described 

in paragraphs (g)(12)(vii)(A) through (D) 

of the regulatory language. 

b. Distribution of Enhanced Diagnostic 

Information 

Today’s action proposes a provision 

that will require the above information 

for generic and enhanced diagnostic 

information be provided to aftermarket 

tool and equipment companies with 

whom appropriate licensing, 

contractual, and confidentiality 

agreements have been arranged. This 

information shall be made available in 

electronic format using common 

document formats such as Microsoft 

Excel, Adobe Acrobat, Microsoft Word, 

etc. Further, any OEM licensing or 

business arrangements with equipment 

and tool companies are subject to a fair 

and reasonable cost determination. 

7. What Requirements Are Being 

Proposed for the Availability of OEMSpecific Diagnostic Scan Tools and 

Other Special Tools? 

a. Availability of OEM-Specific 

Diagnostic Scan Tools 

Today’s action proposes a provision 

that OEMs must make available for sale 

to interested parties the same OEMspecific scan tools that are available to 

franchised dealerships, except as 

discussed below. It is proposed that 

these tools shall be made available at a 

fair and reasonable price. It is also 

proposed, that these tools shall also be 

made available in a timely fashion 

either through the OEM Web site or 

through an OEM-designated 

intermediary. 

b. Decontenting of OEM-Specific 

Diagnostic Scan Tools 

Today’s action proposes a provision 

that requires OEMs who opt to remove 

non-emissions related content from 

their OEM-specific scan tools and sell 

them to the persons specified in 

paragraph (g)(2)(i) and (f)(2)(i) of the 

regulatory language for this final rule 

shall adjust the cost of the tool 

accordingly lower to reflect the 

decreased value of the scan tool. It is 

proposed that all emissions-related 

content that remains in the OEMspecific tool shall be identical to the 

information that is contained in the 

complete version of the OEM-specific 

tool. Any OEM who wishes to 

implement this option must request 

approval from the Administrator prior 

to the introduction of the tool into 

commerce. 

c. Availability of Special Tools 

The 2003 final rule precluded lightduty OEMs from using special tools to 

extinguish the malfunction indicator 

light (MIL) beginning with model year 

2004. For model years 1994 through 

2003, the final rule required OEMs who 


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70Regulatory Impact Analysis: Heavy-Duty 

Engine and Vehicle Standards and Highway Diesel 

Fuel Sulfur Control Requirements; EPA420–R–00–

026; December 2000. 

currently require such tools to 

extinguish the MIL must release the 

necessary information to equipment and 

tool companies to design a comparable 

generic tool. We also required that this 

information shall be made available no 

later than one month following the 

effective date of the Final Rule. EPA 

requests comment on this or other 

special tools that may be unique to the 

heavy-duty industry and on the need for 

provisions covering these tools. 

8. Which Reference Materials are Being 

Proposed for Incorporation by 

Reference? 

Today’s action will finalize a 

provision requiring that OEMs comply 

with the following SAE Recommended 

Practices. 

(1) SAE Recommended Practice J2403 

(October 1998), ‘‘Medium/Heavy-Duty 

EE Systems Diagnosis Nomenclature’’

beginning with the 2010 model year. 

(2) SAE Recommended Practice J2534 

(February, 2002), ‘‘Recommended 

Practice for Pass-Thru Vehicle 

Reprogramming’’. EPA will require that 

OEMs comply with SAE J2534 

beginning with the 2010 model year. 

(3) SAE Recommended Practice 

J1939–73. 

(4) ISO/DIS 15031–5 April 30, 2002. 

V. What Are the Emissions Reductions 

Associated With the Proposed OBD 

Requirements? 

In the 2007HD highway rule, we 

estimated the emissions reductions we 

expected to occur as a result of the 

emissions standards being made final in 

the rule. Since the OBD requirements 

contained in today’s proposal are 

considered by EPA to be an important 

element of the 2007HD highway 

program and its ultimate success, rather 

than a new element being included as 

an addition to that program, we are not 

estimating emissions reductions 

associated with today’s proposal. 

Instead, we consider the new 2007/2010 

tailpipe emissions standards and fuel 

standards to be the drivers of emissions 

reductions and HDOBD to be part of the 

assurance we all have that those 

emissions reductions are indeed 

realized. Therefore, this analysis 

presents the emissions reductions 

estimated for the 2007HD highway 

program. Inherent in those estimates is 

an understanding that, while emissions 

control systems sometimes malfunction, 

they presumably are repaired in a timely 

manner. Today’s proposed OBD 

requirements would provide substantial 

tools to assure that our presumption 

will be realized by helping to ensure 

that emission control systems continue 

to operate properly throughout their life. 

We believe that the OBD requirements 

proposed today would lead to more 

repairs of malfunctioning or 

deteriorating emission control systems, 

and may also lead to emission control 

systems that are more robust throughout 

the life of the engine and less likely to 

trigger illumination of MILs. The 

requirements would therefore provide 

greater assurance that the emission 

reductions expected from the Clean 

Diesel Trucks and Buses program will 

actually occur. Viewed from another 

perspective, while the OBD 

requirements would not increase the 

emission reductions that we estimated 

for the 2007HD highway rule, they 

would be expected to lead to actual 

emission reductions in-use compared 

with a program with no OBD system. 

The costs associated with HDOBD 

were not fully estimated in the 2007HD 

highway rule. Those costs are more fully 

considered in section VI of this 

preamble. These newly developed 

HDOBD costs are added to those costs 

estimated for the 2007/2010 standards 

and a new set of costs for those 

standards are presented in section VII. 

Section VII also calculates a new set of 

costs per ton associated with the 2007/ 

2010 standards which include the 

previously estimated costs and 

emissions reductions for the 2007/2010 

standards and the newly estimated costs 

associated with today’s HDOBD 

proposal. 

Here we present the emission benefits 

we anticipate from heavy-duty vehicles 

as a result of our 2007/2010 NOX, PM, 

and NMHC emission standards for 

heavy-duty engines. The graphs and 

tables that follow illustrate the Agency’s 

projection of future emissions from 

heavy-duty vehicles for each pollutant. 

The baseline case represents future 

emissions from heavy-duty vehicles at 

present standards (including the 

MY2004 standards). The controlled case 

represents the future emissions from 

heavy-duty vehicles once the new 2007/ 

2010 standards are implemented. A 

detailed analysis of the emissions 

reductions associated with the 2007/ 

2010 HD highway standards is 

contained in the Regulatory Impact 

Analysis for that final rule.70 The results 

of that analysis are presented in Table 

V.A–1 and in Figures V.A–1 through 

V.A–3. 

TABLE V.A–1.—ANNUAL EMISSIONS

REDUCTIONS ASSOCIATED WITH THE

2007HD HIGHWAY PROGRAM

[thousand short tons] 

Year NOX PM NMHC 

2007 .................. 58 11 2 

2010 .................. 419 36 21 

2015 .................. 1,260 61 54 

2020 .................. 1,820 82 83 

2030 .................. 2,570 109 115 


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Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3273 

71 Draft Technical Support Document, HDOBD 

NPRM, EPA420–D–06–006, Docket ID# EPA–HQ–

OAR–2005–0047–0008. 

BILLING CODE 6560–50–C 

There were additional estimated 

emissions reductions associated with 

the 2007HD highway rule—namely CO, 

SOX, and air toxics. We have not 

presented those additional emissions 

reductions here since, while HDOBD 

will identify malfunctions and hasten 

their repair with the result of reducing 

all emissions constituents, these 

additional emissions are not those 

specifically targeted by OBD systems. 

VI. What Are the Costs Associated With 

the Proposed OBD Requirements? 

Estimated engine costs are broken into 

variable costs and fixed costs. Variable 

costs are those costs associated with any 

new hardware required to meet the 

proposed requirements, the associated 

assembly time to install that hardware, 

and the increased warranty costs 

associated with the new hardware. 

Variable costs are additionally marked 

up to account for both manufacturer and 

dealer overhead and carrying costs. The 

manufacturer’s carrying cost was 

estimated to be four percent of the direct 

costs to account for the capital cost of 

the extra inventory and the incremental 

costs of insurance, handling, and 

storage. The dealer’s carrying cost was 

estimated to be three percent of their 

direct costs to account for the cost of 

capital tied up in inventory. We adopted 

this same approach to markups in the 

2007HD highway rule and our more 

recent Nonroad Tier 4 rule based on 

industry input. 

Fixed costs considered here are those 

for research and development (R&D), 

certification, and production evaluation 

testing. The fixed costs for engine R&D 

are estimated to be incurred over the 

four-year period preceding introduction 

of the engine. The fixed costs for 

certification include costs associated 

with demonstration testing of OBD 

parent engines including the ‘‘limit’’

parts used to demonstrate detection of 

malfunctions at or near the applicable 

OBD thresholds, and generation of 

certification documentation. Production 

evaluation testing includes testing real 

world products for standardization 

features, monitor function, and 

performance ratios. The certification 

costs are estimated to be incurred one 

year preceding introduction of the 

engine while the production evaluation 

testing is estimated to occur in the same 

year as introduction. 

The details of our cost analysis are 

contained in the technical support 

document which can be found in the 

docket for this rule.71 We have only 

summarized the results of that analysis 

here and point the reader to the 

technical support document for details. 

We request comment on all aspects of 

our cost analysis. 

A. Variable Costs for Engines Used in 

Vehicles Over 14,000 Pounds 

The variable costs we have estimated 

represent those costs associated with 

various sensors that we believe would 

have to be added to the engine to 

provide the required OBD monitoring 

capability. For the 2010 model year, we 

believe that upgraded computers and 

the new sensors needed for OBD would 

result in costs to the buyer of $40 and 

$50 for diesel and gasoline engines, 

respectively. For the 2013 model year, 

we have included costs associated with 

the dedicated MIL and its wiring 

resulting in a hardware cost to the buyer 

of $50 and $60 for both diesel and 

gasoline engines, respectively. By 

multiplying these costs per engine by 

the projected annual sales we get annual 

costs of around $40–50 million for 

diesel engines and $3–4 million for 

gasoline engines, depending on sales. 

The 30 year net present value of the 

annual variable costs would be $666 

million and $352 million at a three 

percent and a seven percent discount 

rate, respectively. These costs are 

summarized in Table VI.A–1. 


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TABLE VI.A–1.—OBD VARIABLE COSTS FOR ENGINES USED IN VEHICLES OVER 14,000 POUNDS

[All costs in $millions except per engine costs; 2004 dollars] 

Diesel Gasoline Total 

Cost per engine (2010–2012) .................................................................................................................. $40 $50 n/a 

Cost per engine (2013+) .......................................................................................................................... 50 60 n/a 

Annual Variable Costs in 2010 a .............................................................................................................. 14 1 $15 

Annual Variable Costs in 2013 a .............................................................................................................. 38 3 40 

Annual Variable Costs in 2030 a .............................................................................................................. 48 4 52 

30 year NPV at a 3% discount rate ........................................................................................................ 620 47 666 

30 year NPV at a 7% discount rate ........................................................................................................ 328 25 352 

aAnnual variable costs increase as projected sales increase. 

B. Fixed Costs for Engines Used in 

Vehicles Over 14,000 Pounds 

We have estimated fixed costs for 

research and development (R&D), 

certification, and production evaluation 

testing. The R&D costs include the costs 

to develop the computer algorithms 

required to diagnose engine and 

emission control systems, and the costs 

for applying the developed algorithms 

to each engine family and to each 

variant within each engine family. R&D 

costs also include the testing time and 

effort needed to develop and apply the 

OBD algorithms. The certification costs 

include the costs associated with testing 

of durability engines (i.e., the OBD 

parent engines), the costs associated 

with generating the ‘‘limit’’ parts that 

are required to demonstrate OBD 

detection at or near the applicable 

emissions thresholds, and the costs 

associated with generating the necessary 

certification documentation. Production 

evaluation testing costs included the 

costs associated with the three types of 

production testing: standardization 

features, monitor function, and 

performance ratios. 

Table VI.B–1 summarizes the R&D, 

certification, and production evaluation 

testing costs that we have estimated. 

The R&D costs we have estimated were 

totaled and then spread over the four 

year period prior to implementation of 

the requirements for which the R&D is 

conducted. By 2013, all of the R&D work 

would be completed in advance of 100 

percent compliance in 2013; hence, R&D 

costs are zero by 2013. Certification 

costs are higher in 2013 than in 2010 

because 2010 requires one engine family 

to comply while 2013 requires all 

engine families to comply. The 30 year 

net present value of the annual fixed 

costs would be $291 million and $241 

million at a three percent and a seven 

percent discount rate, respectively. 

TABLE VI.B–1.—OBD FIXED COSTS FOR ENGINES USED IN VEHICLES OVER 14,000 POUNDS

[All costs in $millions; 2004 dollars] 

Diesel Gasoline 

R&D Certification 

& PE testing Subtotal R&D Certification & PE testing Subtotal Total 

Annual OBD Fixed Costs in given 

years: 

2010 ...................................... $51 $0 .2 $52 $0 .9 <$0 .1 $1 $53 

2013 ...................................... 0 0 .4 0 .4 0 <0 .1 <0 .1 0 .4 

2030 ...................................... 0 3 3 0 <0 .1 <0 .1 3 

30 year NPV at the given discount rate: 

3 percent ............................... $263 $17 $280 $10 $0 .3 $10 $291 

7 percent ............................... 223 10 232 9 0 .2 9 241 

C. Total Costs for Engines Used in 

Vehicles Over 14,000 Pounds 

The total OBD costs for engines used 

in vehicles over 14,000 pounds are 

summarized in Table VI.C–1. As shown 

in the table, the 30 year net present 

value cost is estimated at $1 billion and 

$594 million at a three percent and a 

seven percent discount rate, 

respectively. These costs are much 

lower than the 30 year net present value 

costs estimated for the 2007HD highway 

emissions standards which were $25 

billion and $15 billion at a three percent 

and a seven percent discount rate, 

respectively, for diesel and gasoline 

engines. Including the cost for the diesel 

fuel changes resulted in 30 year net 

present value costs for that rule of $70 

billion and $42 billion at a three percent 

and a seven percent discount rate, 

respectively. See section VII for more 

details regarding the cost estimates from 

the 2007HD highway final rule. 


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72 Draft Technical Support Document, HDOBD 

NPRM, EPA420–D–06–006, Docket ID# EPA–HQ–

OAR–2005–0047–0008. 

73See www.bls.gov/ppi; All other motor vehicle 

parts mfg; Exhaust system parts, new; series ID 

PCU3363993363993; Base date 8812. 

TABLE VI.C–1.—OBD TOTAL COSTS

FOR ENGINES USED IN VEHICLES

OVER 14,000 POUNDS

[All costs in $millions; 2004 dollars] 

Diesel Gasoline Total 

Annual OBD Total Costs in given years 

2010 ...... $65 $2 $67 

2013 ...... 38 3 41 

2030 ...... 51 4 55 

30 year NPV at the given discount rate 

3% ......... 900 57 957 

7% ......... 560 34 594 

D. Costs for Diesel Heavy-Duty Vehicles 

and Engines Used in Heavy-duty 

Vehicles Under 14,000 Pounds 

The total OBD costs for 8,500 to 

14,000 pound diesel applications are 

summarized in Table VI.D–1. As shown 

in the table, the 30 year net present 

value cost is estimated at $6 million and 

$5 million at a three percent and a seven 

percent discount rate, respectively. 

These costs represent the incremental 

costs of the proposed additional OBD 

requirements, as compared to our 

current OBD requirements, for 8,500 to 

14,000 pound diesel applications and 

do not represent the total costs for 8,500 

to 14,000 pound diesel OBD. We are 

proposing no changes to the 8,500 to 

14,000 pound gasoline requirements so, 

therefore, have estimated no costs for 

gasoline vehicles. Details behind these 

estimated costs can be found in the 

technical support document contained 

in the docket for this rule.72

TABLE VI.D–1.—TOTAL OBD COSTS

FOR 8,500 TO 14,000 POUND DIESEL APPLICATIONS

[All costs in $millions; 2004 dollars] 

Diesel Gasoline Total 

Annual OBD Total Costs in given years 

2010 ...... $0.1 $0 $0.1 

2013 ...... 0 0 0 

2030 ...... 0.4 0 0.4 

30 year NPV at the given discount rate 

3% ......... 6 0 6 

7% ......... 5 0 5 

VII. What are the Updated Annual 

Costs and Costs per Ton Associated 

With the 2007/2010 Heavy-duty 

Highway Program? 

In the 2007HD highway rule, we 

estimated the costs we expected to 

occur as a result of the emissions 

standards being made final in that rule. 

As noted in section V, we consider the 

OBD requirements contained in today’s 

proposal to be an important element of 

the 2007HD highway program and its 

ultimate success and not a new element 

being included as an addition to that 

program. In fact, without the proposed 

OBD requirements we would not expect 

the emissions reductions associated 

with the 2007/2010 standards to be fully 

realized because emissions control 

systems cannot be expected to operate 

without some need for repair which, 

absent OBD, may well never be done. 

However, as noted in section VI, 

because we did not include an OBD 

program in the 2007HD highway 

program, we did not estimate OBD 

related costs at that time. We have now 

done so and those costs are presented in 

section VI. 

Here we present the OBD costs as part 

of the greater 2007HD highway program. 

To do this, we present both the costs 

developed for that program and the 

additional OBD costs presented in 

section VI. We also calculate a new set 

of costs per ton associated with the 

2007/2010 standards which include the 

previously estimated costs and 

emissions reductions for the 2007/2010 

standards and the newly estimated costs 

associated with today’s HDOBD 

proposal. 

Note that the costs estimates 

associated with the 2007HD highway 

program were done using 1999 dollars. 

We have estimated OBD costs in 2004 

dollars. We consulted the Producer 

Price Index (PPI) for ‘‘Motor vehicle 

parts manufacturing-new exhaust 

system parts’’ developed by the Bureau 

of Labor Statistics and found that the 

PPI for such parts had actually 

decreased from 1999 to 2004.73 This 

suggests that the cost to produce 

exhaust system parts has decreased 

since 1999. For clarity, rather than 

adjusting downward the 2007HD 

highway program costs from 1999 

dollars, or adjusting upward the OBD 

costs from 2004 dollars, we have chosen 

to present the 2007HD highway rule 

costs as they were presented in that 

final rule alongside the OBD costs 

presented in section VI. In short, we are 

ignoring the PPI effect in the following 

tables. 

A. Updated 2007 Heavy-Duty Highway 

Rule Costs Including OBD 

Table VII.A–1 shows the 2007HD 

highway program costs along with the 

estimated OBD related costs. 

TABLE VII.A–1.—UPDATED 2007HD HIGHWAY PROGRAM COSTS, INCLUDING NEW OBD-RELATED COSTS, NET PRESENT

VALUE OF ANNUAL COSTS FOR THE YEARS 2006–2035 

[All costs in $millions] 

Discount rate 

2007 HD Highway Final Rule 

Proposed 

HD OBD 

Updated 

total program costs Diesel engine costs 

Gasoline 

engine & 

vehicle 

costs 

Diesel fuel 

costs 

Original 

total costs 

3 percent .......................................................................... $23,721 $1,514 $45,191 $70,427 $963 $71,389 

7 percent .......................................................................... 14,369 877 26,957 42,203 599 42,802 


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B. Updated 2007 Heavy-Duty Highway 

Rule Costs per Ton Including OBD 

Table VII.B–1 shows the 2007HD 

highway program costs per ton of 

pollutant reduced. These numbers are 

straight from the 2007HD highway final 

rule which contains the details 

regarding the split between NOX+NMHC 

and PM related costs. 

TABLE VII.B–1.—ORIGINAL 2007HD HIGHWAY PROGRAM COSTS, EMISSIONS REDUCTIONS, AND $/TON REDUCED

[Net present values are for annual costs for the years 2006–2035] 

Discount rate Pollutant 

30 year NPV 

cost 

($billions) 

30 year NPV 

reduction 

(million tons) 

$/ton 

3 percent ................................ NOX+NMHC ............................................................................ 54.6 30.6 1,780 

PM ........................................................................................... 16.0 1.4 11,790 

7 percent ................................ NOX+NMHC ............................................................................ 34.9 16.2 2,150 

PM ........................................................................................... 10.3 0.8 13,610 

Table VII.B–2 shows the updated 

2007HD highway program costs per ton 

of pollutant reduced once the new OBD 

costs have been included. For the split 

between NOX+NMHC and PM-related 

OBD costs, we have used a 50/50 

allocation. As shown in Table VII.B–2, 

the OBD costs associated with the 

proposed OBD requirements have little 

impact on the overall costs and costs per 

ton of emissions reduced within the 

context of the 2007HD highway 

program. 

TABLE VII.B–2.—UPDATED 2007HD HIGHWAY PROGRAM COSTS, EMISSIONS REDUCTIONS, AND $/TON REDUCED

INCLUDING OBD RELATED COSTS

[Net present values are for annual costs for the years 2006–2035] 

Discount rate Pollutant 

30 year NPV 

cost 

($billions) 

30 year NPV 

reduction 

(million tons) 

$/ton 

3 percent ................................ NOX+NMHC ............................................................................ 55.1 30.6 1,800 

PM ........................................................................................... 16.5 1.4 12,210 

7 percent ................................ NOX+NMHC ............................................................................ 35.2 16.2 2,170 

PM ........................................................................................... 10.6 0.8 14,130 

VIII. What Are the Requirements for 

Engine Manufacturers? 

A. Documentation Requirements 

The OBD system certification 

requirements would require 

manufacturers to submit OBD system 

documentation that represents each 

engine family. The certification 

documentation would be required to 

contain all of the information needed to 

determine if the OBD system meets the 

proposed OBD requirements. The 

proposed regulation lists the 

information that would be required as 

part of the certification package. If any 

of the information in the certification 

package is the same for all of a 

manufacturer’s engine families (e.g., the 

OBD system general description), the 

manufacturer would only be required to 

submit one set of documents each 

model year for such items that would 

cover all of its engine families. 

While the majority of the proposed 

OBD requirements would apply to the 

engine and be incorporated by design 

into the engine control module by the 

engine manufacturer, a portion of the 

proposed OBD requirements would 

apply to the vehicle and not be selfcontained within the engine. Examples 

include the proposed requirements to 

have a MIL in the instrument cluster 

and a diagnostic connector in the cab 

compartment. As is currently done by 

the engine manufacturers, a build 

specification is provided to vehicle 

manufacturers detailing mechanical and 

electrical specifications that must be 

adhered to for proper installation and 

use of the engine (and to maintain 

compliance with emissions standards). 

We expect engine manufacturers would 

continue to follow this practice so that 

the vehicle manufacturer would be able 

to maintain compliance with the 

proposed OBD regulations. Installation 

specifications would be expected to 

include instructions regarding the 

location, color, and display icon of the 

MIL (as well as electrical connections to 

ensure proper illumination), location 

and type of diagnostic connector, and 

electronic VIN access. During the 

certification process, in addition to 

submitting the details of all of the 

diagnostic strategies and other 

information required, engine 

manufacturers would be required to 

submit a copy of the OBD-relevant 

installation specifications provided to 

vehicle manufacturers and a description 

of the method used by the engine 

manufacturer to ensure vehicle 

manufacturers adhere to the provided 

installation specifications (e.g., required 

audit procedures or signed agreements 

to adhere to the requirements). We are 

requiring that this information be 

submitted to us to provide a reasonable 

level of verification that the proposed 

OBD requirements would indeed be 

satisfied. In summary, engine 

manufacturers would be responsible for 

submitting a certification package that 

includes: 

• A detailed description of all OBD 

monitors, including monitors on signals 

or messages coming from other modules 

upon which the engine control unit 

relies to perform other OBD monitors; 

and, 

• A copy of the OBD-relevant 

installation specifications provided to 

vehicle manufacturers/chassis builders 

and the method used to reasonably 

ensure compliance with those 

specifications. 

As was discussed in the context of our 

implementation schedule (see section 

II.G.1), the proposed regulations would 

allow engine manufacturers to establish 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3277 

74For diesel engines these would include: the 

fuel system; misfire (HCCI engines); EGR, turbo 

boost control, DPF, NOX adsorber or SCR system, 

Continued 

OBD groups consisting of more than one 

engine family with each having similar 

OBD systems. The manufacturer could 

then submit only one set of 

representative OBD information from 

each OBD group. We anticipate that the 

representative information would 

normally consist of an application from 

a single representative engine rating 

within each OBD group. In selecting the 

engine ratings to represent each OBD 

group, consideration should be given to 

the exhaust emission control 

components for all engine families and 

ratings within an OBD group. For 

example, if one engine family within an 

OBD group has additional emission 

control devices relative to another 

family in the group (e.g., the first family 

has a DPF+SCR while the second has 

only a DPF), the representative rating 

should probably come from the first 

engine family. Manufacturers seeking to 

consolidate several engine families into 

one OBD group would be required to get 

approval of the grouping prior to 

submitting the information for 

certification. 

Two of the most important parts of 

the certification package would be the 

OBD system description and summary 

table. The OBD system description 

would include a complete written 

description for each monitoring strategy 

outlining every step in the decisionmaking process of the monitor, 

including a general explanation of the 

monitoring conditions and malfunction 

criteria. This description should include 

graphs, diagrams, and/or other data that 

would help our compliance staff 

understand how each monitor works 

and interacts. The OBD summary table 

would include specific parameter 

values. This table would provide a 

summary of the OBD system 

specifications, including: the 

component/system, the DTC identifying 

each related malfunction, the 

monitoring strategy, the parameter used 

to detect a malfunction and the 

malfunction criteria limits against 

which the parameter is evaluated, any 

secondary parameter values and the 

operating conditions needed to run the 

monitor, the time required to execute 

and complete a monitoring event for 

both a pass decision and a fail decision, 

and the criteria or procedure for 

illuminating the MIL. In these tables, 

manufacturers would be required to use 

a common set of engineering units to 

simplify and expedite the review 

process. 

We are also proposing that the 

manufacturer submit a logic flowchart 

for each monitor that would illustrate 

the step-by-step decision process for 

determining malfunctions. Additionally, 

we would need any data that supports 

the criteria used to determine 

malfunctions that cause emissions to 

exceed the specified malfunction 

thresholds (see Tables II.B–1 and II.C–

1). The manufacturer would have to 

include data that demonstrates the 

probability of misfire detection by the 

misfire monitor over the full engine 

speed and load operating range (for 

gasoline engines only) or the capability 

of the misfire monitor to correctly 

identify a ‘‘one cylinder out’’ misfire for 

each cylinder (for diesel engines only), 

a description of all the parameters and 

conditions necessary to begin closedloop fuel control operation (for gasoline 

engines only), closed-loop EGR control 

(for diesel engines only), closed-loop 

fuel pressure control (for diesel engines 

only), and closed-loop boost control (for 

diesel engines only). We would also 

need a listing of all electronic 

powertrain input and output signals 

(including those not monitored by the 

OBD system) that identifies which 

signals are monitored by the OBD 

system, and the emission data from the 

OBD demonstration testing (as 

described below). Lastly, the 

manufacturer would be expected to 

provide any other OBD-related 

information necessary to determine the 

OBD compliance status of the 

manufacturer’s product line. 

B. Catalyst Aging Procedures 

For purposes of determining the 

catalyst malfunction criteria for diesel 

NMHC converting catalysts, SCR 

catalysts, and lean NOX catalysts, and 

for gasoline catalysts, where those 

catalysts are monitored individually, the 

manufacturer must use a catalyst 

deteriorated to the malfunction criteria 

using methods established by the 

manufacturer to represent real world 

catalyst deterioration under normal and 

malfunctioning engine operating 

conditions. For purposes of determining 

the catalyst malfunction criteria for 

diesel NMHC converting catalysts, SCR 

catalysts, and lean NOX catalysts, and 

for gasoline catalysts, where those 

catalysts are monitored in combination 

with other catalysts, the manufacturer 

would have to submit their catalyst 

system aging and monitoring plan to the 

Administrator as part of their 

certification documentation package. 

The plan would include the description, 

emission control purpose, and location 

of each component, the monitoring 

strategy for each component and/or 

combination of components, and the 

method for determining the applicable 

malfunction criteria including the 

deterioration/aging process. 

C. Demonstration Testing 

While the proposed certification 

documentation requirements discussed 

above would require manufacturers to 

submit technical details of each monitor 

(e.g., how each monitor worked, when 

the monitor would run), we would still 

need some assurance that the 

manufacturer’s OBD monitors are 

indeed calibrated correctly and are able 

to detect a malfunction before an 

emissions threshold is exceeded. Thus, 

we are proposing that manufacturers 

conduct certification demonstration 

testing of the major monitors to verify 

the malfunction threshold values. This 

testing would be required on one to 

three demonstration engines per year. 

Before receiving a certificate of 

compliance, the manufacturer would be 

required to submit documentation and 

emissions data demonstrating that the 

major OBD monitors are able to detect 

a malfunction when emissions exceed 

the emissions thresholds. On each 

demonstration engine, this testing 

would consist of the following two 

elements: 

• Testing the OBD system with 

‘‘threshold’’ components (i.e., 

components that are deteriorated or 

malfunctioning right at the threshold 

required for MIL illumination); and, 

• Testing the OBD system with 

‘‘worst case’’ components. This element 

of the demonstration test would have to 

be done for the DPF and any NOX

aftertreatment system only. 

By testing with both threshold 

components (i.e., the best performing 

malfunctioning components) and with 

worst case components (i.e., the worst 

performing malfunctioning 

components), we would be better able to 

verify that the OBD system should 

perform as expected regardless of the 

level of deterioration of the component. 

This could become increasingly 

important with new technology 

aftertreatment devices that could be 

subject to complete failure (such as 

DPFs) or even to tampering by vehicle 

operators looking to improve fuel 

economy or vehicle performance. We 

believe that, given the likely 

combinations of emissions control 

hardware, a diesel engine manufacturer 

would likely need to conduct 8 to 10 

emissions tests per demonstration 

engine to satisfy these requirements and 

a gasoline engine manufacturer would 

likely need to conduct five to seven 

emissions tests per demonstration 

engine.74


sroberts on PROD1PC70 with PROPOSALS
3278 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

NMHC catalyst, exhaust gas sensors, VVT, and 

possible other emissions controls (see section 

II.D.5). For gasoline engines these would include: 

the fuel system, misfire, EGR, cold start strategy, 

secondary air system, catalyst, exhaust gas sensors, 

VVT, and possible other emissions controls (see 

section II.D.5). Some of these may require more 

than one emissions test while others may not 

require any due to the use of a functional monitor 

rather than an emissions threshold monitor. 

75For over 14,000 pound OBD, we are proposing 

a different definition of a ‘‘parent’’ engine than is 

used for emissions certification. This is discussed 

at length in section II.G. 

1. Selection of Test Engines 

To minimize the test burden on 

manufacturers, we are proposing that 

this testing be done on only one to three 

demonstration engines per year per 

manufacturer rather than requiring that 

all engines be tested. Such an approach 

should still allow us to be reasonably 

sure that manufacturers have calibrated 

their OBD systems correctly on all of 

their engines. This also spreads the test 

burden over several years and allows 

manufacturers to better utilize their test 

cell resources. This approach is 

consistent with our approach to 

demonstration testing to existing 

emissions standards where a parent 

engine is chosen to represent each 

engine family and emissions test data 

for only that parent engine are 

submitted to EPA.75

The number of demonstration engines 

manufacturers would be required to test 

would be aligned with the phase-in of 

OBD in the 2010 and 2013 model years 

and based on the year and the total 

number of engine families the 

manufacturer would be certifying for 

that model year. Specifically, for the 

2010 model year when a manufacturer 

is only required to implement OBD on 

a single engine family, demonstration 

testing would be required on only one 

engine (a single engine rating within the 

one engine family). This would be the 

OBD parent rating as discussed in 

section II.G. For the 2013 model year, 

manufacturers would be required to 

conduct demonstration testing on one to 

three engines per year (i.e., one to three 

OBD parent ratings). The number of 

parent ratings would be chosen 

depending on the total number of 

engine families certified by the 

manufacturer. A manufacturer certifying 

one to five engine families in the given 

year would be required to test one 

demonstration engine. A manufacturer 

certifying six to ten engine families in 

the given year would be required to test 

two demonstration engines, and a 

manufacturer certifying more than ten 

engine families in the given year would 

be required to test three demonstration 

engines. For the 2016 and subsequent 

model years, we would work closely 

with CARB staff and the manufacturer 

to determine the parent ratings so that 

the same ratings are not acting as the 

parents every year. In other words, our 

definitions for the OBD parent ratings as 

discussed here apply only during the 

years 2010 through 2012 and again for 

the years 2013 through 2015. 

Given the difficulty and expense in 

removing an in-use engine from a 

vehicle for engine dynamometer testing, 

this demonstration testing would likely 

represent nearly all of the OBD emission 

testing that would ever be done on these 

engines. Requiring a manufacturer who 

is fully equipped to do such testing, and 

already has the engines on engine 

dynamometers for emission testing, to 

test one to three engines per year would 

be a minimal testing burden that 

provides invaluable and, in a practical 

sense, otherwise unobtainable proof of 

compliance with the OBD emissions 

thresholds. 

Regarding the selection of which 

engine ratings would have to be 

demonstrated, manufacturers would be 

required to submit descriptions of all 

engine families and ratings planned for 

the upcoming model year. We would 

review the information and make the 

selection(s) in consultation with CARB 

staff and the manufacturer. For each 

engine family and rating, the 

information submitted by the 

manufacturer would need to identify 

engine model(s), power ratings, 

applicable emissions standards or 

family emissions limits, emissions 

controls on the engine, and projected 

engine sales volume. Factors that would 

be used in selecting the one to three 

engine ratings for demonstration testing 

include, but are not limited to, new 

versus old/carryover engines, emissions 

control system design, possible 

transition point to more stringent 

emissions standards and/or OBD 

emissions thresholds, and projected 

sales volume. 

2. Required Testing 

Regarding the actual testing, the 

manufacturer would be required to 

perform ‘‘single fault’’ testing using the 

applicable test procedure and with the 

appropriate components/systems set at 

the manufacturer defined malfunction 

criteria limits for the following 

monitors: 

• For diesel engines: Fuel system; 

misfire; EGR; turbo boost control; 

NMHC catalyst; NOX catalyst/adsorber; 

DPF; exhaust gas sensors; VVT; and any 

other monitor that would fall within the 

discussion of section II.D.5. 

• For gasoline engines: Fuel system; 

misfire; EGR; cold start strategy; 

secondary air; catalyst; exhaust gas 

sensors; VVT; and any other monitor 

that would fall within the discussion of 

section II.D.5. 

Such ‘‘single fault’’ testing would 

require that, when performing a test for 

a specific parameter, that parameter 

must be operating at the malfunction 

criteria limit while all other parameters 

would be operating within normal 

characteristics (unless the malfunction 

prohibits some other parameter from 

operating within its normal 

characteristics). Also, the manufacturer 

would be allowed to use computer 

modifications to cause the specific 

parameter to operate at the malfunction 

limit provided the manufacturer can 

demonstrate that the computer 

modifications produce test results 

equivalent to an induced hardware 

malfunction. Lastly, for each of these 

testing requirements, wherever the 

manufacturer has established that only 

a functional check is required because 

no failure or deterioration of the specific 

tested component/system could result 

in an engine’s emissions exceeding the 

applicable emissions thresholds, the 

manufacturer would not be required to 

perform a demonstration test. In such 

cases, the manufacturer could simply 

provide the data and/or engineering 

analysis used to determine that only a 

functional test of the component/system 

was required. 

Manufacturers required to submit data 

from more than one engine rating would 

be granted some flexibility by allowing 

the data to be collected under less 

rigorous testing requirements than the 

official FTP or SET certification test. 

That is, for the possible second and 

third engine ratings required for 

demonstration testing, manufacturers 

would be allowed to submit data using 

internal sign-off test procedures that are 

representative of the official FTP or SET 

in lieu of running the official test. 

Commonly used procedures include the 

use of engine emissions test cells with 

less rigorous quality control procedures 

than those required for the FTP or SET 

or the use of forced cool-downs to 

minimize time between tests. 

Manufacturers would still be liable for 

meeting the OBD emissions thresholds 

on FTPs and/or SETs conducted in full 

accordance with the Code of Federal 

Regulations. Nonetheless, this latitude 

would allow them to use some short-cut 

methods that they have developed to 

assure themselves that the system is 

calibrated to the correct level without 

incurring the additional testing cost and 

burden of running the official FTP or 

SET on every demonstration engine. 

For the demonstration engine(s), a 

manufacturer would be required to use 

an engine(s) aged for a minimum of 125 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3279 

76The CARB HDOBD rulemaking has a provision 

to charge fees associated with OBD deficiencies 13 

CCR 1971.1(k)(3), Docket ID# EPA–HQ–OAR–2005–

0047–0006. We have never had and are not 

proposing any such fee provision. 

hours plus exhaust aftertreatment 

devices aged to be representative of full 

useful life. Manufacturers would be 

expected to use, subject to approval, an 

aging process that ensures that 

deterioration of the exhaust 

aftertreatment devices is stabilized 

sufficiently such that it properly 

represents the performance of the 

devices at the end of their useful life. 

3. Testing Protocol 

We are proposing that the 

manufacturer be allowed to use any 

applicable test cycle for preconditioning 

test engines prior to conducting each of 

the emissions tests discussed above. 

Additional preconditioning can be done 

if the manufacturer has provided data 

and/or engineering analyses that 

demonstrate that additional 

preconditioning is necessary. 

The manufacturer would then set the 

system or component of interest at the 

criteria limit(s) prior to conducting the 

applicable preconditioning cycle(s). If 

more than one preconditioning cycle is 

being used, the manufacturer may adjust 

the system or component of interest 

prior to conducting the subsequent 

preconditioning cycle. However, the 

manufacturer may not replace, modify, 

or adjust the system or component of 

interest following the last 

preconditioning cycle. 

After preconditioning, the test engine 

would be operated over the applicable 

test cycle to allow for the initial 

detection of the tested system or 

component malfunction. This test cycle 

may be omitted from the testing 

protocol if it is unnecessary. If required 

by the designated monitoring strategy, a 

cold soak may be performed prior to 

conducting this test cycle. The test 

engine would then be operated over the 

applicable exhaust emission test. 

A manufacturer required to test more 

than one test engine may use internal 

calibration sign-off test procedures (e.g., 

forced cool downs, less frequently 

calibrated emission analyzers) instead of 

official test procedures to obtain this 

emissions test data for all but one of the 

required test engines. However, the 

manufacturer should use sound 

engineering judgment to ensure that the 

data generated using such alternative 

test/sign-off procedures are good data 

because manufacturers would still be 

responsible for meeting the malfunction 

criteria when emissions tests are 

performed in accordance with official 

test procedures. 

Manufacturers would be allowed to 

use alternative testing protocols, even 

chassis testing, for demonstration of 

MIL illumination if the engine 

dynamometer emissions test cycle does 

not allow all of a monitor’s enable 

conditions to be satisfied. 

Manufacturers wanting to do so would 

be required to demonstrate the technical 

necessity for using their alternative test 

cycle and that using it demonstrates that 

the MIL would illuminate during in-use 

operation with the malfunctioning 

component. 

4. Evaluation Protocol 

For all demonstration tests on parent 

engines, we would expect that the MIL 

would activate upon detecting the 

malfunctioning system or component, 

and that it should occur before the end 

of the first engine start portion of the 

emissions test. If the MIL were to 

activate prior to emissions exceeding 

the applicable malfunction criteria, no 

further demonstration would be 

required. With respect to the misfire 

monitor demonstration test, if the 

manufacturer has elected to use the 

minimum misfire malfunction criterion 

of one percent (as is allowed), then no 

further demonstration would be 

required provided the MIL were to 

illuminate during a test with an 

implanted misfire of one percent. 

If the MIL does not activate when the 

system or component being tested is set 

at its malfunction criteria limits, then 

the criteria limits or the OBD system 

would not be considered acceptable. 

Retesting would be required with more 

tightly controlled criteria limits (i.e., 

recalibrated limits) and/or another 

suitable system or component that 

would result in MIL activation. If the 

criteria limits are recalibrated, the 

manufacturer would be required to 

confirm that the systems and 

components that were tested prior to 

recalibration would still function 

properly and as required. 

5. Confirmatory Testing 

We may choose to confirmatory test a 

demonstration engine to verify the 

emissions test data submitted by the 

manufacturer. Any such confirmatory 

testing would be limited to the engine 

rating represented by the demonstration 

engine(s) (i.e., the parent engine(s)). To 

do so, we, or our designee, would install 

appropriately deteriorated or 

malfunctioning components (or 

simulate a deteriorated or 

malfunctioning component) in an 

otherwise properly functioning engine 

of the same engine family and rating as 

the demonstration engine. Such 

confirmatory testing would be done on 

those OBD monitors for which 

demonstration testing had been 

conducted as described in this section. 

The manufacturer would be required to 

make available, upon Administrator 

request, a test engine and all test 

equipment—e.g., malfunction 

simulators, deteriorated components—

necessary to duplicate the 

manufacturer’s testing. 

D. Deficiencies 

Our under 14,000 pound OBD 

requirements have contained a 

deficiency provision for years. The OBD 

deficiency provision was first 

introduced on March 23, 1995 (60 FR 

15242), and was revised on December 

22, 1998 (63 FR 70681). Consistent with 

that provision, we are proposing a 

deficiency provision for over 14,000 

pound OBD. We believe that, like has 

occurred and even still occurs with 

under 14,000 pound OBD, some 

manufacturers will encounter 

unforeseen and generally last minute 

problems with some of their OBD 

monitoring strategies despite having 

made a good faith effort to comply with 

the requirements. Therefore, we are 

proposing a provision that would permit 

certification of an over 14,000 pound 

OBD system with ‘‘deficiencies’’ in 

cases where a good faith effort to fully 

comply has been demonstrated. In 

making deficiency determinations, we 

would consider the extent to which the 

proposed OBD requirements have been 

satisfied overall based on our review of 

the certification application, the relative 

performance of the given OBD system 

compared to systems that truly are fully 

compliant with the proposed OBD 

requirements, and a demonstrated goodfaith effort on the part of the 

manufacturer to both meet the proposed 

requirements in full and come into full 

compliance as expeditiously as possible. 

We believe that having the proposed 

deficiency provision is important 

because it would facilitate OBD 

implementation by allowing for 

certification of an engine despite having 

a relatively minor shortfall. Note that we 

do not expect to certify engines with 

OBD systems that have more than one 

deficiency, or to allow carryover of any 

deficiency to the following model year 

unless it can be demonstrated that 

correction of the deficiency requires 

hardware and/or software modifications 

that cannot be accomplished in the time 

available, as determined by the 

Administrator.76 Nonetheless, we 

recognize that there may be situations 

where more than one deficiency is 

necessary and appropriate, or where 

carry-over of a deficiency or deficiencies 

for more than one year is necessary and 


sroberts on PROD1PC70 with PROPOSALS
3280 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

77See 13 CFR 1971.1(k)(6)), Docket ID# EPA–HQ–

OAR–2005–0047–0006. 

78See 40 CFR 85.1903. 

appropriate. In such situations, more 

than one deficiency, or carry-over for 

more than one year, may be approved, 

provided the manufacturer has 

demonstrated an acceptable level of 

effort toward full OBD compliance. 

Most importantly, the deficiency 

provisions cannot be used as a means to 

avoid compliance or delay 

implementation of any OBD monitors or 

as a means to compromise the overall 

effectiveness of the OBD program. 

There has often been some confusion 

by manufacturers regarding what CARB 

has termed ‘‘retroactive’’ deficiencies. 

The CARB rule states that, ‘‘During the 

first 6 months after commencement of 

normal production, manufacturers may 

request that the Executive Officer grant 

a deficiency and amend an engine’s 

certification to conform to the granting 

of the deficiencies for each aspect of the 

monitoring system: (a) Identified by the 

manufacturer (during testing required 

by section (l)(2) or any other testing) to 

be functioning different than the 

certified system or otherwise not 

meeting the requirements of any aspect 

of section 1971.1; and (b) reported to the 

Executive Officer.’’ 77 We have never 

had and are not proposing any such 

retroactive deficiency provision. We 

have regulations in place that govern 

situations, whether they be detected by 

EPA or by the manufacturer, where inuse vehicles or engines are determined 

to be functioning differently than the 

certified system.78 We refer to these 

regulations as our defect reporting 

requirements and manufacturers are 

required to comply with these 

regulations, even for situations deemed 

by CARB to be ‘‘retroactive’’

deficiencies, unless the defect is 

corrected prior to the sale of engines to 

an ultimate purchaser. In other words, 

a retroactive deficiency granted by the 

Executive Officer does not preclude a 

manufacturer from complying with our 

defect reporting requirements. 

E. Production Evaluation Testing 

The OBD system is a complex 

software and hardware system, so there 

are many opportunities for unintended 

interactions that can result in certain 

elements of the system not working as 

intended. We have seen many such 

mistakes in the under 14,000 pound 

arena ranging from OBD systems that 

are unable to communicate any 

information to a scan tool to monitors 

that are unable to store a DTC and 

illuminate the MIL. While over 14,000 

pound heavy-duty vehicles are very 

different from light-duty vehicles in 

terms of emission controls and OBD 

monitoring strategies, among other 

things, these types of problems do not 

depend on these differences and, as 

such, are as likely to occur with over 

14,000 pound OBD as they are with 

under 14,000 pound OBD. Additionally, 

we believe that there is great value in 

having manufacturers self-test actual 

production end products that operate on 

the road, as opposed to pre-production 

products, where errors can be found in 

individual subsystems that may work 

fine by themselves but not when 

integrated into a complete product (e.g., 

due to mistakes like improper wiring). 

Therefore, we are proposing that 

manufacturers self-test a small fraction 

of their product line to verify 

compliance with the OBD requirements. 

The test requirements are divided into 

three distinct sections with each section 

representing a test for a different portion 

of the OBD requirements. These three 

sections being: compliance with the 

applicable SAE and/or ISO 

standardization requirements; 

compliance with the monitoring 

requirements for proper DTC storage 

and MIL illumination; and, compliance 

with the in-use monitoring performance 

ratios. 

1. Verification of Standardization 

Requirements 

An essential part of the OBD system 

is the requirement for standardization. 

The proposed standardization 

requirements include items as simple as 

the location and shape of the diagnostic 

connector (where technicians can ‘‘plug 

in’’ a scan tool to the onboard computer) 

to more complex subjects concerning 

the manner and format in which DTC 

information is accessed by technicians 

via a ‘‘generic’’ scan tool. Manufacturers 

must meet these standardization 

requirements to facilitate the success of 

the proposed OBD program because 

they ensure consistent access by all 

repair technicians to the stored 

information in the onboard computer. 

The need for consistency is even greater 

when considering the potential use of 

OBD system checks in inspection and 

maintenance (I/M) programs for heavyduty. Such OBD base I/M checks would 

benefit from having access to the 

diagnostic information in the onboard 

computer via a single ‘‘generic’’ scan 

tool instead of individual tools for every 

make and model of truck that might be 

inspected. For OBD based inspections to 

work effectively and efficiently, all 

engines/vehicles must be designed and 

built to meet all of the applicable 

standardization requirements. 

While we anticipate that the vast 

majority of vehicles would comply with 

all of the standardization requirements, 

some problems involving the 

communication between vehicles and 

‘‘generic’’ scan tools are likely to occur 

in the field. The cause of such problems 

could range from differing 

interpretations of the existing 

standardization requirements to 

possible oversights by design engineers 

or hardware inconsistencies or even 

last-minute production changes on the 

assembly line. 

To minimize the chance for such 

problems on future over 14,000 pound 

trucks, we are proposing that engine 

manufacturers be required to test a 

sample of production vehicles from the 

assembly line to verify that the vehicles 

have indeed been designed and built to 

the required specifications for 

communication with a ‘‘generic’’ scan 

tool. We are proposing that 

manufacturers be required to test 

complete vehicles to ensure that they 

comply with some of the basic 

‘‘generic’’ scan tool standardization 

requirements, including those that are 

essential for proper inspection in an 

I/M setting. Ideally, manufacturers 

would be required to test one vehicle for 

each truck and engine model 

combination that is introduced into 

commerce. However, for a large engine 

manufacturer, this can be in the 

neighborhood of 5,000 to 10,000 unique 

combinations making it unreasonable to 

require testing of every combination. 

Therefore, we are proposing that 

manufacturers test 10 such 

combinations per engine family. Given 

that a typical engine family has roughly 

five different engine ratings, this works 

out to testing only around two vehicles 

per engine rating. 

More specifically, manufacturers 

would be required to test one vehicle 

per software ‘‘version’’ released by the 

manufacturer. With proper 

demonstration, manufacturers would be 

allowed to group different calibrations 

together to be demonstrated by a 

common vehicle. Prior to acquiring 

these data, the proposal would require 

engine manufacturers to submit for 

approval a test plan verifying that the 

vehicles scheduled for testing would be 

representative of all vehicle 

configurations (e.g., each engine control 

module variant coupled with and 

without the other available vehicle 

components that could affect scan tool 

communication such as automatic 

transmission or hybrid powertrain 

control modules). The plan would have 

to include details on all the different 

applications and configurations that 

would be tested. 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3281 

79 13 CCR 1968.2, August 11, 2006, Docket ID# 

EPA–HQ–OAR–2005–0047–0005. 

80 13 CCR 1971.1, Docket ID# EPA–HQ–OAR–

2005–0047–0006. 

As noted, manufacturers would be 

required to conduct this testing on 

actual production vehicles, not standalone engines. This is important since 

controllers that work properly in a stand 

alone setting (e.g., the engine before it 

is installed in a vehicle) may have 

interaction problems when installed and 

attempting to communicate with other 

vehicle controllers (e.g., the 

transmission controller). In such a case, 

separate testing of the controllers would 

be blind to the problem. Since heavyduty engine manufacturers are expected 

to sell the same engine (with the same 

calibration) to various vehicle 

manufacturers who would put them in 

different final products (e.g., with 

different transmission control modules), 

the same communication problem 

would be expected in each final 

product. 

This testing should occur soon 

enough in the production cycle to 

provide manufacturers with early 

feedback regarding the existence of any 

problems and time to resolve the 

problem prior to the entire model year’s 

products being introduced into the field. 

We are proposing that the testing be 

done and the data submitted to us 

within either three months of the start 

of normal engine production or one 

month of the start of vehicle production, 

whichever is later. 

To be sure that all manufacturers are 

testing vehicles to the same level of 

stringency, we are proposing that engine 

manufacturers submit documentation 

outlining the testing equipment and 

methods they intend to use to perform 

this testing. We anticipate that engine 

manufacturers and scan tool 

manufacturers would probably develop 

a common piece of hardware and 

software that could be used by all 

engine manufacturers at the end of the 

vehicle assembly line to meet this 

requirement. Two different projects 

(SAE J1699 and LOC3T) have developed 

such equipment in response to 

California OBD II requirements.79 The 

equipment is currently being used to 

test 2005 and 2006 model year vehicles 

under 14,000 pounds. We believe that 

similar equipment could be developed 

for vehicles over 14,000 pounds in time 

for the 2013 model year. Ideally, the 

equipment and the test procedure 

would verify each and every 

requirement of the communication 

specifications including the various 

physical layers, message structure, 

response times, and message content. 

Presumably, any such verification 

equipment would not replace the 

function of existing ‘‘generic’’ scan tools 

used by repair technicians or I/M 

inspectors. The equipment would likely 

be custom-designed and be used for the 

express purpose of this assembly line 

testing (i.e., it would not include all of 

the necessary diagnostic features needed 

by repair technicians). 

2. Verification of Monitoring 

Requirements 

As noted above, the OBD system is a 

complex software and hardware system, 

so there are many opportunities for 

unintended interactions that can result 

in certain elements of the system not 

working as intended. The causes of 

possible problems vary from simple 

typing errors in the software code to 

component supplier hardware changes 

late in development or just prior to start 

of production. Given the complexity of 

OBD monitors and their associated 

algorithms, there can be thousands of 

lines of software code required to meet 

the diagnostic requirements. 

Implementing that code without 

interfering with the software code 

required for normal operation is and 

will be a very difficult task with many 

opportunities for human error. We 

expect that manufacturers will conduct 

some validation testing on end products 

to ensure that there are no problems that 

would be noticed by the vehicle 

operator. We believe that manufacturers 

should include in such verification 

testing an evaluation of the OBD system 

(e.g., does the MIL illuminate as 

intended in response to a malfunction?). 

Therefore, we are proposing that 

engine manufacturers be required to 

perform a thorough level of validation 

testing on at least one production 

vehicle and up to two more production 

engines per model year. The production 

vehicles/engines required for testing 

would have to be equipped with/be 

from the same engine families and 

ratings as used for the certification 

demonstration testing described in 

section VIII.B.3. If a manufacturer 

demonstrated one, two, or three engines 

for certification, then at least one 

production vehicle and perhaps an 

additional one to two engines would 

have to be tested, respectively. We 

would work with the manufacturer and 

CARB staff to determine the actual 

vehicles and engines to test. 

The testing itself would consist of 

implanting or simulating malfunctions 

to verify that virtually every single 

engine-related OBD monitor on the 

vehicle correctly identifies the 

malfunction, stores an appropriate DTC, 

and illuminates the MIL. Manufacturers 

would not be required to conduct any 

emissions testing. Instead, for those 

malfunctions designed against an 

emissions threshold, the manufacturer 

would simply implant or simulate a 

malfunction and verify detection, DTC 

storage, and MIL illumination. Actual 

‘‘threshold’’ parts would not be needed 

for such testing. Implanted malfunctions 

could use severely deteriorated parts if 

desired by the manufacturer since the 

point of the testing is to verify detection, 

DTC storage, and MIL illumination. 

Upon submitting the data to the 

Administrator, the manufacturer would 

be required to also provide a description 

of the testing and the methods used to 

implant or simulate each malfunction. 

Note that testing of specific monitors 

would not be required if the 

manufacturer can show that no possible 

test exists that could be done on that 

monitor without causing physical 

damage to the production vehicle. We 

are proposing that the testing be 

completed and reported to us within six 

months after the manufacturer begins 

normal engine production. This should 

provide early feedback on the 

performance of every monitor on the 

vehicle prior to too many entering 

production. Upon good cause, we may 

extend the time period for testing. 

Note that, in their HDOBD rule,80

CARB allows, as an incentive to perform 

a thorough validation test, a 

manufacturer to request that any 

problem discovered during this self-test 

be treated as a ‘‘retroactive’’ deficiency. 

As discussed in section VIII.B.4, we do 

not have a provision for retroactive 

deficiencies. Importantly, a retroactive 

deficiency granted by the Executive 

Officer does not preclude a 

manufacturer from complying with our 

defect reporting requirements. This 

issue was discussed in more detail in 

section VIII.B.4. 

3. Verification of In-Use Monitoring 

Performance Ratios 

We are proposing that manufacturers 

track the performance of several of the 

most important monitors on the engine 

to determine how often they are 

monitoring during in-use operation. 

These requirements are discussed in 

more detail in section II.E. To 

summarize that discussion, monitors 

would be expected to execute in the real 

world and meet a minimum acceptable 

performance level determined as the 

ratio of the number of good monitoring 

events to the number of actual trips. The 

ratio being proposed is 10 percent, 

meaning that monitors should execute 

during at least 10 percent of the trips 

taken by the engine/vehicle. Monitors 


sroberts on PROD1PC70 with PROPOSALS
3282 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

81Review of Light-Duty Diesel and Heavy-Duty 

Diesel/Gasoline Inspection Programs, St. Denis and 

Lindner, Journal of the Air and Waste Management 

Association, December 2005. 

that perform below the minimum ratio 

would be subject to remedial action and 

possibly recall. However, the minimum 

ratio is not effective until the 2013 and 

later model years. For the 2010 through 

2012 model year engines certified to 

today’s proposed OBD requirements, we 

are proposing that the data be collected 

even though the minimum ratio is not 

yet effective. The data gathered on these 

engines will help to determine whether 

the 10 percent ratio is appropriate for all 

applications and, if not, we would 

intend to propose a change to the 

proposed requirement to reflect that 

learning. 

We are proposing that manufacturers 

gather these data on production vehicles 

rather than engines. Since not every 

vehicle can be evaluated, we are 

proposing that manufacturers generate 

groups of engine/vehicle combinations 

to ensure adequate representation of the 

fleet. Specifically, manufacturers would 

be required to separate production 

vehicles into monitoring performance 

groups based on the following criteria 

and submit performance ratio data 

representative of each group: 

• Emission control system 

architecture type—All engines that use 

the same or similar emissions control 

system architecture and associated 

monitoring system would be in the same 

emission architecture category. By 

architecture we mean engines with 

EGR+DPF+SCR, or EGR+DPF+NOX

Adsorber, or EGR+DPF-only, etc. 

• Application type—Within an 

emission architecture category, engines 

would be separated by vehicle 

application. The separate application 

categories would be based on three 

classifications: engines intended 

primarily for line-haul chassis 

applications, engines intended 

primarily for urban delivery chassis 

applications, and all other engines. 

We are proposing that these data be 

submitted to us within 12 months of the 

production vehicles entering the market. 

Upon submitting the collected data to 

us, the manufacturer would also be 

required to provide a detailed 

description of how the data were 

gathered, how vehicles were grouped to 

represent sales of their engines, and the 

number of engines tested per monitoring 

performance group. Manufacturers 

would be required to submit 

performance ratio data from a sample of 

at least 15 vehicles per monitoring 

performance group. For example, a 

manufacturer with two emission control 

system architectures sold into each of 

the line-haul, urban delivery, and 

‘‘other’’ groupings, would be required to 

submit data on up to 90 vehicles (i.e., 

2 × 3 × 15). We are proposing that these 

data be collected every year. Some 

manufacturers may find it easiest to 

collect data from vehicles that come in 

to its authorized repair facilities for 

routine maintenance or warranty work 

during the time period required, while 

others may find it more advantageous to 

hire a contractor to collect the data. 

Upon good cause, we may extend the 

time period for testing. 

As stated before, the data collected 

under this program are intended 

primarily to provide an early indication 

that the systems are working as 

intended in the field, to provide 

information to ‘‘fine-tune’’ the proposed 

requirement to track the performance of 

monitors, and to provide data to be used 

to develop a more appropriate minimum 

ratio for future regulatory revisions. The 

data are not intended to substitute for 

testing that we would perform for 

enforcement reasons to determine if a 

manufacturer is complying with the 

minimum acceptable performance 

ratios. In fact, the data collected would 

not likely meet all the required elements 

for testing to make an official 

determination that the system is 

noncompliant. As such, we believe the 

testing would be of most value to 

manufacturers since monitor 

performance problems can be corrected 

prior to EPA conducting a full 

enforcement action that could result in 

a recall. 

IX. What are the Issues Concerning 

Inspection and Maintenance Programs? 

A. Current Heavy-Duty I/M Programs 

While there are currently no 

regulatory requirements for heavy-duty 

inspection and maintenance (I/M), and 

no State Implementation Plan (SIP) 

credit given for heavy-duty I/M, a recent 

review shows that programs in the 

United States as well as abroad are 

currently testing heavy-duty diesel and 

heavy-duty gasoline vehicles as part of 

their Inspection and Maintenance 

programs. A recent study found that the 

mandated vehicle emission I/M 

programs in the CAAA of 1990, 

originally required in areas where 

ambient levels of ozone and CO 

exceeded the national standards, are 

being utilized as a framework as diesel 

PM becomes increasingly recognized as 

an important health concern in the 

United States.81 Some countries outside 

the U.S., particularly developing 

countries, have been seeking to improve 

air quality by implementing both lightduty and heavy-duty I/M programs. 

In the U.S., the light-duty fleet has 

become cleaner. As a result, heavy-duty 

vehicles are responsible for an 

increasing contribution of the mobile 

source emission inventory. EPA has 

responded to the increased contribution 

by promulgating technology-promoting 

standards, to be phased in during the 

years leading up to 2010. Some nonattainment areas are implementing HD 

vehicle I/M programs to improve their 

regional air quality. The current tailpipe 

emissions measurements result in a 

number of issues, so other technologies 

such as remote sensing are being 

examined. Interrogation of the OBD 

system on over 14,000 pound vehicles 

would likely be a candidate I/M test 

method. 

As of 2004, according to the 

aforementioned study, many I/M 

programs in the U.S. have developed a 

wide range of emission tests for HD 

diesel vehicles and HD gasoline 

vehicles. 19 States currently test HD 

diesel vehicles (these are: AZ, CA, CO, 

CT, ID, IL, KY, ME, MD, MA, NV, NH, 

NJ, NM, NY, OH, UT, VT, WA); 25 states 

test HD gasoline vehicles (these are: AK, 

AZ, CA, CO, CT, ID, IL, IN, KY, MD, 

MA, NV, NJ, NM, NY, NC, OH, OR, PA, 

TN, TX, UT, VA, WA, WI). Canada, 

China, Singapore, Sweden, and the 

United Kingdom test HD diesel vehicles. 

Lastly, Germany, Singapore, and 

Sweden test HD gasoline vehicles. 

Whether or not voluntary or regulated 

inspection and maintenance programs 

become prominent, heavy-duty OBD 

should be designed to allow ease of 

interrogation to maximize the potential 

of this technology to help realize 

environmental benefit. There is 

evidence that localities are utilizing this 

strategy in their air quality protection 

programs. There is also a wealth of 

light-duty OBD experience to support 

making an I/M-type test as user-friendly 

as possible so technician training and 

scan tool designs do not limit the ability 

to assess a vehicle’s status. 

B. Challenges for Heavy-Duty I/M 

There are a number of challenges that 

are being discovered as programs 

implement heavy-duty I/M. Existing HD 

I/M programs utilize of a number of 

different emission test types, such as 

snap-idle testing (based on SAE J1667), 

loaded cruise testing (chassis 

dynamometer), ASM testing, Transient 

IMXXX, Two-Speed Idle or Curb Idle, 

and Lug-down testing. Projections of 

heavy-duty vehicle inventory 

contributions for VOC, NOX, PM, and 

toxics have substantiated the need for 

more stringent regulations. Repairs 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3283 

82 ‘‘Drive Clean Program Emission Benefit 

Analysis and Reporting—Heavy-Duty Diesel 

Vehicles,’’ Canada Ministry of the Environment, 

October 2003. 

83 Draft Technical Support Document, HDOBD 

NPRM, EPA420–D–06–006, Docket ID# EPA–HQ–

OAR–2005–0047–0008. 

based on individual emission test types, 

such as opacity testing, may target and 

reduce one pollutant (e.g., PM) while 

neglecting or increasing others (e.g., 

NOX). A sound test should effectively 

control all harmful pollutants, thus 

must be able to measure multiple 

pollutants—specifically PM and NOX

emissions. 

Systems capable of measuring both 

pollutants at the same time have to date 

been prohibitively expensive for I/M 

programs, and traditionally require a 

heavy-duty dynamometer so that 

vehicles can be tested under load. 

Recent work has begun to investigate 

the use of remote sensing and other 

technologies for measuring heavy-duty 

gaseous and PM emissions. While this 

technology has not yet been routinely 

implemented in HD vehicle I/M 

programs to date, the impetus to 

identify more robust or user-friendly 

emission testing strategies exists. 

Portable emissions measurement 

systems (PEMS) are not really 

conducive to an I/M environment at this 

time because the units are very costly, 

require a great deal of expertise to 

operate, and require considerable time 

for completing a test. Such systems are 

best suited for intensive analysis of 

emissions performance on a limited 

number of vehicles rather than the 

widespread testing of nearly all vehicles 

as is the attempt in most I/M programs. 

All these factors heighten the potential 

that OBD systems will be utilized in I/ 

M programs for vehicles over 14,000 

pounds. 

C. Heavy-Duty OBD and I/M 

Heavy-duty OBD should be designed 

with the anticipation that there may be 

new use of OBD to help insure local or 

regional emission benefits. If multiple 

individuals are querying OBD, 

standardization of testing equipment 

and protocol, and information format 

and availability should be considered to 

maximize the effective use of this 

technology. Many of the lessons learned 

from the use of light-duty OBD in I/M 

programs point to a need to ensure 

standard protocols for testing, so that 

test equipment and data collection 

requirements can be accommodated in 

system designs. Along with common 

connectors, data formats, and specific 

parameter monitoring requirements, 

future technologies enabling 

standardization of data stream logic 

(e.g., built-in checks, broadcasted 

updates, etc.) and other currently nonexisting strategies may be attractive to 

minimize training requirements for test 

personnel and data management for 

model year-specific information. 

Due to the regional or national 

registrations of many heavy-duty 

vehicles, there is the potential that 

eventual I/M use of OBD to control 

heavy-duty vehicle emission 

exceedences could be at the fleet or 

corporate level, rather than at the state 

level as is the current light-duty 

convention. Stakeholders will need to 

inform the debate but today’s HD I/M 

programs may not follow the same 

development pattern as light-duty I/M 

programs did a decade ago. The lessons 

learned from light-duty OBD I/M should 

be complemented with early data on HD 

I/M programs being piloted in the U.S. 

and globally. 

As one example, Ontario’s Ministry of 

the Environment has prepared a report 

on their Heavy-Duty Drive Clean 

program. This study developed 

estimates of emissions benefits for 

inspected diesel vehicles and compares 

them to estimated baseline emissions for 

the case with no Drive Clean program, 

for calendar years 2000, 2001, and 2002. 

According to this study, over the three 

years of the program the total 

accumulated emission reductions 

generated by the program’s operation 

were estimated to be 1092 tonnes of 

PM10 emissions, 654 tonnes of HC 

emissions, and 721 tonnes of NOX

emissions.82 This particular study 

utilized opacity testing, and compared 

failed and fixed vehicles for different 

model year vehicles and for different 

weight classes. The malperformance 

model developed originally by Radian 

Corporation for ARB in 1986 was 

utilized since the statistical correlation 

between smoke opacity an mass 

emissions is weak, especially in newer 

vehicles; and the EPA MOBILE model 

assume zero deterioration of emissions 

for most HD diesel engines, thereby 

implying no benefit for I/M. The 

relationship between maintenance and 

emission deterioration is complicated 

by the use of high efficiency 

aftertreatment devices, which lose 

emission conversion efficiency with age, 

so this model’s basic premise is likely 

appropriate only until the year 2008. 

Nevertheless, as the benefits of 

inspection and maintenance become 

more clearly articulated, the interest in 

assessing test methodologies that 

provide ease of use as well as multipollutant screening will likely increase. 

For these reasons consideration of 

potential I/M program use of OBD for 

the heavy-duty fleet is warranted, and 

should include lessons-learned from the 

light-duty fleet as well as anticipate new 

strategies for utilizing OBD information. 

We request comment with respect to 

the level of interest in I/M programs that 

make use of the proposed OBD system 

on over 14,000 pound vehicles. 

Specifically, are states interested in I/M 

for over 14,000 pound vehicles that 

mirrors existing programs for passenger 

cars and other light trucks? For those 

that might be interested, does the 

proposed OBD system meet the needs of 

their potential I/M program? 

X. Statutory and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

This action is not a ‘‘significant 

regulatory action’’ under the terms of 

Executive Order (EO) 12866 (58 FR 

51735, October 4, 1993) and is, 

therefore, not subject to review under 

the EO. 

EPA prepared an analysis of the 

potential costs associated with this 

action. This analysis is contained in the 

technical support document.83 A copy 

of the analysis is available in the docket 

and was summarized in section VI of 

this preamble. 

B. Paperwork Reduction Act 

The proposed information collection 

requirements for this action have been 

submitted for approval to the Office of 

Management and Budget (OMB) under 

the Paperwork Reduction Act, 44 U.S.C. 

3501 et seq. The Information Collection 

Request (ICR) document prepared by 

EPA has been assigned EPA ICR number 

1684.09. Under Title II of the Clean Air 

Act (42 U.S.C. 7521 et seq.; CAA), EPA 

is charged with issuing certificates of 

conformity for those engines that 

comply with applicable emission 

standards. Such a certificate must be 

issued before engines may be legally 

introduced into commerce. EPA uses 

certification information to verify that 

the proper engine prototypes have been 

selected and that the necessary testing 

has been performed to assure that each 

engine complies with emission 

standards. In addition, EPA also has the 

authority under Title II of the Clean Air 

to ensure compliance by require in-use 

testing of vehicles and engines. EPA is 

proposing to require additional 

information at the time of certification 

to ensure that that on-board diagnostic 

(OBD) requirements are being met. EPA 

is also proposing that manufacturers 

conduct and report the results of in-use 

testing of the OBD systems to 


sroberts on PROD1PC70 with PROPOSALS
3284 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

demonstrate that they are performing 

properly. Therefore, EPA is proposing 

207 hours of annual burden per each of 

the 12 respondents to conduct the OBD 

certification, compliance, and in-use 

testing requirements proposed by this 

action. EPA estimates that the total of 

the of the 2484 hours of annual cost 

burden will be $16,018 per respondent 

for a total annual industry cost burden 

for the 12 respondents of $1,236,481. 

Burden means the total time, effort, or 

financial resources expended by persons 

to generate, maintain, retain, or disclose 

or provide information to or for a 

Federal agency. technology and systems 

for the purposes of collecting, 

validating, and verifying. This includes 

the time needed to review instructions; 

develop, acquire, install, and utilize 

information, processing and 

maintaining information, and disclosing 

and providing information; adjust the 

existing ways to comply with any 

previously applicable instructions and 

requirements; train personnel to be able 

to respond to a collection of 

information; search data sources; 

complete and review the collection of 

information; and transmit or otherwise 

disclose the information. 

An agency may not conduct or 

sponsor, and a person is not required to 

respond to a collection of information 

unless it displays a currently valid OMB 

control number. The OMB control 

numbers for EPA’s regulations in 40 

CFR are listed in 40 CFR part 9. 

To comment on the Agency’s need for 

this information, the accuracy of the 

provided burden estimates, and any 

suggested methods for minimizing 

respondent burden, including the use of 

automated collection techniques, EPA 

has established a public docket for this 

rule, which includes this ICR, under 

Docket ID number EPA–HQ–OAR–

2005–0047. Submit any comments 

related to the ICR for this proposed rule 

to EPA and OMB. See the ADDRESSES

section at the beginning of this notice 

for where to submit comments to EPA. 

Send comments to OMB at the Office of 

Information and Regulatory Affairs, 

Office of Management and Budget, 725 

17th Street, NW., Washington, DC 

20503, Attention: Desk Office for EPA. 

Since OMB is required to make a 

decision concerning the ICR between 30 

and 60 days after January 24, 2007, a 

comment to OMB is best assured of 

having its full effect if OMB receives it 

by February 23, 2007. The final rule will 

respond to any OMB or public 

comments on the information collection 

requirements contained in this proposal. 

C. Regulatory Flexibility Act (RFA), as 

Amended by the Small Business 

Regulatory Enforcement Fairness Act of 

1996 (SBREFA), 5 U.S.C. 601 et. seq. 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act or any 

other statute unless the agency certifies 

that the rule will not have a significant 

economic impact on a substantial 

number of small entities. Small entities 

include small businesses, small 

organizations, and small governmental 

jurisdictions. 

For purposes of assessing the impacts 

of today’s proposed rule on small 

entities, small entity is defined as: (1) A 

motor vehicle manufacturer with fewer 

than 1,000 employees; (2) a motor 

vehicle converter with fewer than 750 

employees; (3) a small governmental 

jurisdiction that is a government of a 

city, county, town, school district or 

special district with a population of less 

than 50,000; and (4) a small 

organization that is any not-for-profit 

enterprise which is independently 

owned and operated and is not 

dominant in its field. After considering 

the economic impacts of today’s 

proposed rule on small entities, we have 

determined that this action would not 

have a significant economic impact on 

a substantial number of small entities. 

This proposed rule would not have any 

adverse economic impact on small 

entities. Today’s rule places new 

requirements on manufacturers of large 

engines meant for highway use. These 

are large manufacturers. Today’s rule 

also changes existing requirements on 

manufacturers of passenger car and 

smaller heavy-duty engines meant for 

highway use. These changes place no 

meaningful new requirements on those 

manufacturers. 

D. Unfunded Mandates Reform Act 

Title II of the Unfunded Mandates 

Reform Act of 1995 (UMRA), Public 

Law 104–4, establishes requirements for 

federal agencies to assess the effects of 

their regulatory actions on state, local, 

and tribal governments, and the private 

sector. Under section 202 of the UMRA, 

EPA generally must prepare a written 

statement, including a cost-benefit 

analysis, for proposed and final rules 

with ‘‘Federal mandates’’ that may 

result in expenditures to state, local, 

and tribal governments, in the aggregate, 

or to the private sector, of $100 million 

or more for any single year. Before 

promulgating a rule for which a written 

statement is needed, section 205 of the 

UMRA generally requires EPA to 

identify and consider a reasonable 

number of regulatory alternatives and to 

adopt the least costly, most costeffective, or least burdensome 

alternative that achieves the objectives 

of the rule. The provisions of section 

205 do not apply when they are 

inconsistent with applicable law. 

Moreover, section 205 allows EPA to 

adopt an alternative that is not the least 

costly, most cost-effective, or least 

burdensome alternative if the 

Administrator publishes with the final 

rule an explanation of why such an 

alternative was not adopted. 

Before EPA establishes any regulatory 

requirement that may significantly or 

uniquely affect small governments, 

including tribal governments, it must 

have developed under section 203 of the 

UMRA a small government agency plan. 

The plan must provide for notifying 

potentially affected small governments, 

enabling officials of affected small 

governments to have meaningful and 

timely input in the development of EPA 

regulatory proposals with significant 

Federal intergovernmental mandates, 

and informing, educating, and advising 

small governments on compliance with 

the regulatory requirements. 

This rule contains no federal 

mandates (under the regulatory 

provisions of Title II of the UMRA) for 

State, local, or tribal governments or the 

private sector. The rule imposes no 

enforceable duties on any of these 

entities. Nothing in the rule would 

significantly or uniquely affect small 

governments. We have determined that 

this rule does not contain a federal 

mandate that may result in estimated 

expenditures of more than $100 million 

to the private sector in any single year. 

Therefore, the requirements of the 

UMRA do not apply to this action. 

E. Executive Order 13132: Federalism 

Executive Order 13132, entitled 

‘‘Federalism’’ (64 FR 43255, August 10, 

1999), requires EPA to develop an 

accountable process to ensure 

‘‘meaningful and timely input by State 

and local officials in the development of 

regulatory policies that have federalism 

implications.’’ ‘‘Policies that have 

federalism implications’’ is defined in 

the Executive Order to include 

regulations that have ‘‘substantial direct 

effects on the States, on the relationship 

between the national government and 

the States, or on the distribution of 

power and responsibilities among the 

various levels of government.’’

This proposed rule does not have 

federalism implications. It will not have 

substantial direct effects on the States, 

on the relationship between the national 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3285 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in 

Executive Order 13132. This proposed 

rule places new requirements on 

manufacturers of large engines meant 

for highway use and changes existing 

requirements on manufacturers of 

passenger car and smaller heavy-duty 

engines meant for highway use. These 

changes do not affect States or the 

relationship between the national 

government and the States. Thus, 

Executive Order 13132 does not apply 

to this rule. 

In the spirit of Executive Order 13132, 

and consistent with EPA policy to 

promote communications between EPA 

and State and local governments, EPA 

specifically solicits comment on this 

proposed rule from State and local 

officials. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

Executive Order 13175, entitled 

‘‘Consultation and Coordination with 

Indian Tribal Governments’’ (65 FR 

67249, November 9, 2000), requires EPA 

to develop an accountable process to 

ensure ‘‘meaningful and timely input by 

tribal officials in the development of 

regulatory policies that have tribal 

implications.’’ This proposed rule does 

not have tribal implications, as specified 

in Executive Order 13175. Today’s rule 

does not uniquely affect the 

communities of American Indian tribal 

governments since the motor vehicle 

requirements for private businesses in 

today’s rule would have national 

applicability. Furthermore, today’s rule 

does not impose any direct compliance 

costs on these communities and no 

circumstances specific to such 

communities exist that would cause an 

impact on these communities beyond 

those discussed in the other sections of 

today’s document. Thus, Executive 

Order 13175 does not apply to this rule. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

and Safety Risks 

Executive Order 13045, ‘‘Protection of 

Children from Environmental Health 

Risks and Safety Risks’’ (62 FR 19885, 

April 23, 1997) applies to any rule that: 

(1) Is determined to be ‘‘economically 

significant’’ as defined under Executive 

Order 12866; and, (2) concerns an 

environmental health or safety risk that 

EPA has reason to believe may have a 

disproportionate effect on children. If 

the regulatory action meets both criteria, 

the Agency must evaluate the 

environmental health or safety effects of 

the planned rule on children, and 

explain why the planned regulation is 

preferable to other potentially effective 

and reasonably feasible alternatives 

considered by the Agency. 

This proposed rule is not subject to 

the Executive Order because it is not an 

economically significant regulatory 

action as defined by Executive Order 

12866, and because the Agency does not 

have reason to believe the 

environmental health or safety risks 

addressed by this action present a 

disproportionate risk to children. 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This rule is not subject to Executive 

Order 13211, ‘‘Actions Concerning 

Regulations That Significantly Affect 

Energy Supply, Distribution, or Use’’ (66 

FR 28355, May 22, 2001) because it is 

not a significant regulatory action under 

Executive Order 12866. 

I. National Technology Transfer 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (NTTAA), Section 12(d) of 

Public Law 104–113, directs EPA to use 

voluntary consensus standards in its 

regulatory activities unless to do so 

would be inconsistent with applicable 

law or otherwise impractical. Voluntary 

consensus standards are technical 

standards (e.g., materials specifications, 

test methods, sampling procedures, and 

business practices) developed or 

adopted by voluntary consensus 

standards bodies. The NTTAA directs 

EPA to provide Congress, through OMB, 

explanations when the Agency decides 

not to use available and applicable 

voluntary consensus standards. 

This proposed rule references 

technical standards. The technical 

standards being proposed are listed in 

Table II.F–1 of this preamble, and 

directions for how they may be obtained 

are provided in section II.F.1. EPA 

welcomes comments on this aspect of 

the proposed rulemaking and, 

specifically, invites the public to 

identify other potentially-applicable 

voluntary consensus standards and to 

explain why such standards should be 

used in this regulation. 

XI. Statutory Provisions and Legal 

Authority 

Statutory authority for today’s 

proposed rule is found in the Clean Air 

Act, 42 U.S.C. 7401 et seq., in particular, 

sections 202 and 206 of the Act, 42 

U.S.C. 7521, 7525. This rule is being 

promulgated under the administrative 

and procedural provisions of Clean Air 

Act section 307(d), 42 U.S.C. 7607(d). 

List of Subjects in 40 CFR Part 86 

Environmental Protection, 

Administrative practice and procedure, 

Motor vehicle pollution. 

Dated: December 11, 2006. 

Stephen L. Johnson, 

Administrator. 

For the reasons set out in the 

preamble, part 86 of title 40 of the Code 

of Federal Regulations is proposed to be 

amended as follows: 

PART 86—CONTROL OF EMISSIONS 

FROM NEW AND IN-USE HIGHWAY 

VEHICLES AND ENGINES 

1. The authority citation for part 86 

continues to read as follows: 

Authority: 42 U.S.C. 7401–7671q. 

2. Section 86.1 is amended as follows: 

a. In the table to paragraph (b)(2) by 

adding new entries to the end of the 

table. 

b. In the table to paragraph (b)(5) by 

adding a new entry to the end of the 

table. 

§ 86.1 Reference materials. 

* * * * * 

(b) * * * 

(2) * * * 

Document No. and name 40 CFR part 86 reference 

* * * * * * * 

SAE J1930, Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, and Acronyms—Equivalent 

to ISO/TR 15031–2: April 2002.

86.010–18 

SAE J1939, MONTH 2006, Recommended Practice for a Serial Control and Communications Vehicle Network ...... 86.010–18; 86.010–38 

SAE J1939–13, MONTH 2006, Off-Board Diagnostic Connector .................................................................................. 86.013–18 

SAE J1962, Diagnostic Connector—Equivalent to ISO/DIS ..........................................................................................

15031–3: April 2002 .......................................................................................................................................................

86.013–18 

SAE J1978, OBD II Scan Tool—Equivalent to ISO/DIS 15031–4: April 2002 .............................................................. 86.010–18 


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Document No. and name 40 CFR part 86 reference 

SAE J1979, E/E Diagnostic Test Modes—Equivalent to ISO/DIS 15031–5: April 2002 ............................................... 86.010–18; 86.010–38 

SAE J2012, Diagnostic Trouble Code Definitions—Equivalent to ISO/DIS 15031–6: April 2002 ................................. 86.010–18 

SAE J2403, Medium/Heavy-Duty E/E Systems Diagnosis Nomenclature; August 2004 .............................................. 86.007–17; 86.010–18; 

86.010–38; 86.1806–07 

SAE J2534, Recommended Practice for Pass-Thru Vehicle Reprogramming: February 2002 .................................... 86.010–18; 86.010–38 

* * * * * (5) * * * 

Document No. and name 40 CFR part 86 reference 

* * * * * * * 

ISO 15765–4:2001, Road Vehicles—Diagnostics on Controller Area Network (CAN)—Part 4: Requirements for 

emission-related systems: December 2001.

86.010–18 

* * * * * 

3. Section 86.007–17 is added to 

Subpart A to read as follows: 

§ 86.007–17 On-board Diagnostics for 

engines used in applications less than or 

equal to 14,000 pounds GVWR. 

Section 86.007–17 includes text that 

specifies requirements that differ from 

§ 86.005–17. Where a paragraph in 

§ 86.005–17 is identical and applicable 

to § 86.007–17, this may be indicated by 

specifying the corresponding paragraph 

and the statement ‘‘[Reserved]. For 

guidance see § 86.005–17.’’

(a)(1) [Reserved]. For guidance see 

§ 86.005–17. 

(a)(2) An OBD system demonstrated to 

fully meet the requirements in 

§ 86.1806–07 may be used to meet the 

requirements of this section, provided 

that the Administrator finds that a 

manufacturer’s decision to use the 

flexibility in this paragraph (a)(2) is 

based on good engineering judgment. 

(b) introductory text and (b)(1)(i) 

[Reserved]. For guidance see § 86.005–

17. 

(b)(1)(ii) Diesel. 

(A) If equipped, catalyst deterioration 

or malfunction before it results in 

exhaust NOX emissions exceeding 

either: 1.75 times the applicable NOX

standard for engines certified to a NOX

FEL greater than 0.50 g/bhp-hr; or, the 

applicable NOX FEL+0.5 g/bhp-hr for 

engines certified to a NOX FEL less than 

or equal to 0.50 g/bhp-hr. This 

requirement applies only to reduction 

catalysts; monitoring of oxidation 

catalysts is not required. This 

monitoring need not be done if the 

manufacturer can demonstrate that 

deterioration or malfunction of the 

system will not result in exceedance of 

the threshold. 

(b)(1)(ii)(B) and (b)(2) [Reserved]. For 

guidance see § 86.005–17. 

(b)(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, 1.75 times the 

applicable NOX standard for engines 

certified to a NOX FEL greater than 0.50 

g/bhp-hr; or, the applicable NOX

FEL+0.5 g/bhp-hr for engines certified 

to a NOX FEL less than or equal to 0.50 

g/bhp-hr; or, 2.5 times the applicable 

NMHC standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, 1.75 times the 

applicable NOX standard for engines 

certified to a NOX FEL greater than 0.50 

g/bhp-hr; or, the applicable NOX

FEL+0.5 g/bhp-hr for engines certified 

to a NOX FEL less than or equal to .50 

g/bhp-hr; or, 2.5 times the applicable 

NMHC standard; or, 2.5 times the 

applicable CO standard. 

(iii) NOX sensors. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: The applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, 1.75 times the 

applicable NOX standard for engines 

certified to a NOX FEL greater than 0.50 

g/bhp-hr; or, the applicable NOX

FEL+0.5 g/bhp-hr for engines certified 

to a NOX FEL less than or equal to 0.50 

g/bhp-hr. 

(b)(4) [Reserved]. For guidance see 

§ 86.005—17. 

(b)(5) Other emission control systems 

and components. 

(i) Otto-cycle. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

the secondary air system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding 1.5 times the applicable 

emission standard or FEL for NMHC, 

NOX or CO. For engines equipped with 

a secondary air system, a functional 

check, as described in § 86.005–17(b)(6), 

may satisfy the requirements of this 

paragraph (b)(5) provided the 

manufacturer can demonstrate that 

deterioration of the flow distribution 

system is unlikely. This demonstration 

is subject to Administrator approval 

and, if the demonstration and associated 

functional check are approved, the 

diagnostic system must indicate a 

malfunction when some degree of 

secondary airflow is not detectable in 

the exhaust system during the check. 

For engines equipped with positive 

crankcase ventilation (PCV), monitoring 

of the PCV system is not necessary 

provided the manufacturer can 

demonstrate to the Administrator’s 

satisfaction that the PCV system is 

unlikely to fail. 

(ii) Diesel. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 


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recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 

The applicable PM FEL+0.04 g/bhp-hr 

or 0.05 g/bhp-hr PM, whichever is 

higher; or, 1.75 times the applicable 

NOX standard for engines certified to a 

NOX FEL greater than 0.50 g/bhp-hr; or, 

the applicable NOX FEL+0.5 g/bhp-hr 

for engines certified to a NOX FEL less 

than or equal to 0.50 g/bhp-hr; or, 2.5 

times the applicable NMHC standard; 

or, 2.5 times the applicable CO 

standard. A functional check, as 

described in § 86.005–17(b)(6), may 

satisfy the requirements of this 

paragraph (b)(5) provided the 

manufacturer can demonstrate that a 

malfunction would not cause emissions 

to exceed the applicable levels. This 

demonstration is subject to 

Administrator approval. For engines 

equipped with crankcase ventilation 

(CV), monitoring of the CV system is not 

necessary provided the manufacturer 

can demonstrate to the Administrator’s 

satisfaction that the CV system is 

unlikely to fail. 

(b)(6) [Reserved]. For guidance see 

§ 86.005–17. 

(b)(7) Performance of OBD functions. 

Any sensor or other component 

deterioration or malfunction which 

renders that sensor or component 

incapable of performing its function as 

part of the OBD system must be detected 

and identified on engines so equipped. 

(c), (d), (e), (f), (g), and (h)(1)(i) 

through (h)(1)(iv) [Reserved]. For 

guidance see § 86.005–17. 

(h)(1)(v) All acronyms, definitions 

and abbreviations shall be formatted 

according to SAE J1930 ‘‘Electrical/ 

Electronic Systems Diagnostic Terms, 

Definitions, Abbreviations, and 

Acronyms Equivalent to ISO/TR 15031–

2: April 30, 2002’’, (Revised, April 

2002), or SAE J2403, ‘‘Medium/HeavyDuty E/E Systems Diagnosis 

Nomenclature: August 2004.’’

(h)(1)(vi) through (h)(3) [Reserved]. 

For guidance see § 86.005–17. 

(i) Deficiencies and alternative fueled 

engines. Upon application by the 

manufacturer, the Administrator may 

accept an OBD system as compliant 

even though specific requirements are 

not fully met. Such compliances 

without meeting specific requirements, 

or deficiencies, will be granted only if 

compliance would be infeasible or 

unreasonable considering such factors 

as, but not limited to: Technical 

feasibility of the given monitor and lead 

time and production cycles including 

phase-in or phase-out of engines or 

vehicle designs and programmed 

upgrades of computers. Unmet 

requirements should not be carried over 

from the previous model year except 

where unreasonable hardware or 

software modifications would be 

necessary to correct the deficiency, and 

the manufacturer has demonstrated an 

acceptable level of effort toward 

compliance as determined by the 

Administrator. Furthermore, EPA will 

not accept any deficiency requests that 

include the complete lack of a major 

diagnostic monitor (‘‘major’’ diagnostic 

monitors being those for exhaust 

aftertreatment devices, oxygen sensor, 

air-fuel ratio sensor, NOX sensor, engine 

misfire, evaporative leaks, and diesel 

EGR, if equipped), with the possible 

exception of the special provisions for 

alternative fueled engines. For 

alternative fueled heavy-duty engines 

(e.g. natural gas, liquefied petroleum 

gas, methanol, ethanol), manufacturers 

may request the Administrator to waive 

specific monitoring requirements of this 

section for which monitoring may not 

be reliable with respect to the use of the 

alternative fuel. At a minimum, 

alternative fuel engines must be 

equipped with an OBD system meeting 

OBD requirements to the extent feasible 

as approved by the Administrator. 

(j) California OBDII compliance 

option. For heavy-duty engines used in 

applications weighing 14,000 pounds 

GVWR or less, demonstration of 

compliance with California OBD II 

requirements (Title 13 California Code 

of Regulations section 1968.2 (13 CCR 

1968.2)), as modified and released on 

August 11, 2006, shall satisfy the 

requirements of this section, except that 

compliance with 13 CCR 

1968.2(e)(4.2.2)(C), pertaining to 0.02 

inch evaporative leak detection, and 13 

CCR 1968.2(d)(1.4), pertaining to 

tampering protection, are not required 

to satisfy the requirements of this 

section. Also, the deficiency provisions 

of 13 CCR 1968.2(k) do not apply. The 

deficiency provisions of paragraph (i) of 

this section and the evaporative leak 

detection requirement of § 86.005–

17(b)(4) apply to manufacturers 

selecting this paragraph for 

demonstrating compliance. In addition, 

demonstration of compliance with 13 

CCR 1968.2(e)(15.2.1)(C), to the extent it 

applies to the verification of proper 

alignment between the camshaft and 

crankshaft, applies only to vehicles 

equipped with variable valve timing. 

(k) [Reserved]. For guidance see 

§ 86.005–17. 

4. Section 86.007–30 is added to 

Subpart A to read as follows: 

Section 86.007–30 includes text that 

specifies requirements that differ from 

§§ 86.094–30, 86.095–30, 86.096–30, 

86.098–30, 86.001–30 or 86.004–30. 

Where a paragraph in § 86.094–30, 

§ 86.095–30, § 86.096–30, § 86.098–30, 

§ 86.001–30 or § 86.004–30 is identical 

and applicable to § 86.007–30, this may 

be indicated by specifying the 

corresponding paragraph and the 

statement ‘‘[Reserved]. For guidance see 

§ 86.094–30.’’ or ‘‘[Reserved]. For 

guidance see § 86.095–30.’’ or 

‘‘[Reserved]. For guidance see § 86.096–

30.’’ or ‘‘[Reserved]. For guidance see 

§ 86.098–30.’’ or ‘‘[Reserved]. For 

guidance see § 86.001–30.’’ or 

‘‘[Reserved]. For guidance see 86.004–

30.’’

§ 86.007–30 Certification. 

(a)(1) and (a)(2) [Reserved]. For 

guidance see § 86.094–30. 

(a)(3)(i) through (a)(4)(ii) [Reserved]. 

For guidance see § 86.004–30. 

(a)(4)(iii) introductory text through 

(a)(4)(iii)(C) [Reserved]. For guidance 

see § 86.094–30. 

(a)(4)(iv) introductory text [Reserved]. 

For guidance see § 86.095–30. 

(a)(4)(iv)(A)–(a)(9) [Reserved]. For 

guidance see § 86.094–30. 

(a)(10) and (a)(11) [Reserved]. For 

guidance see § 86.004–30. 

(a)(12) [Reserved]. For guidance see 

§ 86.094–30. 

(a)(13) [Reserved]. For guidance see 

§ 86.095–30. 

(a)(14) [Reserved]. For guidance see 

§ 86.094–30. 

(a) (15)–(18) [Reserved]. For guidance 

see § 86.096–30. 

(a)(19) [Reserved]. For guidance see 

§ 86.098–30. 

(a)(20) [Reserved]. For guidance see 

§ 86.001–30. 

(a)(21) [Reserved]. For guidance see 

§ 86.004–30. 

(b)(1) introductory text through 

(b)(1)(ii)(A) [Reserved]. For guidance see 

§ 86.094–30. 

(b)(1)(ii)(B) [Reserved]. For guidance 

see § 86.004–30. 

(b)(1)(ii)(C) [Reserved]. For guidance 

see § 86.094–30. 

(b)(1)(ii)(D) [Reserved]. For guidance 

see § 86.004–30. 

(b)(1)(iii) and (b)(1)(iv) [Reserved]. For 

guidance see § 86.094–30. 

(b)(2) [Reserved]. For guidance see 

§ 86.098–30. 

(b)(3)–(b)(4)(i) [Reserved]. For 

guidance see § 86.094–30. 

(b)(4)(ii) introductory text [Reserved]. 

For guidance see § 86.098–30. 

(b)(4)(ii)(A) [Reserved]. For guidance 

see § 86.094–30. 

(b)(4)(ii)(B)–(b)(4)(iv) [Reserved]. For 

guidance see § 86.098–30. 

(b)(5)–(e) [Reserved]. For guidance see 

§ 86.094–30. 

(f) introductory text through (f)(1)(i) 

[Reserved]. For guidance see § 86.004–

30. 


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(f)(1)(ii) Diesel. 

(A) If monitored for emissions 

performance—a catalyst is replaced 

with a deteriorated or defective catalyst, 

or an electronic simulation of such, 

resulting in exhaust emissions 

exceeding 1.75 times the applicable 

NOX standard for engines certified to a 

NOX FEL greater than 0.50 g/bhp-hr; or, 

the applicable NOX FEL+0.5 g/bhp-hr 

for engines certified to a NOX FEL less 

than or equal to 0.50 g/bhp-hr. This 

requirement applies only to reduction 

catalysts. 

(B) If monitored for performance—a 

particulate trap is replaced with a trap 

that has catastrophically failed, or an 

electronic simulation of such. 

(f)(2) [Reserved]. For guidance see 

§ 86.004–30. 

(f)(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. 

(A) Otto-cycle. If so equipped, any 

oxygen sensor or air-fuel ratio sensor 

located downstream of aftertreatment 

devices is replaced with a deteriorated 

or defective sensor, or an electronic 

simulation of such, resulting in exhaust 

emissions exceeding 1.5 times the 

applicable standard or FEL for NMHC, 

NOX or CO. 

(B) Diesel. If so equipped, any oxygen 

sensor or air-fuel ratio sensor located 

downstream of aftertreatment devices is 

replaced with a deteriorated or defective 

sensor, or an electronic simulation of 

such, resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM FEL+0.04 g/bhp-hr or 

0.05 g/bhp-hr PM, whichever is higher; 

or, 1.75 times the applicable NOX

standard for engines certified to a NOX

FEL greater than 0.50 g/bhp-hr; or, the 

applicable NOX FEL+0.5 g/bhp-hr for 

engines certified to a NOX FEL less than 

or equal to 0.50 g/bhp-hr; or, 2.5 times 

the applicable NMHC standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. 

(A) Otto-cycle. If so equipped, any 

oxygen sensor or air-fuel ratio sensor 

located upstream of aftertreatment 

devices is replaced with a deteriorated 

or defective sensor, or an electronic 

simulation of such, resulting in exhaust 

emissions exceeding 1.5 times the 

applicable standard or FEL for NMHC, 

NOX or CO. 

(B) Diesel. If so equipped, any oxygen 

sensor or air-fuel ratio sensor located 

upstream of aftertreatment devices is 

replaced with a deteriorated or defective 

sensor, or an electronic simulation of 

such, resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM FEL+0.04 g/bhp-hr or 

0.05 g/bhp-hr PM, whichever is higher; 

or, 1.75 times the applicable NOX

standard for engines certified to a NOX

FEL greater than 0.50 g/bhp-hr; or, the 

applicable NOX FEL+0.5 g/bhp-hr for 

engines certified to a NOX FEL less than 

or equal to 0.50 g/bhp-hr; or, 2.5 times 

the applicable NMHC standard; or, 2.5 

times the applicable CO standard. 

(iii) NOX sensors. 

(A) Otto-cycle. If so equipped, any 

NOX sensor is replaced with a 

deteriorated or defective sensor, or an 

electronic simulation of such, resulting 

in exhaust emissions exceeding 1.5 

times the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If so equipped, any NOX

sensor is replaced with a deteriorated or 

defective sensor, or an electronic 

simulation of such, resulting in exhaust 

emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, 1.75 times the 

applicable NOX standard for engines 

certified to a NOX FEL greater than 0.50 

g/bhp-hr; or, the applicable NOX

FEL+0.5 g/bhp-hr for engines certified 

to a NOX FEL less than or equal to 0.50 

g/bhp-hr. 

(f)(4) [Reserved]. For guidance see 

§ 86.004–30. 

(f)(5)(i) Otto-cycle. A malfunction 

condition is induced in any emissionrelated engine system or component, 

including but not necessarily limited to, 

the exhaust gas recirculation (EGR) 

system, if equipped, the secondary air 

system, if equipped, and the fuel control 

system, singularly resulting in exhaust 

emissions exceeding 1.5 times the 

applicable emission standard or FEL for 

NMHC, NOX, or CO. 

(ii) Diesel. A malfunction condition is 

induced in any emission-related engine 

system or component, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM FEL+0.04 g/bhp-hr or 

0.05 g/bhp-hr PM, whichever is higher; 

or, 1.75 times the applicable NOX

standard for engines certified to a NOX

FEL greater than 0.50 g/bhp-hr; or, the 

applicable NOX FEL+0.5 g/bhp-hr for 

engines certified to a NOX FEL less than 

or equal to 0.50 g/bhp-hr; or, 2.5 times 

the applicable NMHC standard; or, 2.5 

times the applicable CO standard. 

(f)(6) [Reserved]. For guidance see 

§ 86.004–30. 

5. Section 86.010–2 is added to 

Subpart A to read as follows: 

§ 86.010–2 Definitions. 

The definitions of § 86.004–2 

continue to apply to 2004 and later 

model year vehicles. The definitions 

listed in this section apply beginning 

with the 2010 model year. 

Drive cycle or driving cycle means 

operation that consists of engine startup 

and engine shutoff during which a given 

onboard diagnostic (OBD) monitor 

makes a diagnostic decision. A drive 

cycle need not consist of all OBD 

monitors making a diagnostic decision 

during the engine startup and engine 

shutoff cycle. An engine restart 

following an engine shutoff that has 

been neither commanded by the vehicle 

operator nor by the engine control 

strategy but caused by an event such as 

an engine stall may be considered a new 

drive cycle or a continuation of the 

existing drive cycle. 

DTC means diagnostic trouble code. 

Engine start as used in § 86.010–18 

means the point when the engine 

reaches a speed 150 rpm below the 

normal, warmed-up idle speed (as 

determined in the drive position for 

vehicles equipped with an automatic 

transmission). For hybrid vehicles or for 

engines employing alternative engine 

start hardware or strategies (e.g., 

integrated starter and generators.), the 

manufacturer may use an alternative 

definition for engine start (e.g., key-on) 

provided the alternative definition is 

based on equivalence to an engine start 

for a conventional vehicle. 

Functional check, in the context of 

onboard diagnostics, means verifying 

that a component and/or system that 

receives information from a control 

computer responds properly to a 

command from the control computer. 

Ignition cycle as used in § 86.010–18 

means a cycle that begins with engine 

start, meets the engine start definition 

for at least two seconds plus or minus 

one second, and ends with engine 

shutoff. 

Limp-home operation as used in 

§ 86.010–18 means an operating mode 

that an engine is designed to enter upon 

determining that normal operation 

cannot be maintained. In general, limphome operation implies that a 

component or system is not operating 

properly or is believed to be not 

operating properly. 

Malfunction means the conditions 

have been met that require the 

activation of an OBD malfunction 

indicator light and storage of a DTC. 

MIL-on DTC means the diagnostic 

trouble code stored when an OBD 

system has detected and confirmed that 

a malfunction exists (e.g., typically on 

the second drive cycle during which a 

given OBD monitor has evaluated a 

system or component). Industry 

standards may refer to this as a 

confirmed or an active DTC. 


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Pending DTC means the diagnostic 

trouble code stored upon the detection 

of a potential malfunction. 

Permanent DTC means a DTC that 

corresponds to a MIL-on DTC and is 

stored in non-volatile random access 

memory (NVRAM). A permanent DTC 

can only be erased by the OBD system 

itself and cannot be erased through 

human interaction with the OBD system 

or any onboard computer. 

Previous-MIL-on DTC means a DTC 

that corresponds to a MIL-on DTC but 

is distinguished by representing a 

malfunction that the OBD system has 

determined no longer exists but for 

which insufficient operation has 

occurred to satisfy the DTC erasure 

provisions. 

Potential malfunction means that 

conditions have been detected that meet 

the OBD malfunction criteria but for 

which more drive cycles are allowed to 

provide further evaluation prior to 

confirming that a malfunction exists. 

Rationality check, in the context of 

onboard diagnostics, means verifying 

that a component that provides input to 

a control computer provides an accurate 

input to the control computer while in 

the range of normal operation and when 

compared to all other available 

information. 

Similar conditions, in the context of 

onboard diagnostics, means engine 

conditions having an engine speed 

within 375 rpm, load conditions within 

20 percent, and the same warm up 

status (i.e., cold or hot). The 

manufacturer may use other definitions 

of similar conditions based on 

comparable timeliness and reliability in 

detecting similar engine operation. 

6. Section 86.010–17 is added to 

Subpart A to read as follows: 

§ 86.010–17 On-board Diagnostics for 

engines used in applications less than or 

equal to 14,000 pounds GVWR. 

Section 86.010–17 includes text that 

specifies requirements that differ from 

§ 86.005–17 and § 86.007–17. Where a 

paragraph in § 86.005–17 or § 86.007–17 

is identical and applicable to § 86.010–

17, this may be indicated by specifying 

the corresponding paragraph and the 

statement ‘‘[Reserved]. For guidance see 

§ 86.005–17.’’ or ‘‘[Reserved]. For 

guidance see § 86.007–17.’’

(a) General. 

(1) All heavy-duty engines intended 

for use in a heavy-duty vehicle weighing 

14,000 pounds GVWR or less must be 

equipped with an on-board diagnostic 

(OBD) system capable of monitoring all 

emission-related engine systems or 

components during the applicable 

useful life. All monitored systems and 

components must be evaluated 

periodically, but no less frequently than 

once per applicable certification test 

cycle as defined in Appendix I, 

paragraph (f), of this part, or similar trip 

as approved by the Administrator. 

(2) An OBD system demonstrated to 

fully meet the requirements in 

§ 86.1806–10 may be used to meet the 

requirements of this section, provided 

that the Administrator finds that a 

manufacturer’s decision to use the 

flexibility in this paragraph (a)(2) is 

based on good engineering judgment. 

(b) Introductory text and (b)(1)(i) 

[Reserved]. For guidance see § 86.005–

17. 

(b)(1)(ii) Diesel. 

(A) If equipped, reduction catalyst 

deterioration or malfunction before it 

results in exhaust NOX emissions 

exceeding the applicable NOX FEL+0.3 

g/bhp-hr. If equipped, oxidation catalyst 

deterioration or malfunction before it 

results in exhaust NMHC emissions 

exceeding 2.5 times the applicable 

NMHC standard. These catalyst 

monitoring requirements need not be 

done if the manufacturer can 

demonstrate that deterioration or 

malfunction of the system will not 

result in exceedance of the threshold. 

(B) If equipped, diesel particulate trap 

deterioration or malfunction before it 

results in exhaust emissions exceeding 

any of the following levels: The 

applicable PM FEL+0.04 g/bhp-hr or 

0.05 g/bhp-hr PM, whichever is higher; 

or, exhaust NMHC emissions exceeding 

2.5 times the applicable NMHC 

standard. Catastrophic failure of the 

particulate trap must also be detected. 

In addition, the absence of the 

particulate trap or the trapping substrate 

must be detected. 

(b)(2) [Reserved]. For guidance see 

§ 86.005–17. 

(b)(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2.5 times the 

applicable NMHC standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.02 g/bhp-hr or 0.03 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2.5 times the 

applicable NMHC standard; or, 2.5 

times the applicable CO standard. 

(iii) NOX sensors. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr. 

(b)(4) [Reserved]. For guidance see 

§ 86.005–17. 

(b)(5) Other emission control systems 

and components. 

(i) Otto-cycle. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

the secondary air system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding 1.5 times the applicable 

emission standard or FEL for NMHC, 

NOX or CO. For engines equipped with 

a secondary air system, a functional 

check, as described in § 86.005–17(b)(6), 

may satisfy the requirements of this 

paragraph (b)(5) provided the 

manufacturer can demonstrate that 

deterioration of the flow distribution 

system is unlikely. This demonstration 

is subject to Administrator approval 

and, if the demonstration and associated 

functional check are approved, the 

diagnostic system must indicate a 

malfunction when some degree of 

secondary airflow is not detectable in 

the exhaust system during the check. 

For engines equipped with positive 

crankcase ventilation (PCV), monitoring 

of the PCV system is not necessary 

provided the manufacturer can 

demonstrate to the Administrator’s 

satisfaction that the PCV system is 

unlikely to fail. 

(ii) Diesel. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 


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exceeding any of the following levels: 

the applicable PM FEL+0.02 g/bhp-hr or 

0.03 g/bhp-hr PM, whichever is higher; 

or, the applicable NOX FEL+0.3 g/bhphr; or, 2.5x the applicable NMHC 

standard; or, 2.5x the applicable CO 

standard. A functional check, as 

described in § 86.005–17(b)(6), may 

satisfy the requirements of this 

paragraph (b)(5) provided the 

manufacturer can demonstrate that a 

malfunction would not cause emissions 

to exceed the applicable levels. This 

demonstration is subject to 

Administrator approval. For engines 

equipped with crankcase ventilation 

(CV), monitoring of the CV system is not 

necessary provided the manufacturer 

can demonstrate to the Administrator’s 

satisfaction that the CV system is 

unlikely to fail. 

(b)(6) [Reserved]. For guidance see 

§ 86.005–17. 

(b)(7) [Reserved]. For guidance see 

§ 86.007–17. 

(c) [Reserved]. For guidance see 

§ 86.005–17. 

(d) MIL illumination. 

(1) The MIL must illuminate and 

remain illuminated when any of the 

conditions specified in paragraph (b) of 

this section are detected and verified, or 

whenever the engine control enters a 

default or secondary mode of operation 

considered abnormal for the given 

engine operating conditions. The MIL 

must blink once per second under any 

period of operation during which engine 

misfire is occurring and catalyst damage 

is imminent. If such misfire is detected 

again during the following driving cycle 

(i.e., operation consisting of, at a 

minimum, engine start-up and engine 

shut-off) or the next driving cycle in 

which similar conditions are 

encountered, the MIL must maintain a 

steady illumination when the misfire is 

not occurring and then remain 

illuminated until the MIL extinguishing 

criteria of this section are satisfied. The 

MIL must also illuminate when the 

vehicle’s ignition is in the ‘‘key-on’’

position before engine starting or 

cranking and extinguish after engine 

starting if no malfunction has 

previously been detected. If a fuel 

system or engine misfire malfunction 

has previously been detected, the MIL 

may be extinguished if the malfunction 

does not reoccur during three 

subsequent sequential trips during 

which similar conditions are 

encountered and no new malfunctions 

have been detected. Similar conditions 

are defined as engine speed within 375 

rpm, engine load within 20 percent, and 

engine warm-up status equivalent to 

that under which the malfunction was 

first detected. If any malfunction other 

than a fuel system or engine misfire 

malfunction has been detected, the MIL 

may be extinguished if the malfunction 

does not reoccur during three 

subsequent sequential trips during 

which the monitoring system 

responsible for illuminating the MIL 

functions without detecting the 

malfunction, and no new malfunctions 

have been detected. Upon Administrator 

approval, statistical MIL illumination 

protocols may be employed, provided 

they result in comparable timeliness in 

detecting a malfunction and evaluating 

system performance, i.e., three to six 

driving cycles would be considered 

acceptable. 

(2) Drive cycle or driving cycle, in the 

context of this section § 86.010–17, the 

definition for drive cycle or driving 

cycle given in § 86.010–2 is enhanced. 

A drive cycle means an OBD trip that 

consists of engine startup and engine 

shutoff and includes the period of 

engine off time up to the next engine 

startup. For vehicles that employ engine 

shutoff strategies (e.g., engine shutoff at 

idle), the manufacturer may use an 

alternative definition for drive cycle 

(e.g., key-on followed by key-off). Any 

alternative definition must be based on 

equivalence to engine startup and 

engine shutoff signaling the beginning 

and ending of a single driving event for 

a conventional vehicle. For applications 

that span 14,000 pounds GVWR, the 

manufacturer may use the drive cycle 

definition of § 86.010–18 in lieu of the 

definition in this paragraph. 

(e), (f), (g), and (h)(1)(i) through 

(h)(1)(iv) [Reserved]. For guidance see 

§ 86.005–17. 

(h)(1)(v) [Reserved]. For guidance see 

§ 86.007–17. 

(h)(1)(vi) through (h)(3) [Reserved]. 

For guidance see § 86.005–17. 

(i) and (j) [Reserved]. For guidance see 

§ 86.007–17. 

(k) [Reserved.] 

7. Section 86.010–18 is added to 

Subpart A to read as follows: 

§ 86.010–18 On-board Diagnostics for 

engines used in applications greater than 

14,000 pounds GVWR. 

(a) General. According to the 

implementation schedule shown in 

paragraph (o) of this section, heavy-duty 

engines intended for use in a heavyduty vehicle weighing more than 14,000 

pounds GVWR must be equipped with 

an on-board diagnostic (OBD) system 

capable of monitoring all emissionrelated engine systems or components 

during the life of the engine. The OBD 

system is required to detect all 

malfunctions specified in paragraphs 

(g), (h), and (i) of this section although 

the OBD system is not required to use 

a unique monitor to detect each of those 

malfunctions. 

(1) When the OBD system detects a 

malfunction, it must store a pending, a 

MIL-on, or a previous-MIL-on diagnostic 

trouble code (DTC) in the onboard 

computer’s memory. A malfunction 

indicator light (MIL) must also be 

activated as specified in paragraph (b) of 

this section. 

(2) The OBD system must be equipped 

with a data link connector to provide 

access to the stored DTCs as specified in 

paragraph (k)(2) of this section. 

(3) The OBD system cannot be 

programmed or otherwise designed to 

deactivate based on age and/or mileage. 

This requirement does not alter existing 

law and enforcement practice regarding 

a manufacturer’s liability for an engine 

beyond its regulatory useful life, except 

where an engine has been programmed 

or otherwise designed so that an OBD 

system deactivates based on age and/or 

mileage of the engine. 

(4) Drive cycle or driving cycle, in the 

context of this section, the definition for 

drive cycle or driving cycle given in 

§ 86.010–2 is enhanced. A drive cycle 

means an OBD trip that meets any of the 

conditions of paragraphs (a)(4)(i) 

through (a)(4)(iv) of this section. 

Further, for OBD monitors that run 

during engine-off conditions, the period 

of engine-off time following engine 

shutoff and up to the next engine start 

may be considered part of the drive 

cycle for the conditions of paragraphs 

(a)(4)(i) and (a)(4)(iv) of this section. For 

engines/vehicles that employ engine 

shutoff OBD monitoring strategies that 

do not require the vehicle operator to 

restart the engine to continue vehicle 

operation (e.g., a hybrid bus with engine 

shutoff at idle), the manufacturer may 

use an alternative definition for drive 

cycle (e.g., key-on followed by key-off). 

Any alternative definition must be 

based on equivalence to engine startup 

and engine shutoff signaling the 

beginning and ending of a single driving 

event for a conventional vehicle. For 

engines that are not likely to be 

routinely operated for long continuous 

periods of time, a manufacturer may 

also request approval to use an 

alternative definition for drive cycle 

(e.g., solely based on engine start and 

engine shutoff without regard to four 

hours of continuous engine-on time). 

Administrator approval of the 

alternative definition will be based on 

manufacturer-submitted data and/or 

information demonstrating the typical 

usage, operating habits, and/or driving 

patterns of these vehicles. 

(i) Begins with engine start and ends 

with engine shutoff; 


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(ii) Begins with engine start and ends 

after four hours of continuous engine-on 

operation; 

(iii) Begins at the end of the previous 

four hours of continuous engine-on 

operation and ends after four hours of 

continuous engine-on operation; or 

(iv) Begins at the end of the previous 

four hours of continuous engine-on 

operation and ends with engine shutoff. 

(b) Malfunction indicator light (MIL) 

and Diagnostic Trouble Codes (DTC). 

The OBD system must incorporate a 

malfunction indicator light (MIL) or 

equivalent and must store specific types 

of diagnostic trouble codes (DTC). 

(1) MIL specifications. 

(i) [Reserved.] 

(ii) The OBD system must activate the 

MIL when the ignition is in the key-on/ 

engine-off position before engine 

cranking to indicate that the MIL is 

functional. The MIL shall be activated 

continuously during this functional 

check for a minimum of 5 seconds. 

During this MIL key-on functional 

check, the data stream value (see 

paragraph (k)(4)(ii) of this section) for 

MIL status must indicate ‘‘commanded 

off’’ unless the OBD system has detected 

a malfunction and has stored a MIL-on 

DTC. This MIL key-on functional check 

is not required during vehicle operation 

in the key-on/engine-off position 

subsequent to the initial engine 

cranking of an ignition cycle (e.g., due 

to an engine stall or other noncommanded engine shutoff). 

(iii) As an option, the MIL may be 

used to indicate readiness status (see 

paragraph (k)(4)(i) of this section) in a 

standardized format in the key-on/ 

engine-off position. 

(iv) A manufacturer may also use the 

MIL to indicate which, if any, DTCs are 

currently stored (e.g., to ‘‘blink’’ the 

stored DTCs). Such use must not 

activate unintentionally during routine 

driver operation. 

(v) [Reserved.] 

(2) MIL activation and DTC storage 

protocol. 

(i) Within 10 seconds of detecting a 

potential malfunction, the OBD system 

must store a pending DTC that identifies 

the potential malfunction. 

(ii) If the potential malfunction is 

again detected before the end of the next 

drive cycle during which monitoring 

occurs (i.e., the potential malfunction 

has been confirmed as a malfunction), 

then within 10 seconds of such 

detection the OBD system must activate 

the MIL continuously and store a MILon DTC. If the potential malfunction is 

not detected before the end of the next 

drive cycle during which monitoring 

occurs (i.e., there is no indication of the 

malfunction at any time during the 

drive cycle), the corresponding pending 

DTC should be erased at the end of the 

drive cycle. Similarly, if a malfunction 

is detected for the first time and 

confirmed on a given drive cycle 

without need for further evaluation, 

then within 10 seconds of such 

detection the OBD system must activate 

the MIL continuously and store a MILon DTC. 

(iii) A manufacturer may request 

Administrator approval to employ 

alternative statistical MIL activation and 

DTC storage protocols to those specified 

in paragraphs (b)(2)(i) and (b)(2)(ii) of 

this section. Approval will depend upon 

the manufacturer providing data and/or 

engineering evaluations that 

demonstrate that the alternative 

protocols can evaluate system 

performance and detect malfunctions in 

a manner that is equally effective and 

timely. Strategies requiring on average 

more than six drive cycles for MIL 

activation will not be accepted. 

(iv) The OBD system must store a 

‘‘freeze frame’’ of the operating 

conditions (as defined in paragraph 

(k)(4)(iii) of this section) present upon 

detecting a malfunction or a potential 

malfunction. In the event that a pending 

DTC has matured to a MIL-on DTC, the 

manufacturer shall either retain the 

currently stored freeze frame conditions 

or replace the stored freeze frame with 

freeze frame conditions regarding the 

MIL-on DTC. Any freeze frame stored in 

conjunction with any pending DTC or 

MIL-on DTC should be erased upon 

erasure of the corresponding DTC. 

(v) If the engine enters a limp-home 

mode of operation that can affect 

emissions or the performance of the 

OBD system, or in the event of a 

malfunction of an onboard computer(s) 

itself that can affect the performance of 

the OBD system, the OBD system must 

activate the MIL and store a MIL-on 

DTC within 10 seconds to inform the 

vehicle operator. If the limp-home mode 

of operation is recoverable (i.e., 

operation automatically returns to 

normal at the beginning of the following 

ignition cycle), the OBD system may 

wait to activate the MIL and store the 

MIL-on DTC if the limp-home mode of 

operation is again entered before the 

end of the next ignition cycle rather 

than activating the MIL within 10 

seconds on the first drive cycle during 

which the limp-home mode of operation 

is entered. 

(vi) Before the end of an ignition 

cycle, the OBD system must store a 

permanent DTC(s) that corresponds to 

any stored MIL-on DTC(s). 

(3) MIL deactivation and DTC erasure 

protocol. 

(i) Deactivating the MIL. Except as 

otherwise provided for in paragraph 

(g)(6)(iv)(B) of this section for empty 

reductant tanks, and paragraphs 

(h)(1)(iv)(F), (h)(2)(viii), and (h)(7)(iv)(B) 

of this section for gasoline fuel system, 

misfire, and evaporative system 

malfunctions, once the MIL has been 

activated, it may be deactivated after 

three subsequent sequential drive cycles 

during which the monitoring system 

responsible for activating the MIL 

functions and the previously detected 

malfunction is no longer present and 

provided no other malfunction has been 

detected that would independently 

activate the MIL according to the 

requirements outlined in paragraph 

(b)(2) of this section. 

(ii) Erasing a MIL-on DTC. The OBD 

system may erase a MIL-on DTC if the 

identified malfunction has not again 

been detected in at least 40 engine warm 

up cycles and the MIL is presently not 

activated for that malfunction. The OBD 

system may also erase a MIL-on DTC 

upon deactivating the MIL according to 

paragraph (b)(3)(i) of this section 

provided a previous-MIL-on DTC is 

stored upon erasure of the MIL-on DTC. 

The OBD system may erase a previousMIL-on DTC if the identified 

malfunction has not again been detected 

in at least 40 engine warm up cycles and 

the MIL is presently not activated for 

that malfunction. 

(iii) Erasing a permanent DTC. The 

OBD system can erase a permanent DTC 

only if either of the following conditions 

occur: 

(A) The OBD system itself determines 

that the malfunction that caused the 

corresponding MIL-on DTC to be stored 

is no longer present and is not 

commanding activation of the MIL, 

concurrent with the requirements of 

paragraph (b)(3)(i) of this section. 

(B) Subsequent to erasing the DTC 

information from the on-board computer 

(i.e., through the use of a scan tool or 

a battery disconnect), the OBD monitor 

for the malfunction that caused the 

permanent DTC to be stored has 

executed the minimum number of 

monitoring events necessary for MIL 

activation and has determined that the 

malfunction is no longer present. 

(4) Exceptions to MIL and DTC 

requirements. 

(i) If a limp-home mode of operation 

causes an overt indication (e.g., 

activation of a red engine shut-down 

warning light) such that the driver is 

certain to respond and have the problem 

corrected, a manufacturer may choose 

not to activate the MIL as required by 

paragraph (b)(2)(v) of this section. 

Additionally, if an auxiliary emission 

control device has been properly 


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activated as approved by the 

Administrator, a manufacturer may 

choose not to activate the MIL. 

(ii) For gasoline engines, a 

manufacturer may choose to meet the 

MIL and DTC requirements in § 86.010–

17 in lieu of meeting the requirements 

of paragraph (b) of § 86.010–18. 

(a) Monitoring conditions. The OBD 

system must monitor and detect the 

malfunctions specified in paragraphs 

(g), (h), and (i) of this section under the 

following general monitoring 

conditions. The more specific 

monitoring conditions of paragraph (d) 

of this section are sometimes required 

according to the provisions of 

paragraphs (g), (h), and (i) of this 

section. 

(1) As specifically provided for in 

paragraphs (g), (h), and (i) of this 

section, the monitoring conditions for 

detecting malfunctions must be 

technically necessary to ensure robust 

detection of malfunctions (e.g., avoid 

false passes and false indications of 

malfunctions); designed to ensure 

monitoring will occur under conditions 

that may reasonably be expected to be 

encountered in normal vehicle 

operation and normal vehicle use; and, 

designed to ensure monitoring will 

occur during the FTP transient test cycle 

contained in Appendix I paragraph (f), 

of this part, or similar drive cycle as 

approved by the Administrator. 

(2) Monitoring must occur at least 

once per drive cycle in which the 

monitoring conditions are met. 

(3) Manufacturers may request 

approval to define monitoring 

conditions that are not encountered 

during the FTP cycle as required in 

paragraph (c)(1) of this section. In 

evaluating the manufacturer’s request, 

the Administrator will consider the 

degree to which the requirement to run 

during the FTP transient cycle restricts 

monitoring during in-use operation, the 

technical necessity for defining 

monitoring conditions that are not 

encountered during the FTP cycle, data 

and/or an engineering evaluation 

submitted by the manufacturer that 

demonstrate that the component/system 

does not normally function during the 

FTP, whether monitoring is otherwise 

not feasible during the FTP cycle, and/ 

or the ability of the manufacturer to 

demonstrate that the monitoring 

conditions satisfy the minimum 

acceptable in-use monitor performance 

ratio requirement as defined in 

paragraph (d) of this section. 

(d) In-use performance tracking. As 

specifically required in paragraphs (g), 

(h), and (i) of this section, the OBD 

system must monitor and detect the 

malfunctions specified in paragraphs 

(g), (h), and (i) of this section according 

to the criteria of this paragraph (d). The 

OBD system is not required to track and 

report in-use performance for monitors 

other than those specifically identified 

in paragraph (d)(1) of this section. 

(1) The manufacturer must implement 

software algorithms in the OBD system 

to individually track and report the inuse performance of the following 

monitors, if equipped, in the 

standardized format specified in 

paragraph (e) of this section: NMHC 

converting catalyst (paragraph (g)(5) of 

this section); NOX converting catalyst 

(paragraph (g)(6) of this section); 

gasoline catalyst (paragraph (h)(6) of 

this section); exhaust gas sensor 

(paragraph (g)(9) or (h)(8) of this 

section); evaporative system (paragraph 

(h)(7) of this section); EGR system 

(paragraph (g)(3) or (h)(3) of this 

section); VVT system (paragraph (g)(10) 

or (h)(9) of this section); secondary air 

system (paragraph (h)(5) of this section); 

DPF system (paragraph (g)(8) of this 

section); boost pressure control system 

(paragraph (g)(4) of this section); and, 

NOX adsorber system (paragraph (g)(7) 

of this section). 

(i) The manufacturer shall not use the 

calculated ratio specified in paragraph 

(d)(2) of this section or any other 

indication of monitor frequency as a 

monitoring condition for a monitor (e.g., 

using a low ratio to enable more 

frequent monitoring through diagnostic 

executive priority or modification of 

other monitoring conditions, or using a 

high ratio to enable less frequent 

monitoring). 

(ii) [Reserved.] 

(2) In-use performance ratio 

definition. For monitors required to 

meet the requirements of paragraph (d) 

of this section, the performance ratio 

must be calculated in accordance with 

the specifications of this paragraph 

(d)(2). 

(i) The numerator of the performance 

ratio is defined as the number of times 

a vehicle has been operated such that all 

monitoring conditions have been 

encountered that are necessary for the 

specific monitor to detect a malfunction. 

(ii) The denominator is defined as the 

number of times a vehicle has been 

operated in accordance with the 

provisions of paragraph (d)(4) of this 

section. 

(iii) The performance ratio is defined 

as the numerator divided by the 

denominator. 

(3) Specifications for incrementing the 

numerator. 

(i) Except as provided for in 

paragraph (d)(3)(v) of this paragraph 

(d)(3), the numerator, when 

incremented, must be incremented by 

an integer of one. The numerator shall 

not be incremented more than once per 

drive cycle. 

(ii) The numerator for a specific 

monitor must be incremented within 10 

seconds if and only if the following 

criteria are satisfied on a single drive 

cycle: 

(A) Every monitoring condition has 

been satisfied that is necessary for the 

specific monitor to detect a malfunction 

and store a pending DTC, including 

applicable enable criteria, presence or 

absence of related DTCs, sufficient 

length of monitoring time, and 

diagnostic executive priority 

assignments (e.g., diagnostic ‘‘A’’ must 

execute prior to diagnostic ‘‘B’’). For the 

purpose of incrementing the numerator, 

satisfying all the monitoring conditions 

necessary for a monitor to determine 

that the monitor is not malfunctioning 

shall not, by itself, be sufficient to meet 

this criteria. 

(B) For monitors that require multiple 

stages or events in a single drive cycle 

to detect a malfunction, every 

monitoring condition necessary for all 

events to complete must be satisfied. 

(C) For monitors that require intrusive 

operation of components to detect a 

malfunction, a manufacturer must 

request approval of the strategy used to 

determine that, had a malfunction been 

present, the monitor would have 

detected the malfunction. Administrator 

approval of the request will be based on 

the equivalence of the strategy to actual 

intrusive operation and the ability of the 

strategy to determine accurately if every 

monitoring condition was satisfied that 

was necessary for the intrusive event to 

occur. 

(D) For the secondary air system 

monitor, the criteria in paragraphs 

(d)(3)(ii)(A) through (d)(3)(ii)(C) of this 

section are satisfied during normal 

operation of the secondary air system. 

Monitoring during intrusive operation 

of the secondary air system later in the 

same drive cycle for the sole purpose of 

monitoring shall not, by itself, be 

sufficient to meet these criteria. 

(iii) For monitors that can generate 

results in a ‘‘gray zone’’ or ‘‘nondetection zone’’ (i.e., monitor results 

that indicate neither a properly 

operating system nor a malfunctioning 

system) or in a ‘‘non-decision zone’’

(e.g., monitors that increment and 

decrement counters until a pass or fail 

threshold is reached), the numerator, in 

general, shall not be incremented when 

the monitor indicates a result in the 

‘‘non-detection zone’’ or prior to the 

monitor reaching a complete decision. 

When necessary, the Administrator will 

consider data and/or engineering 

analyses submitted by the manufacturer 


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demonstrating the expected frequency 

of results in the ‘‘non-detection zone’’

and the ability of the monitor to 

determine accurately, had an actual 

malfunction been present, whether or 

not the monitor would have detected a 

malfunction instead of a result in the 

‘‘non-detection zone.’’

(iv) For monitors that run or complete 

their evaluation with the engine off, the 

numerator must be incremented either 

within 10 seconds of the monitor 

completing its evaluation in the engine 

off state, or during the first 10 seconds 

of engine start on the subsequent drive 

cycle. 

(v) Manufacturers that use alternative 

statistical MIL activation protocols as 

allowed in paragraph (b)(2)(iii) of this 

section for any of the monitors requiring 

a numerator, are required to increment 

the numerator(s) appropriately. The 

manufacturer may be required to 

provide supporting data and/or 

engineering analyses demonstrating 

both the equivalence of their 

incrementing approach to the 

incrementing specified in this paragraph 

(d)(3) for monitors using the standard 

MIL activation protocol. 

(4) Specifications for incrementing the 

denominator. 

(i) The denominator, when 

incremented, must be incremented by 

an integer of one. The denominator shall 

not be incremented more than once per 

drive cycle. 

(ii) The denominator for each monitor 

must be incremented within 10 seconds 

if and only if the following criteria are 

satisfied on a single drive cycle: 

(A) Cumulative time since the start of 

the drive cycle is greater than or equal 

to 600 seconds while at an elevation of 

less than 8,000 feet (2,400 meters) above 

sea level and at an ambient temperature 

of greater than or equal to 20 degrees 

Fahrenheit (¥7 C); 

(B) Cumulative gasoline engine 

operation at or above 25 miles per hour 

or diesel engine operation at or above 

15% calculated load, either of which 

occurs for greater than or equal to 300 

seconds while at an elevation of less 

than 8,000 feet (2,400 meters) above sea 

level and at an ambient temperature of 

greater than or equal to 20 degrees 

Fahrenheit (¥7 C); and 

(C) Continuous vehicle operation at 

idle (e.g., accelerator pedal released by 

driver and vehicle speed less than or 

equal to one mile per hour) for greater 

than or equal to 30 seconds while at an 

elevation of less than 8,000 feet (2,400 

meters) above sea level and at an 

ambient temperature of greater than or 

equal to 20 degrees Fahrenheit (¥7 C). 

(iii) In addition to the requirements of 

paragraph (d)(4)(ii) of this section, the 

evaporative system monitor 

denominator(s) may be incremented if 

and only if: 

(A) Cumulative time since the start of 

the drive cycle is greater than or equal 

to 600 seconds while at an ambient 

temperature of greater than or equal to 

40 degrees Fahrenheit (4 C) but less than 

or equal to 95 degrees Fahrenheit (35 C); 

and, 

(B) Engine cold start occurs with the 

engine coolant temperature greater than 

or equal to 40 degrees Fahrenheit (4 C) 

but less than or equal to 95 degrees 

Fahrenheit (35 C) and less than or equal 

to 12 degrees Fahrenheit (7 C) higher 

than the ambient temperature. 

(iv) In addition to the requirements of 

paragraph (d)(4)(ii) of this section, the 

denominator(s) for the following 

monitors may be incremented if and 

only if the component or strategy is 

commanded ‘‘on’’ for a time greater than 

or equal to 10 seconds. For purposes of 

determining this commanded ‘‘on’’

time, the OBD system shall not include 

time during intrusive operation of any 

of the components or strategies that 

occurs later in the same drive cycle for 

the sole purpose of monitoring. 

(A) Secondary air system (paragraph 

(h)(5) of this section). 

(B) Cold start emission reduction 

strategy (paragraph (h)(4) of this 

section). 

(C) Components or systems that 

operate only at engine start-up (e.g., 

glow plugs, intake air heaters) and are 

subject to monitoring under ‘‘other 

emission control systems’’ (paragraph 

(i)(4) of this section) or comprehensive 

component output components 

(paragraph (i)(3)(iii) of this section). 

(v) In addition to the requirements of 

paragraph (d)(4)(ii) of this section, the 

denominator(s) for the following 

monitors of output components (except 

those operated only at engine start-up 

and subject to the requirements of 

paragraph (d)(4)(iv) of this section, may 

be incremented if and only if the 

component is commanded to function 

(e.g., commanded ‘‘on’’, ‘‘opened’’, 

‘‘closed’’, ‘‘locked’’) on two or more 

occasions during the drive cycle or for 

a time greater than or equal to 10 

seconds, whichever occurs first: 

(A) Variable valve timing and/or 

control system (paragraph (g)(10) or 

(h)(9) of this section). 

(B) ‘‘Other emission control systems’’

(paragraph (i)(4) of this section). 

(C) Comprehensive component output 

component (paragraph (i)(3) of this 

section) (e.g., turbocharger waste-gates, 

variable length manifold runners). 

(vi) For monitors of the following 

components, the manufacturer may use 

alternative or additional criteria for 

incrementing the denominator to that 

set forth in paragraph (d)(4)(ii) of this 

section. To do so, the alternative criteria 

must be based on equivalence to the 

criteria of paragraph (d)(4)(ii) of this 

section in measuring the frequency of 

monitor operation relative to the 

amount of engine operation: 

(A) Engine cooling system input 

components (paragraph (i)(1) of this 

section). 

(B) ‘‘Other emission control systems’’

(paragraph (i)(4) of this section). 

(C) Comprehensive component input 

components that require extended 

monitoring evaluation (paragraph (i)(3) 

of this section) (e.g., stuck fuel level 

sensor rationality). 

(vii) For monitors of the following 

components or other emission controls 

that experience infrequent regeneration 

events, the manufacturer may use 

alternative or additional criteria for 

incrementing the denominator to that 

set forth in paragraph (d)(4)(ii) of this 

section. To do so, the alternative criteria 

must be based on equivalence to the 

criteria of paragraph (d)(4)(ii) of this 

section in measuring the frequency of 

monitor operation relative to the 

amount of engine operation: 

(A) Oxidation catalyst (paragraph 

(g)(5) of this section). 

(B) DPF (paragraph (g)(8) of this 

section). 

(viii) For hybrids that employ 

alternative engine start hardware or 

strategies (e.g., integrated starter and 

generators), or alternative fuel vehicles 

(e.g. dedicated, bi-fuel, or dual-fuel 

applications), the manufacturer may use 

alternative criteria for incrementing the 

denominator to that set forth in 

paragraph (d)(4)(ii) of this section. In 

general, the Administrator will not 

approve alternative criteria for those 

hybrids that employ engine shut off 

only at or near idle and/or vehicle stop 

conditions. To use alternative criteria, 

the alternative criteria must be based on 

the equivalence to the criteria of 

paragraph (d)(4)(ii) of this section in 

measuring the amount of vehicle 

operation relative to the measure of 

conventional vehicle operation. 

(5) Disablement of numerators and 

denominators. 

(i) Within 10 seconds of detecting a 

malfunction (i.e. a pending or a MIL-on 

DTC has been stored) that disables a 

monitor for which the monitoring 

conditions in paragraph (d) of this 

section must be met, the OBD system 

must stop incrementing the numerator 

and denominator for any monitor that 

may be disabled as a consequence of the 

detected malfunction. Within 10 

seconds of the time at which the 

malfunction is no longer being detected 


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(e.g., the pending DTC is erased through 

OBD system self-clearing or through a 

scan tool command), incrementing of all 

applicable numerators and 

denominators must resume. 

(ii) Within 10 seconds of the start of 

a power take-off unit (e.g., dump bed, 

snow plow blade, or aerial bucket, etc.) 

that disables a monitor for which the 

monitoring conditions in paragraph (d) 

of this section must be met, the OBD 

system must stop incrementing the 

numerator and denominator for any 

monitor that may be disabled as a 

consequence of power take-off 

operation. Within 10 seconds of the 

time at which the power take-off 

operation ends, incrementing of all 

applicable numerators and 

denominators must resume. 

(iii) Within 10 seconds of detecting a 

malfunction (i.e., a pending or a MIL-on 

DTC has been stored) of any component 

used to determine if the criteria of 

paragraphs (d)(4)(ii) and (d)(4)(iii) of 

this section are satisfied, the OBD 

system must stop incrementing all 

applicable numerators and 

denominators. Within 10 seconds of the 

time at which the malfunction is no 

longer being detected (e.g., the pending 

DTC is erased through OBD system selfclearing or through a scan tool 

command), incrementing of all 

applicable numerators and 

denominators must resume. 

(e) Standardized tracking and 

reporting of in-use monitor 

performance. 

(1) General. For monitors required to 

track and report in-use monitor 

performance according to paragraph (d) 

of this section, the performance data 

must be tracked and reported in 

accordance with the specifications in 

paragraphs (d)(2), (e), and (k)(5) of this 

section. The OBD system must 

separately report an in-use monitor 

performance numerator and 

denominator for each of the following 

components: 

(i) For diesel engines, NMHC catalyst 

bank 1, NMHC catalyst bank 2, NOX

catalyst bank 1, NOX catalyst bank 2, 

exhaust gas sensor bank 1, exhaust gas 

sensor bank 2, EGR/VVT system, DPF, 

boost pressure control system, and NOX

adsorber. The OBD system must also 

report a general denominator and an 

ignition cycle counter in the 

standardized format specified in 

paragraphs (e)(5), (e)(6), and (k)(5) of 

this section. 

(ii) For gasoline engines, catalyst bank 

1, catalyst bank 2, exhaust gas sensor 

bank 1, exhaust gas sensor bank 2, 

evaporative leak detection system, EGR/ 

VVT system, and secondary air system. 

The OBD system must also report a 

general denominator and an ignition 

cycle counter in the standardized format 

specified in paragraphs (e)(5), (e)(6), and 

(k)(5) of this section. 

(iii) For specific components or 

systems that have multiple monitors 

that are required to be reported under 

paragraphs (g) and (h) of this section 

(e.g., exhaust gas sensor bank 1 may 

have multiple monitors for sensor 

response or other sensor characteristics), 

the OBD system must separately track 

numerators and denominators for each 

of the specific monitors and report only 

the corresponding numerator and 

denominator for the specific monitor 

that has the lowest numerical ratio. If 

two or more specific monitors have 

identical ratios, the corresponding 

numerator and denominator for the 

specific monitor that has the highest 

denominator must be reported for the 

specific component. 

(2) Numerator. 

(i) The OBD system must report a 

separate numerator for each of the 

applicable components listed in 

paragraph (e)(1) of this section. 

(ii) The numerator(s) must be reported 

in accordance with the specifications in 

paragraph (k)(5)(ii) of this section. 

(3) Denominator. 

(i) The OBD system must report a 

separate denominator for each of the 

applicable components listed in 

paragraph (e)(1) of this section. 

(ii) The denominator(s) must be 

reported in accordance with the 

specifications in paragraph (k)(5)(ii) of 

this section. 

(4) Monitor performance ratio. For 

purposes of determining which 

corresponding numerator and 

denominator to report as required in 

paragraph (e)(1)(iii) of this section, the 

ratio must be calculated in accordance 

with the specifications in paragraph 

(k)(5)(iii) of this section. 

(5) Ignition cycle counter. 

(i) The ignition cycle counter is 

defined as a counter that indicates the 

number of ignition cycles a vehicle has 

experienced according to the 

specifications of paragraph (e)(5)(ii)(B) 

of this section. The ignition cycle 

counter must be reported in accordance 

with the specifications in paragraph 

(k)(5)(ii) of this section. 

(ii) The ignition cycle counter must be 

incremented as follows: 

(A) The ignition cycle counter, when 

incremented, must be incremented by 

an integer of one. The ignition cycle 

counter shall not be incremented more 

than once per ignition cycle. 

(B) The ignition cycle counter must be 

incremented within 10 seconds if and 

only if the engine exceeds an engine 

speed of 50 to 150 rpm below the 

normal, warmed-up idle speed (as 

determined in the drive position for 

engines paired with an automatic 

transmission) for at least two seconds 

plus or minus one second. 

(iii) Within 10 seconds of detecting a 

malfunction (i.e., a pending or a MIL-on 

DTC has been stored) of any component 

used to determine if the criteria in 

paragraph (e)(5)(ii)(B) of this section are 

satisfied (i.e., engine speed or time of 

operation), the OBD system must stop 

incrementing the ignition cycle counter. 

Incrementing of the ignition cycle 

counter shall not be stopped for any 

other condition. Within 10 seconds of 

the time at which the malfunction is no 

longer being detected (e.g., the pending 

DTC is erased through OBD system selfclearing or through a scan tool 

command), incrementing of the ignition 

cycle counter must resume. 

(6) General denominator. 

(i) The general denominator is defined 

as a measure of the number of times an 

engine has been operated according to 

the specifications of paragraph 

(e)(6)(ii)(B) of this section. The general 

denominator must be reported in 

accordance with the specifications in 

paragraph (k)(5)(ii) of this section. 

(ii) The general denominator must be 

incremented as follows: 

(A) The general denominator, when 

incremented, must be incremented by 

an integer of one. The general 

denominator shall not be incremented 

more than once per drive cycle. 

(B) The general denominator must be 

incremented within 10 seconds if and 

only if the criteria identified in 

paragraph (d)(4)(ii) of this section are 

satisfied on a single drive cycle. 

(C) Within 10 seconds of detecting a 

malfunction (i.e., a pending or a MIL-on 

DTC has been stored) of any component 

used to determine if the criteria in 

paragraph (d)(4)(ii) of this section are 

satisfied (i.e., vehicle speed/load, 

ambient temperature, elevation, idle 

operation, or time of operation), the 

OBD system must stop incrementing the 

general denominator. Incrementing of 

the general denominator shall not be 

stopped for any other condition (e.g., 

the disablement criteria in paragraphs 

(d)(5)(i) and (d)(5)(ii) of this section 

shall not disable the general 

denominator). Within 10 seconds of the 

time at which the malfunction is no 

longer being detected (e.g., the pending 

DTC is erased through OBD system selfclearing or through a scan tool 

command), incrementing of the general 

denominator must resume. 

(f) Malfunction criteria determination. 

(1) In determining the malfunction 

criteria for the diesel engine monitors 

required under paragraphs (g) and (i) of 


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this section that are required to indicate 

a malfunction before emissions exceed 

an emission threshold based on any 

applicable standard, the manufacturer 

must: 

(i) Use the emission test cycle and 

standard (i.e., the transient FTP or the 

supplemental emissions test (SET)) 

determined by the manufacturer to be 

more stringent (i.e., to result in higher 

emissions with the same level of 

monitored component malfunction). 

The manufacturer must use data and/or 

engineering analysis to determine the 

test cycle and standard that is more 

stringent. 

(ii) Identify in the certification 

documentation required under 

paragraph (m) of this section, the test 

cycle and standard determined by the 

manufacturer to be the most stringent 

for each applicable monitor. 

(iii) If the Administrator reasonably 

believes that a manufacturer has 

determined incorrectly the test cycle 

and standard that is most stringent, the 

manufacturer must be able to provide 

emission data and/or engineering 

analysis supporting their choice of test 

cycle and standard. 

(2) On engines equipped with 

emission controls that experience 

infrequent regeneration events, a 

manufacturer must adjust the emission 

test results that are used to determine 

the malfunction criteria for monitors 

that are required to indicate a 

malfunction before emissions exceed a 

certain emission threshold. For each 

such monitor, the manufacturer must 

adjust the emission result as done in 

accordance with the provisions of 

section 86.004–28(i) with the 

component for which the malfunction 

criteria are being established having 

been deteriorated to the malfunction 

threshold. The adjusted emission value 

must be used for purposes of 

determining whether or not the 

applicable emission threshold is 

exceeded. 

(i) For purposes of this paragraph 

(f)(2) of this section, regeneration means 

an event, by design, during which 

emissions levels change while the 

emission control performance is being 

restored. 

(ii) For purposes of this paragraph 

(f)(2) of this section, infrequent means 

having an expected frequency of less 

than once per transient FTP cycle. 

(3) For gasoline engines, rather than 

meeting the malfunction criteria 

specified under paragraphs (h) and (i) of 

this section, the manufacturer may 

request approval to use an OBD system 

certified to the requirements of 

§ 86.010–17. To do so, the manufacturer 

must demonstrate use of good 

engineering judgment in determining 

equivalent malfunction detection 

criteria to those required in this section. 

(g) OBD monitoring requirements for 

diesel-fueled/compression-ignition 

engines. The following table shows the 

thresholds at which point certain 

components or systems, as specified in 

this paragraph (g), are considered 

malfunctioning. 

TABLE 1.—OBD EMISSIONS THRESHOLDS FOR DIESEL-FUELED/COMPRESSION-IGNITION ENGINES MEANT FOR PLACEMENT

IN APPLICATIONS GREATER THAN 14,000 POUNDS GVWR (G/BHP-HR) 

Component § 86.010–18 reference NMHC CO NOX PM 

NMHC catalyst system .................................................................. (g)(5) .......................... 2.5x .......... .................. .................. ....................

NOX aftertreatment system ............................................................ (g)(6), (g)(7) ............... .................. .................. +0.3 ......... ....................

Diesel particulate filter (DPF) system ............................................ (g)(8) .......................... 2.5x .......... .................. .................. 0.05/+0.04 

Air-fuel ratio sensors upstream of aftertreatment devices ............ (g)(9) .......................... 2.5x .......... 2.5x .......... +0.3 ......... 0.03/+0.02 

Air-fuel ratio sensors downstream of aftertreatment devices ........ (g)(9) .......................... 2.5x .......... .................. +0.3 ......... 0.05/+0.04 

NOX sensors .................................................................................. (g)(9) .......................... .................. .................. +0.3 ......... 0.05/+0.04 

‘‘Other monitors’’ with emissions thresholds ................................. (g)(1), (g)(3), (g)(4), 

(g)(10).

2.5x .......... 2.5x .......... +0.3 ......... 0.03/+0.02 

Notes: FEL=Family Emissions Limit; 2.5x std means a multiple of 2.5 times the applicable emissions standard; +0.3 means the standard or 

FEL plus 0.3; 0.05/+0.04 means an absolute level of 0.05 or an additive level of the standard or FEL plus 0.04, whilchever level is higher; these 

emissions thresholds apply to the monitoring requirements of paragraph (g) of this section 86.010–18. 

(1) Fuel system monitoring. 

(i) General. The OBD system must 

monitor the fuel delivery system to 

verify that it is functioning properly. 

The individual electronic components 

(e.g., actuators, valves, sensors, pumps) 

that are used in the fuel system and are 

not specifically addressed in this 

paragraph (g)(1) must be monitored in 

accordance with the requirements of 

paragraph (i)(3) of this section. 

(ii) Fuel system malfunction criteria. 

(A) Fuel system pressure control. The 

OBD system must monitor the fuel 

system’s ability to control to the desired 

fuel pressure. This monitoring must be 

done continuously unless new hardware 

has to be added, in which case the 

monitoring must be done at least once 

per drive cycle. The OBD system must 

detect a malfunction of the fuel system’s 

pressure control system when the 

pressure control system is unable to 

maintain an engine’s emissions at or 

below the emissions thresholds for 

‘‘other monitors’’ as shown in Table 1 of 

this paragraph (g). For engines in which 

no failure or deterioration of the fuel 

system pressure control could result in 

an engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

when the system has reached its control 

limits such that the commanded fuel 

system pressure cannot be delivered. 

(B) Fuel system injection quantity. 

The OBD system must detect a 

malfunction of the fuel injection system 

when the system is unable to deliver the 

commanded quantity of fuel necessary 

to maintain an engine’s emissions at or 

below the emissions thresholds for 

‘‘other monitors’’ as shown in Table 1 of 

this paragraph (g). For engines in which 

no failure or deterioration of the fuel 

injection quantity could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

when the system has reached its control 

limits such that the commanded fuel 

quantity cannot be delivered. 

(C) Fuel system injection timing. The 

OBD system must detect a malfunction 

of the fuel injection system when the 

system is unable to deliver fuel at the 

proper crank angle/timing (e.g., 

injection timing too advanced or too 

retarded) necessary to maintain an 

engine’s emissions at or below the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table 1 of this 

paragraph (g). For engines in which no 

failure or deterioration of the fuel 

injection timing could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

when the system has reached its control 

limits such that the commanded fuel 

injection timing cannot be achieved. 


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(D) Fuel system feedback control. See 

paragraph (i)(6) of this section. 

(iii) Fuel system monitoring 

conditions. 

(A) The OBD system must monitor 

continuously for malfunctions 

identified in paragraphs (g)(1)(ii)(A) and 

(g)(1)(ii)(D) of this section. 

(B) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraphs (g)(1)(ii)(B) and 

(g)(1)(ii)(C) in accordance with 

paragraphs (c) and (d) of this section. 

(iv) Fuel system MIL activation and 

DTC storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(2) Engine misfire monitoring. 

(i) General. The OBD system must 

monitor the engine for misfire causing 

excess emissions. 

(ii) Engine misfire malfunction 

criteria. The OBD system must be 

capable of detecting misfire occurring in 

one or more cylinders. To the extent 

possible without adding hardware for 

this specific purpose, the OBD system 

must also identify the specific misfiring 

cylinder. If more than one cylinder is 

misfiring continuously, a separate DTC 

must be stored indicating that multiple 

cylinders are misfiring. When 

identifying multiple cylinder misfire, 

the OBD system is not required to 

identify individually through separate 

DTCs each of the continuously misfiring 

cylinders. 

(iii) Engine misfire monitoring 

conditions. 

(A) The OBD system must monitor for 

engine misfire during engine idle 

conditions at least once per drive cycle 

in which the monitoring conditions for 

misfire are met. The manufacturer must 

be able to demonstrate via engineering 

analysis and/or data that the selfdefined monitoring conditions: Are 

technically necessary to ensure robust 

detection of malfunctions (e.g., avoid 

false passes and false detection of 

malfunctions); require no more than 

1000 cumulative engine revolutions; 

and, do not require any single 

continuous idle operation of more than 

15 seconds to make a determination that 

a malfunction is present (e.g., a decision 

can be made with data gathered during 

several idle operations of 15 seconds or 

less); or, satisfy the requirements of 

paragraph (c) of this section with 

alternative engine operating conditions. 

(B) Manufacturers may employ 

alternative monitoring conditions (e.g., 

off-idle) provided the manufacturer is 

able to demonstrate that the alternative 

monitoring ensure equivalent robust 

detection of malfunctions and 

equivalent timeliness in detection of 

malfunctions. 

(iv) Engine misfire MIL activation and 

DTC storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(3) EGR system monitoring. 

(i) General. The OBD system must 

monitor the EGR system on engines so 

equipped for low flow rate, high flow 

rate, and slow response malfunctions. 

For engines equipped with EGR coolers 

(e.g., heat exchangers), the OBD system 

must monitor the cooler for insufficient 

cooling malfunctions. The individual 

electronic components (e.g., actuators, 

valves, sensors) that are used in the EGR 

system must be monitored in 

accordance with the comprehensive 

component requirements in paragraph 

(i)(3) of this section. 

(ii) EGR system malfunction criteria. 

(A) EGR low flow. The OBD system 

must detect a malfunction of the EGR 

system prior to a decrease from the 

manufacturer’s specified EGR flow rate 

that would cause an engine’s emissions 

to exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 1 of 

this paragraph (g). For engines in which 

no failure or deterioration of the EGR 

system that causes a decrease in flow 

could result in an engine’s emissions 

exceeding the applicable emissions 

thresholds, the OBD system must detect 

a malfunction when the system has 

reached its control limits such that it 

cannot increase EGR flow to achieve the 

commanded flow rate. 

(B) EGR high flow. The OBD system 

must detect a malfunction of the EGR 

system, including a leaking EGR valve 

(i.e., exhaust gas flowing through the 

valve when the valve is commanded 

closed) prior to an increase from the 

manufacturer’s specified EGR flow rate 

that would cause an engine’s emissions 

to exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 1 of 

this paragraph (g). For engines in which 

no failure or deterioration of the EGR 

system that causes an increase in flow 

could result in an engine’s emissions 

exceeding the applicable emissions 

thresholds, the OBD system must detect 

a malfunction when the system has 

reached its control limits such that it 

cannot reduce EGR flow to achieve the 

commanded flow rate. 

(C) EGR slow response. The OBD 

system must detect a malfunction of the 

EGR system prior to any failure or 

deterioration in the capability of the 

EGR system to achieve the commanded 

flow rate within a manufacturerspecified time that would cause an 

engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table 1 of this 

paragraph (g). The OBD system must 

monitor both the capability of the EGR 

system to respond to a commanded 

increase in flow and the capability of 

the EGR system to respond to a 

commanded decrease in flow. 

(D) EGR system feedback control. See 

paragraph (i)(6) of this section. 

(E) EGR cooler performance. The OBD 

system must detect a malfunction of the 

EGR cooler prior to a reduction from the 

manufacturer’s specified cooling 

performance that would cause an 

engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table 1 of this 

paragraph (g). For engines in which no 

failure or deterioration of the EGR 

cooler could result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the OBD system 

must detect a malfunction when the 

system has no detectable amount of EGR 

cooling. 

(iii) EGR system monitoring 

conditions. 

(A) The OBD system must monitor 

continuously for malfunctions 

identified in paragraphs (g)(3)(ii)(A), 

(g)(3)(ii)(B), and (g)(3)(ii)(D) of this 

section. 

(B) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (g)(3)(ii)(C) in 

accordance with paragraphs (c) and (d) 

of this section, with the exception that 

monitoring must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in paragraph 

(c)(2) of this section. For purposes of 

tracking and reporting as required in 

paragraph (d)(1) of this section, all 

monitors used to detect malfunctions 

identified in paragraph (g)(3)(ii)(C) of 

this section must be tracked separately 

but reported as a single set of values as 

specified in paragraph (e)(1)(iii) of this 

section. 

(C) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (g)(3)(ii)(E) of 

this section in accordance with 

paragraphs (c) and (d) of this section. 

For purposes of tracking and reporting 

as required in paragraph (d)(1) of this 

section, all monitors used to detect 

malfunctions identified in paragraph 

(g)(3)(ii)(E) of this section must be 

tracked separately but reported as a 

single set of values as specified in 

paragraph (e)(1)(iii) of this section. 

(D) The manufacturer may request 

Administrator approval to disable 

temporarily the EGR system monitor(s) 

under specific conditions (e.g., when 

freezing may affect performance of the 

system) provided the manufacturer is 


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able to demonstrate via data or 

engineering analysis that a reliable 

monitor cannot be run when these 

conditions exist. 

(iv) EGR system MIL activation and 

DTC storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(4) Turbo boost control system 

monitoring. 

(i) General. The OBD system must 

monitor the boost pressure control 

system (e.g., turbocharger) on engines so 

equipped for under and over boost 

malfunctions. For engines equipped 

with variable geometry turbochargers 

(VGT), the OBD system must monitor 

the VGT system for slow response 

malfunctions. For engines equipped 

with charge air cooler systems, the OBD 

system must monitor the charge air 

cooler system for cooling system 

performance malfunctions. The 

individual electronic components (e.g., 

actuators, valves, sensors) that are used 

in the boost pressure control system 

must be monitored in accordance with 

the comprehensive component 

requirements in paragraph (i)(3) of this 

section. 

(ii) Turbo boost control system 

malfunction criteria. 

(A) Turbo underboost. The OBD 

system must detect a malfunction of the 

boost pressure control system prior to a 

decrease from the manufacturer’s 

commanded boost pressure that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table 1 of this 

paragraph (g). For engines in which no 

failure or deterioration of the boost 

pressure control system that causes a 

decrease in boost could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

when the system has reached its control 

limits such that it cannot increase boost 

to achieve the commanded boost 

pressure. 

(B) Turbo overboost. The OBD system 

must detect a malfunction of the boost 

pressure control system prior to an 

increase from the manufacturer’s 

commanded boost pressure that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table 1 of this 

paragraph (g). For engines in which no 

failure or deterioration of the boost 

pressure control system that causes an 

increase in boost could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

when the system has reached its control 

limits such that it cannot decrease boost 

to achieve the commanded boost 

pressure. 

(C) VGT slow response. The OBD 

system must detect a malfunction prior 

to any failure or deterioration in the 

capability of the VGT system to achieve 

the commanded turbocharger geometry 

within a manufacturer-specified time 

that would cause an engine’s emissions 

to exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 1 of 

this paragraph (g). For engines in which 

no failure or deterioration of the VGT 

system response could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

of the VGT system when proper 

functional response of the system to 

computer commands does not occur. 

(D) Turbo boost feedback control. See 

paragraph (i)(6) of this section. 

(E) Charge air undercooling. The OBD 

system must detect a malfunction of the 

charge air cooling system prior to a 

decrease from the manufacturer’s 

specified cooling rate that would cause 

an engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table 1 of this 

paragraph (g). For engines in which no 

failure or deterioration of the charge air 

cooling system that causes a decrease in 

cooling performance could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

when the system has no detectable 

amount of charge air cooling. 

(iii) Turbo boost monitoring 

conditions. 

(A) The OBD system must monitor 

continuously for malfunctions 

identified in paragraphs (g)(4)(ii)(A), 

(g)(4)(ii)(B), and (g)(4)(ii)(D) of this 

section. 

(B) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (g)(4)(ii)(C) of 

this section in accordance with 

paragraphs (c) and (d) of this section, 

with the exception that monitoring must 

occur every time the monitoring 

conditions are met during the drive 

cycle rather than once per drive cycle as 

required in paragraph (c)(2) of this 

section. For purposes of tracking and 

reporting as required in paragraph (d)(1) 

of this section, all monitors used to 

detect malfunctions identified in 

paragraph (g)(4)(ii)(C) of this section 

must be tracked separately but reported 

as a single set of values as specified in 

paragraph (e)(1)(iii) of this section. 

(C) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (g)(4)(ii)(E) of 

this section in accordance with 

paragraphs (c) and (d) of this section. 

For purposes of tracking and reporting 

as required in paragraph (d)(1) of this 

section, all monitors used to detect 

malfunctions identified in paragraph 

(g)(4)(ii)(E) of this section must be 

tracked separately but reported as a 

single set of values as specified in 

paragraph (e)(1)(iii) of this section. 

(iv) Turbo boost system MIL activation 

and DTC storage. The MIL must activate 

and DTCs must be stored according to 

the provisions of paragraph (b) of this 

section. 

(5) NMHC converting catalyst 

monitoring. 

(i) General. The OBD system must 

monitor the NMHC converting 

catalyst(s) for proper NMHC conversion 

capability. For engines equipped with 

catalyzed diesel particulate filter(s) 

(DPF) that convert NMHC emissions, the 

catalyst function of the DPF must be 

monitored in accordance with the DPF 

requirements of paragraph (g)(8) of this 

section. For purposes of this paragraph 

(g)(5), each catalyst that converts NMHC 

must be monitored either individually 

or in combination with others. 

(ii) NMHC converting catalyst 

malfunction criteria. 

(A) NMHC converting catalyst 

conversion efficiency. The OBD system 

must detect a catalyst malfunction when 

the catalyst conversion capability 

decreases to the point that NMHC 

emissions exceed the emissions 

thresholds for the NMHC catalyst 

system as shown in Table 1 of this 

paragraph (g). If no failure or 

deterioration of the catalyst NMHC 

conversion capability could result in an 

engine’s NMHC emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

when the catalyst has no detectable 

amount of NMHC conversion capability. 

(B) NMHC converting catalyst 

aftertreatment assistance functions. For 

catalysts used to generate an exotherm 

to assist DPF regeneration, the OBD 

system must detect a malfunction when 

the catalyst is unable to generate a 

sufficient exotherm to achieve DPF 

regeneration. For catalysts used to 

generate a feedgas constituency to assist 

selective catalytic reduction (SCR) 

systems (e.g., to increase NO2

concentration upstream of an SCR 

system), the OBD system must detect a 

malfunction when the catalyst is unable 

to generate the necessary feedgas 

constituents for proper SCR system 

operation. For catalysts located 

downstream of a DPF and used to 

convert NMHC emissions during DPF 

regeneration, the OBD system must 

detect a malfunction when the catalyst 

has no detectable amount of NMHC 

conversion capability. 


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(iii) NMHC converting catalyst 

monitoring conditions. The 

manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraphs (g)(5)(ii)(A) and 

(g)(5)(ii)(B) of this section in accordance 

with paragraphs (c) and (d) of this 

section. For purposes of tracking and 

reporting as required in paragraph (d)(1) 

of this section, all monitors used to 

detect malfunctions identified in 

paragraphs (g)(5)(ii)(A) and (g)(5)(ii)(B) 

of this section must be tracked 

separately but reported as a single set of 

values as specified in paragraph 

(e)(1)(iii) of this section. 

(iv) NMHC converting catalyst MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. The monitoring 

method for the NMHC converting 

catalyst(s) must be capable of detecting 

all instances, except diagnostic selfclearing, when a catalyst DTC has been 

erased but the catalyst has not been 

replaced (e.g., catalyst over-temperature 

histogram approaches are not 

acceptable). 

(6) Selective catalytic reduction (SCR) 

and lean NOX catalyst monitoring. 

(i) General. The OBD system must 

monitor the SCR and/or the lean NOX

converting catalyst(s) for proper 

conversion capability. For engines 

equipped with SCR systems or other 

catalyst systems that use an active/ 

intrusive reductant injection (e.g., active 

lean NOX catalysts that use diesel fuel 

post-injection or in-exhaust injection), 

the OBD system must monitor the 

active/intrusive reductant injection 

system for proper performance. The 

individual electronic components (e.g., 

actuators, valves, sensors, heaters, 

pumps) in the active/intrusive reductant 

injection system must be monitored in 

accordance with the comprehensive 

component requirements in paragraph 

(i)(3) of this section. For purposes of this 

paragraph (g)(6), each catalyst that 

converts NOX must be monitored either 

individually or in combination with 

others. 

(ii) SCR and lean NOX catalyst 

malfunction criteria. 

(A) SCR and lean NOX catalyst 

conversion efficiency. The OBD system 

must detect a catalyst malfunction when 

the catalyst conversion capability 

decreases to the point that would cause 

an engine’s emissions to exceed the 

emissions thresholds for NOX

aftertreatment systems as shown in 

Table 1 of this paragraph (g). If no 

failure or deterioration of the catalyst 

NOX conversion capability could result 

in an engine’s emissions exceeding any 

of the applicable emissions thresholds, 

the OBD system must detect a 

malfunction when the catalyst has no 

detectable amount of NOX conversion 

capability. 

(B) SCR and lean NOX catalyst active/ 

intrusive reductant delivery 

performance. The OBD system must 

detect a malfunction prior to any failure 

or deterioration of the system to 

properly regulate reductant delivery 

(e.g., urea injection, separate injector 

fuel injection, post injection of fuel, air 

assisted injection/mixing) that would 

cause an engine’s emissions to exceed 

any of the applicable emissions 

thresholds for NOX aftertreatment 

systems as shown in Table 1 of this 

paragraph (g). If no failure or 

deterioration of the reductant delivery 

system could result in an engine’s 

emissions exceeding any of the 

applicable thresholds, the OBD system 

must detect a malfunction when the 

system has reached its control limits 

such that it is no longer able to deliver 

the desired quantity of reductant. 

(C) SCR and lean NOX catalyst active/ 

intrusive reductant quantity. If the SCR 

or lean NOX catalyst system uses a 

reductant other than the fuel used for 

the engine, or uses a reservoir/tank for 

the reductant that is separate from the 

fuel tank used for the engine, the OBD 

system must detect a malfunction when 

there is no longer sufficient reductant 

available (e.g., the reductant tank is 

empty). 

(D) SCR and lean NOX catalyst active/ 

intrusive reductant quality. If the SCR or 

lean NOX catalyst system uses a 

reservoir/tank for the reductant that is 

separate from the fuel tank used for the 

engine, the OBD system must detect a 

malfunction when an improper 

reductant is used in the reductant 

reservoir/tank (e.g., the reductant tank is 

filled with something other than the 

reductant). 

(E) SCR and lean NOX catalyst active/ 

intrusive reductant feedback control. 

See paragraph (i)(6) of this section. 

(iii) SCR and lean NOX catalyst 

monitoring conditions. 

(A) The manufacturers must define 

the monitoring conditions for 

malfunctions identified in paragraphs 

(g)(6)(ii)(A) and (g)(6)(ii)(D) of this 

section in accordance with paragraphs 

(c) and (d) of this section. For purposes 

of tracking and reporting as required in 

paragraph (d)(1) of this section, all 

monitors used to detect malfunctions 

identified in paragraph (g)(6)(ii)(A) of 

this section must be tracked separately 

but reported as a single set of values as 

specified in paragraph (e)(1)(iii) of this 

section. 

(B) The OBD system must monitor 

continuously for malfunctions 

identified in paragraphs (g)(6)(ii)(B), 

(g)(6)(ii)(C), and (g)(6)(ii)(E) of this 

section. 

(iv) SCR and lean NOX catalyst MIL 

activation and DTC storage. 

(A) For malfunctions identified in 

paragraph (g)(6)(ii)(A) of this section, 

the MIL must activate and DTCs must be 

stored according to the provisions of 

paragraph (b) of this section. 

(B) For malfunctions identified in 

paragraphs (g)(6)(ii)(B), (g)(6)(ii)(C), and 

(g)(6)(ii)(D) of this section, the 

manufacturer may delay activating the 

MIL if the vehicle is equipped with an 

alternative indicator for notifying the 

vehicle operator of the malfunction. The 

alternative indicator must be of 

sufficient illumination and be located 

such that it is readily visible to the 

vehicle operator under all lighting 

conditions. If the vehicle is not 

equipped with such an alternative 

indicator and the OBD MIL activates, 

the MIL may be immediately 

deactivated and the corresponding 

DTC(s) erased once the OBD system has 

verified that the reductant tank has been 

refilled properly and the MIL has not 

been activated for any other 

malfunction. The Administrator may 

approve other strategies that provide 

equivalent assurance that a vehicle 

operator would be promptly notified 

and that corrective action would be 

taken. 

(C) The monitoring method for the 

SCR and lean NOX catalyst(s) must be 

capable of detecting all instances, 

except diagnostic self-clearing, when a 

catalyst DTC(s) has been erased but the 

catalyst has not been replaced (e.g., 

catalyst over-temperature histogram 

approaches are not acceptable). 

(7) NOX adsorber system monitoring. 

(i) General. The OBD system must 

monitor the NOX adsorber on engines 

so-equipped for proper performance. 

For engines equipped with active/ 

intrusive injection (e.g., in-exhaust fuel 

and/or air injection) to achieve 

desorption of the NOX adsorber, the 

OBD system must monitor the active/ 

intrusive injection system for proper 

performance. The individual electronic 

components (e.g., injectors, valves, 

sensors) that are used in the active/ 

intrusive injection system must be 

monitored in accordance with the 

comprehensive component 

requirements in paragraph (i)(3) of this 

section. 

(ii) NOX adsorber system malfunction 

criteria. 

(A) NOX adsorber system capability. 

The OBD system must detect a NOX

adsorber malfunction when its 

capability (i.e., its combined adsorption 

and conversion capability) decreases to 


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the point that would cause an engine’s 

NOX emissions to exceed the emissions 

thresholds for NOX aftertreatment 

systems as shown in Table 1 of this 

paragraph (g). If no failure or 

deterioration of the NOX adsorber 

capability could result in an engine’s 

NOX emissions exceeding the applicable 

emissions thresholds, the OBD system 

must detect a malfunction when the 

system has no detectable amount of 

NOX adsorber capability. 

(B) NOX adsorber system active/ 

intrusive reductant delivery 

performance. For NOX adsorber systems 

that use active/intrusive injection (e.g., 

in-cylinder post fuel injection, inexhaust air-assisted fuel injection) to 

achieve desorption of the NOX adsorber, 

the OBD system must detect a 

malfunction if any failure or 

deterioration of the injection system’s 

ability to properly regulate injection 

causes the system to be unable to 

achieve desorption of the NOX adsorber. 

(C) NOX adsorber system feedback 

control. Malfunction criteria for the 

NOX adsorber and the NOX adsorber 

active/instrusive reductant delivery 

system are contained in paragraph 

(i)(6)of this section. 

(iii) NOX adsorber system monitoring 

conditions. 

(A) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (g)(7)(ii)(A) of 

this section in accordance with 

paragraphs (c) and (d) of this section. 

For purposes of tracking and reporting 

as required in paragraph (d)(1) of this 

section, all monitors used to detect 

malfunctions identified in paragraph 

(g)(7)(ii)(A) of this section must be 

tracked separately but reported as a 

single set of values as specified in 

paragraph (e)(1)(iii) of this section. 

(B) The OBD system must monitor 

continuously for malfunctions 

identified in paragraphs (g)(7)(ii)(B) and 

(g)(7)(ii)(C) of this section. 

(iv) NOX adsorber system MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. 

(8) Diesel particulate filter (DPF) 

system monitoring. 

(i) General. The OBD system must 

monitor the DPF on engines soequipped for proper performance. For 

engines equipped with active 

regeneration systems that use an active/ 

intrusive injection (e.g., in-exhaust fuel 

injection, in-exhaust fuel/air burner), 

the OBD system must monitor the 

active/intrusive injection system for 

proper performance. The individual 

electronic components (e.g., injectors, 

valves, sensors) that are used in the 

active/intrusive injection system must 

be monitored in accordance with the 

comprehensive component 

requirements in paragraph (i)(3) of this 

section. 

(ii) DPF system malfunction criteria. 

(A) DPF filtering performance. The 

OBD system must detect a malfunction 

prior to a decrease in the PM filtering 

capability of the DPF (e.g., cracking, 

melting, etc.) that would cause an 

engine’s PM emissions to exceed the 

emissions thresholds for DPF systems as 

shown in Table 1 of this paragraph (g). 

If no failure or deterioration of the PM 

filtering performance could result in an 

engine’s PM emissions exceeding the 

applicable emissions thresholds, the 

OBD system must detect a malfunction 

when no detectable amount of PM 

filtering occurs. 

(B) DPF regeneration frequency. The 

OBD system must detect a malfunction 

when the DPF regeneration frequency 

increases from (i.e., occurs more often 

than) the manufacturer’s specified 

regeneration frequency to a level such 

that it would cause an engine’s NMHC 

emissions to exceed the emissions 

threshold for DPF systems as shown in 

Table 1 of this paragraph (g). If no such 

regeneration frequency exists that could 

cause NMHC emissions to exceed the 

applicable emission threshold, the OBD 

system must detect a malfunction when 

the DPF regeneration frequency exceeds 

the manufacturer’s specified design 

limits for allowable regeneration 

frequency. 

(C) DPF incomplete regeneration. The 

OBD system must detect a regeneration 

malfunction when the DPF does not 

properly regenerate under 

manufacturer-defined conditions where 

regeneration is designed to occur. 

(D) DPF NMHC conversion. For any 

DPF that serves to convert NMHC 

emissions, the OBD system must detect 

a malfunction when the NMHC 

conversion capability decreases to the 

point that NMHC emissions exceed the 

emissions threshold for DPF systems as 

shown in Table 1 of this paragraph (g). 

If no failure or deterioration of the 

NMHC conversion capability could 

result in NMHC emissions exceeding 

the applicable threshold, the OBD 

system must detect a malfunction when 

the system has no detectable amount of 

NMHC conversion capability. 

(E) DPF missing substrate. The OBD 

system must detect a malfunction if 

either the DPF substrate is completely 

destroyed, removed, or missing, or if the 

DPF assembly has been replaced with a 

muffler or straight pipe. 

(F) DPF system active/intrusive 

injection. For DPF systems that use 

active/intrusive injection (e.g., incylinder post fuel injection, in-exhaust 

air-assisted fuel injection) to achieve 

regeneration of the DPF, the OBD 

system must detect a malfunction if any 

failure or deterioration of the injection 

system’s ability to properly regulate 

injection causes the system to be unable 

to achieve regeneration of the DPF. 

(G) DPF regeneration feedback 

control. See paragraph (i)(6) of this 

section. 

(iii) DPF monitoring conditions. The 

manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (g)(8)(ii) of this 

section in accordance with paragraphs 

(c) and (d) of this section, with the 

exception that monitoring must occur 

every time the monitoring conditions 

are met during the drive cycle rather 

than once per drive cycle as required in 

paragraph (c)(2) of this section. For 

purposes of tracking and reporting as 

required in paragraph (d)(1) of this 

section, all monitors used to detect 

malfunctions identified in paragraph 

(g)(8)(ii) of this section must be tracked 

separately but reported as a single set of 

values as specified in paragraph 

(e)(1)(iii) of this section. 

(iv) DPF system MIL activation and 

DTC storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(9) Exhaust gas sensor and sensor 

heater monitoring. 

(i) General. The OBD system must 

monitor for proper output signal, 

activity, response rate, and any other 

parameter that can affect emissions, all 

exhaust gas sensors (e.g., oxygen, airfuel ratio, NOX) used for emission 

control system feedback (e.g., EGR 

control/feedback, SCR control/feedback, 

NOX adsorber control/feedback) and/or 

as a monitoring device. For engines 

equipped with heated exhaust gas 

sensors, the OBD system must monitor 

the heater for proper performance. 

(ii) Malfunction criteria for air-fuel 

ratio sensors located upstream of 

aftertreatment devices. 

(A) Sensor performance. The OBD 

system must detect a malfunction prior 

to any failure or deterioration of the 

sensor voltage, resistance, impedance, 

current, response rate, amplitude, offset, 

or other characteristic(s) that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table 1 of this 

paragraph (g). 

(B) Circuit integrity. The OBD system 

must detect malfunctions of the sensor 

related to a lack of circuit continuity or 

signal out-of-range values. 

(C) Feedback function. The OBD 

system must detect a malfunction of the 


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sensor if the emission control system 

(e.g., EGR, SCR, or NOX adsorber) is 

unable to use that sensor as a feedback 

input (e.g., causes limp-home or openloop operation). 

(D) Monitoring function. To the extent 

feasible, the OBD system must detect a 

malfunction of the sensor when the 

sensor output voltage, resistance, 

impedance, current, amplitude, activity, 

offset, or other characteristics are no 

longer sufficient for use as an OBD 

system monitoring device (e.g., for 

catalyst, EGR, SCR, or NOX adsorber 

monitoring). 

(iii) Malfunction criteria for air-fuel 

ratio sensors located downstream of 

aftertreatment devices. 

(A) Sensor performance. The OBD 

system must detect a malfunction prior 

to any failure or deterioration of the 

sensor voltage, resistance, impedance, 

current, response rate, amplitude, offset, 

or other characteristic(s) that would 

cause an engine’s emissions to exceed 

the emissions thresholds for air-fuel 

ratio sensors downstream of 

aftertreatment devices as shown in 

Table 1 of this paragraph (g). 

(B) Circuit integrity. The OBD system 

must detect malfunctions of the sensor 

related to a lack of circuit continuity or 

signal out-of-range values. 

(C) Feedback function. The OBD 

system must detect a malfunction of the 

sensor if the emission control system 

(e.g., EGR, SCR, or NOX adsorber) is 

unable to use that sensor as a feedback 

input (e.g., causes limp-home or openloop operation). 

(D) Monitoring function. To the extent 

feasible, the OBD system must detect a 

malfunction of the sensor when the 

sensor output voltage, resistance, 

impedance, current, amplitude, activity, 

offset, or other characteristics are no 

longer sufficient for use as an OBD 

system monitoring device (e.g., for 

catalyst, EGR, SCR, or NOX adsorber 

monitoring). 

(iv) Malfunction criteria for NOX

sensors. 

(A) Sensor performance. The OBD 

system must detect a malfunction prior 

to any failure or deterioration of the 

sensor voltage, resistance, impedance, 

current, response rate, amplitude, offset, 

or other characteristic(s) that would 

cause an engine’s emissions to exceed 

the emissions thresholds for NOX

sensors as shown in Table 1 of this 

paragraph (g). 

(B) Circuit integrity. The OBD system 

must detect malfunctions of the sensor 

related to a lack of circuit continuity or 

signal out-of-range values. 

(C) Feedback function.The OBD 

system must detect a malfunction of the 

sensor if the emission control system 

(e.g., EGR, SCR, or NOX adsorber) is 

unable to use that sensor as a feedback 

input (e.g., causes limp-home or openloop operation). 

(D) Monitoring function. To the extent 

feasible, the OBD system must detect a 

malfunction of the sensor when the 

sensor output voltage, resistance, 

impedance, current, amplitude, activity, 

offset, or other characteristics are no 

longer sufficient for use as an OBD 

system monitoring device (e.g., for 

catalyst, EGR, SCR, or NOX adsorber 

monitoring). 

(v) Malfunction criteria for other 

exhaust gas sensors. For other exhaust 

gas sensors, the manufacturer must 

submit a monitoring plan to the 

Administrator for approval. The plan 

must include data and/or engineering 

evaluations that demonstrate that the 

monitoring plan is as reliable and 

effective as the monitoring required in 

paragraphs (g)(9)(ii) through (g)(9)(iv) of 

this section. 

(vi) Malfunction criteria for exhaust 

gas sensor heaters. 

(A) The OBD system must detect a 

malfunction of the heater performance 

when the current or voltage drop in the 

heater circuit is no longer within the 

manufacturer’s specified limits for 

normal operation (i.e., within the 

criteria required to be met by the 

component vendor for heater circuit 

performance at high mileage). The 

manufacturer may use other 

malfunction criteria for heater 

performance malfunctions. To do so, the 

manufacturer must be able to 

demonstrate via data and/or an 

engineering evaluation that the monitor 

is reliable and robust. 

(B) The OBD system must detect 

malfunctions of the heater circuit 

including open or short circuits that 

conflict with the commanded state of 

the heater (e.g., shorted to 12 Volts 

when commanded to 0 Volts (ground)). 

(vii) Monitoring conditions for 

exhaust gas sensors. 

(A) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraphs (g)(9)(ii)(A), 

(g)(9)(iii)(A), and (g)(9)(iv)(A) of this 

section (i.e., sensor performance) in 

accordance with paragraphs (c) and (d) 

of this section. For purposes of tracking 

and reporting as required in paragraph 

(d)(1) of this section, all monitors used 

to detect malfunctions identified in 

paragraphs (g)(9)(ii)(A), (g)(9)(iii)(A), 

and (g)(9)(iv)(A) of this section must be 

tracked separately but reported as a 

single set of values as specified in 

paragraph (e)(1)(iii) of this section. 

(B) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraphs (g)(9)(ii)(D), 

(g)(9)(iii)(D), and (g)(9)(iv)(D) of this 

section (i.e., monitoring function) in 

accordance with paragraphs (c) and (d) 

of this section with the exception that 

monitoring must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in paragraph 

(c)(2) of this section. 

(C) Except as provided for in 

paragraph (g)(9)(vii)(D) of this paragraph 

(g)(9), the OBD system must monitor 

continuously for malfunctions 

identified in paragraphs (g)(9)(ii)(B), 

(g)(9)(ii)(C), (g)(9)(iii)(B), (g)(9)(iii)(C), 

(g)(9)(iv)(B), and (g)(9)(iv)(C) (i.e., circuit 

integrity and feedback function). 

(D) A manufacturer may request 

approval to disable continuous exhaust 

gas sensor monitoring when an exhaust 

gas sensor malfunction cannot be 

distinguished from other effects (e.g., 

disable monitoring for out-of-range on 

the low side during fuel cut conditions). 

To do so, the manufacturer must 

demonstrate via data and/or engineering 

analyses that a properly functioning 

sensor cannot be distinguished from a 

malfunctioning sensor and that the 

disablement interval is limited only to 

that necessary for avoiding false 

malfunction detection. 

(viii) Monitoring conditions for 

exhaust gas sensor heaters. 

(A) The manufacturer must define 

monitoring conditions for malfunctions 

identified in paragraph (g)(9)(vi)(A) of 

this section (i.e., sensor heater 

performance) in accordance with 

paragraphs (c) and (d) of this section. 

(B) The OBD system must monitor 

continuously for malfunctions 

identified in paragraph (g)(9)(vi)(B) of 

this section (i.e., circuit malfunctions). 

(ix) Exhaust gas sensor and sensor 

heater MIL activation and DTC storage. 

The MIL must activate and DTCs must 

be stored according to the provisions of 

paragraph (b) of this section. 

(10) Variable Valve Timing (VVT) 

system monitoring. 

(i) General. The OBD system must 

monitor the VVT system on engines so 

equipped for target error and slow 

response malfunctions. The individual 

electronic components (e.g., actuators, 

valves, sensors) that are used in the VVT 

system must be monitored in 

accordance with the comprehensive 

components requirements in paragraph 

(i)(3) of this section. 

(ii) VVT system malfunction criteria. 

(A) VVT system target error. The OBD 

system must detect a malfunction prior 

to any failure or deterioration in the 

capability of the VVT system to achieve 

the commanded valve timing and/or 

control within a crank angle and/or lift 

tolerance that would cause an engine’s 


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emissions to exceed the emission 

thresholds for ‘‘other monitors’’ as 

shown in Table 1 of this paragraph (g). 

(B) VVT slow response. The OBD 

system must detect a malfunction prior 

to any failure or deterioration in the 

capability of the VVT system to achieve 

the commanded valve timing and/or 

control within a manufacturer-specified 

time that would cause an engine’s 

emissions to exceed the emission 

thresholds for ‘‘other monitors’’ as 

shown in Table 1 of this paragraph (g). 

(C) For engines in which no failure or 

deterioration of the VVT system could 

result in an engine’s emissions 

exceeding the applicable emissions 

thresholds of paragraphs (g)(10)(ii)(A) 

and (g)(10)(ii)(B) of this section, the 

OBD system must detect a malfunction 

of the VVT system when proper 

functional response of the system to 

computer commands does not occur. 

(iii) VVT system monitoring 

conditions. Manufacturers must define 

the monitoring conditions for VVT 

system malfunctions identified in 

paragraph (g)(10)(ii) of this section in 

accordance with paragraphs (c) and (d) 

of this section, with the exception that 

monitoring must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in paragraph 

(c)(2) of this section. For purposes of 

tracking and reporting as required in 

paragraph (d)(1) of this section, all 

monitors used to detect malfunctions 

identified in paragraph (g)(10)(ii) of this 

section must be tracked separately but 

reported as a single set of values as 

specified in paragraph (e)(1)(iii) of this 

section. 

(iv) VVT MIL activation and DTC 

storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(h) OBD monitoring requirements for 

gasoline-fueled/spark-ignition engines. 

The following table shows the 

thresholds at which point certain 

components or systems, as specified in 

this paragraph (h), are considered 

malfunctioning. 

TABLE 2.—OBD EMISSIONS THRESHOLDS FOR GASOLINE-FUELED/SPARK-IGNITION ENGINES MEANT FOR PLACEMENT IN

APPLICATIONS GREATER THAN 14,000 POUNDS GVWR (G/BHP-HR) 

Component NOX NMHC CO § 86.010–18 reference 

Catalyst system .............................................................. 1.75x std .. 1.75x std ............................ .................. (h)(6). 

Evaporative emissions control system ........................... .................. 0.150 inch leak .................. .................. (h)(7). 

‘‘Other monitors’’ with emissions thresholds .................. 1.5x std .... 1.5x std .............................. 1.5x std .... (h)(1), (h)(2), (h)(3), (h)(4), 

(h)(5), (h)(8), (h)(9). 

Notes: 1.75x std means a multiple of 1.75 times the applicable emissions standard; these emissions thresholds apply to the monitoring requirements of paragraph (h) of this section 86.010–18; The evaporative emissions control system threshold is not, technically, an emissions 

threshold but rather a leak size that must be detected; nonetheless, for ease we refer to this as the threshold. 

(1) Fuel system monitoring. 

(i) General. The OBD system must 

monitor the fuel delivery system to 

determine its ability to provide 

compliance with emission standards. 

(ii) Fuel system malfunction criteria. 

(A) The OBD system must detect a 

malfunction of the fuel delivery system 

(including feedback control based on a 

secondary oxygen sensor) when the fuel 

delivery system is unable to maintain an 

engine’s emissions at or below the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table 2 of this 

paragraph (h). 

(B) Except as provided for in 

paragraph (h)(1)(ii)(C) of this section, if 

the engine is equipped with adaptive 

feedback control, the OBD system must 

detect a malfunction when the adaptive 

feedback control has used up all of the 

adjustment allowed by the 

manufacturer. 

(C) If the engine is equipped with 

feedback control that is based on a 

secondary oxygen (or equivalent) 

sensor, the OBD system is not required 

to detect a malfunction of the fuel 

system solely when the feedback control 

based on a secondary oxygen sensor has 

used up all of the adjustment allowed 

by the manufacturer. However, if a 

failure or deterioration results in engine 

emissions that exceed the emissions 

thresholds for ‘‘other monitors’’ as 

shown in Table 2 of this paragraph (h), 

the OBD system is required to detect a 

malfunction. 

(D) The OBD system must detect a 

malfunction whenever the fuel control 

system fails to enter closed loop 

operation following engine start within 

a manufacturer specified time interval. 

The specified time interval must be 

supported by data and/or engineering 

analyses submitted by the manufacturer. 

(E) The manufacturer may adjust the 

malfunction criteria and/or monitoring 

conditions to compensate for changes in 

altitude, for temporary introduction of 

large amounts of purge vapor, or for 

other similar identifiable operating 

conditions when such conditions occur. 

(iii) Fuel system monitoring 

conditions. The fuel system must be 

monitored continuously for the 

presence of a malfunction. 

(iv) Fuel system MIL activation and 

DTC storage. 

(A) A pending DTC must be stored 

immediately upon the fuel system 

exceeding the malfunction criteria 

established in paragraph (h)(1)(ii) of this 

section. 

(B) Except as provided for in 

paragraph (h)(1)(iv)(C) of this section, if 

a pending DTC is stored, the OBD 

system must activate the MIL 

immediately and store a MIL-on DTC if 

a malfunction is again detected during 

either the drive cycle immediately 

following storage of the pending DTC 

regardless of the conditions encountered 

during that drive cycle, or on the next 

drive cycle in which similar conditions 

are encountered to those that occurred 

when the pending DTC was stored. 

Similar conditions means engine 

conditions having an engine speed 

within 375 rpm, load conditions within 

20 percent, and the same warm up 

status (i.e., cold or hot) as the engine 

conditions stored pursuant to paragraph 

(h)(1)(iv)(E) of this section. Other 

definitions of similar conditions may be 

used but must result in comparable 

timeliness and reliability in detecting 

similar engine operation. 

(C) The pending DTC may be erased 

at the end of the next drive cycle in 

which similar conditions have been 

encountered without having again 

exceeded the specified fuel system 

malfunction criteria. The pending DTC 

may also be erased if similar conditions 

are not encountered during the 80 drive 

cycles immediately following detection 

of the potential malfunction for which 

the pending DTC was stored. 

(D) Storage of freeze frame conditions. 

The OBD system must store and erase 

freeze frame conditions either in 

conjunction with storing and erasing a 

pending DTC or in conjunction with 

storing and erasing a MIL-on DTC. 

Freeze frame information associated 

with a fuel system malfunction shall be 


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stored in preference to freeze frame 

information required elsewhere in 

paragraphs (h) or (i) of this section. 

(E) Storage of fuel system conditions 

for determining similar conditions of 

operation. The OBD must store the 

engine speed, load, and warm-up status 

present at the time it first detects a 

potential malfunction meeting the 

criteria of paragraph (h)(1)(ii) of this 

section and stores a pending DTC. 

(F) Deactivating the MIL. The MIL 

may be extinguished after three 

sequential driving cycles in which 

similar conditions have been 

encountered without detecting a 

malfunction of the fuel system. 

(2) Engine misfire monitoring. 

(i) General. 

(A) The OBD system must monitor the 

engine for misfire causing catalyst 

damage and misfire causing excess 

emissions. 

(B) The OBD system must identify the 

specific cylinder that is misfiring. The 

manufacturer may store a general 

misfire DTC instead of a cylinder 

specific DTC under certain operating 

conditions. To do so, the manufacturer 

must submit data and/or engineering 

analyses that demonstrate that the 

misfiring cylinder cannot be identified 

reliably when the conditions occur. 

(C) If more than one cylinder is 

misfiring, a separate DTC must be stored 

to indicate that multiple cylinders are 

misfiring unless otherwise allowed by 

this paragraph (h)(2). When identifying 

multiple cylinder misfire, the OBD 

system is not required to also identify 

using separate DTCs each of the 

misfiring cylinders individually. If more 

than 90 percent of the detected misfires 

occur in a single cylinder, an 

appropriate DTC may be stored that 

indicates the specific misfiring cylinder 

rather than storing the multiple cylinder 

misfire DTC. If two or more cylinders 

individually have more than 10 percent 

of the total number of detected misfires, 

a multiple cylinder DTC must be stored. 

(ii) Engine misfire malfunction 

criteria. 

(A) Misfire causing catalyst damage. 

The manufacturer must determine the 

percentage of misfire evaluated in 200 

revolution increments for each engine 

speed and load condition that would 

result in a temperature that causes 

catalyst damage. If this percentage of 

misfire is exceeded, it shall be 

considered a malfunction that must be 

detected. For every engine speed and 

load condition for which this percentage 

of misfire is determined to be lower 

than five percent, the manufacturer may 

set the malfunction criteria at five 

percent. The manufacturer may use a 

longer interval than 200 revolutions but 

only for determining, on a given drive 

cycle, the first misfire exceedance as 

provided in paragraph (h)(2)(iv)(A) of 

this section. To do so, the manufacturer 

must demonstrate that the interval is not 

so long that catalyst damage would 

occur prior to the interval being elapsed. 

(B) Misfire causing emissions to 

exceed the applicable thresholds. The 

manufacturer must determine the 

percentage of misfire evaluated in 1000 

revolution increments that would cause 

emissions from an emissions durability 

demonstration engine to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table 2 of this 

paragraph (h) if that percentage of 

misfire were present from the beginning 

of the test. If this percentage of misfire 

is exceeded, regardless of the pattern of 

misfire events (e.g., random, equally 

spaced, continuous), it shall be 

considered a malfunction that must be 

detected. To establish this percentage of 

misfire, the manufacturer must use 

misfire events occurring at equally 

spaced, complete engine cycle intervals, 

across randomly selected cylinders 

throughout each 1000-revolution 

increment. If this percentage of misfire 

is determined to be lower than one 

percent, the manufacturer may set the 

malfunction criteria at one percent. The 

manufacturer may use a longer interval 

than 1000 revolutions. To do so, the 

manufacturer must demonstrate that the 

strategy would be equally effective and 

timely at detecting misfire. 

(iii) Engine misfire monitoring 

conditions. 

(A) The OBD system must monitor 

continuously for misfire under the 

following conditions: from no later than 

the end of the second crankshaft 

revolution after engine start; during the 

rise time and settling time for engine 

speed to reach the desired idle engine 

speed at engine start-up (i.e., ‘‘flare-up’’

and ‘‘flare-down’’); and, under all 

positive torque engine speeds and load 

conditions except within the engine 

operating region bound by the positive 

torque line (i.e., engine load with the 

transmission in neutral), and the points 

represented by an engine speed of 3000 

rpm with the engine load at the positive 

torque line and the redline engine speed 

with the engine’s manifold vacuum at 

four inches of mercury lower than that 

at the positive torque line. For this 

purpose, redline engine speed is defined 

as either the recommended maximum 

engine speed as displayed on the 

instrument panel tachometer, or the 

engine speed at which fuel shutoff 

occurs. 

(B) If an OBD monitor cannot detect 

all misfire patterns under all required 

engine speed and load conditions as 

required by paragraph (h)(2)(iii)(A) of 

this section, the OBD system may still 

be acceptable. The Administrator will 

evaluate the following factors in making 

a determination: the magnitude of the 

region(s) in which misfire detection is 

limited; the degree to which misfire 

detection is limited in the region(s) (i.e., 

the probability of detection of misfire 

events); the frequency with which said 

region(s) are expected to be encountered 

in-use; the type of misfire patterns for 

which misfire detection is troublesome; 

and demonstration that the monitoring 

technology employed is not inherently 

incapable of detecting misfire under the 

required conditions (i.e., compliance 

can be achieved on other engines). The 

evaluation will be based on the 

following misfire patterns: equally 

spaced misfire occurring on randomly 

selected cylinders; single cylinder 

continuous misfire; and paired cylinder 

(cylinders firing at the same crank 

angle) continuous misfire. 

(C) The manufacturer may use 

monitoring system that has reduced 

misfire detection capability during the 

portion of the first 1000 revolutions 

after engine start that a cold start 

emission reduction strategy is active 

that reduces engine torque (e.g., spark 

retard strategies). To do so, the 

manufacturer must demonstrate that the 

probability of detection is greater than 

or equal to 75 percent during the worst 

case condition (i.e., lowest generated 

torque) for a vehicle operated 

continuously at idle (park/neutral idle) 

on a cold start between 50 and 86 

degrees Fahrenheit and that the 

technology cannot reliably detect a 

higher percentage of the misfire events 

during the conditions. 

(D) The manufacturer may disable 

misfire monitoring or use an alternative 

malfunction criterion when misfire 

cannot be distinguished from other 

effects. To do so, the manufacturer must 

demonstrate that the disablement 

interval or the period of use of an 

alternative malfunction criterion is 

limited only to that necessary for 

avoiding false detection and for one or 

more of the following operating 

conditions: rough road; fuel cut; gear 

changes for manual transmission 

vehicles; traction control or other 

vehicle stability control activation such 

as anti-lock braking or other engine 

torque modifications to enhance vehicle 

stability; off-board control or intrusive 

activation of vehicle components or 

monitors during service or assembly 

plant testing; portions of intrusive 

evaporative system or EGR monitors 

that can significantly affect engine 

stability (i.e., while the purge valve is 

open during the vacuum pull-down of a 


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evaporative system leak check but not 

while the purge valve is closed and the 

evaporative system is sealed or while an 

EGR monitor causes the EGR valve to be 

cycled intrusively on and off during 

positive torque conditions); or, engine 

speed, load, or torque transients due to 

throttle movements more rapid than 

those that occur over the FTP cycle for 

the worst case engine within each 

engine family. In general, the 

Administrator will not approve 

disablement for conditions involving 

normal air conditioning compressor 

cycling from on-to-off or off-to-on, 

automatic transmission gear shifts 

(except for shifts occurring during wide 

open throttle operation), transitions 

from idle to off-idle, normal engine 

speed or load changes that occur during 

the engine speed rise time and settling 

time (i.e., ‘‘flare-up’’ and ‘‘flare-down’’) 

immediately after engine starting 

without any vehicle operator-induced 

actions (e.g., throttle stabs), or excess 

acceleration (except for acceleration 

rates that exceed the maximum 

acceleration rate obtainable at wide 

open throttle while the vehicle is in gear 

due to abnormal conditions such as 

slipping of a clutch). 

(iv) MIL activation and DTC storage 

for engine misfire causing catalyst 

damage. 

(A) Pending DTCs. A pending DTC 

must be stored immediately if, during a 

single drive cycle, the specified misfire 

percentage described in paragraph 

(h)(2)(ii)(A) of this section is exceeded 

three times when operating in the 

positive torque region encountered 

during a FTP cycle or is exceeded on a 

single occasion when operating at any 

other engine speed and load condition 

in the positive torque region defined in 

paragraph (h)(2)(iii)(A) of this section. 

Immediately after a pending DTC is 

stored pursuant to this paragraph, the 

MIL must blink once per second at all 

times during the drive cycle that engine 

misfire is occurring. The MIL may be 

deactivated during those times that 

misfire is not occurring. If, at the time 

that a catalyst damaging misfire 

malfunction occurs, the MIL is already 

activated for a malfunction other than 

misfire, the MIL must still blink once 

per second at all times during the drive 

cycle that engine misfire is occurring. If 

misfire ceases, the MIL must stop 

blinking but remain activated as 

appropriate in accordance with the 

other malfunction. 

(B) MIL-on DTCs. If a pending DTC is 

stored in accordance with paragraph 

(h)(2)(iv)(A) of this section, the OBD 

system must immediately store a MILon DTC if the percentage of misfire 

described in paragraph (h)(2)(ii)(A) of 

this section is again exceeded one or 

more times during either the drive cycle 

immediately following storage of the 

pending DTC, regardless of the 

conditions encountered during that 

drive cycle, or on the next drive cycle 

in which similar conditions are 

encountered to those that occurred 

when the pending DTC was stored. If, 

during a previous drive cycle, a pending 

DTC is stored in accordance with 

paragraph (h)(2)(iv)(A) of this section, a 

MIL-on DTC must be stored 

immediately upon exceeding the 

percentage misfire described in 

paragraph (h)(2)(ii)(A) of this section 

regardless of the conditions 

encountered. Upon storage of a MIL-on 

DTC, the MIL must blink once per 

second at all times during the drive 

cycle that engine misfire is occurring. If 

misfire ceases, the MIL must stop 

blinking but remain activated until the 

conditions are met for extinguishing the 

MIL. 

(C) Erasure of pending DTCs. Pending 

DTCs stored in accordance with 

paragraph (h)(2)(iv)(A) of this section 

must be erased at the end of the next 

drive cycle in which similar conditions 

are encountered to those that occurred 

when the pending DTC was stored 

provided no exceedances have been 

detected of the misfire percentage 

described in paragraph (h)(2)(ii)(A) of 

this section. The pending DTC may also 

be erased if similar conditions are not 

encountered during the next 80 drive 

cycles immediately following storage of 

the pending DTC. 

(D) Exemptions for engines with fuel 

shutoff and default fuel control. In 

engines that provide for fuel shutoff and 

default fuel control to prevent over 

fueling during catalyst damaging misfire 

conditions, the MIL need not blink as 

required by paragraphs (h)(2)(iv)(A) and 

(h)(2)(iv)(B) of this section. Instead, the 

MIL may be activated continuously 

upon misfire detection provided that the 

fuel shutoff and default fuel control are 

activated immediately upon misfire 

detection. Fuel shutoff and default fuel 

control may be deactivated only when 

the engine is outside of the misfire range 

except that the manufacturer may 

periodically, but not more than once 

every 30 seconds, deactivate fuel shutoff 

and default fuel control to determine if 

the catalyst damaging misfire is still 

occurring. Normal fueling and fuel 

control may be resumed if the catalyst 

damaging misfire is no longer occurring. 

(E) The manufacturer may use a 

strategy that activates the MIL 

continuously rather than blinking the 

MIL during extreme catalyst damage 

misfire conditions (i.e., catalyst damage 

misfire occurring at all engine speeds 

and loads). Use of such a strategy must 

be limited to catalyst damage misfire 

levels that cannot be avoided during 

reasonable driving conditions. To use 

such a strategy, the manufacturer must 

be able to demonstrate that the strategy 

will encourage operation of the vehicle 

in conditions that will minimize 

catalyst damage (e.g., at low engine 

speeds and loads). 

(v) MIL activation and DTC storage for 

engine misfire causing emissions to 

exceed applicable emissions thresholds. 

(A) Immediately upon detection, 

during the first 1000 revolutions after 

engine start of the misfire percentage 

described in paragraph (h)(2)(ii)(B) of 

this section, a pending DTC must be 

stored. If such a pending DTC is stored 

already and another such exceedance of 

the misfire percentage is detected 

within the first 1000 revolutions after 

engine start on any subsequent drive 

cycle, the MIL must activate and a MILon DTC must be stored. The pending 

DTC may be erased if, at the end of the 

next drive cycle in which similar 

conditions are encountered to those that 

occurred when the pending DTC was 

stored, there has been no exceedance of 

the misfire percentage described in 

paragraph (h)(2)(ii)(B) of this section. 

The pending DTC may also be erased if 

similar conditions are not encountered 

during the next 80 drive cycles 

immediately following storage of the 

pending DTC. 

(B) No later than the fourth detection 

during a single drive cycle, following 

the first 1000 revolutions after engine 

start of the misfire percentage described 

in paragraph (h)(2)(ii)(B) of this section, 

a pending DTC must be stored. If such 

a pending DTC is stored already, then 

the MIL must activate and a MIL-on 

DTC must be stored within 10 seconds 

of the fourth detection of the misfire 

percentage described in paragraph 

(h)(2)(ii)(B) of this section during either 

the drive cycle immediately following 

storage of the pending DTC, regardless 

of the conditions encountered during 

that drive cycle excepting those 

conditions within the first 1000 

revolutions after engine start, or on the 

next drive cycle in which similar 

conditions are encountered to those that 

occurred when the pending DTC was 

stored excepting those conditions 

within the first 1000 revolutions after 

engine start. The pending DTC may be 

erased if, at the end of the next drive 

cycle in which similar conditions are 

encountered to those that occurred 

when the pending DTC was stored, 

there has been no exceedance of the 

misfire percentage described in 

paragraph (h)(2)(ii)(B) of this section. 

The pending DTC may also be erased if 


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similar conditions are not encountered 

during the next 80 drive cycles 

immediately following storage of the 

pending DTC. 

(vi) Storage of freeze frame conditions 

for engine misfire. 

(A) The OBD system must store and 

erase freeze frame conditions (as 

defined in paragraph (k)(4)(iii) of this 

section) either in conjunction with 

storing and erasing a pending DTC or in 

conjunction with storing and erasing a 

MIL-on DTC. 

(B) If, upon storage of a DTC as 

required by paragraphs (h)(2)(iv) and 

(h)(2)(v) of this section, there already 

exist stored freeze frame conditions for 

a malfunction other than a misfire or 

fuel system malfunction (see paragraph 

(h)(1) of this section) then the stored 

freeze frame information shall be 

replaced with freeze frame information 

associated with the misfire malfunction. 

(vii) Storage of engine conditions in 

association with engine misfire. Upon 

detection of the misfire percentages 

described in paragraphs (h)(2)(ii)(A) and 

(h)(2)(ii)(B) of this section, the following 

engine conditions must be stored for use 

in determining similar conditions: 

engine speed, load, and warm up status 

of the first misfire event that resulted in 

pending DTC storage. 

(viii) MIL deactivation in association 

with engine misfire. The MIL may be 

deactivated after three sequential drive 

cycles in which similar conditions have 

been encountered without an 

exceedance of the misfire percentages 

described in paragraphs (h)(2)(ii)(A) and 

(h)(2)(ii)(B) of this section. 

(3) Exhaust gas recirculation system 

monitoring. 

(i) General. The OBD system must 

monitor the EGR system on engines so 

equipped for low and high flow rate 

malfunctions. The individual electronic 

components (e.g., actuators, valves, 

sensors) that are used in the EGR system 

must be monitored in accordance with 

the comprehensive component 

requirements in paragraph (i)(3) of this 

section. 

(ii) EGR system malfunction criteria. 

(A) The OBD system must detect a 

malfunction of the EGR system prior to 

a decrease from the manufacturer’s 

specified EGR flow rate that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table 2 of this 

paragraph (h). For engines in which no 

failure or deterioration of the EGR 

system that causes a decrease in flow 

could result in an engine’s emissions 

exceeding the applicable emissions 

thresholds, the OBD system must detect 

a malfunction when the system has no 

detectable amount of EGR flow. 

(B) The OBD system must detect a 

malfunction of the EGR system prior to 

an increase from the manufacturer’s 

specified EGR flow rate that would 

cause an engine’s emissions to exceed 

the emissions thresholds for ‘‘other 

monitors’’ as shown in Table 2 of this 

paragraph (h). For engines in which no 

failure or deterioration of the EGR 

system that causes an increase in flow 

could result in an engine’s emissions 

exceeding the applicable emissions 

thresholds, the OBD system must detect 

a malfunction when the system has 

reached its control limits such that it 

cannot reduce EGR flow. 

(iii) EGR system monitoring 

conditions. 

(A) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (h)(3)(ii) of this 

section in accordance with paragraphs 

(c) and (d) of this section. For purposes 

of tracking and reporting as required by 

paragraph (d)(1) of this section, all 

monitors used to detect malfunctions 

identified in paragraph (h)(3)(ii) of this 

section must be tracked separately but 

reported as a single set of values as 

specified in paragraph (e)(1)(iii) of this 

section. 

(B) The manufacturer may disable 

temporarily the EGR monitor under 

conditions when monitoring may not be 

reliable (e.g., when freezing may affect 

performance of the system). To do so, 

the manufacturer must be able to 

demonstrate that the monitor is 

unreliable when such conditions exist. 

(iv) EGR system MIL activation and 

DTC storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(4) Cold start emission reduction 

strategy monitoring. 

(i) General. If an engine incorporates 

a specific engine control strategy to 

reduce cold start emissions, the OBD 

system must monitor the key 

components (e.g., idle air control valve), 

other than secondary air, while the 

control strategy is active to ensure 

proper operation of the control strategy. 

(ii) Cold start strategy malfunction 

criteria. 

(A) The OBD system must detect a 

malfunction prior to any failure or 

deterioration of the individual 

components associated with the cold 

start emission reduction control strategy 

that would cause an engine’s emissions 

to exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 2 of 

this paragraph (h). The manufacturer 

must establish the malfunction criteria 

based on data from one or more 

representative engine(s) and provide an 

engineering evaluation for establishing 

the malfunction criteria for the 

remainder of the manufacturer’s product 

line. 

(B) Where no failure or deterioration 

of a component used for the cold start 

emission reduction strategy could result 

in an engine’s emissions exceeding the 

applicable emissions thresholds, the 

individual component must be 

monitored for proper functional 

response while the control strategy is 

active in accordance with the 

malfunction criteria in paragraphs 

(i)(3)(ii) and (i)(3)(iii) of this section. 

(iii) Cold start strategy monitoring 

conditions. The manufacturer must 

define monitoring conditions for 

malfunctions identified in paragraph 

(h)(4)(ii) of this section in accordance 

with paragraphs (c) and (d) of this 

section. 

(iv) Cold start strategy MIL activation 

and DTC storage. The MIL must activate 

and DTCs must be stored according to 

the provisions of paragraph (b) of this 

section. 

(5) Secondary air system monitoring. 

(i) General. The OBD system on 

engines equipped with any form of 

secondary air delivery system must 

monitor the proper functioning of the 

secondary air delivery system including 

all air switching valves(s). The 

individual electronic components (e.g., 

actuators, valves, sensors) that are used 

in the secondary air system must be 

monitored in accordance with the 

comprehensive component 

requirements in paragraph (i)(3) of this 

section. For purposes of this paragraph 

(h)(5), ‘‘air flow’’ is defined as the air 

flow delivered by the secondary air 

system to the exhaust system. For 

engines using secondary air systems 

with multiple air flow paths/ 

distribution points, the air flow to each 

bank (i.e., a group of cylinders that 

share a common exhaust manifold, 

catalyst, and control sensor) must be 

monitored in accordance with the 

malfunction criteria in paragraph 

(h)(5)(ii) of this section. Also for 

purposes of this paragraph (h)(5), 

‘‘normal operation’’ is defined as the 

condition when the secondary air 

system is activated during catalyst and/ 

or engine warm-up following engine 

start. ‘‘Normal operation’’ does not 

include the condition when the 

secondary air system is turned on 

intrusively for the sole purpose of 

monitoring. 

(ii) Secondary air system malfunction 

criteria. 

(A) Except as provided in paragraph 

(h)(5)(ii)(C) of this section, the OBD 

system must detect a secondary air 

system malfunction prior to a decrease 

from the manufacturer’s specified air 


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flow during normal operation that 

would cause an engine’s emissions to 

exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 2 of 

this paragraph (h). 

(B) Except as provided in paragraph 

(h)(5)(ii)(C) of this section, the OBD 

system must detect a secondary air 

system malfunction prior to an increase 

from the manufacturer’s specified air 

flow during normal operation that 

would cause an engine’s emissions to 

exceed the emissions thresholds for 

‘‘other monitors’’ as shown in Table 2 of 

this paragraph (h). 

(C) For engines in which no 

deterioration or failure of the secondary 

air system would result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the OBD system 

must detect a malfunction when no 

detectable amount of air flow is 

delivered by the secondary air system 

during normal operation. 

(iii) Secondary air system monitoring 

conditions. The manufacturer must 

define monitoring conditions for 

malfunctions identified in paragraph 

(h)(5)(ii) of this section in accordance 

with paragraphs (c) and (d) of this 

section. For purposes of tracking and 

reporting as required by paragraph (d)(1) 

of this section, all monitors used to 

detect malfunctions identified in 

paragraph (h)(5)(ii) of this section must 

be tracked separately but reported as a 

single set of values as specified in 

paragraph (e)(1)(iii) of this section. 

(iv) Secondary air system MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. 

(6) Catalyst system monitoring. 

(i) General. The OBD system must 

monitor the catalyst system for proper 

conversion capability. 

(ii) Catalyst system malfunction 

criteria. The OBD system must detect a 

catalyst system malfunction when the 

catalyst system’s conversion capability 

decreases to the point that emissions 

exceed the emissions thresholds for the 

catalyst system as shown in Table 2 of 

this paragraph (h). 

(iii) Catalyst system monitoring 

conditions. The manufacturer must 

define monitoring conditions for 

malfunctions identified in paragraph 

(h)(6)(ii) of this section in accordance 

with paragraphs (c) and (d) of this 

section. For purposes of tracking and 

reporting as required by paragraph (d)(1) 

of this section, all monitors used to 

detect malfunctions identified in 

paragraph (h)(6)(ii) of this section must 

be tracked separately but reported as a 

single set of values as specified in 

paragraph (e)(1)(iii) of this section. 

(iv) Catalyst system MIL activation 

and DTC storage. 

(A) The MIL must activate and DTCs 

must be stored according to the 

provisions of paragraph (b) of this 

section. 

(B) The monitoring method for the 

catalyst system must be capable of 

detecting when a catalyst DTC has been 

erased (except OBD system self erasure), 

but the catalyst has not been replaced 

(e.g., catalyst overtemperature histogram 

approaches are not acceptable). 

(7) Evaporative system monitoring. 

(i) General. The OBD system must 

verify purge flow from the evaporative 

system and monitor the complete 

evaporative system, excluding the 

tubing and connections between the 

purge valve and the intake manifold, for 

vapor leaks to the atmosphere. 

Individual components of the 

evaporative system (e.g., valves, sensors) 

must be monitored in accordance with 

the comprehensive components 

requirements in paragraph (i)(3) of this 

section. 

(ii) Evaporative system malfunction 

criteria. 

(A) Purge monitor. The OBD system 

must detect an evaporative system 

malfunction when no purge flow from 

the evaporative system to the engine can 

be detected by the OBD system. 

(B) Leak monitor. The OBD system 

must detect an evaporative system 

malfunction when the complete 

evaporative system contains a leak or 

leaks that cumulatively are greater than 

or equal to a leak caused by a 0.150 inch 

diameter hole. 

(C) The manufacturer may 

demonstrate that detection of a larger 

hole is more appropriate than that 

specified in paragraph (h)(7)(ii)(B) of 

this section. To do so, the manufacturer 

must demonstrate through data and/or 

engineering analyses that holes smaller 

than the proposed detection size would 

not result in evaporative or running loss 

emissions that exceed 1.5 times the 

applicable evaporative emissions 

standards. Upon such a demonstration, 

the proposed detection size could be 

substituted for the requirement of 

paragraph (h)(7)(ii)(B) of this section. 

(iii) Evaporative system monitoring 

conditions. 

(A) The manufacturer must define 

monitoring conditions for malfunctions 

identified in paragraph (h)(7)(ii)(A) of 

this section in accordance with 

paragraphs (c) and (d) of this section. 

(B) The manufacturer must define 

monitoring conditions for malfunctions 

identified in paragraph (h)(7)(ii)(B) of 

this section in accordance with 

paragraphs (c) and (d) of this section. 

For purposes of tracking and reporting 

as required by paragraph (d)(1) of this 

section, all monitors used to detect 

malfunctions identified in paragraph 

(h)(7)(ii)(B) of this section must be 

tracked separately but reported as a 

single set of values as specified in 

paragraph (e)(1)(iii) of this section. 

(C) The manufacturer may disable or 

abort an evaporative system monitor 

when the fuel tank level is over 85 

percent of nominal tank capacity or 

during a refueling event. 

(D) The manufacturer may request 

Administrator approval to run the 

evaporative system monitor during only 

those drive cycles characterized as cold 

starts provided such a condition is 

needed to ensure reliable monitoring. In 

making the request, the manufacturer 

must demonstrate through data and/or 

engineering analyses that a reliable 

monitor can only be run on drive cycles 

that begin with a specific set of cold 

start criteria. A set of cold start criteria 

based solely on ambient temperature 

exceeding engine coolant temperature 

will not be acceptable. 

(E) The OBD system may disable 

temporarily the evaporative purge 

system to run an evaporative system 

leak monitor. 

(iv) Evaporative system MIL activation 

and DTC storage. 

(A) Except as provided for in 

paragraph (h)(7)(iv)(B) of this section, 

the MIL must activate and DTCs must be 

stored according to the provisions of 

paragraph (b) of this section. 

(B) If the OBD system is capable of 

discerning that a system leak is being 

caused by a missing or improperly 

secured gas cap, the OBD system need 

not activate the MIL or store a DTC 

provided the vehicle is equipped with 

an alternative indicator for notifying the 

operator of the gas cap problem. The 

alternative indicator must be of 

sufficient illumination and location to 

be readily visible under all lighting 

conditions. If the vehicle is not 

equipped with such an alternative 

indicator, the MIL must activate and a 

DTC be stored as required in paragraph 

(h)(7)(iv)(A) of this section; however, 

these may be deactivated and erased, 

respectively, if the OBD system 

determines that the gas cap problem has 

been corrected and the MIL has not been 

activated for any other malfunction. The 

Administrator may approve other 

strategies that provide equivalent 

assurance that a vehicle operator will be 

notified promptly of a missing or 

improperly secured gas cap and that 

corrective action will be undertaken. 

(8) Exhaust gas sensor monitoring. 

(i) General. 

(A) The OBD system must monitor for 

malfunctions the output signal, 


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response rate, and any other parameter 

that can affect emissions of all primary 

(i.e., fuel control) exhaust gas sensors 

(e.g., oxygen, wide-range air/fuel). Both 

the lean-to-rich and rich-to-lean 

response rates must be monitored. 

(B) The OBD system must also 

monitor all secondary exhaust gas 

sensors (those used for secondary fuel 

trim control or as a monitoring device) 

for proper output signal, activity, and 

response rate. 

(C) For engines equipped with heated 

exhaust gas sensor, the OBD system 

must monitor the heater for proper 

performance. 

(ii) Primary exhaust gas sensor 

malfunction criteria. 

(A) The OBD system must detect a 

malfunction prior to any failure or 

deterioration of the exhaust gas sensor 

output voltage, resistance, impedance, 

current, response rate, amplitude, offset, 

or other characteristic(s) (including drift 

or bias corrected for by secondary 

sensors) that would cause an engine’s 

emissions to exceed the emissions 

thresholds for ‘‘other monitors’’ as 

shown in Table 2 of this paragraph (h). 

(B) The OBD system must detect 

malfunctions of the exhaust gas sensor 

caused by either a lack of circuit 

continuity or out-of-range values. 

(C) The OBD system must detect a 

malfunction of the exhaust gas sensor 

when a sensor failure or deterioration 

causes the fuel system to stop using that 

sensor as a feedback input (e.g., causes 

default or open-loop operation). 

(D) The OBD system must detect a 

malfunction of the exhaust gas sensor 

when the sensor output voltage, 

resistance, impedance, current, 

amplitude, activity, or other 

characteristics are no longer sufficient 

for use as an OBD system monitoring 

device (e.g., for catalyst monitoring). 

(iii) Secondary exhaust gas sensor 

malfunction criteria. 

(A) The OBD system must detect a 

malfunction prior to any failure or 

deterioration of the exhaust gas sensor 

voltage, resistance, impedance, current, 

response rate, amplitude, offset, or other 

characteristic(s) that would cause an 

engine’s emissions to exceed the 

emissions thresholds for ‘‘other 

monitors’’ as shown in Table 2 of this 

paragraph (h). 

(B) The OBD system must detect 

malfunctions of the exhaust gas sensor 

caused by a lack of circuit continuity. 

(C) To the extent feasible, the OBD 

system must detect a malfunction of the 

exhaust gas sensor when the sensor 

output voltage, resistance, impedance, 

current, amplitude, activity, offset, or 

other characteristics are no longer 

sufficient for use as an OBD system 

monitoring device (e.g., for catalyst 

monitoring). 

(D) The OBD system must detect 

malfunctions of the exhaust gas sensor 

caused by out-of-range values. 

(E) The OBD system must detect a 

malfunction of the exhaust gas sensor 

when a sensor failure or deterioration 

causes the fuel system (e.g., fuel control) 

to stop using that sensor as a feedback 

input (e.g., causes default or open-loop 

operation). 

(iv) Exhaust gas sensor heater 

malfunction criteria. 

(A) The OBD system must detect a 

malfunction of the heater performance 

when the current or voltage drop in the 

heater circuit is no longer within the 

manufacturer’s specified limits for 

normal operation (i.e., within the 

criteria required to be met by the 

component vendor for heater circuit 

performance at high mileage). Other 

malfunction criteria for heater 

performance malfunctions may be used 

upon demonstrating via data or 

engineering analyses that the 

monitoring reliability and timeliness is 

equivalent to the stated criteria in this 

paragraph (h)(8)(iv)(A). 

(B) The OBD system must detect 

malfunctions of the heater circuit 

including open or short circuits that 

conflict with the commanded state of 

the heater (e.g., shorted to 12 Volts 

when commanded to 0 Volts (ground)). 

(v) Primary exhaust gas sensor 

monitoring conditions. 

(A) The manufacturer must define 

monitoring conditions for malfunctions 

identified in paragraphs (h)(8)(ii)(A) and 

(h)(8)(ii)(D) of this section in accordance 

with paragraphs (c) and (d) of this 

section. For purposes of tracking and 

reporting as required by paragraph (d)(1) 

of this section, all monitors used to 

detect malfunctions identified in 

paragraphs (h)(8)(ii)(A) and (h)(8)(ii)(D) 

of this section must be tracked 

separately but reported as a single set of 

values as specified in paragraph 

(e)(1)(iii) of this section. 

(B) Except as provided for in 

paragraph (h)(8)(v)(C) of this section, 

monitoring for malfunctions identified 

in paragraphs (h)(8)(ii)(B) and 

(h)(8)(ii)(C) of this section must be 

conducted continuously. 

(C) The manufacturer may disable 

continuous primary exhaust gas sensor 

monitoring when a primary exhaust gas 

sensor malfunction cannot be 

distinguished from other effects (e.g., 

disable out-of-range low monitoring 

during fuel cut conditions). To do so, 

the manufacturer must demonstrate via 

data or engineering analyses that a 

properly functioning sensor cannot be 

distinguished from a malfunctioning 

sensor and that the disablement interval 

is limited only to that necessary for 

avoiding false detection. 

(vi) Secondary exhaust gas sensor 

monitoring conditions. 

(A) The manufacturer must define 

monitoring conditions for malfunctions 

identified in paragraphs (h)(8)(iii)(A) 

through (h)(8)(iii)(C) of this section in 

accordance with paragraphs (c) and (d) 

of this section. 

(B) Except as provided for in 

paragraph (h)(8)(vi)(C) of this section, 

monitoring for malfunctions identified 

in paragraphs (h)(8)(iii)(D) and 

(h)(8)(iii)(E) of this section must be 

conducted continuously. 

(C) The manufacturer may disable 

continuous secondary exhaust gas 

sensor monitoring when a secondary 

exhaust gas sensor malfunction cannot 

be distinguished from other effects (e.g., 

disable out-of-range low monitoring 

during fuel cut conditions). To do so, 

the manufacturer must demonstrate via 

data or engineering analyses that a 

properly functioning sensor cannot be 

distinguished from a malfunctioning 

sensor and that the disablement interval 

is limited only to that necessary for 

avoiding false detection. 

(vii) Exhaust gas sensor heater 

monitoring conditions. 

(A) The manufacturer must define 

monitoring conditions for malfunctions 

identified in paragraph (h)(8)(iv)(A) of 

this section in accordance with 

paragraphs (c) and (d) of this section. 

(B) Monitoring for malfunctions 

identified in paragraph (h)(8)(iv)(B) of 

this section must be conducted 

continuously. 

(viii) Exhaust gas sensor MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. 

(9) Variable valve timing (VVT) 

system monitoring. 

(i) General. The OBD system must 

monitor the VVT system on engines so 

equipped for target error and slow 

response malfunctions. The individual 

electronic components (e.g., actuators, 

valves, sensors) that are used in the VVT 

system must be monitored in 

accordance with the comprehensive 

components requirements in paragraph 

(i)(3) of this section. 

(ii) VVT system malfunction criteria. 

(A) VVT system target error. The OBD 

system must detect a malfunction prior 

to any failure or deterioration in the 

capability of the VVT system to achieve 

the commanded valve timing and/or 

control within a crank angle and/or lift 

tolerance that would cause an engine’s 

emissions to exceed the emission 


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thresholds for ‘‘other monitors’’ as 

shown in Table 2 of this paragraph (h). 

(B) VVT slow response. The OBD 

system must detect a malfunction prior 

to any failure or deterioration in the 

capability of the VVT system to achieve 

the commanded valve timing and/or 

control within a manufacturer-specified 

time that would cause an engine’s 

emissions to exceed the emission 

thresholds for ‘‘other monitors’’ as 

shown in Table 2 of this paragraph (h). 

(C) For engines in which no failure or 

deterioration of the VVT system could 

result in an engine’s emissions 

exceeding the applicable emissions 

thresholds of paragraphs (h)(9)(ii)(A) 

and (h)(9)(ii)(B) of this paragraph (h), 

the OBD system must detect a 

malfunction of the VVT system when 

proper functional response of the 

system to computer commands does not 

occur. 

(iii) VVT system monitoring 

conditions. Manufacturers must define 

the monitoring conditions for VVT 

system malfunctions identified in 

paragraph (h)(9)(ii) of this section in 

accordance with paragraphs (c) and (d) 

of this section, with the exception that 

monitoring must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in paragraph 

(c)(2) of this section. For purposes of 

tracking and reporting as required in 

paragraph (d)(1) of this section, all 

monitors used to detect malfunctions 

identified in paragraph (h)(9)(ii) of this 

section must be tracked separately but 

reported as a single set of values as 

specified in paragraph (e)(1)(iii) of this 

section. 

(iv) VVT MIL activation and DTC 

storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(i) OBD monitoring requirements for 

all engines. 

(1) Engine cooling system monitoring. 

(i) General. 

(A) The OBD system must monitor the 

thermostat on engines so equipped for 

proper operation. 

(B) The OBD system must monitor the 

engine coolant temperature (ECT) sensor 

for electrical circuit continuity, out-ofrange values, and rationality 

malfunctions. 

(C) For engines that use a system 

other than the cooling system and ECT 

sensor (e.g., oil temperature, cylinder 

head temperature) to determine engine 

operating temperature for emission 

control purposes (e.g., to modify spark 

or fuel injection timing or quantity), the 

manufacturer may forego cooling system 

monitoring and instead monitor the 

components or systems used in their 

approach. To do so, the manufacturer 

must to submit data and/or engineering 

analyses that demonstrate that their 

monitoring plan is as reliable and 

effective as the monitoring required in 

this paragraph (i)(1). 

(ii) Malfunction criteria for the 

thermostat. 

(A) The OBD system must detect a 

thermostat malfunction if, within the 

manufacturer specified time interval 

following engine start, any of the 

following conditions occur: the coolant 

temperature does not reach the highest 

temperature required by the OBD 

system to enable other diagnostics; and, 

the coolant temperature does not reach 

a warmed-up temperature within 20 

degrees Fahrenheit of the 

manufacturer’s nominal thermostat 

regulating temperature. For the second 

of these two conditions, the 

manufacturer may use a lower 

temperature for this criterion provided 

the manufacturer can demonstrate that 

the fuel, spark timing, and/or other 

coolant temperature-based modification 

to the engine control strategies would 

not cause an emissions increase greater 

than or equal to 50 percent of any of the 

applicable emissions standards. 

(B) The manufacturer may use 

alternative malfunction criteria to those 

of paragraph (i)(1)(ii)(A) of this section 

and/or alternative monitoring 

conditions to those of paragraph 

(i)(1)(iv) of this section that are a 

function of temperature at engine start 

on engines that do not reach the 

temperatures specified in the 

malfunction criteria when the 

thermostat is functioning properly. To 

do so, the manufacturer is required to 

submit data and/or engineering analyses 

that demonstrate that a properly 

operating system does not reach the 

specified temperatures and that the 

possibility is minimized for cooling 

system malfunctions to go undetected 

thus disabling other OBD monitors. 

(C) The manufacturer may request 

Administrator approval to forego 

monitoring of the thermostat if the 

manufacturer can demonstrate that a 

malfunctioning thermostat cannot cause 

a measurable increase in emissions 

during any reasonable driving condition 

nor cause any disablement of other OBD 

monitors. 

(iii) Malfunction criteria for the ECT 

sensor. 

(A) Circuit integrity. The OBD system 

must detect malfunctions of the ECT 

sensor related to a lack of circuit 

continuity or out-of-range values. 

(B) Time to reach closed-loop/ 

feedback enable temperature. The OBD 

system must detect if, within the 

manufacturer specified time interval 

following engine start, the ECT sensor 

does not achieve the highest stabilized 

minimum temperature that is needed to 

initiate closed-loop/feedback control of 

all affected emission control systems 

(e.g., fuel system, EGR system). The 

manufacturer specified time interval 

must be a function of the engine coolant 

temperature and/or intake air 

temperature at startup. The 

manufacturer time interval must be 

supported by data and/or engineering 

analyses demonstrating that it provides 

robust monitoring and minimizes the 

likelihood of other OBD monitors being 

disabled. The manufacturer may forego 

the requirements of this paragraph 

(i)(1)(iii)(B) provided the manufacturer 

does not use engine coolant temperature 

or the ECT sensor to enable closed-loop/ 

feedback control of any emission control 

systems. 

(C) Stuck in range below the highest 

minimum enable temperature. To the 

extent feasible when using all available 

information, the OBD system must 

detect a malfunction if the ECT sensor 

inappropriately indicates a temperature 

below the highest minimum enable 

temperature required by the OBD 

system to enable other monitors (e.g., an 

OBD system that requires ECT to be 

greater than 140 degrees Fahrenheit to 

enable a diagnostic must detect 

malfunctions that cause the ECT sensor 

to inappropriately indicate a 

temperature below 140 degrees 

Fahrenheit). The manufacturer may 

forego this requirement for temperature 

regions in which the monitors required 

under paragraphs (i)(1)(ii) or (i)(1)(iii)(B) 

of this section will detect ECT sensor 

malfunctions as defined in this 

paragraph (i)(1)(iii)(C). 

(D) Stuck in range above the lowest 

maximum enable temperature. The 

OBD system must detect a malfunction 

if the ECT sensor inappropriately 

indicates a temperature above the 

lowest maximum enable temperature 

required by the OBD system to enable 

other monitors (e.g., an OBD system that 

requires an engine coolant temperature 

less than 90 degrees Fahrenheit at 

startup prior to enabling an OBD 

monitor must detect malfunctions that 

cause the ECT sensor to indicate 

inappropriately a temperature above 90 

degrees Fahrenheit). The manufacturer 

may forego this requirement within 

temperature regions in which the 

monitors required under paragraphs 

(i)(1)(ii), (i)(1)(iii)(B), and (i)(1)(iii)(C) of 

this section will detect ECT sensor 

malfunctions as defined in this 

paragraph (i)(1)(iii)(D) or in which the 

MIL will be activated according to the 

provisions of paragraph (b)(2)(v) of this 


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section. The manufacturer may also 

forego this monitoring within 

temperature regions where a 

temperature gauge on the instrument 

panel indicates a temperature in the 

‘‘red zone’’ (engine overheating zone) 

and displays the same temperature 

information as used by the OBD system. 

(iv) Monitoring conditions for the 

thermostat. 

(A) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (i)(1)(ii)(A) of 

this section in accordance with 

paragraph (c) of this section. 

Additionally, except as provided for in 

paragraphs (i)(1)(iv)(B) and (i)(1)(iv)(C) 

of this section, monitoring for 

malfunctions identified in paragraph 

(i)(1)(ii)(A) of this section must be 

conducted once per drive cycle on every 

drive cycle in which the ECT sensor 

indicates, at engine start, a temperature 

lower than the temperature established 

as the malfunction criteria in paragraph 

(i)(1)(ii)(A) of this section. 

(B) The manufacturer may disable 

thermostat monitoring at ambient 

engine start temperatures below 20 

degrees Fahrenheit. 

(C) The manufacturer may request 

Administrator approval to suspend or 

disable thermostat monitoring if the 

engine is subjected to conditions that 

could lead to false diagnosis. To do so, 

the manufacturer must submit data and/ 

or engineering analyses that 

demonstrate that the suspension or 

disablement is necessary. In general, the 

manufacturer will not be allowed to 

suspend or disable the thermostat 

monitor on engine starts where the 

engine coolant temperature at engine 

start is more than 35 degrees Fahrenheit 

lower than the thermostat malfunction 

threshold temperature determined 

under paragraph (i)(1)(ii)(A) of this 

paragraph (i)(1). 

(v) Monitoring conditions for the ECT 

sensor. 

(A) Except as provided for in 

paragraph (i)(1)(v)(E) of this section, the 

OBD system must monitor continuously 

for malfunctions identified in paragraph 

(i)(1)(iii)(A) of this section (i.e., circuit 

integrity and out-of-range). 

(B) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (i)(1)(iii)(B) of 

this section in accordance with 

paragraph (c) of this section. 

Additionally, except as provided for in 

paragraph (i)(1)(v)(D) of this section, 

monitoring for malfunctions identified 

in paragraph (i)(1)(iii)(B) of this section 

must be conducted once per drive cycle 

on every drive cycle in which the ECT 

sensor indicates a temperature lower 

than the closed-loop enable temperature 

at engine start (i.e., all engine start 

temperatures greater than the ECT 

sensor out-of-range low temperature and 

less than the closed-loop enable 

temperature). 

(C) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraphs (i)(1)(iii)(C) and 

(i)(1)(iii)(D) of this section in accordance 

with paragraphs (c) and (d) of this 

section. 

(D) The manufacturer may suspend or 

delay the monitor for the time to reach 

closed-loop enable temperature if the 

engine is subjected to conditions that 

could lead to false diagnosis (e.g., 

vehicle operation at idle for more than 

50 to 75 percent of the warm-up time). 

(E) The manufacturer may request 

Administrator approval to disable 

continuous ECT sensor monitoring 

when an ECT sensor malfunction cannot 

be distinguished from other effects. To 

do so, the manufacturer must submit 

data and/or engineering analyses that 

demonstrate a properly functioning 

sensor cannot be distinguished from a 

malfunctioning sensor and that the 

disablement interval is limited only to 

that necessary for avoiding false 

detection. 

(vi) Engine cooling system MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. 

(2) Crankcase ventilation (CV) system 

monitoring. 

(i) General. The OBD system must 

monitor the CV system on engines so 

equipped for system integrity. Engines 

not required to be equipped with CV 

systems are exempt from monitoring the 

CV system. For diesel engines, the 

manufacturer must submit a plan for 

Administrator prior to OBD 

certification. That plan must include 

descriptions of the monitoring strategy, 

malfunction criteria, and monitoring 

conditions for CV system monitoring. 

The plan must demonstrate that the CV 

system monitor is of equivalent 

effectiveness, to the extent feasible, to 

the malfunction criteria and the 

monitoring conditions of this paragraph 

(i)(2). 

(ii) Crankcase ventilation system 

malfunction criteria. 

(A) For the purposes of this paragraph 

(i)(2), ‘‘CV system’’ is defined as any 

form of crankcase ventilation system, 

regardless of whether it utilizes positive 

pressure. ‘‘CV valve’’ is defined as any 

form of valve or orifice used to restrict 

or control crankcase vapor flow. 

Further, any additional external CV 

system tubing or hoses used to equalize 

crankcase pressure or to provide a 

ventilation path between various areas 

of the engine (e.g., crankcase and valve 

cover) are considered part of the CV 

system ‘‘between the crankcase and the 

CV valve’’ and subject to the 

malfunction criteria in paragraph 

(i)(2)(ii)(B) of this section. 

(B) Except as provided for in 

paragraphs (i)(2)(ii)(C) through 

(i)(2)(ii)(E) of this section, the OBD 

system must detect a malfunction of the 

CV system when a disconnection of the 

system occurs between either the 

crankcase and the CV valve, or between 

the CV valve and the intake manifold. 

(C) The manufacturer may forego 

monitoring for a disconnection between 

the crankcase and the CV valve 

provided the CV system is designed 

such that the CV valve is fastened 

directly to the crankcase such that it is 

significantly more difficult to remove 

the CV valve from the crankcase than to 

disconnect the line between the CV 

valve and the intake manifold (taking 

aging effects into consideration). To do 

so, the manufacturer must be able to 

provide data and/or an engineering 

evaluation demonstrating that the CV 

system is so designed. 

(D) The manufacturer may forego 

monitoring for a disconnection between 

the crankcase and the CV valve 

provided the CV system is designed 

such that it uses tubing connections 

between the CV valve and the crankcase 

that are: resistant to deterioration or 

accidental disconnection; significantly 

more difficult to disconnect than is the 

line between the CV valve and the 

intake manifold; and, not subject to 

disconnection per the manufacturer’s 

repair procedures for any non-CV 

system repair. To do so, the 

manufacturer must be able to provide 

data and/or engineering evaluation 

demonstrating that the CV system is so 

designed. 

(E) The manufacturer may forego 

monitoring for a disconnection between 

the CV valve and the intake manifold 

provided the CV system is designed 

such that any disconnection either 

causes the engine to stall immediately 

during idle operation, or is unlikely to 

occur due to a CV system design that is 

integral to the induction system (e.g., 

machined passages rather than tubing or 

hoses). To do so, the manufacturer must 

be able to provide data and/or an 

engineering evaluation demonstrating 

that the CV system is so designed. 

(iii) Crankcase ventilation system 

monitoring conditions. The 

manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph (i)(2) of this 

section in accordance with paragraphs 

(c) and (d) of this section. 


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(iv) Crankcase ventilation system MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. The stored DTC need 

not identify specifically the CV system 

(e.g., a DTC for idle speed control or fuel 

system monitoring can be stored) if the 

manufacturer can demonstrate that 

additional monitoring hardware is 

necessary to make such an identification 

and provided the manufacturer’s 

diagnostic and repair procedures for the 

detected malfunction include directions 

to check the integrity of the CV system. 

(3) Comprehensive component 

monitoring. 

(i) General. Except as provided for in 

paragraph (i)(4) of this section, the OBD 

system must detect a malfunction of any 

electronic engine component or system 

not otherwise described in paragraphs 

(g), (h), (i)(1), and (i)(2) of this section 

that either provides input to (directly or 

indirectly, such components may 

include the crank angle sensor, knock 

sensor, throttle position sensor, cam 

position sensor, intake air temperature 

sensor, boost pressure sensor, manifold 

pressure sensor, mass air flow sensor, 

exhaust temperature sensor, exhaust 

pressure sensor, fuel pressure sensor, 

fuel composition sensor of a flexible 

fuel vehicle, etc.) or receives commands 

from (such components or systems may 

include the idle speed control system, 

glow plug system, variable length intake 

manifold runner systems, supercharger 

or turbocharger electronic components, 

heated fuel preparation systems, the 

wait-to-start lamp on diesel 

applications, the MIL, etc.) the onboard 

computer(s) and meets either of the 

criteria described in paragraphs 

(i)(3)(i)(A) and/or (i)(3)(i)(B) of this 

section. Note that, for the purposes of 

this paragraph (i)(3), ‘‘electronic engine 

component or system’’ does not include 

components that are driven by the 

engine and are not related to the control 

of the fueling, air handling, or emissions 

of the engine (e.g., power take-off (PTO) 

components, air conditioning system 

components, and power steering 

components). 

(A) It can affect emissions during any 

reasonable in-use driving condition. The 

manufacturer must be able to provide 

emission data showing that the 

component or system, when 

malfunctioning and installed on a 

suitable test engine, does not have an 

emission effect. 

(B) It is used as part of the monitoring 

strategy for any other monitored system 

or component. 

(ii) Comprehensive component 

malfunction criteria for input 

components. 

(A) The OBD system must detect 

malfunctions of input components 

caused by a lack of circuit continuity 

and out-of-range values. In addition, 

where feasible, rationality checks must 

also be done and shall verify that a 

sensor output is neither inappropriately 

high nor inappropriately low (i.e., ‘‘twosided’’ monitoring). 

(B) To the extent feasible, the OBD 

system must separately detect and store 

different DTCs that distinguish 

rationality malfunctions from lack of 

circuit continuity and out-of-range 

malfunctions. For lack of circuit 

continuity and out-of-range 

malfunctions, the OBD system must, to 

the extent feasible, separately detect and 

store different DTCs for each distinct 

malfunction (e.g., out-of-range low, outof-range high, open circuit). The OBD 

system is not required to store separate 

DTCs for lack of circuit continuity 

malfunctions that cannot be 

distinguished from other out-of-range 

circuit malfunctions. 

(C) For input components that are 

used to activate alternative strategies 

that can affect emissions (e.g., AECDs, 

engine shutdown systems), the OBD 

system must conduct rationality checks 

to detect malfunctions that cause the 

system to activate erroneously or 

deactivate the alternative strategy. To 

the extent feasible when using all 

available information, the rationality 

check must detect a malfunction if the 

input component inappropriately 

indicates a value that activates or 

deactivates the alternative strategy. For 

example, for an alternative strategy that 

activates when the intake air 

temperature is greater than 120 degrees 

Fahrenheit, the OBD system must detect 

malfunctions that cause the intake air 

temperature sensor to indicate 

inappropriately a temperature above 120 

degrees Fahrenheit. 

(D) For engines that require precise 

alignment between the camshaft and the 

crankshaft, the OBD system must 

monitor the crankshaft position 

sensor(s) and camshaft position 

sensor(s) to verify proper alignment 

between the camshaft and crankshaft in 

addition to monitoring the sensors for 

circuit continuity and proper 

rationality. Proper alignment monitoring 

between a camshaft and a crankshaft is 

required only in cases where both are 

equipped with position sensors. For 

engines equipped with VVT systems 

and a timing belt or chain, the OBD 

system must detect a malfunction if the 

alignment between the camshaft and 

crankshaft is off by one or more cam/ 

crank sprocket cogs (e.g., the timing 

belt/chain has slipped by one or more 

teeth/cogs). If a manufacturer 

demonstrates that a single tooth/cog 

misalignment cannot cause a 

measurable increase in emissions during 

any reasonable driving condition, the 

OBD system must detect a malfunction 

when the minimum number of teeth/ 

cogs misalignment has occurred that 

does cause a measurable emission 

increase. 

(iii) Comprehensive component 

malfunction criteria for output 

components/systems. 

(A) The OBD system must detect a 

malfunction of an output component/ 

system when proper functional response 

does not occur in response to computer 

commands. If such a functional check is 

not feasible, the OBD system must 

detect malfunctions of output 

components/systems caused by a lack of 

circuit continuity or circuit malfunction 

(e.g., short to ground or high voltage). 

For output component lack of circuit 

continuity malfunctions and circuit 

malfunctions, the OBD system is not 

required to store different DTCs for each 

distinct malfunction (e.g., open circuit, 

shorted low). Manufacturers are not 

required to activate an output 

component/system when it would not 

normally be active for the sole purpose 

of performing a functional check of it as 

required in this paragraph (i)(3). 

(B) For gasoline engines, the idle 

control system must be monitored for 

proper functional response to computer 

commands. For gasoline engines using 

monitoring strategies based on deviation 

from target idle speed, a malfunction 

must be detected when either of the 

following conditions occurs: the idle 

speed control system cannot achieve the 

target idle speed within 200 revolutions 

per minute (rpm) above the target speed 

or 100 rpm below the target speed; or, 

the idle speed control system cannot 

achieve the target idle speed within the 

smallest engine speed tolerance range 

required by the OBD system to enable 

any other monitors. Regarding the 

former of these conditions, the 

manufacturer may use larger engine 

speed tolerances. To do so, the 

manufacturer must be able to provide 

data and/or engineering analyses that 

demonstrate that the tolerances can be 

exceeded without a malfunction being 

present. 

(C) For diesel engines, the idle control 

system must be monitored for proper 

functional response to computer 

commands. For diesel engines, a 

malfunction must be detected when 

either of the following conditions 

occurs: the idle fuel control system 

cannot achieve the target idle speed or 

fuel injection quantity within ±50 

percent of the manufacturer-specified 

fuel quantity and engine speed 


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tolerances; or, the idle fuel control 

system cannot achieve the target idle 

speed or fueling quantity within the 

smallest engine speed or fueling 

quantity tolerance range required by the 

OBD system to enable any other 

monitors. 

(D) Glow plugs/intake air heater 

systems must be monitored for proper 

functional response to computer 

commands and for circuit continuity 

malfunctions. The glow plug/intake air 

heater circuit(s) must be monitored for 

proper current and voltage drop. The 

manufacturer may use other monitoring 

strategies but must be able to provide 

data and/or engineering analyses that 

demonstrate reliable and timely 

detection of malfunctions. The OBD 

system must also detect a malfunction 

when a single glow plug no longer 

operates within the manufacturer’s 

specified limits for normal operation. If 

a manufacturer can demonstrate that a 

single glow plug malfunction cannot 

cause a measurable increase in 

emissions during any reasonable driving 

condition, the OBD system must instead 

detect a malfunction when the number 

of glow plugs needed to cause an 

emission increase is malfunctioning. To 

the extent feasible, the stored DTC must 

identify the specific malfunctioning 

glow plug(s). 

(E) The wait-to-start lamp circuit and 

the MIL circuit must be monitored for 

malfunctions that cause either lamp to 

fail to activate when commanded to do 

so (e.g., burned out bulb). 

(iv) Monitoring conditions for input 

components. 

(A) The OBD system must monitor 

input components continuously for outof-range values and circuit continuity. 

The manufacturer may disable 

continuous monitoring for circuit 

continuity and out-of-range values when 

a malfunction cannot be distinguished 

from other effects. To do so, the 

manufacturer must be able to provide 

data and/or engineering analyses that 

demonstrate that a properly functioning 

input component cannot be 

distinguished from a malfunctioning 

input component and that the 

disablement interval is limited only to 

that necessary for avoiding false 

malfunction detection. 

(B) For input component rationality 

checks (where applicable), the 

manufacturer must define the 

monitoring conditions for detecting 

malfunctions in accordance with 

paragraphs (c) and (d) of this section, 

with the exception that rationality 

checks must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in paragraph 

(c)(2) of this section. 

(v) Monitoring conditions for output 

components/systems. 

(A) The OBD system must monitor 

output components/systems 

continuously for circuit continuity and 

circuit malfunctions. The manufacturer 

may disable continuous monitoring for 

circuit continuity and circuit 

malfunctions when a malfunction 

cannot be distinguished from other 

effects. To do so, the manufacturer must 

be able to provide data and/or 

engineering analyses that demonstrate 

that a properly functioning output 

component/system cannot be 

distinguished from a malfunctioning 

one and that the disablement interval is 

limited only to that necessary for 

avoiding false malfunction detection. 

(B) For output component/system 

functional checks, the manufacturer 

must define the monitoring conditions 

for detecting malfunctions in 

accordance with paragraphs (c) and (d) 

of this section. Specifically for the idle 

control system, the manufacturer must 

define the monitoring conditions for 

detecting malfunctions in accordance 

with paragraphs (c) and (d) of this 

section, with the exception that 

functional checks must occur every time 

the monitoring conditions are met 

during the drive cycle rather than once 

per drive cycle as required in paragraph 

(c)(2) of this section. 

(vi) Comprehensive component MIL 

activation and DTC storage. 

(A) Except as provided for in 

paragraphs (i)(3)(vi)(B) and (i)(3)(vi)(C) 

of this section, the MIL must activate 

and DTCs must be stored according to 

the provisions of paragraph (b) of this 

section. 

(B) The MIL need not be activated in 

conjunction with storing a MIL-on DTC 

for any comprehensive component if: 

the component or system, when 

malfunctioning, could not cause engine 

emissions to increase by 15 percent or 

more of the applicable FTP standard 

during any reasonable driving 

condition; or, the component or system 

is not used as part of the monitoring 

strategy for any other system or 

component that is required to be 

monitored. 

(C) The MIL need not be activated if 

a malfunction has been detected in the 

MIL circuit that prevents the MIL from 

activating (e.g., burned out bulb or lightemitting diode, LED). Nonetheless, the 

electronic MIL status (see paragraph 

(k)(4)(ii) of this section) must be 

reported as MIL commanded-on and a 

MIL-on DTC must be stored. 

(4) Other emission control system 

monitoring. 

(i) General. For other emission control 

systems that are either not addressed in 

paragraphs (g) through (i)(3) of this 

section (e.g., hydrocarbon traps, 

homogeneous charge compression 

ignition control systems), or addressed 

in paragraph (i)(3) of this section but not 

corrected or compensated for by an 

adaptive control system (e.g., swirl 

control valves), the manufacturer must 

submit a plan for Administrator 

approval of the monitoring strategy, 

malfunction criteria, and monitoring 

conditions prior to introduction on a 

production engine. The plan must 

demonstrate the effectiveness of the 

monitoring strategy, the malfunction 

criteria used, the monitoring conditions 

required by the monitor, and, if 

applicable, the determination that the 

requirements of paragraph (i)(4)(ii) of 

this section are satisfied. 

(ii) For engines that use emission 

control systems that alter intake air flow 

or cylinder charge characteristics by 

actuating valve(s), flap(s), etc., in the 

intake air delivery system (e.g., swirl 

control valve systems), the 

manufacturer, in addition to meeting the 

requirements of paragraph (i)(4)(i) of 

this section, may elect to have the OBD 

system monitor the shaft to which all 

valves in one intake bank are physically 

attached rather than performing a 

functional check of the intake air flow, 

cylinder charge, or individual valve(s)/ 

flap(s). For non-metal shafts or 

segmented shafts, the monitor must 

verify all shaft segments for proper 

functional response (e.g., by verifying 

that the segment or portion of the shaft 

farthest from the actuator functions 

properly). For systems that have more 

than one shaft to operate valves in 

multiple intake banks, the manufacturer 

is not required to add more than one set 

of detection hardware (e.g., sensor, 

switch) per intake bank to meet this 

requirement. 

(5) Exceptions to OBD monitoring 

requirements. 

(i) The Administrator may revise the 

PM filtering performance malfunction 

criteria for DPFs to exclude detection of 

specific failure modes such as partially 

melted substrates, if the most reliable 

monitoring method developed requires 

it. 

(ii) The manufacturer may disable an 

OBD system monitor at ambient engine 

start temperatures below 20 degrees 

Fahrenheit (low ambient temperature 

conditions may be determined based on 

intake air or engine coolant temperature 

at engine start) or at elevations higher 

than 8,000 feet above sea level. To do 

so, the manufacturer must submit data 

and/or engineering analyses that 

demonstrate that monitoring is 


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unreliable during the disable 

conditions. A manufacturer may request 

that an OBD system monitor be disabled 

at other ambient engine start 

temperatures by submitting data and/or 

engineering analyses demonstrating that 

misdiagnosis would occur at the given 

ambient temperatures due to their effect 

on the component itself (e.g., 

component freezing). 

(iii) The manufacturer may disable an 

OBD system monitor when the fuel level 

is 15 percent or less of the nominal fuel 

tank capacity for those monitors that 

can be affected by low fuel level or 

running out of fuel (e.g., misfire 

detection). To do so, the manufacturer 

must submit data and/or engineering 

analyses that demonstrate that 

monitoring at the given fuel levels is 

unreliable, and that the OBD system is 

still able to detect a malfunction if the 

component(s) used to determine fuel 

level indicates erroneously a fuel level 

that causes the disablement. 

(iv) The manufacturer may disable 

OBD monitors that can be affected by 

engine battery or system voltage levels. 

(A) For an OBD monitor affected by 

low vehicle battery or system voltages, 

manufacturers may disable monitoring 

when the battery or system voltage is 

below 11.0 Volts. The manufacturer may 

use a voltage threshold higher than 11.0 

Volts to disable monitors but must 

submit data and/or engineering analyses 

that demonstrate that monitoring at 

those voltages is unreliable and that 

either operation of a vehicle below the 

disablement criteria for extended 

periods of time is unlikely or the OBD 

system monitors the battery or system 

voltage and will detect a malfunction at 

the voltage used to disable other 

monitors. 

(B) For an OBD monitor affected by 

high engine battery or system voltages, 

the manufacturer may disable 

monitoring when the battery or system 

voltage exceeds a manufacturer-defined 

voltage. To do so, the manufacturer 

must submit data and/or engineering 

analyses that demonstrate that 

monitoring above the manufacturerdefined voltage is unreliable and that 

either the electrical charging system/ 

alternator warning light will be 

activated (or voltage gauge would be in 

the ‘‘red zone’’) or the OBD system 

monitors the battery or system voltage 

and will detect a malfunction at the 

voltage used to disable other monitors. 

(v) The manufacturer may also disable 

affected OBD monitors in systems 

designed to accommodate the 

installation of power take off (PTO) 

units provided monitors are disabled 

only while the PTO unit is active and 

the OBD readiness status (see paragraph 

(k)(4)(i) of this section) is cleared by the 

onboard computer (i.e., all monitors set 

to indicate ‘‘not complete’’ or ‘‘not 

ready’’) while the PTO unit is activated. 

If monitors are so disabled and when 

the disablement ends, the readiness 

status may be restored to its state prior 

to PTO activation. 

(6) Feedback control system 

monitoring. If the engine is equipped 

with feedback control of any of the 

systems covered in paragraphs (g), (h) 

and (i) of this section, then the OBD 

system must detect as malfunctions the 

conditions specified in this paragraph 

(i)(6) for each of the individual feedback 

controls. 

(i) The OBD system must detect when 

the system fails to begin feedback 

control within a manufacturer specified 

time interval. 

(ii) When any malfunction or 

deterioration causes open loop or limphome operation. 

(iii) When feedback control has used 

up all of the adjustment allowed by the 

manufacturer. 

(iv) A manufacturer may temporarily 

disable monitoring for malfunctions 

specified in paragraph (i)(6)(iii) of this 

section during conditions that the 

specific monitor cannot distinguish 

robustly between a malfunctioning 

system and a properly operating system. 

To do so, the manufacturer is required 

to submit data and/or engineering 

analyses demonstrating that the 

individual feedback control system, 

when operating as designed on an 

engine with all emission controls 

working properly, routinely operates 

during these conditions while having 

used up all of the adjustment allowed 

by the manufacturer. In lieu of 

detecting, with a system specific 

monitor, the malfunctions specified in 

paragraphs (i)(6)(i) and (i)(6)(ii) of this 

section the OBD system may monitor 

the individual parameters or 

components that are used as inputs for 

individual feedback control systems 

provided that the monitors detect all 

malfunctions that meet the criteria of 

paragraphs (i)(6)(i) and (i)(6)(ii) of this 

section. 

(a) Production evaluation testing. 

(1) [Reserved.] 

(2) Verification of monitoring 

requirements. 

(i) Within either the first six months 

of the start of engine production or the 

first three months of the start of vehicle 

production, whichever is later, the 

manufacturer must conduct a complete 

evaluation of the OBD system of one or 

more production vehicles (test vehicles) 

and submit the results of the evaluation 

to the Administrator. 

(ii) Selection of test vehicles. 

(A) For each engine selected for 

monitoring system demonstration in 

paragraph (l) of this section, the 

manufacturer must evaluate one 

production vehicle equipped with an 

engine from the same engine family and 

rating as the demonstration engine. The 

vehicle selection must be approved by 

the Administrator. 

(B) If the manufacturer is required to 

test more than one test vehicle, the 

manufacturer may test an engine in lieu 

of a vehicle for all but one of the 

required test vehicles. 

(C) The requirement for submittal of 

data from one or more of the test 

vehicles may be waived if data have 

been submitted previously for all of the 

engine ratings and variants. 

(iii) Evaluation requirements. 

(A) The evaluation must demonstrate 

the ability of the OBD system on the 

selected test vehicle to detect a 

malfunction, activate the MIL, and, 

where applicable, store an appropriate 

DTC readable by a scan tool when a 

malfunction is present and the 

monitoring conditions have been 

satisfied for each individual monitor 

required by this section. 

(B) The evaluation must verify that 

the malfunction of any component used 

to enable another OBD monitor but that 

does not itself result in MIL activation 

(e.g., fuel level sensor) will not inhibit 

the ability of other OBD monitors to 

detect malfunctions properly. 

(C) The evaluation must verify that 

the software used to track the numerator 

and denominator for the purpose of 

determining in-use monitoring 

frequency increments as required by 

paragraph (d)(2) of this section. 

(D) Malfunctions may be implanted 

mechanically or simulated 

electronically, but internal onboard 

computer hardware or software changes 

shall not be used to simulate 

malfunctions. For monitors that are 

required to indicate a malfunction 

before emissions exceed an emission 

threshold, manufacturers are not 

required to use malfunctioning 

components/systems set exactly at their 

malfunction criteria limits. Emission 

testing is not required to confirm that 

the malfunction is detected before the 

appropriate emission thresholds are 

exceeded. 

(E) The manufacturer must submit a 

proposed test plan for approval prior to 

performing evaluation testing. The test 

plan must identify the method used to 

induce a malfunction for each monitor. 

(F) If the demonstration of a specific 

monitor cannot be reasonably performed 

without causing physical damage to the 

test vehicle (e.g., onboard computer 

internal circuit malfunctions), the 


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manufacturer may omit the specific 

demonstration. 

(G) For evaluation of test vehicles 

selected in accordance with paragraph 

(j)(2)(ii) of this section, the manufacturer 

is not required to demonstrate monitors 

that were demonstrated prior to 

certification as required in paragraph (l) 

of this section. 

(iv) The manufacturer must submit a 

report of the results of all testing 

conducted as required by paragraph 

(j)(2) of this section. The report must 

identify the method used to induce a 

malfunction in each monitor, the MIL 

activation status, and the DTC(s) stored. 

(3) Verification of in-use monitoring 

performance ratios. 

(i) The manufacturer must collect and 

report in-use monitoring performance 

data representative of production 

vehicles (i.e., engine rating and chassis 

application combination). The 

manufacturer must collect and report 

the data to the Administrator within 12 

months after the first production vehicle 

was first introduced into commerce. 

(ii) The manufacturer must separate 

production vehicles into the monitoring 

performance groups and submit data 

that represents each of these groups. 

The groups shall be based on the 

following criteria: 

(A) Emission control system 

architecture. All engines that use the 

same or similar emissions control 

system architecture (e.g., EGR with DPF 

and SCR; EGR with DPF and NOX

adsorber; EGR with DPF-only) and 

associated monitoring system would be 

in the same emission architecture 

category. 

(B) Vehicle application type. Within 

an emission architecture category, 

engines shall be separated into one of 

three vehicle application types: engines 

intended primarily for line-haul chassis 

applications, engines intended 

primarily for urban delivery chassis 

applications, and all other engines. 

(iii) The manufacturer may use an 

alternative grouping method to collect 

representative data. To do so, the 

manufacturer must show that the 

alternative groups include production 

vehicles using similar emission 

controls, OBD strategies, monitoring 

condition calibrations, and vehicle 

application driving/usage patterns such 

that they are expected to have similar 

in-use monitoring performance. The 

manufacturer will still be required to 

submit one set of data for each of the 

alternative groups. 

(iv) For each monitoring performance 

group, the data must include all of the 

in-use performance tracking data (i.e., 

all numerators, denominators, the 

general denominator, and the ignition 

cycle counter), the date the data were 

collected, the odometer reading, the 

VIN, and the calibration ID. 

(v) The manufacturer must submit a 

plan to the Administrator that details 

the types of production vehicles in each 

monitoring performance group, the 

number of vehicles per group to be 

sampled, the sampling method, the 

timeline to collect the data, and the 

reporting format. The plan must provide 

for effective collection of data from, at 

least, 15 vehicles per monitoring 

performance group and provide for data 

that represent a broad range of 

temperature conditions. The plan shall 

not, by design, exclude or include 

specific vehicles in an attempt to collect 

data only from vehicles expected to 

have the highest in-use performance 

ratios. 

(vi) The 12 month deadline for 

reporting may be extended to 18 months 

if the manufacturer can show that the 

delay is justified. In such a case, an 

interim report of progress to date must 

be submitted within the 12 month 

deadline. 

(k) Standardization requirements. 

(1) Reference materials. The OBD 

system must conform with the following 

Society of Automotive Engineers (SAE) 

standards and/or the following 

International Standards Organization 

(ISO) standards. The following 

documents are incorporated by 

reference, see § 86.1: 

(i) SAE material. Copies of these 

materials may be obtained from the 

Society of Automotive Engineers, Inc., 

400 Commonwealth Drive, Warrendale, 

PA 15096–0001. 

(A) SAE J1930 ‘‘Electrical/Electronic 

Systems Diagnostic Terms, Definitions, 

Abbreviations, and Acronyms—

Equivalent to ISO/TR 15031–2:April 30, 

2002,’’ April 2002. 

(B) SAE J1939 ‘‘Recommended 

Practice for a Serial Control and 

Communications Vehicle Network’’ and 

the associated subparts included in SAE 

HS–1939, ‘‘Truck and Bus Control and 

Communications Network Standards 

Manual,’’ 2006 Edition. 

(C) [Reserved.] 

(D) SAE J1978 ‘‘OBD II Scan Tool—

Equivalent to ISO/DIS 15031–4: 

December 14, 2001,’’ April 2002. 

(E) SAE J1979 ‘‘E/E Diagnostic Test 

Modes—Equivalent to ISO/DIS 15031–

5:April 30, 2002,’’ April 2002. 

(F) SAE J2012 ‘‘Diagnostic Trouble 

Code Definitions—Equivalent to ISO/ 

DIS 15031–6:April 30, 2002,’’ April 

2002. 

(G) SAE J2403 ‘‘Medium/Heavy-Duty 

E/E Systems Diagnosis Nomenclature,’’

August 2004. 

(H) SAE J2534 ‘‘Recommended 

Practice for Pass-Thru Vehicle 

Reprogramming,’’ February 2002. 

(ii) ISO materials. Copies of these 

materials may be obtained from the 

International Organization for 

Standardization, Case Postale 56, CH–

1211 Geneva 20, Switzerland. 

(A) ISO 15765–4:2001 ‘‘Road 

Vehicles-Diagnostics on Controller Area 

Network (CAN)—Part 4: Requirements 

for emission-related systems,’’

December 2001. 

(2) The manufacturer defined data 

link connector must be accessible to a 

trained service technician. 

(3) [Reserved.] 

(4) Required emission related 

functions. The following functions must 

be implemented and must be accessible 

by, at a minimum, a manufacturer scan 

tool: 

(i) Ready status. The OBD system 

must indicate ‘‘complete’’ or ‘‘not 

complete’’ for each of the installed 

monitored components and systems 

identified in paragraphs (g), (h) with the 

exception of (h)(4), and (i)(3) of this 

section. All components or systems 

identified in paragraphs (h)(1), (h)(2), or 

(i)(3) of this section that are monitored 

continuously must always indicate 

‘‘complete.’’ Components or systems 

that are not subject to being monitored 

continuously must immediately indicate 

‘‘complete’’ upon the respective 

monitor(s) being executed fully and 

determining that the component or 

system is not malfunctioning. A 

component or system must also indicate 

‘‘complete’’ if, after the requisite 

number of decisions necessary for 

determining MIL status has been 

executed fully, the monitor indicates a 

malfunction of the component or 

system. The status for each of the 

monitored components or systems must 

indicate ‘‘not complete’’ whenever 

diagnostic memory has been cleared or 

erased by a means other than that 

allowed in paragraph (b) of this section. 

Normal vehicle shut down (i.e., key-off/ 

engine-off) shall not cause the status to 

indicate ‘‘not complete.’’

(A) The manufacturer may request 

that the ready status for a monitor be set 

to indicate ‘‘complete’’ without the 

monitor having completed if monitoring 

is disabled for a multiple number of 

drive cycles due to the continued 

presence of extreme operating 

conditions (e.g., cold ambient 

temperatures, high altitudes). Any such 

request must specify the conditions for 

monitoring system disablement and the 

number of drive cycles that would pass 

without monitor completion before 

ready status would be indicated as 

‘‘complete.’’


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(B) For the evaporative system 

monitor, the ready status must be set in 

accordance with this paragraph (k)(4)(i) 

when both the functional check of the 

purge valve and, if applicable, the leak 

detection monitor of the hole size 

specified in paragraph (h)(7)(ii)(B) of 

this section indicate that they are 

complete. 

(C) If the manufacturer elects to 

indicate ready status through the MIL in 

the key-on/engine-off position as 

provided for in paragraph (b)(1)(iii) of 

this section, the ready status must be 

indicated in the following manner: If the 

ready status for all monitored 

components or systems is ‘‘complete,’’

the MIL shall remain continuously 

activated in the key-on/engine-off 

position for at least 10–20 seconds. If 

the ready status for one or more of the 

monitored components or systems is 

‘‘not complete,’’ after at least 5 seconds 

of operation in the key-on/engine-off 

position with the MIL activated 

continuously, the MIL shall blink once 

per second for 5–10 seconds. The data 

stream value for MIL status as required 

in paragraph (k)(4)(ii) of this section 

must indicate ‘‘commanded off’’ during 

this sequence unless the MIL has also 

been ‘‘commanded on’’ for a detected 

malfunction. 

(ii) Data stream. The following signals 

must be made available on demand 

through the data link connector. The 

actual signal value must always be used 

instead of a limp home value. 

(A) For gasoline engines. 

(1) Calculated load value, engine 

coolant temperature, engine speed, 

vehicle speed, and time elapsed since 

engine start. 

(2) Absolute load, fuel level (if used 

to enable or disable any other monitors), 

barometric pressure (directly measured 

or estimated), engine control module 

system voltage, and commanded 

equivalence ratio. 

(3) Number of stored MIL-on DTCs, 

catalyst temperature (if directly 

measured or estimated for purposes of 

enabling the catalyst monitor(s)), 

monitor status (i.e., disabled for the rest 

of this drive cycle, complete this drive 

cycle, or not complete this drive cycle) 

since last engine shut-off for each 

monitor used for ready status, distance 

traveled (or engine run time for engines 

not using vehicle speed information) 

while MIL activated, distance traveled 

(or engine run time for engines not 

using vehicle speed information) since 

DTC memory last erased, and number of 

warm-up cycles since DTC memory last 

erased, OBD requirements to which the 

engine is certified (e.g., California OBD, 

EPA OBD, European OBD, non-OBD) 

and MIL status (i.e., commanded-on or 

commanded-off). 

(B) For diesel engines. 

(1) Calculated load (engine torque as 

a percentage of maximum torque 

available at the current engine speed), 

driver’s demand engine torque (as a 

percentage of maximum engine torque), 

actual engine torque (as a percentage of 

maximum engine torque), reference 

engine maximum torque, reference 

maximum engine torque as a function of 

engine speed (suspect parameter 

numbers (SPN) 539 through 543 defined 

by SAE J1939 within parameter group 

number (PGN) 65251 for engine 

configuration), engine coolant 

temperature, engine oil temperature (if 

used for emission control or any OBD 

monitors), engine speed, and time 

elapsed since engine start. 

(2) Fuel level (if used to enable or 

disable any other monitors), vehicle 

speed (if used for emission control or 

any OBD monitors), barometric pressure 

(directly measured or estimated), and 

engine control module system voltage. 

(3) Number of stored MIL-on DTCs, 

monitor status (i.e., disabled for the rest 

of this drive cycle, complete this drive 

cycle, or not complete this drive cycle) 

since last engine shut-off for each 

monitor used for ready status, distance 

traveled (or engine run time for engines 

not using vehicle speed information) 

while MIL activated, distance traveled 

(or engine run time for engines not 

using vehicle speed information) since 

DTC memory last erased, number of 

warm-up cycles since DTC memory last 

erased, OBD requirements to which the 

engine is certified (e.g., California OBD, 

EPA OBD, European OBD, non-OBD), 

and MIL status (i.e., commanded-on or 

commanded-off). 

(4) NOX NTE control area status (i.e., 

inside control area, outside control area, 

inside manufacturer-specific NOX NTE 

carve-out area, or deficiency active area) 

and PM NTE control area status (i.e., 

inside control area, outside control area, 

inside manufacturer-specific PM NTE 

carve-out area, or deficiency active 

area). 

(5) For purposes of the calculated load 

and torque parameters in paragraph 

(k)(4)(ii)(B)(1) of this section, 

manufacturers must report the most 

accurate values that are calculated 

within the applicable electronic control 

unit (e.g., the engine control module). 

Most accurate, in this context, must be 

of sufficient accuracy, resolution, and 

filtering to be used for the purposes of 

in-use emission testing with the engine 

still in a vehicle (e.g., using portable 

emission measurement equipment). 

(C) For all engines so equipped. 

(1) Absolute throttle position, relative 

throttle position, fuel control system 

status (e.g., open loop, closed loop), fuel 

trim, fuel pressure, ignition timing 

advance, fuel injection timing, intake 

air/manifold temperature, engine 

intercooler temperature, manifold 

absolute pressure, air flow rate from 

mass air flow sensor, secondary air 

status (upstream, downstream, or 

atmosphere), ambient air temperature, 

commanded purge valve duty cycle/ 

position, commanded EGR valve duty 

cycle/position, actual EGR valve duty 

cycle/position, EGR error between 

actual and commanded, PTO status 

(active or not active), redundant 

absolute throttle position (for electronic 

throttle or other systems that utilize two 

or more sensors), absolute pedal 

position, redundant absolute pedal 

position, commanded throttle motor 

position, fuel rate, boost pressure, 

commanded/target boost pressure, turbo 

inlet air temperature, fuel rail pressure, 

commanded fuel rail pressure, DPF inlet 

pressure, DPF inlet temperature, DPF 

outlet pressure, DPF outlet temperature, 

DPF delta pressure, exhaust pressure 

sensor output, exhaust gas temperature 

sensor output, injection control 

pressure, commanded injection control 

pressure, turbocharger/turbine speed, 

variable geometry turbo position, 

commanded variable geometry turbo 

position, turbocharger compressor inlet 

temperature, turbocharger compressor 

inlet pressure, turbocharger turbine inlet 

temperature, turbocharger turbine outlet 

temperature, waste gate valve position, 

and glow plug lamp status. 

(2) Oxygen sensor output, air/fuel 

ratio sensor output, NOX sensor output, 

and evaporative system vapor pressure. 

(iii) Freeze frame. 

(A) ‘‘Freeze frame’’ information 

required to be stored pursuant to 

paragraphs (b)(2)(iv), (h)(1)(iv)(D), and 

(h)(2)(vi) of this section must be made 

available on demand through the data 

link connector. 

(B) ‘‘Freeze frame’’ conditions must 

include the DTC that caused the data to 

be stored along with all of the signals 

required in paragraphs (k)(4)(ii)(A)(1) or 

(k)(4)(ii)(B)(1) of this section. Freeze 

frame conditions must also include all 

of the signals required on the engine in 

paragraphs (k)(4)(ii)(A)(2) and 

(k)(4)(ii)(B)(2) of this section, and 

paragraph (k)(4)(ii)(C)(1) of this section 

that are used for diagnostic or control 

purposes in the specific monitor or 

emission-critical powertrain control 

unit that stored the DTC. 

(C) Only one frame of data is required 

to be recorded. The manufacturer may 

choose to store additional frames 

provided that at least the required frame 


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can be read by, at a minimum, a 

manufacturer scan tool. 

(iv) Diagnostic trouble codes. 

(A) For all monitored components and 

systems, any stored pending, MIL-on, 

and previous-MIL-on DTCs must be 

made available through the diagnostic 

connector. 

(B) The stored DTC must, to the extent 

possible, pinpoint the probable cause of 

the malfunction or potential 

malfunction. To the extent feasible, the 

manufacturer must use separate DTCs 

for every monitor where the monitor 

and repair procedure or probable cause 

of the malfunction is different. In 

general, rationality and functional 

checks must use different DTCs than the 

respective circuit integrity checks. 

Additionally, input component circuit 

integrity checks must use different DTCs 

for distinct malfunctions (e.g., out-ofrange low, out-of-range high, open 

circuit). 

(C) The manufacturer must use 

appropriate standard-defined DTCs 

whenever possible. With Administrator 

approval, the manufacturer may use 

manufacturer-defined DTCs in 

accordance with the applicable 

standard’s specifications. To do so, the 

manufacturer must be able to show a 

lack of available standard-defined DTCs, 

uniqueness of the monitor or monitored 

component, expected future usage of the 

monitor or component, and estimated 

usefulness in providing additional 

diagnostic and repair information to 

service technicians. Manufacturerdefined DTCs must be used in a 

consistent manner (i.e., the same DTC 

shall not be used to represent two 

different failure modes) across a 

manufacturer’s entire product line. 

(D) A pending or MIL-on DTC (as 

required in paragraphs (g) through (i) of 

this section) must be stored and 

available to, at a minimum, a 

manufacturer scan tool within 10 

seconds after a monitor has determined 

that a malfunction or potential 

malfunction has occurred. A permanent 

DTC must be stored and available to, at 

a minimum, a manufacturer scan tool no 

later than the end of an ignition cycle 

in which the corresponding MIL-on 

DTC that caused MIL activation has 

been stored. 

(E) Pending DTCs for all components 

and systems (including those monitored 

continuously and non-continuously) 

must be made available through the 

diagnostic connector. A manufacturer 

using alternative statistical protocols for 

MIL activation as allowed in paragraph 

(b)(2)(iii) of this section must submit the 

details of their protocol for setting 

pending DTCs. The protocol must be, 

overall, equivalent to the requirements 

of this paragraph (k)(4)(iv)(E) and 

provide service technicians with a quick 

and accurate indication of a potential 

malfunction. 

(F) Permanent DTC for all 

components and systems must be made 

available through the diagnostic 

connector in a format that distinguishes 

permanent DTCs from pending DTCs, 

MIL-on DTCs, and previous-MIL-on 

DTCs. A MIL-on DTC must be stored as 

a permanent DTC no later than the end 

of the ignition cycle and subsequently at 

all times that the MIL-on DTC is 

commanding the MIL on. Permanent 

DTCs must be stored in non-volatile 

random access memory (NVRAM) and 

shall not be erasable by any scan tool 

command or by disconnecting power to 

the on-board computer. Permanent 

DTCs must be erasable if the engine 

control module is reprogrammed and 

the ready status described in paragraph 

(k)(4)(i) of this section for all monitored 

components and systems are set to ‘‘not 

complete.’’ The OBD system must have 

the ability to store a minimum of four 

current MIL-on DTCs as permanent 

DTCs in NVRAM. If the number of MILon DTCs currently commanding 

activation of the MIL exceeds the 

maximum number of permanent DTCs 

that can be stored, the OBD system must 

store the earliest detected MIL-on DTC 

as permanent DTC. If additional MIL-on 

DTCs are stored when the maximum 

number of permanent DTCs is already 

stored in NVRAM, the OBD system shall 

not replace any existing permanent DTC 

with the additional MIL-on DTCs. 

(v) Test results. 

(A) Except as provided for in 

paragraph (k)(4)(v)(G) of this section, for 

all monitored components and systems 

identified in paragraphs (g) and (h) of 

this section, results of the most recent 

monitoring of the components and 

systems and the test limits established 

for monitoring the respective 

components and systems must be stored 

and available through the data link. 

(B) The test results must be reported 

such that properly functioning 

components and systems (e.g., 

‘‘passing’’ systems) do not store test 

values outside of the established test 

limits. Test limits must include both 

minimum and maximum acceptable 

values and must be defined so that a test 

result equal to either test limit is a 

‘‘passing’’ value, not a ‘‘failing’’ value. 

(C) [Reserved.] 

(D) The test results must be stored 

until updated by a more recent valid test 

result or the DTC memory of the OBD 

system computer is cleared. Upon DTC 

memory being cleared, test results 

reported for monitors that have not yet 

completed with valid test results since 

the last time the fault memory was 

cleared must report values of zero for 

the test result and test limits. 

(E) All test results and test limits must 

always be reported and the test results 

must be stored until updated by a more 

recent valid test result or the DTC 

memory of the OBD system computer is 

cleared. 

(F) The OBD system must store and 

report unique test results for each 

separate monitor. 

(G) The requirements of this 

paragraph (k)(4)(v) do not apply to 

continuous fuel system monitoring, cold 

start emission reduction strategy 

monitoring, and continuous circuit 

monitoring. 

(vi) Software calibration identification 

(CAL ID). On all engines, a single 

software calibration identification 

number (CAL ID) for each monitor or 

emission critical control unit(s) must be 

made available through the data link 

connector. A unique CAL ID must be 

used for every emission-related 

calibration and/or software set having at 

least one bit of different data from any 

other emission-related calibration and/ 

or software set. Control units coded 

with multiple emission or diagnostic 

calibrations and/or software sets must 

indicate a unique CAL ID for each 

variant in a manner that enables an offboard device to determine which variant 

is being used by the vehicle. Control 

units that use a strategy that will result 

in MIL activation if the incorrect variant 

is used (e.g., control units that contain 

variants for manual and automatic 

transmissions but will activate the MIL 

if the selected variant does not match 

the type of transmission mated to the 

engine) are not required to use unique 

CAL IDs. 

(vii) Software calibration verification 

number (CVN). 

(A) All engines must use an algorithm 

to calculate a single calibration 

verification number (CVN) that verifies 

the on-board computer software 

integrity for each monitor or emission 

critical control unit that is electronically 

reprogrammable. The CVN must be 

made available through the data link 

connector. The CVN must indicate 

whether the emission-related software 

and/or calibration data are valid and 

applicable for the given vehicle and 

CAL ID. 

(B) The CVN algorithm used to 

calculate the CVN must be of sufficient 

complexity that the same CVN is 

difficult to achieve with modified 

calibration values. 

(C) The CVN must be calculated at 

least once per drive cycle and stored 

until the CVN is subsequently updated. 

Except for immediately after a 


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reprogramming event or a non-volatile 

memory clear or for the first 30 seconds 

of engine operation after a volatile 

memory clear or battery disconnect, the 

stored value must be made available 

through the data link connector to, at a 

minimum, a manufacturer scan tool. 

The stored CVN value shall not be 

erased when DTC memory is erased or 

during normal vehicle shut down (i.e., 

key-off/engine-off). 

(D) [Reserved.] 

(viii) Vehicle identification number 

(VIN). 

(A) All vehicles must have the vehicle 

identification number (VIN) available 

through the data link connector to, at a 

minimum, a manufacturer scan tool. 

Only one electronic control unit per 

vehicle may report the VIN to a scan 

tool. 

(B) If the VIN is reprogrammable, all 

emission-related diagnostic information 

identified in paragraph (k)(4)(ix)(A) of 

this section must be erased in 

conjunction with reprogramming of the 

VIN. 

(ix) Erasure of diagnostic information. 

(A) For purposes of this paragraph 

(k)(4)(ix), ‘‘emission-related diagnostic 

information’’ includes all of the 

following: ready status as required by 

paragraph (k)(4)(i) of this section; data 

stream information as required by 

paragraph (k)(4)(ii) of this section 

including the number of stored MIL-on 

DTCs, distance traveled while MIL 

activated, number of warm-up cycles 

since DTC memory last erased, and 

distance traveled since DTC memory 

last erased; freeze frame information as 

required by paragraph (k)(4)(iii) of this 

section; pending, MIL-on, and previousMIL-on DTCs as required by paragraph 

(k)(4)(iv) of this section; and, test results 

as required by paragraph (k)(4)(v) of this 

section. 

(B) For all engines, the emissionrelated diagnostic information must be 

erased if commanded by any scan tool 

and may be erased if the power to the 

on-board computer is disconnected. If 

any of the emission-related diagnostic 

information is commanded to be erased 

by any scan tool, all emission-related 

diagnostic information must be erased 

from all diagnostic or emission critical 

control units. The OBD system shall not 

allow a scan tool to erase a subset of the 

emission-related diagnostic information 

(e.g., the OBD system shall not allow a 

scan tool to erase only one of three 

stored DTCs or only information from 

one control unit without erasing 

information from the other control 

unit(s)). 

(5) In-use performance ratio tracking 

requirements. 

(i) For each monitor required in 

paragraphs (g) through (i) of this section 

to separately report an in-use 

performance ratio, manufacturers must 

implement software algorithms to report 

a numerator and denominator. 

(ii) For the numerator, denominator, 

general denominator, and ignition cycle 

counters required by paragraph (e) of 

this section, the following numerical 

value specifications apply: 

(A) Each number shall have a 

minimum value of zero and a maximum 

value of 65,535 with a resolution of one. 

(B) Each number shall be reset to zero 

only when a non-volatile random access 

memory (NVRAM) reset occurs (e.g., 

reprogramming event) or, if the numbers 

are stored in keep-alive memory (KAM), 

when KAM is lost due to an 

interruption in electrical power to the 

control unit (e.g., battery disconnect). 

Numbers shall not be reset to zero under 

any other circumstances including 

when a scan tool command to clear 

DTCs or reset KAM is received. 

(C) To avoid overflow problems, if 

either the numerator or denominator for 

a specific component reaches the 

maximum value of 65,535 ±2, both 

numbers shall be divided by two before 

either is incremented again. 

(D) To avoid overflow problems, if the 

ignition cycle counter reaches the 

maximum value of 65,535 ±2, the 

ignition cycle counter shall roll over 

and increment to zero on the next 

ignition cycle. 

(E) To avoid overflow problems, if the 

general denominator reaches the 

maximum value of 65,535 ±2, the 

general denominator shall roll over and 

increment to zero on the next drive 

cycle that meets the general 

denominator definition. 

(F) If a vehicle is not equipped with 

a component (e.g., oxygen sensor bank 

2, secondary air system), the 

corresponding numerator and 

denominator for that specific 

component shall always be reported as 

zero. 

(iii) For the ratio required by 

paragraph (e) of this section, the 

following numerical value 

specifications apply: 

(A) The ratio shall have a minimum 

value of zero and a maximum value of 

7.99527 with a resolution of 0.000122. 

(B) The ratio for a specific component 

shall be considered to be zero whenever 

the corresponding numerator is equal to 

zero and the corresponding 

denominator is not zero. 

(C) The ratio for a specific component 

shall be considered to be the maximum 

value of 7.99527 if the corresponding 

denominator is zero or if the actual 

value of the numerator divided by the 

denominator exceeds the maximum 

value of 7.99527. 

(6) Engine run time tracking 

requirements. 

(i) For all gasoline and diesel engines, 

the manufacturer must implement 

software algorithms to track and report 

individually the amount of time the 

engine has been operated in the 

following conditions: 

(A) Total engine run time. 

(B) Total idle run time (with ‘‘idle’’

defined as accelerator pedal released by 

the driver, vehicle speed less than or 

equal to one mile per hour, engine 

speed greater than or equal to 50 to 150 

rpm below the normal, warmed-up idle 

speed (as determined in the drive 

position for vehicles equipped with an 

automatic transmission), and power 

take-off not active). 

(C) Total run time with power take off 

active. 

(ii) For each counter specified in 

paragraph (k)(6)(i) of this section, the 

following numerical value 

specifications apply: 

(A) Each number shall be a four-byte 

value with a minimum value of zero, a 

resolution of one second per bit, and an 

accuracy of ± ten seconds per drive 

cycle. 

(B) Each number shall be reset to zero 

only when a non-volatile memory reset 

occurs (e.g., reprogramming event). 

Numbers shall not be reset to zero under 

any other circumstances including 

when a scan tool (generic or enhanced) 

command to clear fault codes or reset 

KAM is received. 

(C) To avoid overflow problems, if 

any of the individual counters reach the 

maximum value, all counters shall be 

divided by two before any are 

incremented again. 

(D) The counters shall be made 

available to, at a minimum, a 

manufacturer scan tool and may be 

rescaled when transmitted from a 

resolution of one second per bit to no 

more than three minutes per bit. 

(l) Monitoring system demonstration 

requirements for certification. 

(1) General. 

(i) The manufacturer must submit 

emissions test data from one or more 

durability demonstration test engines 

(test engines). 

(ii) The Administrator may approve 

other demonstration protocols if the 

manufacturer can provide comparable 

assurance that the malfunction criteria 

are chosen based on meeting the 

malfunction criteria requirements and 

that the timeliness of malfunction 

detection is within the constraints of the 

applicable monitoring requirements. 

(iii) For flexible fuel engines capable 

of operating on more than one fuel or 


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fuel combinations, the manufacturer 

must submit a plan for providing 

emission test data. The plan must 

demonstrate that testing will represent 

properly the expected in-use fuel or fuel 

combinations. 

(2) Selection of test engines. 

(i) Prior to submitting any 

applications for certification for a model 

year, the manufacturer must notify the 

Administrator regarding the planned 

engine families and engine ratings 

within each family for that model year. 

The Administrator will select the engine 

family(ies) and the specific engine 

rating within the engine family(ies) that 

the manufacturer shall use as 

demonstration test engines. The 

selection of test vehicles for production 

evaluation testing as specified in 

paragraph (j)(2) of this section may take 

place during this selection process. 

(ii) The manufacturer must provide 

emissions test data from the OBD parent 

rating as defined in paragraph (o)(1) of 

this section. 

(iii) For the test engine, the 

manufacturer must use an engine aged 

for a minimum of 125 hours fitted with 

exhaust aftertreatment emission controls 

aged to be representative of useful life 

aging. The manufacturer is required to 

submit a description of the accelerated 

aging process and/or supporting data. 

The process and/or data must 

demonstrate assurance that 

deterioration of the exhaust 

aftertreatment emission controls is 

stabilized sufficiently such that it 

represents emission control 

performance at the end of the useful life. 

(3) Required testing. Except as 

otherwise described in this paragraph 

(l)(3), the manufacturer must perform 

single malfunction testing based on the 

applicable test with the components/ 

systems set at their malfunction criteria 

limits as determined by the 

manufacturer for meeting the emissions 

thresholds required in paragraphs (g), 

(h), and (i) of this section. 

(i) Required testing for diesel-fueled/ 

compression ignition engines. 

(A) Fuel system. The manufacturer 

must perform a separate test for each 

malfunction limit established by the 

manufacturer for the fuel system 

parameters (e.g., fuel pressure, injection 

timing) specified in paragraphs 

(g)(1)(ii)(A) through (g)(1)(ii)(C) of this 

section. When performing a test for a 

specific parameter, the fuel system must 

be operating at the malfunction criteria 

limit for the applicable parameter only. 

All other parameters must be operating 

with normal characteristics. In 

conducting the fuel system 

demonstration tests, the manufacturer 

may use computer modifications to 

cause the fuel system to operate at the 

malfunction limit if the manufacturer 

can demonstrate that the computer 

modifications produce test results 

equivalent to an induced hardware 

malfunction. 

(B) [Reserved.] 

(C) EGR system. The manufacturer 

must perform a separate test for each 

malfunction limit established by the 

manufacturer for the EGR system 

parameters (e.g., low flow, high flow, 

slow response) specified in paragraphs 

(g)(3)(ii)(A) through (g)(3)(ii)(C) of this 

section and in (g)(3)(ii)(E) of this 

section. In conducting the EGR system 

slow response demonstration tests, the 

manufacturer may use computer 

modifications to cause the EGR system 

to operate at the malfunction limit if the 

manufacturer can demonstrate that the 

computer modifications produce test 

results equivalent to an induced 

hardware malfunction. 

(D) Turbo boost control system. The 

manufacturer must perform a separate 

test for each malfunction limit 

established by the manufacturer for the 

turbo boost control system parameters 

(e.g., underboost, overboost, response) 

specified in paragraphs (g)(4)(ii)(A) 

through (g)(4)(ii)(C) of this section and 

in (g)(4)(ii)(E) of this section. 

(E) NMHC catalyst. The manufacturer 

must perform a separate test for each 

monitored NMHC catalyst(s). The 

catalyst(s) being evaluated must be 

deteriorated to the applicable 

malfunction limit established by the 

manufacturer for the monitoring 

required by paragraph (g)(5)(ii)(A) of 

this section and using methods 

established by the manufacturer in 

accordance with paragraph (l)(7) of this 

section. For each monitored NMHC 

catalyst(s), the manufacturer must also 

demonstrate that the OBD system will 

detect a catalyst malfunction with the 

catalyst at its maximum level of 

deterioration (i.e., the substrate(s) 

completely removed from the catalyst 

container or ‘‘empty’’ can). Emissions 

data are not required for the empty can 

demonstration. 

(F) NOX catalyst. The manufacturer 

must perform a separate test for each 

monitored NOX catalyst(s) (e.g., SCR 

catalyst). The catalyst(s) being evaluated 

must be deteriorated to the applicable 

malfunction criteria established by the 

manufacturer for the monitoring 

required by paragraphs (g)(6)(ii)(A) and 

(g)(6)(ii)(B) of this section and using 

methods established by the 

manufacturer in accordance with 

paragraph (l)(7) of this section. For each 

monitored NOX catalyst(s), the 

manufacturer must also demonstrate 

that the OBD system will detect a 

catalyst malfunction with the catalyst at 

its maximum level of deterioration (i.e., 

the substrate(s) completely removed 

from the catalyst container or ‘‘empty’’

can). Emissions data are not required for 

the empty can demonstration. 

(G) NOX adsorber. The manufacturer 

must perform a test using a NOX

adsorber(s) deteriorated to the 

applicable malfunction limit established 

by the manufacturer for the monitoring 

required by paragraph (g)(7)(ii)(A) of 

this section. The manufacturer must 

also demonstrate that the OBD system 

will detect a NOX adsorber malfunction 

with the NOX adsorber at its maximum 

level of deterioration (i.e., the 

substrate(s) completely removed from 

the container or ‘‘empty’’ can). 

Emissions data are not required for the 

empty can demonstration. 

(H) Diesel particulate filter. The 

manufacturer must perform a separate 

test using a DPF deteriorated to the 

applicable malfunction limits 

established by the manufacturer for the 

monitoring required by paragraphs 

(g)(8)(ii)(A), (g)(8)(ii)(B), and (g)(8)(ii)(D) 

of this section. The manufacturer must 

also demonstrate that the OBD system 

will detect a DPF malfunction with the 

DPF at its maximum level of 

deterioration (i.e., the filter(s) 

completely removed from the filter 

container or ‘‘empty’’ can). Emissions 

data are not required for the empty can 

demonstration. 

(I) Exhaust gas sensor. The 

manufacturer must perform a separate 

test for each malfunction limit 

established by the manufacturer for the 

monitoring required in paragraphs 

(g)(9)(ii)(A), (g)(9)(iii)(A), and 

(g)(9)(iv)(A) of this section. When 

performing a test, all exhaust gas 

sensors used for the same purpose (e.g., 

for the same feedback control loop, for 

the same control feature on parallel 

exhaust banks) must be operating at the 

malfunction criteria limit for the 

applicable parameter only. All other 

exhaust gas sensor parameters must be 

operating with normal characteristics. 

(J) VVT system. The manufacturer 

must perform a separate test for each 

malfunction limit established by the 

manufacturer for the monitoring 

required in paragraphs (g)(10)(ii)(A) and 

(g)(10)(ii)(B) of this section. In 

conducting the VVT system 

demonstration tests, the manufacturer 

may use computer modifications to 

cause the VVT system to operate at the 

malfunction limit if the manufacturer 

can demonstrate that the computer 

modifications produce test results 

equivalent to an induced hardware 

malfunction. 


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(K) For each of the testing 

requirements of this paragraph (l)(3)(i), 

if the manufacturer has established that 

only a functional check is required 

because no failure or deterioration of the 

specific tested system could result in an 

engine’s emissions exceeding the 

applicable emissions thresholds, the 

manufacturer is not required to perform 

a demonstration test; however, the 

manufacturer is required to provide the 

data and/or engineering analysis used to 

determine that only a functional test of 

the system(s) is required. 

(ii) Required testing for gasolinefueled/spark-ignition engines. 

(A) Fuel system. For engines with 

adaptive feedback based on the primary 

fuel control sensor(s), the manufacturer 

must perform a test with the adaptive 

feedback based on the primary fuel 

control sensor(s) at the rich limit(s) and 

a test at the lean limit(s) established by 

the manufacturer as required by 

paragraph (h)(1)(ii)(A) of this section to 

detect a malfunction before emissions 

exceed applicable emissions thresholds. 

For engines with feedback based on a 

secondary fuel control sensor(s) and 

subject to the malfunction criteria in 

paragraph (h)(1)(ii)(A) of this section, 

the manufacturer must perform a test 

with the feedback based on the 

secondary fuel control sensor(s) at the 

rich limit(s) and a test at the lean 

limit(s) established by the manufacturer 

as required by paragraph (h)(1)(ii)(A) of 

this section to detect a malfunction 

before emissions exceed the applicable 

emissions thresholds. For other fuel 

metering or control systems, the 

manufacturer must perform a test at the 

criteria limit(s). For purposes of fuel 

system testing as required by this 

paragraph (l)(3)(ii)(A), the 

malfunction(s) induced may result in a 

uniform distribution of fuel and air 

among the cylinders. Non uniform 

distribution of fuel and air used to 

induce a malfunction shall not cause 

misfire. In conducting the fuel system 

demonstration tests, the manufacturer 

may use computer modifications to 

cause the fuel system to operate at the 

malfunction limit. To do so, the 

manufacturer must be able to 

demonstrate that the computer 

modifications produce test results 

equivalent to an induced hardware 

malfunction. 

(B) Misfire. The manufacturer must 

perform a test at the malfunction criteria 

limit specified in paragraph (h)(2)(ii)(B) 

of this section. 

(C) EGR system. The manufacturer 

must perform a test at each flow limit 

calibrated to the malfunction criteria 

specified in paragraphs (h)(3)(ii)(A) and 

(h)(3)(ii)(B) of this section. 

(D) Cold start emission reduction 

strategy. The manufacturer must 

perform a test at the malfunction criteria 

for each component monitored 

according to paragraph (h)(4)(ii)(A) of 

this section. 

(E) Secondary air system. The 

manufacturer must perform a test at 

each flow limit calibrated to the 

malfunction criteria specified in 

paragraphs (h)(5)(ii)(A) and (h)(5)(ii)(B) 

of this section. 

(F) Catalyst. The manufacturer must 

perform a test using a catalyst system 

deteriorated to the malfunction criteria 

specified in paragraph (h)(6)(ii) of this 

section using methods established by 

the manufacturer in accordance with 

paragraph (l)(7)(ii) of this section. The 

manufacturer must also demonstrate 

that the OBD system will detect a 

catalyst system malfunction with the 

catalyst system at its maximum level of 

deterioration (i.e., the substrate(s) 

completely removed from the catalyst 

container or ‘‘empty’’ can). Emission 

data are not required for the empty can 

demonstration. 

(G) Exhaust gas sensor. The 

manufacturer must perform a test with 

all primary exhaust gas sensors used for 

fuel control simultaneously possessing a 

response rate deteriorated to the 

malfunction criteria limit specified in 

paragraph (h)(8)(ii)(A) of this section. 

The manufacturer must also perform a 

test for any other primary or secondary 

exhaust gas sensor parameter under 

parargraphs (h)(8)(ii)(A) and 

(h)(8)(iii)(A) of this section that can 

cause engine emissions to exceed the 

applicable emissions thresholds (e.g., 

shift in air/fuel ratio at which oxygen 

sensor switches, decreased amplitude). 

When performing additional test(s), all 

primary and secondary (if applicable) 

exhaust gas sensors used for emission 

control must be operating at the 

malfunction criteria limit for the 

applicable parameter only. All other 

primary and secondary exhaust gas 

sensor parameters must be operating 

with normal characteristics. 

(H) VVT system. The manufacturer 

must perform a test at each target error 

limit and slow response limit calibrated 

to the malfunction criteria specified in 

(h)(9)(ii)(A) and (h)(9)(ii)(B) of this 

section. In conducting the VVT system 

demonstration tests, the manufacturer 

may use computer modifications to 

cause the VVT system to operate at the 

malfunction limit. To do so, the 

manufacturer must be able to 

demonstrate that the computer 

modifications produce test results 

equivalent to an induced hardware 

malfunction. 

(I) For each of the testing 

requirements of this paragraph (l)(3)(ii), 

if the manufacturer has established that 

only a functional check is required 

because no failure or deterioration of the 

specific tested system could cause an 

engine’s emissions to exceed the 

applicable emissions thresholds, the 

manufacturer is not required to perform 

a demonstration test; however the 

manufacturer is required to provide the 

data and/or engineering analyses used 

to determine that only a functional test 

of the system(s) is required. 

(iii) Required testing for all engines. 

(A) Other emission control systems. 

The manufacturer must conduct 

demonstration tests for all other 

emission control components (e.g., 

hydrocarbon traps, adsorbers) designed 

and calibrated to a malfunction limit 

based on an emissions threshold based 

on the requirements of paragraph (i)(4) 

of this section. 

(B) For each of the testing 

requirements of paragraph (l)(3)(iii)(A) 

of this section, if the manufacturer has 

established that only a functional check 

is required because no failure or 

deterioration of the specific tested 

system could result in an engine’s 

emissions exceeding the applicable 

emissions thresholds, the manufacturer 

is not required to perform a 

demonstration test; however, the 

manufacturer is required to provide the 

data and/or engineering analysis used to 

determine that only a functional test of 

the system(s) is required. 

(iv) The manufacturer may 

electronically simulate deteriorated 

components but shall not make any 

engine control unit modifications when 

performing demonstration tests unless 

approved by the Administrator. All 

equipment necessary to duplicate the 

demonstration test must be made 

available to the Administrator upon 

request. 

(4) Testing protocol. 

(i) Preconditioning. The manufacturer 

must use an applicable cycle for 

preconditioning test engines prior to 

conducting each of the emission tests 

required by paragraph (l)(3) of this 

section. The manufacturer may perform 

a single additional preconditioning 

cycle, identical to the initial one, after 

a 20 minute hot soak but must 

demonstrate that such an additional 

cycle is necessary to stabilize the 

emissions control system. A practice of 

requiring a cold soak prior to 

conducting preconditioning cycles is 

not permitted. 

(ii) Test sequence. 

(A) The manufacturer must set 

individually each system or component 

on the test engine at the malfunction 


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criteria limit prior to conducting the 

applicable preconditioning cycle(s). If a 

second preconditioning cycle is 

permitted in accordance with paragraph 

(l)(4)(i) of this section, the manufacturer 

may adjust the system or component to 

be tested before conducting the second 

preconditioning cycle. The 

manufacturer shall not replace, modify, 

or adjust the system or component after 

the last preconditioning cycle has been 

completed. 

(B) After preconditioning, the test 

engine must be operated over the 

applicable cycle to allow for the initial 

detection of the tested system or 

component malfunction. This test cycle 

may be omitted from the testing 

protocol if it is unnecessary. If required 

by the monitoring strategy being tested, 

a cold soak may be performed prior to 

conducting this test cycle. 

(C) The test engine must then be 

operated over the applicable exhaust 

emissions test. 

(iii) [Reserved.] 

(iv) The manufacturer may request 

approval to use an alternative testing 

protocol for demonstration of MIL 

activation if the engine dynamometer 

emission test cycle does not allow all of 

a given monitor’s enable conditions to 

be satisfied. The manufacturer may 

request the use of an alternative engine 

dynamometer test cycle or the use of 

chassis testing to demonstrate proper 

MIL activation. To do so, the 

manufacturer must demonstrate the 

technical necessity for using an 

alternative test cycle and the degree to 

which the alternative test cycle 

demonstrates that in-use operation with 

the malfunctioning component will 

result in proper MIL activation. 

(5) Evaluation protocol. Full OBD 

engine ratings, as defined by paragraph 

(o)(1) of this section, shall be evaluated 

according to the following protocol: 

(i) For all tests conducted as required 

by paragraph (l) of this section, the MIL 

must activate before the end of the first 

engine start portion of the applicable 

test. 

(ii) If the MIL activates prior to 

emissions exceeding the applicable 

malfunction criteria limits specified in 

paragraphs (g) through (i) of this section, 

no further demonstration is required. 

With respect to the misfire monitor 

demonstration test, if the manufacturer 

has elected to use the minimum misfire 

malfunction criteria of one percent as 

allowed in paragraph (h)(2)(ii)(B) of this 

section, no further demonstration is 

required provided the MIL activates 

with engine misfire occurring at the 

malfunction criteria limit. 

(iii) If the MIL does not activate when 

the system or component is set at its 

malfunction criteria limit(s), the criteria 

limit(s) or the OBD system is not 

acceptable. 

(A) Except for testing of the catalyst 

or DPF system, if the MIL first activates 

after emissions exceed the applicable 

malfunction criteria specified in 

paragraphs (g) through (i) of this section, 

the test engine shall be retested with the 

tested system or component adjusted so 

that the MIL will activate before 

emissions exceed the applicable 

malfunction criteria specified in 

paragraphs (g) through (i) of this section. 

If the component cannot be so adjusted 

because an alternative fuel or emission 

control strategy is used when a 

malfunction is detected (e.g., open loop 

fuel control used after an oxygen sensor 

malfunction is detected), the test engine 

shall be retested with the component 

adjusted to the worst acceptable limit 

(i.e., the applicable OBD monitor 

indicates that the component is 

performing at or slightly better than the 

malfunction criteria limit). When tested 

with the component so adjusted, the 

MIL must not activate during the test 

and the engine emissions must be below 

the applicable malfunction criteria 

specified in paragraphs (g) through (i) of 

this section. 

(B) In testing the catalyst or DPF 

system, if the MIL first activates after 

emissions exceed the applicable 

emissions threshold(s) specified in 

paragraphs (g) and (h) of this section, 

the tested engine shall be retested with 

a less deteriorated catalyst or DPF 

system (i.e., more of the applicable 

engine out pollutants are converted or 

trapped). For the OBD system to be 

approved, testing shall be continued 

until the MIL activates with emissions 

below the applicable thresholds of 

paragraphs (g) and (h) of this section, or 

the MIL activates with emissions within 

a range no more than 20 percent below 

the applicable emissions thresholds and 

10 percent or less above those emissions 

thresholds. 

(iv) If an OBD system is determined 

to be unacceptable by the criteria of this 

paragraph (l)(5) of this section, the 

manufacturer may recalibrate and retest 

the system on the same test engine. In 

such a case, the manufacturer must 

confirm, by retesting, that all systems 

and components that were tested prior 

to the recalibration and are affected by 

it still function properly with the 

recalibrated OBD system. 

(6) Confirmatory testing. 

(i) The Administrator may perform 

confirmatory testing to verify the 

emission test data submitted by the 

manufacturer as required by this 

paragraph (l) of this section comply 

with its requirements and the 

malfunction criteria set forth in 

paragraphs (g) through (i) of this section. 

Such confirmatory testing is limited to 

the test engine required by paragraph 

(l)(2) of this section. 

(ii) To conduct this confirmatory 

testing, the Administrator may install 

appropriately deteriorated or 

malfunctioning components (or 

simulate them) in an otherwise properly 

functioning test engine of an engine 

rating represented by the demonstration 

test engine in order to test any of the 

components or systems required to be 

tested by paragraph (l) of this section. 

The manufacturer shall make available, 

if requested, an engine and all test 

equipment (e.g., malfunction simulators, 

deteriorated components) necessary to 

duplicate the manufacturer’s testing. 

Such a request from the Administrator 

shall occur within six months of 

reviewing and approving the 

demonstration test engine data 

submitted by the manufacturer for the 

specific engine rating. 

(7) Catalyst aging. 

(i) Diesel catalysts. For purposes of 

determining the catalyst malfunction 

limits for the monitoring required by 

paragraphs (g)(5)(ii)(A), (g)(5)(ii)(B), and 

(g)(6)(ii)(A) of this section, where those 

catalysts are monitored individually, the 

manufacturer must use a catalyst 

deteriorated to the malfunction criteria 

using methods established by the 

manufacturer to represent real world 

catalyst deterioration under normal and 

malfunctioning engine operating 

conditions. For purposes of determining 

the catalyst malfunction limits for the 

monitoring required by paragraphs 

(g)(5)(ii)(A), (g)(5)(ii)(B), and (g)(6)(ii)(A) 

of this section, where those catalysts are 

monitored in combination with other 

catalysts, the manufacturer must submit 

their catalyst system aging and 

monitoring plan to the Administrator as 

part of their certification documentation 

package. The plan must include the 

description, emission control purpose, 

and location of each component, the 

monitoring strategy for each component 

and/or combination of components, and 

the method for determining the 

applicable malfunction criteria 

including the deterioration/aging 

process. 

(ii) Gasoline catalysts. For the 

purposes of determining the catalyst 

system malfunction criteria in 

paragraph (h)(6)(ii) of this section, the 

manufacturer must use a catalyst system 

deteriorated to the malfunction criteria 

using methods established by the 

manufacturer to represent real world 

catalyst deterioration under normal and 

malfunctioning operating conditions. 

The malfunction criteria must be 


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established by using a catalyst system 

with all monitored and unmonitored 

(downstream of the sensor utilized for 

catalyst monitoring) catalysts 

simultaneously deteriorated to the 

malfunction criteria except for those 

engines that use fuel shutoff to prevent 

over-fueling during engine misfire 

conditions. For such engines, the 

malfunction criteria must be established 

by using a catalyst system with all 

monitored catalysts simultaneously 

deteriorated to the malfunction criteria 

while unmonitored catalysts shall be 

deteriorated to the end of the engine’s 

useful life. 

(m) Certification documentation 

requirements. 

(1) When submitting an application 

for certification of an engine, the 

manufacturer must submit the following 

documentation. If any of the items listed 

here are standardized for all of the 

manufacturer’s engines, the 

manufacturer may, for each model year, 

submit one set of documents covering 

the standardized items for all of its 

engines. 

(i) For the required documentation 

that is not standardized across all 

engines, the manufacturer may be 

allowed to submit documentation for 

certification from one engine that is 

representative of other engines. All such 

engines shall be considered to be part of 

an OBD certification documentation 

group. To represent the OBD group, the 

chosen engine must be certified to the 

most stringent emissions standards and 

OBD monitoring requirements and cover 

all of the emissions control devices for 

the engines in the group and covered by 

the submitted documentation. Such 

OBD groups must be approved in 

advance of certification. 

(ii) Upon approval, one or more of the 

documentation requirements of this 

paragraph (m) of this section may be 

waived or modified if the information 

required is redundant or unnecessarily 

burdensome to generate. 

(iii) To the extent possible, the 

certification documentation must use 

SAE J1930 or J2403 terms, 

abbreviations, and acronyms. 

(2) Unless otherwise specified, the 

following information must be 

submitted as part of the certification 

application and prior to receiving a 

certificate. 

(i) A description of the functional 

operation of the OBD system including 

a complete written description for each 

monitoring strategy that outlines every 

step in the decision-making process of 

the monitor. Algorithms, diagrams, 

samples of data, and/or other graphical 

representations of the monitoring 

strategy shall be included where 

necessary to adequately describe the 

information. 

(ii) A table including the following 

information for each monitored 

component or system (either computersensed or computer-controlled) of the 

emissions control system: 

(A) Corresponding diagnostic trouble 

code. 

(B) Monitoring method or procedure 

for malfunction detection. 

(C) Primary malfunction detection 

parameter and its type of output signal. 

(D) Malfunction criteria limits used to 

evaluate output signal of primary 

parameter. 

(E) Other monitored secondary 

parameters and conditions (in 

engineering units) necessary for 

malfunction detection. 

(F) Monitoring time length and 

frequency of monitoring events. 

(G) Criteria for storing a diagnostic 

trouble code. 

(H) Criteria for activating a 

malfunction indicator light. 

(I) Criteria used for determining outof-range values and input component 

rationality checks. 

(iii) Whenever possible, the table 

required by paragraph (m)(2)(ii) of this 

section shall use the following 

engineering units: 

(A) Degrees Celsius for all 

temperature criteria. 

(B) KiloPascals (KPa) for all pressure 

criteria related to manifold or 

atmospheric pressure. 

(C) Grams (g) for all intake air mass 

criteria. 

(D) Pascals (Pa) for all pressure 

criteria related to evaporative system 

vapor pressure. 

(E) Miles per hour (mph) for all 

vehicle speed criteria. 

(F) Relative percent (%) for all relative 

throttle position criteria (as defined in 

SAE J1979/J1939). 

(G) Voltage (V) for all absolute throttle 

position criteria (as defined in SAE 

J1979/J1939). 

(H) Per crankshaft revolution (/rev) for 

all changes per ignition event based 

criteria (e.g., g/rev instead of g/stroke or 

g/firing). 

(I) Per second (/sec) for all changes 

per time based criteria (e.g., g/sec). 

(J) Percent of nominal tank volume 

(%) for all fuel tank level criteria. 

(iv) A logic flowchart describing the 

step-by-step evaluation of the enable 

criteria and malfunction criteria for each 

monitored emission related component 

or system. 

(v) Emissions test data, a description 

of the testing sequence (e.g., the number 

and types of preconditioning cycles), 

approximate time (in seconds) of MIL 

activation during the test, diagnostic 

trouble code(s) and freeze frame 

information stored at the time of 

detection, corresponding test results 

(e.g. SAE J1979 Mode/Service $06, SAE 

J1939 Diagnostic Message 8 (DM8)) 

stored during the test, and a description 

of the modified or deteriorated 

components used for malfunction 

simulation with respect to the 

demonstration tests specified in 

paragraph (l) of this section. The freeze 

frame data are not required for engines 

subject to paragraph (o)(2) of this 

section. 

(vi) For gasoline engines, data 

supporting the misfire monitor, 

including: 

(A) The established percentage of 

misfire that can be tolerated without 

damaging the catalyst over the full range 

of engine speed and load conditions. 

(B) Data demonstrating the probability 

of detection of misfire events by the 

misfire monitoring system over the full 

engine speed and load operating range 

for the following misfire patterns: 

random cylinders misfiring at the 

malfunction criteria established in 

paragraph (h)(2)(ii)(B) of this section, 

one cylinder continuously misfiring, 

and paired cylinders continuously 

misfiring. 

(C) Data identifying all disablement of 

misfire monitoring that occurs during 

the FTP. For every disablement that 

occurs during the cycles, the data shall 

identify: when the disablement occurred 

relative to the driver’s trace, the number 

of engine revolutions during which each 

disablement was present, and which 

disable condition documented in the 

certification application caused the 

disablement. 

(D) Manufacturers are not required to 

use the durability demonstration engine 

to collect the misfire data required by 

paragraph (m)(2)(vi) of this section. 

(vii) Data supporting the limit for the 

time between engine starting and 

attaining the designated heating 

temperature for after-start heated 

catalyst systems. 

(viii) Data supporting the criteria used 

to detect a malfunction of the fuel 

system, EGR system, boost pressure 

control system, catalyst, NOX adsorber, 

DPF, cold start emission reduction 

strategy, secondary air, evaporative 

system, VVT system, exhaust gas 

sensors, and other emission controls 

that causes emissions to exceed the 

applicable malfunction criteria specified 

in paragraphs (g) through (i) of this 

section. For diesel engine monitors 

required by paragraphs (g) and (i) of this 

section that are required to indicate a 

malfunction before emissions exceed an 

emission threshold based on any 

applicable standard (e.g., 2.5 times any 


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of the applicable standards), the test 

cycle and standard determined by the 

manufacturer to be the most stringent 

for each applicable monitor in 

accordance with paragraph (f)(1) of this 

section. 

(ix) A list of all electronic powertrain 

input and output signals (including 

those not monitored by the OBD system) 

that identifies which signals are 

monitored by the OBD system. For input 

and output signals that are monitored as 

comprehensive components, the listing 

shall also identify the specific 

diagnostic trouble code for each 

malfunction criteria (e.g., out-of-range 

low, out-of-range high, open circuit, 

rationality low, rationality high). 

(x) A written description of all 

parameters and conditions necessary to 

begin closed-loop/feedback control of 

emission control systems (e.g., fuel 

system, boost pressure, EGR flow, SCR 

reductant delivery, DPF regeneration, 

fuel system pressure). 

(xi) A written identification of the 

communication protocol utilized by 

each engine for communication with a 

scan tool. 

(xii) Reserved. 

(xiii) A written description of the 

method used by the manufacturer to 

meet the requirements of paragraph 

(i)(2) of this section (crankcase 

ventilation system monitoring) 

including diagrams or pictures of valve 

and/or hose connections. 

(xiv) Build specifications provided to 

engine purchasers or chassis 

manufacturers detailing all 

specifications or limitations imposed on 

the engine purchaser relevant to OBD 

requirements or emissions compliance 

(e.g., cooling system heat rejection 

rates). A description of the method or 

copies of agreements used to ensure 

engine purchasers or chassis 

manufacturers will comply with the 

OBD and emissions relevant build 

specifications (e.g., signed agreements, 

required audit/evaluation procedures). 

(xv) Any other information 

determined by the Administrator to be 

necessary to demonstrate compliance 

with the requirements of this section. 

(n) Deficiencies. 

(1) Upon application by the 

manufacturer, the Administrator may 

accept an OBD system as compliant 

even though specific requirements are 

not fully met. Such compliances 

without meeting specific requirements, 

or deficiencies, will be granted only if 

compliance is infeasible or 

unreasonable considering such factors 

as, but not limited to: technical 

feasibility of the given monitor and lead 

time and production cycles including 

phase-in or phase-out of engines or 

vehicle designs and programmed 

upgrades of computers. Unmet 

requirements shall not be carried over 

from the previous model year except 

where unreasonable hardware or 

software modifications are necessary to 

correct the deficiency, and the 

manufacturer has demonstrated an 

acceptable level of effort toward 

compliance as determined by the 

Administrator. Furthermore, EPA will 

not accept any deficiency requests that 

include the complete lack of a major 

diagnostic monitor (‘‘major’’ diagnostic 

monitors being those for exhaust 

aftertreatment devices, oxygen sensor, 

air-fuel ratio sensor, NOX sensor, engine 

misfire, evaporative leaks, and diesel 

EGR, if equipped), with the possible 

exception of the special provisions for 

alternative fueled engines. For 

alternative fueled heavy-duty engines 

(e.g. natural gas, liquefied petroleum 

gas, methanol, ethanol), manufacturers 

may request the Administrator to waive 

specific monitoring requirements of this 

section for which monitoring may not 

be reliable with respect to the use of the 

alternative fuel. At a minimum, 

alternative fuel engines must be 

equipped with an OBD system meeting 

OBD requirements to the extent feasible 

as approved by the Administrator. 

(2) In the event the manufacturer 

seeks to carry-over a deficiency from a 

past model year to the current model 

year, the manufacturer must re-apply for 

approval to do so. In considering the 

request to carry-over a deficiency, the 

Administrator shall consider the 

manufacturer’s progress towards 

correcting the deficiency. The 

Administrator may not allow 

manufacturers to carry over monitoring 

system deficiencies for more than two 

model years unless it can be 

demonstrated that substantial engine 

hardware modifications and additional 

lead time beyond two years are 

necessary to correct the deficiency. 

(3) A deficiency shall not be granted 

retroactively (i.e., after the engine has 

been certified). 

(o) Implementation schedule. Except 

as provided for in paragraphs (o)(4) and 

(o)(5) of this section, the requirements of 

this section must be met according to 

the following provisions: 

(1) Full OBD. The manufacturer must 

implement an OBD system meeting the 

requirements of this section on one 

engine rating within one engine family 

of the manufacturer’s product line. This 

‘‘full OBD’’ rating will be known as the 

‘‘OBD parent’’ rating. The OBD parent 

rating must be chosen as the rating 

having the highest weighted projected 

U.S. sales within the engine family 

having the highest weighted projected 

U.S. sales, with U.S. sales being 

weighted by the useful life of the engine 

rating. 

(2) Extrapolated OBD. For all other 

engine ratings within the engine family 

from which the OBD parent rating has 

been selected, the manufacturer must 

implement an OBD system meeting the 

requirements of this section except that 

the OBD system is not required to detect 

a malfunction prior to exceeding the 

emission thresholds shown in Table 1 of 

paragraph (g) of this section and Table 

2 of paragraph (h) of this section. These 

extrapolated OBD engines will be 

known as the ‘‘OBD child’’ ratings. On 

these OBD child ratings, rather than 

detecting a malfunction prior to 

exceeding the emission thresholds, the 

manufacturer must submit a plan for 

Administrator review and approval that 

details the engineering evaluation the 

manufacturer will use to establish the 

malfunction criteria for the OBD child 

ratings. The plan must demonstrate both 

the use of good engineering judgment in 

establishing the malfunction criteria, 

and robust detection of malfunctions, 

including consideration of differences of 

base engine, calibration, emission 

control components, and emission 

control strategies. 

(3) Engine families other than those 

from which the parent and child ratings 

have been selected are not subject to the 

requirements of this section. 

(4) Small volume manufacturers, as 

defined in § 86.094–14(b)(1) and (2), are 

exempt from the requirements of 

§ 86.010–18. 

(5) Engines certified as alternative 

fueled engines are exempt from the 

requirements of § 86.010–18. 

(p) In-use compliance standards. For 

monitors required to indicate a 

malfunction before emissions exceed a 

certain emission threshold (e.g., 2.5 

times any of the applicable standards): 

(1) On the full OBD rating (i.e., the 

parent rating) as defined in paragraph 

(o)(1) of this section, separate in-use 

emissions thresholds shall apply. These 

thresholds are determined by doubling 

the applicable thresholds as shown in 

Table 1 of paragraph (g) and Table 2 of 

paragraph (h) of this section. The 

resultant thresholds apply only in-use 

and do not apply for certification or 

selective enforcement auditing. 

(2) The extrapolated OBD ratings (i.e., 

the child ratings) as defined in 

paragraph (o)(2) of this section shall not 

be evaluated against emissions levels for 

purposes of OBD compliance in-use. 

(3) Only the test cycle and standard 

determined and identified by the 

manufacturer at the time of certification 

in accordance with paragraph (f) of this 

section as the most stringent shall be 


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used for the purpose of determining 

OBD system noncompliance in-use. 

(4) An OBD system shall not be 

considered noncompliant solely due to 

a failure or deterioration mode of a 

monitored component or system that 

could not have been reasonably foreseen 

to occur by the manufacturer. 

8. Section 86.010–30 is added to 

Subpart A to read as follows: 

§ 86.010–30 Certification. 

Section 86.010–30 includes text that 

specifies requirements that differ from 

§§ 86.094–30, 86.095–30, 86.096–30, 

86.098–30, 86.001–30, 86.004–30 or 

86.007–30. Where a paragraph in 

§ 86.094–30, § 86.095–30, § 86.096–30, 

§ 86.098–30, § 86.001–30, § 86.004–30 or 

§ 86.007–30 is identical and applicable 

to § 86.010–30, this may be indicated by 

specifying the corresponding paragraph 

and the statement ‘‘[Reserved]. For 

guidance see § 86.094–30.’’ or 

‘‘[Reserved]. For guidance see § 86.095–

30.’’ or ‘‘[Reserved]. For guidance see 

§ 86.096–30.’’ or ‘‘[Reserved]. For 

guidance see § 86.098–30.’’ or 

‘‘[Reserved]. For guidance see § 86.001–

30.’’ or ‘‘[Reserved]. For guidance see 

§ 86.004–30.’’ or ‘‘[Reserved]. For 

guidance see § 86.007–30.’’

(a)(1) and (a)(2) [Reserved]. For 

guidance see § 86.094–30. 

(a)(3)(i) through (a)(4)(ii) [Reserved]. 

For guidance see § 86.004–30. 

(a)(4)(iii) introductory text through 

(a)(4)(iii)(C) [Reserved]. For guidance 

see § 86.094–30. 

(a)(4)(iv) introductory text [Reserved]. 

For guidance see § 86.095–30. 

(a)(4)(iv)(A)–(a)(9) [Reserved]. For 

guidance see § 86.094–30. 

(a)(10) and (a)(11) [Reserved]. For 

guidance see § 86.004–30. 

(a)(12) [Reserved]. For guidance see 

§ 86.094–30. 

(a)(13) [Reserved]. For guidance see 

§ 86.095–30. 

(a)(14) [Reserved]. For guidance see 

§ 86.094–30. 

(a)(15)–(18) [Reserved]. For guidance 

see § 86.096–30. 

(a)(19) [Reserved]. For guidance see 

§ 86.098–30. 

(a)(20) [Reserved]. For guidance see 

§ 86.001–30. 

(a)(21) [Reserved]. For guidance see 

§ 86.004–30. 

(b)(1) introductory text through 

(b)(1)(ii)(A) [Reserved]. For guidance see 

§ 86.094–30. 

(b)(1)(ii)(B) [Reserved]. For guidance 

see § 86.004–30. 

(b)(1)(ii)(C) [Reserved]. For guidance 

see § 86.094–30. 

(b)(1)(ii)(D) [Reserved]. For guidance 

see § 86.004–30. 

(b)(1)(iii) and (b)(1)(iv) [Reserved]. For 

guidance see § 86.094–30. 

(b)(2) [Reserved]. For guidance see 

§ 86.098–30. 

(b)(3)–(b)(4)(i) [Reserved]. For 

guidance see § 86.094–30. 

(b)(4)(ii) introductory text [Reserved]. 

For guidance see § 86.098–30. 

(b)(4)(ii)(A) [Reserved]. For guidance 

see § 86.094–30. 

(b)(4)(ii)(B)–(b)(4)(iv) [Reserved]. For 

guidance see § 86.098–30. 

(b)(5)–(e) [Reserved]. For guidance see 

§ 86.094–30. 

(f) For engine families required to 

have an OBD system and meant for 

applications less than or equal to 14,000 

pounds GVWR, certification will not be 

granted if, for any test vehicle approved 

by the Administrator in consultation 

with the manufacturer, the malfunction 

indicator light does not activate under 

any of the following circumstances, 

unless the manufacturer can 

demonstrate that any identified OBD 

problems discovered during the 

Administrator’s evaluation will be 

corrected on production vehicles. 

(f)(1)(i) Otto-cycle. [Reserved]. For 

guidance see § 86.004–30. 

(f)(1)(ii) Diesel. 

(A) If monitored for emissions 

performance—a reduction catalyst is 

replaced with a deteriorated or defective 

catalyst, or an electronic simulation of 

such, resulting in exhaust NOX

emissions exceeding the applicable NOX

FEL+0.3 g/bhp-hr. Also if monitored for 

emissions performance—an oxidation 

catalyst is replaced with a deteriorated 

or defective catalyst, or an electronic 

simulation of such, resulting in exhaust 

NMHC emissions exceeding 2.5 times 

the applicable NMHC standard. 

(B) If monitored for performance—a 

particulate trap is replaced with a 

deteriorated or defective trap, or an 

electronic simulation of such, resulting 

in either exhaust PM emissions 

exceeding the applicable FEL+0.04 g/ 

bhp-hr or 0.05 g/bhp-hr PM, whichever 

is higher; or, exhaust NMHC emissions 

exceeding 2.5 times the applicable 

NMHC standard. Also, if monitored for 

performance—a particulate trap is 

replaced with a catastrophically failed 

trap or a simulation of such. 

(f)(2) [Reserved]. For guidance see 

§ 86.004–30. 

(f)(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. 

(f)(3)(i)(A) [Reserved]. For guidance 

see § 86.007–30. 

(f)(3)(i)(B) Diesel. If so equipped, any 

oxygen sensor or air-fuel ratio sensor 

located downstream of aftertreatment 

devices is replaced with a deteriorated 

or defective sensor, or an electronic 

simulation of such, resulting in exhaust 

emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2.5 times the 

applicable NMHC standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. 

(f)(3)(ii)(A) [Reserved]. For guidance 

see § 86.007–30. 

(f)(3)(ii)(B) Diesel. If so equipped, any 

oxygen sensor or air-fuel ratio sensor 

located upstream of aftertreatment 

devices is replaced with a deteriorated 

or defective sensor, or an electronic 

simulation of such, resulting in exhaust 

emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.02 g/bhp-hr or 0.03 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2.5 times the 

applicable NMHC standard; or, 2.5 

times the applicable CO standard. 

(iii) NOX sensors. 

(f)(3)(iii)(A) [Reserved]. For guidance 

see § 86.007–30. 

(f)(3)(iii)(B) Diesel. If so equipped, any 

NOX sensor is replaced with a 

deteriorated or defective sensor, or an 

electronic simulation of such, resulting 

in exhaust emissions exceeding any of 

the following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr. 

(f)(4) [Reserved]. For guidance see 

§ 86.004–30. 

(f)(5)(i) [Reserved]. For guidance see 

§ 86.007–30. 

(f)(5)(ii) Diesel. A malfunction 

condition is induced in any emissionrelated engine system or component, 

including but not necessarily limited to, 

the exhaust gas recirculation (EGR) 

system, if equipped, and the fuel control 

system, singularly resulting in exhaust 

emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.02 g/bhp-hr or 0.03 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2.5 times the 

applicable NMHC standard; or, 2.5 

times the applicable CO standard. 

(f)(6) [Reserved]. For guidance see 

§ 86.004–30. 

9. Section 86.010–38 is added to 

subpart A to read as follows: 

§ 86.010–38 Maintenance instructions. 

This Section 86.010–38 includes text 

that specifies requirements that differ 

from those specified in § 86.007–38. 

Where a paragraph in § 86.096–38, or 

§ 86.004–38, or § 86.007–38 is identical 

and applicable to § 86.010–38, this may 

be indicated by specifying the 

corresponding paragraph and the 

statement ‘‘[Reserved]. For guidance see 

§ 86.096–38,’’ ‘‘[Reserved]. For guidance 


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see or § 86.004–38, ’’ or ‘‘[Reserved]. For 

guidance see § 86.007–38.’’

(a)–(f) [Reserved]. For guidance see 

§ 86.004–38. 

(g) [Reserved]. For guidance see 

§ 86.096–38. For incorporation by 

reference see §§ 86.1 and 86.096–38. 

(h) [Reserved]. For guidance see 

§ 86.004–38. 

(i) [Reserved]. For guidance see 

§ 86.007–38. 

(j) Emission control diagnostic service 

information for heavy-duty engines used 

in vehicles over 14,000 pounds gross 

vehicle weight (GVW) 

(1) Manufacturers of heavy-duty 

engines used in applications weighing 

more than 14,000 pounds gross vehicle 

weight (GVW) that are subject to the 

applicable OBD requirements of this 

subpart A are subject to the provisions 

of this paragraph (j) beginning in the 

2010 model year. The provisions of this 

paragraph (j) apply only to those heavyduty engines subject to the applicable 

OBD requirements. 

(2) Upon Administrator approval, 

manufacturers may alternatively comply 

with all service information and tool 

provisions found in § 86.096–38 that are 

applicable to 1996 and subsequent 

vehicles weighing less than 14,000 

pounds gross vehicle weight (GVW). 

(3) General Requirements 

(i) Manufacturers shall furnish or 

cause to be furnished to any person 

engaged in the repairing or servicing of 

heavy-duty engines, or the 

Administrator upon request, any and all 

information needed to make use of the 

on-board diagnostic system and such 

other information, including 

instructions for making emission-related 

diagnosis and repairs, including but not 

limited to service manuals, technical 

service bulletins, recall service 

information, bi-directional control 

information, and training information, 

unless such information is protected by 

section 208(c) as a trade secret. No such 

information may be withheld under 

section 208(c) of the Act if that 

information is provided (directly or 

indirectly) by the manufacturer to 

franchised dealers or other persons 

engaged in the repair, diagnosing, or 

servicing of heavy-duty engines. 

(ii) Definitions. The following 

definitions apply for this paragraph (j): 

(A) Aftermarket service provider 

means any individual or business 

engaged in the diagnosis, service, and 

repair of a heavy-duty engine, who is 

not directly affiliated with a 

manufacturer or manufacturer 

franchised dealership. 

(B) Bi-directional control means the 

capability of a diagnostic tool to send 

messages on the data bus that 

temporarily overrides the module’s 

control over a sensor or actuator and 

gives control to the diagnostic tool 

operator. Bi-directional controls do not 

create permanent changes to engine or 

component calibrations. 

(C) Data stream information means 

information (i.e., messages and 

parameters) originated within the 

engine by a module or intelligent 

sensors (i.e., a sensor that contains and 

is ontrolled by its own module) and 

transmitted between a network of 

modules and/or intelligent sensors 

connected in parallel with either one or 

more communication wires. The 

information is broadcast over the 

communication wires for use by the 

OBD system to gather information on 

emissions-related components or 

systems and from other engine modules 

that may impact emissions. For the 

purposes of this section, data stream 

information does not include engine 

calibration related information, or any 

data stream information from systems or 

modules that do not impact emissions. 

(D) Emissions-related information 

means any information related to the 

diagnosis, service, and repair of 

emissions-related components. 

Emissions-related information includes, 

but is not limited to, information 

regarding any system, component or 

part of an engine that controls emissions 

and any system, component and/or part 

associated with the engine, including, 

but not limited to: the engine, the fuel 

system and ignition system; information 

for any system, component or part that 

is likely to impact emissions, and any 

other information specified by the 

Administrator to be relevant to the 

diagnosis and repair of an emissionsrelated problem; any other information 

specified by the Administrator to be 

relevant for the diagnosis and repair of 

an emissions-related failure found 

through an evaluation of vehicles in-use 

and after such finding has been 

communicated to the affected 

manufacturer(s). 

(E) Emissions-related training 

information means any information 

related training or instruction for the 

purpose of the diagnosis, service, and 

repair of emissions-related components. 

(F) Enhanced service and repair 

information means information which is 

specific for an original equipment 

manufacturer’s brand of tools and 

equipment. This includes computer or 

anti-theft system initialization 

information necessary for the 

completion of any emissions-related 

repair on engines that employ integral 

security systems. 

(G) Equipment and Tool Company 

means a registered equipment or 

software company either public or 

private that is engaged in, or plans to 

engage in, the manufacture of scan tool 

reprogramming equipment or software. 

(H) Generic service and repair 

information means information which is 

not specific for an original equipment 

manufacturer’s brand of tools and 

equipment. 

(I) Indirect information means any 

information that is not specifically 

contained in the service literature, but is 

contained in items such as tools or 

equipment provided to franchised 

dealers (or others). This includes 

computer or anti-theft system 

initialization information necessary for 

the completion of any emissions-related 

repair on engines that employ integral 

security systems. 

(J) Intermediary means any individual 

or entity, other than an original 

equipment manufacturer, which 

provides service or equipment to 

aftermarket service providers. 

(K) Manufacturer franchised 

dealership means any service provider 

with which a manufacturer has a direct 

business relationship. 

(L) Third party information provider 

means any individual or entity, other 

than an original equipment 

manufacturer, who consolidates 

manufacturer service information and 

makes this information available to 

aftermarket service providers. 

(M) Third party training provider 

means any individual or entity, other 

than an original equipment 

manufacturer who develops and/or 

delivers instructional and educational 

material for training courses. 

(4) Information dissemination. By July 

1, 2010 each manufacturer shall provide 

or cause to be provided to the persons 

specified in paragraph (j)(3)(i) of this 

section and to any other interested 

parties a manufacturer-specific World 

Wide Web site containing the 

information specified in paragraph 

(j)(3)(i) of this section for 2010 and later 

model year engines which have been 

certified to the OBD requirements 

specified in § 86.010–18 and are offered 

for sale; this requirement does not apply 

to indirect information, including the 

information specified in paragraphs 

(j)(13) through (j)(17) of this section. 

Upon request and approval of the 

Administrator, manufacturers who can 

demonstrate significant hardship in 

complying with this provision within 

four months after the effective date may 

request an additional six months lead 

time to meet this requirement. Each 

manufacturer Web site shall: 

(i) Provide access in full-text to all of 

the information specified in paragraph 

(j)(5) of this section. 


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(ii) Be updated at the same time as 

manufacturer franchised dealership 

World Wide Web sites. 

(iii) Provide users with a description 

of the minimum computer hardware 

and software needed by the user to 

access that manufacturer’s information 

(e.g., computer processor speed and 

operating system software). This 

description shall appear when users 

first log-on to the home page of the 

manufacturer’s Web site. 

(iv) Provide Short-Term (24 to 72 

hours), Mid-Term (30 day period), and 

Long-Term (365 day period) Web site 

subscription options to any person 

specified in paragraph (j)(2)(i) of this 

section whereby the user will be able to 

access the site, search for the 

information, and purchase, view and 

print the information at a fair and 

reasonable cost as specified in 

paragraph (j)(7) of this section for each 

of the options. In addition, for each of 

the tiers, manufacturers are required to 

make their entire site accessible for the 

respective period of time and price. In 

other words, a manufacturer may not 

limit any or all of the tiers to just one 

make or one model. 

(v) Allow the user to search the 

manufacturer Web site by various topics 

including but not limited to model, 

model year, key words or phrases, etc., 

while allowing ready identification of 

the latest calibration. Manufacturers 

who do not use model year to classify 

their engines in their service 

information may use an alternate 

delineation such as body series. Any 

manufacturer utilizing this flexibility 

shall create a cross-reference to the 

corresponding model year and provide 

this cross-reference on the manufacturer 

Web site home page. 

(vi) Provide accessibility using 

common, readily available software and 

shall not require the use of software, 

hardware, viewers, or browsers that are 

not readily available to the general 

public. Manufacturers shall also provide 

hyperlinks to any plug-ins, viewers or 

browsers (e.g. Adobe Acrobat or 

Netscape) needed to access the 

manufacturer Web site. 

(vii) Allow simple hyper-linking to 

the manufacturer Web site from 

Government Web sites and automotiverelated Web sites. 

(viii) Posses sufficient server capacity 

to allow ready access by all users and 

has sufficient capacity to assure that all 

users may obtain needed information 

without undue delay. 

(ix) Correct or delete broken Web 

links on a weekly basis. 

(x) Allow for Web site navigation that 

does not require a user to return to the 

manufacturer home page or a search 

engine in order to access a different 

portion of the site. 

(xi) Allow users to print out any and 

all of the materials required to be made 

available on the manufacturers Web site, 

including the ability to print it at the 

user’s location. 

(5) Small volume provisions for 

information dissemination. 

(i) Manufacturers with total annual 

sales of less than 5,000 engines shall 

have until July 1, 2011 to launch their 

individual Web sites as required by 

paragraph (j)(4) of this section. 

(ii) Manufacturers with total annual 

sales of less than 1,000 engines may, in 

lieu of meeting the requirement of 

paragraph (j)(4) of this section, request 

the Administrator to approve an 

alternative method by which the 

required emissions-related information 

can be obtained by the persons specified 

in paragraph (j)(3)(i) of this section. 

(6) Required information. All 

information relevant to the diagnosis 

and completion of emissions-related 

repairs shall be posted on manufacturer 

Web sites. This excludes indirect 

information specified in paragraphs 

(j)(7) and (j)(13) through (j)(17) of this 

section. To the extent that this 

information does not already exist in 

some form for their manufacturer 

franchised dealerships, manufacturers 

are required to develop and make 

available the information required by 

this section to both their manufacturer 

franchised dealerships and the 

aftermarket. The required information 

includes, but is not limited to: 

(i) Manuals, including subsystem and 

component manuals developed by a 

manufacturer’s third party supplier that 

are made available to manufacturer 

franchised dealerships, technical service 

bulletins (TSBs), recall service 

information, diagrams, charts, and 

training materials. Manuals and other 

such service information from third 

party suppliers are not required to be 

made available in full-text on 

manufacturer Web sites as described in 

paragraph (j)(3) of this section. Rather, 

manufacturers must make available on 

the manufacturer Web site as required 

by paragraph (j)(3) of this section an 

index of the relevant information and 

instructions on how to order such 

information. In the alternate, a 

manufacturer can create a link from its 

Web site to the Web site(s) of the third 

party supplier. 

(ii) OBD system information which 

includes, but is not limited to, the 

following: 

(A) A general description of the 

operation of each monitor, including a 

description of the parameter that is 

being monitored; 

(B) A listing of all typical OBD 

diagnostic trouble codes associated with 

each monitor; 

(C) A description of the typical 

enabling conditions (either generic or 

monitor-specific) for each monitor (if 

equipped) to execute during engine 

operation, including, but not limited to, 

minimum and maximum intake air and 

engine coolant temperature, speed 

range, and time after engine startup. In 

addition, manufacturers shall list all 

monitor-specific OBD drive cycle 

information for all major OBD monitors 

as equipped including, but not limited 

to, catalyst, catalyst heater, oxygen 

sensor, oxygen sensor heater, 

evaporative system, exhaust gas recirculation (EGR), secondary air, and air 

conditioning system. Additionally, for 

diesel engines which also perform 

misfire, fuel system and comprehensive 

component monitoring under specific 

driving conditions (i.e., non-continuous 

monitoring; as opposed to spark ignition 

engines that monitor these systems 

under all conditions or continuous 

monitoring), the manufacturer shall 

make available monitor-specific drive 

cycles for these monitors. Any 

manufacturer who develops generic 

drive cycles, either in addition to, or 

instead of, monitor-specific drive cycles 

shall also make these available in fulltext on manufacturer Web sites; 

(D) A listing of each monitor 

sequence, execution frequency and 

typical duration; 

(E) A listing of typical malfunction 

thresholds for each monitor; 

(F) For OBD parameters for specific 

engines that deviate from the typical 

parameters, the OBD description shall 

indicate the deviation and provide a 

separate listing of the typical values for 

those engines; 

(G) Identification and scaling 

information necessary to interpret and 

understand data available through 

Diagnostic Message 8 pursuant to SAE 

Recommended Practice J1939–73, 

Application Layer—Diagnostics, revised 

June 2001 or through Service/Mode $06 

pursuant to SAE Recommended Practice 

J1979, E/E Diagnostic Test Modes—

Equivalent to ISO/DIS 15031–5: April 

30, 2002. These documents are 

Incorporated by Reference in § 86.1. 

(H) Algorithms, look-up tables, or any 

values associated with look-up tables 

are not required to be made available. 

(iii) Any information regarding any 

system, component, or part of a engine 

monitored by the OBD system that 

could in a failure mode cause the OBD 

system to illuminate the malfunction 

indicator light (MIL); 

(iv) Manufacturer-specific emissionsrelated diagnostic trouble codes (DTCs) 


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and any related service bulletins, 

trouble shooting guides, and/or repair 

procedures associated with these 

manufacturer-specific DTCs; and 

(v) Information regarding how to 

obtain the information needed to 

perform reinitialization of any computer 

or anti-theft system following an 

emissions-related repair. 

(7) Anti-theft System Initialization 

Information. Computer or anti-theft 

system initialization information and/or 

related tools necessary for the proper 

installation of on-board computers or 

necessary for the completion of any 

emissions-related repair on engines that 

employ integral security systems or the 

repair or replacement of any other 

emission-related part shall be made 

available at a fair and reasonable cost to 

the persons specified in paragraph 

(j)(3)(i) of this section. 

(i) Except as provided under 

paragraph (j)(7)(ii) of this section, 

manufacturers must make this 

information available to persons 

specified in paragraph (j)(3)(i) of this 

section, such that such persons will not 

need any special tools or manufacturerspecific scan tools to perform the 

initialization. Manufacturers may make 

such information available through, for 

example, generic aftermarket tools, a 

pass-through device, or inexpensive 

manufacturer specific cables. 

(ii) A manufacturer may request 

Administrator approval for an 

alternative means to re-initialize engines 

for some or all model years through the 

2013 model year by 90 days following 

the effective date of the final rule. The 

Administrator shall approve the request 

only after the following conditions have 

been met: 

(A) The manufacturer must 

demonstrate that the availability of such 

information to aftermarket service 

providers would significantly increase 

the risk of theft. 

(B) The manufacturer must make 

available a reasonable alternative means 

to install or repair computers, or to 

otherwise repair or replace an emissionrelated part. 

(C) Any alternative means proposed 

by a manufacturer cannot require 

aftermarket technicians to use a 

manufacturer franchised dealership to 

obtain information or special tools to reinitialize the anti-theft system. All 

information must come directly from 

the manufacturer or a single 

manufacturer-specified designee. 

(D) Any alternative means proposed 

by a manufacturer must be available to 

aftermarket technicians at a fair and 

reasonable price. 

(E) Any alternative must be available 

to aftermarket technicians within 

twenty-four hours of the initial request. 

(F) Any alternative must not require 

the purchase of a special tool or tools, 

including manufacturer-specific tools, 

to complete this repair. Alternatives 

may include lease of such tools, but 

only for appropriately minimal cost. 

(G) In lieu of leasing their 

manufacturer-specific tool to meet this 

requirement, a manufacturer may also 

choose to release the necessary 

information to equipment and tool 

manufacturers for incorporation into 

aftermarket scan tools. Any 

manufacturer choosing this option must 

release the information to equipment 

and tool manufacturers within 60 days 

of Administrator approval. 

(8) Cost of required information. 

(i) All information required to be 

made available by this section, shall be 

made available at a fair and reasonable 

price. In determining whether a price is 

fair and reasonable, consideration may 

be given to relevant factors, including, 

but not limited to, the following: 

(A) The net cost to the manufacturer 

franchised dealerships for similar 

information obtained from 

manufacturers, less any discounts, 

rebates, or other incentive programs; 

(B) The cost to the manufacturer for 

preparing and distributing the 

information, excluding any research and 

development costs incurred in 

designing and implementing, upgrading 

or altering the onboard computer and its 

software or any other engine part or 

component. Amortized capital costs for 

the preparation and distribution of the 

information may be included; 

(C) The price charged by other 

manufacturers for similar information; 

(D) The price charged by 

manufacturers for similar information 

prior to the launch of manufacturer Web 

sites; 

(E) The ability of the average 

aftermarket technician or shop to afford 

the information; 

(F) The means by which the 

information is distributed; 

(G) The extent to which the 

information is used, which includes the 

number of users, and frequency, 

duration, and volume of use; and 

(H) Inflation. 

(ii) Manufacturers must submit to 

EPA a request for approval of their 

pricing structure for their Web sites and 

amounts to be charged for the 

information required to be made 

available under paragraphs (j)(4) and 

(j)(6) of this section at least 180 days in 

advance of the launch of the web site. 

Subsequent to the approval of the 

manufacturer Web site pricing structure, 

manufacturers shall notify EPA upon 

the increase in price of any one or all 

of the subscription options of 20 percent 

or more above the previously approved 

price, taking inflation into account. 

(A) The manufacturer shall submit a 

request to EPA that sets forth a detailed 

description of the pricing structure and 

amounts, and support for the position 

that the pricing structure and amounts 

are fair and reasonable by addressing, at 

a minimum, each of the factors specified 

in paragraph (j)(8)(i) of this section. 

(B) EPA will act upon on the request 

within180 days following receipt of a 

complete request or following receipt of 

any additional information requested by 

EPA. 

(C) EPA may decide not to approve, 

or to withdraw approval for a 

manufacturer’s pricing structure and 

amounts based on a conclusion that this 

pricing structure and/or amounts are 

not, or are no longer, fair and 

reasonable, by sending written notice to 

the manufacturer explaining the basis 

for this decision. 

(D) In the case of a decision by EPA 

not to approve or to withdraw approval, 

the manufacturer shall within three 

months following notice of this 

decision, obtain EPA approval for a 

revised pricing structure and amounts 

by following the approval process 

described in this paragraph. 

(9) Unavailable information. Any 

information which is not provided at a 

fair and reasonable price shall be 

considered unavailable, in violation of 

these regulations and section 202(m)(5) 

of the Clean Air Act. 

(10) Third party information 

providers. By January 1, 2011 

manufacturers shall, for model year 

2010 and later engines, make available 

to third-party information providers as 

defined in paragraph (j)(3)(ii) of this 

section with whom they engage in 

licensing or business arrangements; 

(i) The required emissions-related 

information as specified in paragraph 

(j)(6) of this section either: 

(A) Directly in electronic format such 

as diskette or CD–ROM using nonproprietary software, in English; or 

(B) Indirectly via a Web site other 

than that required by paragraph (j)(4) of 

this section; 

(ii) For any manufacturer who utilizes 

an automated process in their 

manufacturer-specific scan tool for 

diagnostic fault trees, the data schema, 

detail specifications, including category 

types/codes and engine codes, and data 

format/content structure of the 

diagnostic trouble trees. 

(iii) Manufacturers can satisfy the 

requirement of paragraph (j)(10)(ii) of 

this section by making available 


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diagnostic trouble trees on their 

manufacturer Web sites in full-text. 

(iv) Manufacturers are not responsible 

for the accuracy of the information 

distributed by third parties. However, 

where manufacturers charge 

information intermediaries for 

information, whether through licensing 

agreements or other arrangements, 

manufacturers are responsible for 

inaccuracies contained in the 

information they provide to third party 

information providers. 

(11) Required emissions-related 

training information. By January 1, 

2011, for emissions-related training 

information, manufacturers shall: 

(i) Video tape or otherwise duplicate 

and make available for sale on 

manufacturer Web sites within 30 days 

after transmission any emissions-related 

training courses provided to 

manufacturer franchised dealerships via 

the Internet or satellite transmission; 

(ii) Provide on the manufacturer Web 

site an index of all emissions-related 

training information available for 

purchase by aftermarket service 

providers for 2010 and newer engines. 

The required information must be made 

available for purchase within 3 months 

of model introduction and then must be 

made available at the same time it is 

made available to manufacturer 

franchised dealerships, whichever is 

earlier. The index shall describe the title 

of the course or instructional session, 

the cost of the video tape or duplicate, 

and information on how to order the 

item(s) from the manufacturer Web site. 

All of the items available must be 

shipped within 24 hours of the order 

being placed and are to made available 

at a fair and reasonable price as 

described in paragraph (j)(8) of this 

section. Manufacturers unable to meet 

the 24 hour shipping requirement under 

circumstances where orders exceed 

supply and additional time is needed by 

the distributor to reproduce the item 

being ordered, may exceed the 24 hour 

shipping requirement, but in no 

instance can take longer than 14 days to 

ship the item. 

(iii) Provide access to third party 

training providers as defined in 

paragraph (j)(3)(ii) of this section all 

emission-related training courses 

transmitted via satellite or Internet 

offered to their manufacturer franchised 

dealerships. Manufacturers may not 

charge unreasonable up-front fees to 

third party training providers for this 

access, but may require a royalty, 

percentage, or other arranged fee based 

on per-use enrollment/subscription 

basis. Manufacturers may take 

reasonable steps to protect any 

copyrighted information and are not 

required to provide this information to 

parties that do not agree to such steps. 

(12) Timeliness and maintenance of 

information dissemination. 

(i) Subsequent to the initial launch of 

the manufacturer’s Web site, 

manufacturers must make the 

information required under paragraph 

(j)(6) of this section available on their 

Web site within six months of model 

introduction, or at the same time it is 

made available to manufacturer 

franchised dealerships. After this six 

month period, the information must be 

available and updated on the 

manufacturer Web site at the same time 

that the updated information is made 

available to manufacturer franchised 

dealerships, except as otherwise 

specified in this section. 

(ii) Archived information. 

Manufacturers must maintain the 

required information on their Web sites 

in full-text as defined in paragraph (j)(6) 

of this section for a minimum of 15 

years after model introduction. 

Subsequent to this fifteen year period, 

manufacturers may archive the 

information in the manufacturer’s 

format of choice and provide an index 

of the archived information on the 

manufacturer Web site and how it can 

be obtained by interested parties. 

Manufacturers shall index their 

available information with a title that 

adequately describes the contents of the 

document to which it refers. 

Manufacturers may allow for the 

ordering of information directly from 

their Web site, or from a Web site 

hyperlinked to the manufacturer Web 

site. In the alternate, manufacturers 

shall list a phone number and address 

where aftermarket service providers can 

call or write to obtain the desired 

information. Manufacturers must also 

provide the price of each item listed, as 

well as the price of items ordered on a 

subscription basis. To the extent that 

any additional information is added or 

changed for these model years, 

manufacturers shall update the index as 

appropriate. Manufacturers will be 

responsible for ensuring that their 

information distributors do so within 

one regular business day of receiving 

the order. Items that are less than 20 

pages (e.g. technical service bulletins) 

shall be faxed to the requestor and 

distributors are required to deliver the 

information overnight if requested and 

paid for by the ordering party. Archived 

information must be made available on 

demand and at a fair and reasonable 

price. 

(13) Recalibration Information. 

(i) Manufacturers shall make available 

to the persons specified in paragraph 

(j)(3)(i) of this section all emissionsrelated recalibration or reprogramming 

events (including driveability 

reprogramming events that may affect 

emissions) in the format of their choice 

at the same time they are made available 

to manufacturer franchised dealerships. 

This requirement takes effect on July 1, 

2010. 

(ii) Manufacturers shall provide 

persons specified in paragraph (j)(3)(i) 

of this section with an efficient and 

cost-effective method for identifying 

whether the calibrations on engines are 

the latest to be issued. This requirement 

takes effect on July 1, 2010. 

(iii) For all 2010 and later OBD 

engines equipped with reprogramming 

capability, manufacturers shall comply 

with either SAE J2534, ‘‘Recommended 

Practice for Pass-Thru Vehicle 

Programming’’ , December 2004, or the 

Technology and Maintenance Council’s 

(TMC) Recommended Practice 

RP1210A. ‘‘WindowsTM Communication 

API’’ , July 1999. These documents are 

Incorporated by Reference in § 86.1. 

(iv) For model years 2010 and later, 

manufacturers shall make available to 

aftermarket service providers the 

necessary manufacturer-specific 

software applications and calibrations 

needed to initiate pass-through 

reprogramming. This software shall be 

able to run on a standard personal 

computer that utilizes standard 

operating systems as specified in either 

J2534 or RP1210A. 

(v) Manufacturers may take any 

reasonable business precautions 

necessary to protect proprietary 

business information and are not 

required to provide this information to 

any party that does not agree to these 

reasonable business precautions. The 

requirements to make hardware 

available and to release the information 

to equipment and tool companies takes 

effect on July 1, 2010, and within 3 

months of model introduction for all 

new model years. 

(14) Generic and enhanced 

information for scan tools. By July 1, 

2010, manufacturers shall make 

available to equipment and tool 

companies all generic and enhanced 

service information including bidirectional control and data stream 

information as defined in paragraph 

(j)(4)(ii) of this section. This 

requirement applies for 2010 and later 

model year engines. 

(i) The information required by this 

paragraph (j)(14) shall be provided 

electronically using common document 

formats to equipment and tool 

companies with whom they have 

appropriate licensing, contractual, and/ 

or confidentiality arrangements. To the 

extent that a central repository for this 


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information (e.g. the TEK–NET library 

developed by the Equipment and Tool 

Institute) is used to warehouse this 

information, the Administrator shall 

have free unrestricted access. In 

addition, information required by this 

paragraph (j)(14) shall be made available 

to equipment and tool companies who 

are not otherwise members of any 

central repository and shall have access 

if the non-members have arranged for 

the appropriate licensing, contractual 

and/or confidentiality arrangements 

with the manufacturer and/or a central 

repository. 

(ii) In addition to the generic and 

enhanced information defined in 

paragraph (j)(3)(ii) of this section, 

manufacturers shall also make available 

the following information necessary for 

developing generic diagnostic scan 

tools: 

(A) The physical hardware 

requirements for data communication 

(e.g. system voltage requirements, cable 

terminals/pins, connections such as 

RS232 or USB, wires, etc.) 

(B) Electronic Control Unit (ECU) data 

communication (e.g. serial data 

protocols, transmission speed or baud 

rate, bit timing requirements, etc), 

(C) Information on the application 

physical interface (API) or layers. (i.e., 

processing algorithms or software 

design descriptions for procedures such 

as connection, initialization, and 

termination), 

(D) Engine application information or 

any other related service information 

such as special pins and voltages or 

additional connectors that require 

enablement and specifications for the 

enablement. 

(iii) Any manufacturer who utilizes an 

automated process in their 

manufacturer-specific scan tool for 

diagnostic fault trees shall make 

available to equipment and tool 

companies the data schema, detail 

specifications, including category types/ 

codes and codes, and data format/ 

content structure of the diagnostic 

trouble trees. 

(iv) Manufacturers can satisfy the 

requirement of paragraph (j)(14)(iii) of 

this section by making available 

diagnostic trouble trees on their 

manufacturer Web sites in full-text. 

(v) Manufacturers shall make all 

required information available to the 

requesting equipment and tool company 

within 14 days after the request to 

purchase has been made unless the 

manufacturer requests Administrator 

approval to refuse to disclose such 

information to the requesting company 

or requests Administrator approval for 

additional time to comply. After receipt 

of a request and consultation with the 

affected parties, the Administrator shall 

either grant or refuse the petition based 

on the evidence submitted during the 

consultation process: 

(A) If the evidence demonstrates that 

the engine manufacturer has a 

reasonably based belief that the 

requesting equipment and tool company 

could not produce safe and functionally 

accurate tools that would not cause 

damage to the engine, the petition for 

non-disclosure will be granted. Engine 

manufacturers are not required to 

provide data stream and bi-directional 

control information that would permit 

an equipment and tool company’s 

products to modify an EPA-certified 

engine or transmission configuration. 

(B) If the evidence does not 

demonstrate that the engine 

manufacturer has a reasonably-based 

belief that the requesting equipment and 

tool company could not produce safe 

and functionally accurate tools that 

would not cause damage to the engine, 

the petition for non-disclosure will be 

denied and the engine manufacturer, as 

applicable, shall make the requested 

information available to the requesting 

equipment and tool company within 2 

days of the denial. 

(vi) If the manufacturer submits a 

request for Administrator approval for 

additional time, and satisfactorily 

demonstrates to the Administrator that 

the engine manufacturer is able to 

comply but requires additional time 

within which to do so, the 

Administrator shall grant the request 

and provide additional time to fully and 

expeditiously comply. 

(vii) Manufacturers may require that 

tools using information covered under 

paragraph (j)(14) of this section comply 

with the Component Identifier message 

specified in SAE J1939–71 as Parameter 

Group Number (PGN) 65249 (including 

the message parameter’s make, model, 

and serial number) and the SAE J1939–

81 Address Claim PGN. 

(15) Availability of manufacturerspecific scan tools. Manufacturers shall 

make available for sale to the persons 

specified in paragraph (j)(3)(i) of this 

section their own manufacturer-specific 

diagnostic tools at a fair and reasonable 

cost. These tools shall also be made 

available in a timely fashion either 

through the manufacturer Web site or 

through a manufacturer-designated 

intermediary. Manufacturers shall ship 

purchased tools in a timely manner after 

a request and training, if any, has been 

completed. Any required training 

materials and classes must be made 

available at a fair and reasonable price. 

Manufacturers who develop different 

versions of one or more of their 

diagnostic tools that are used in whole 

or in part for emission-related diagnosis 

and repair shall also insure that all 

emission-related diagnosis and repair 

information is available for sale to the 

aftermarket at a fair and reasonable cost. 

Factors for determining fair and 

reasonable cost include, but are not 

limited to: 

(i) The net cost to the manufacturer’s 

franchised dealerships for similar tools 

obtained from manufacturers, less any 

discounts, rebates, or other incentive 

programs; 

(ii) The cost to the manufacturer for 

preparing and distributing the tools, 

excluding any research and 

development costs; 

(iii) The price charged by other 

manufacturers of similar sizes for 

similar tools; 

(iv) The capabilities and functionality 

of the manufacturer tool; 

(v) The means by which the tools are 

distributed; 

(vi) Inflation; 

(vii) The ability of aftermarket 

technicians and shops to afford the 

tools. Manufacturers shall provide 

technical support to aftermarket service 

providers for the tools described in this 

section, either themselves or through a 

third-party of their choice. 

(16) Changing content of 

manufacturer-specific scan tools. 

Manufacturers who opt to remove nonemissions related content from their 

manufacturer-specific scan tools and 

sell them to the persons specified in 

paragraph (j)(3)(i) of this section shall 

adjust the cost of the tool accordingly 

lower to reflect the decreased value of 

the scan tool. All emissions-related 

content that remains in the 

manufacturer-specific tool shall be 

identical to the information that is 

contained in the complete version of the 

manufacturer specific tool. Any 

manufacturer who wishes to implement 

this option must request approval from 

the Administrator prior to the 

introduction of the tool into commerce. 

(17) Reference Materials. 

Manufacturers shall conform with the 

following Society of Automotive 

Engineers (SAE) standards. These 

documents are incorporated by 

reference in § 86.1. 

(i) For Web-based delivery of service 

information, manufacturers shall 

comply with SAE Recommended 

Practice J2403, Medium/Heavy-Duty 

E/E Systems Diagnosis Nomenclature; 

August 2004. This recommended 

practice standardizes various terms, 

abbreviations, and acronyms associated 

with on-board diagnostics. 

Manufacturers shall comply with SAE 

J2403 beginning with the Model Year 

2013. 


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(ii) For identification and scaling 

information necessary to interpret and 

understand data available through 

Diagnostic Message 8, manufacturers 

shall comply with SAE Recommended 

Practice J1939–73, Application Layer—

Diagnostics, revised June 2001. In the 

alternate, manufacturers may comply 

with Service/Mode $06 pursuant to SAE 

Recommended Practice J1979, E/E 

Diagnostic Test Modes—Equivalent to 

ISO/DIS 15031–5: April 30, 2002. These 

recommended practices describe the 

implementation of diagnostic test modes 

for emissions related test data. 

Manufacturers shall comply with either 

SAE J1939–73 or SAE J1979 beginning 

with Model Year 2013. These 

recommended practices describe the 

implementation of diagnostic test modes 

for emissions related test data. 

(iii) For pass-thru reprogramming 

capabilities, manufacturers shall comply 

with Technology and Maintenance 

Council’s (TMC) Recommended Practice 

RP1210A, ‘‘WindowsTM Communication 

API’’ , July 1999. In the alternate, 

manufacturers may comply with SAE 

J2534, Recommended Practice for PassThru Vehicle Programming, December 

2004. These recommended practices 

provide technical specifications and 

information that manufacturers must 

supply to equipment and tool 

companies to develop aftermarket passthru reprogramming tools. 

Manufacturers shall comply with either 

RP1210A or SAE J2534 beginning with 

Model Year 2013. 

(18) Reporting Requirements. 

Performance reports that adequately 

demonstrate that each manufacturer’s 

Web site meets the information 

requirements outlined in paragraphs 

(j)(6)(i) through (j)(6)(vi) of this section 

shall be submitted to the Administrator 

annually or upon request by the 

Administrator. These reports shall 

indicate the performance and 

effectiveness of the Web sites by using 

commonly used Internet statistics (e.g., 

successful requests, frequency of use, 

number of subscriptions purchased, 

etc.) Manufacturers shall provide to the 

Administrator reports on an annual 

basis within 30 days of the end of the 

calendar year. These annual reports 

shall be submitted to the Administrator 

electronically utilizing non-proprietary 

software in the format as agreed to by 

the Administrator and the 

manufacturers. 

(19) Prohibited Acts, Liability and 

Remedies. 

(i) It is a prohibited act for any person 

to fail to promptly provide or cause a 

failure to promptly provide information 

as required by this paragraph (j), or to 

otherwise fail to comply or cause a 

failure to comply with any provision of 

this subsection. 

(ii) Any person who fails or causes the 

failure to comply with any provision of 

this paragraph (j) is liable for a violation 

of that provision. A corporation is 

presumed liable for any violations of 

this subpart that are committed by any 

of its subsidiaries, affiliates or parents 

that are substantially owned by it or 

substantially under its control. 

(iii) Any person who violates a 

provision of this paragraph (j) shall be 

subject to a civil penalty of not more 

than $31,500 per day for each violation. 

This maximum penalty is shown for 

calendar year 2002. Maximum penalty 

limits for later years may be set higher 

based on the Consumer Price Index, as 

specified in 40 CFR part 19. In addition, 

such person shall be liable for all other 

remedies set forth in Title II of the Clean 

Air Act, remedies pertaining to 

provisions of Title II of the Clean Air 

Act, or other applicable provisions of 

law. 

10. Section 86.013–2 is added to 

Subpart A to read as follows: 

§ 86.013–2 Definitions. 

The definitions of § 86.004–2 

continue to apply to 2004 and later 

model year vehicles, and the definitions 

of § 86.010–2 continue to apply to 2010 

and later model year vehicles. The 

definitions listed in this section apply 

beginning with the 2013 model year. 

Onboard Diagnostics (OBD) group 

means a combination of engines, engine 

families, or engine ratings that use the 

same OBD strategies and similar 

calibrations. 

11. Section 86.013–17 is added to 

Subpart A to read as follows: 

§ 86.013–17 On-board Diagnostics for 

engines used in applications less than or 

equal to 14,000 pounds GVWR. 

Section 86.013–17 includes text that 

specifies requirements that differ from 

§ 86.005–17, § 86.007–17, and § 86.010–

17. Where a paragraph in § 86.005–17 or 

§ 86.007–17 or § 86.010–17 is identical 

and applicable to § 86.013–17, this may 

be indicated by specifying the 

corresponding paragraph and the 

statement ‘‘[Reserved]. For guidance see 

§ 86.005–17.’’ or ‘‘[Reserved]. For 

guidance see § 86.007–17.’’ or 

‘‘[Reserved]. For guidance see § 86.010–

17.’’

(a) through (b)(1)(i) [Reserved]. For 

guidance see § 86.010–17. 

(b)(1)(ii) Diesel. 

(A) If equipped, reduction catalyst 

deterioration or malfunction before it 

results in exhaust NOX emissions 

exceeding the applicable NOX FEL+0.3 

g/bhp-hr. If equipped, oxidation catalyst 

deterioration or malfunction before it 

results in exhaust NMHC emissions 

exceeding 2 times the applicable NMHC 

standard. These catalyst monitoring 

requirements need not be done if the 

manufacturer can demonstrate that 

deterioration or malfunction of the 

system will not result in exceedance of 

the threshold. 

(B) If equipped, diesel particulate trap 

deterioration or malfunction before it 

results in exhaust emissions exceeding 

any of the following levels: the 

applicable PM FEL+0.04 g/bhp-hr or 

0.05 g/bhp-hr PM, whichever is higher; 

or, exhaust NMHC emissions exceeding 

2 times the applicable NMHC standard. 

Catastrophic failure of the particulate 

trap must also be detected. In addition, 

the absence of the particulate trap or the 

trapping substrate must be detected. 

(b)(2) [Reserved]. For guidance see 

§ 86.005–17. 

(b)(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2 times the 

applicable NMHC standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.02 g/bhp-hr or 0.03 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2 times the 

applicable NMHC standard; or, 2 times 

the applicable CO standard. 

(iii) NOX sensors. 

(A) Otto-cycle. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding 1.5 times 

the applicable standard or FEL for 

NMHC, NOX or CO. 

(B) Diesel. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr. 


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(b)(4) [Reserved]. For guidance see 

§ 86.005–17. 

(b)(5) Other emission control systems 

and components. 

(i) Otto-cycle. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

the secondary air system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding 1.5 times the applicable 

emission standard or FEL for NMHC, 

NOX or CO. For engines equipped with 

a secondary air system, a functional 

check, as described in §86.005–17(b)(6), 

may satisfy the requirements of this 

paragraph (b)(5) provided the 

manufacturer can demonstrate that 

deterioration of the flow distribution 

system is unlikely. This demonstration 

is subject to Administrator approval 

and, if the demonstration and associated 

functional check are approved, the 

diagnostic system must indicate a 

malfunction when some degree of 

secondary airflow is not detectable in 

the exhaust system during the check. 

For engines equipped with positive 

crankcase ventilation (PCV), monitoring 

of the PCV system is not necessary 

provided the manufacturer can 

demonstrate to the Administrator’s 

satisfaction that the PCV system is 

unlikely to fail. 

(ii) Diesel. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM FEL+0.02 g/bhp-hr or 

0.03 g/bhp-hr PM, whichever is higher; 

or, the applicable NOX FEL+0.3 g/bhphr; or, 2 times the applicable NMHC 

standard; or, 2 times the applicable CO 

standard. A functional check, as 

described in §86.005–17(b)(6), may 

satisfy the requirements of this 

paragraph (b)(5) provided the 

manufacturer can demonstrate that a 

malfunction would not cause emissions 

to exceed the applicable levels. This 

demonstration is subject to 

Administrator approval. For engines 

equipped with crankcase ventilation 

(CV), monitoring of the CV system is not 

necessary provided the manufacturer 

can demonstrate to the Administrator’s 

satisfaction that the CV system is 

unlikely to fail. 

(b)(6) through (j) [Reserved]. For 

guidance see § 86.010–17. 

(k) [Reserved.] 

12. Section 86.013–18 is added to 

Subpart A to read as follows: 

§ 86.013–18 On-board Diagnostics for 

engines used in applications greater than 

14,000 pounds GVWR. 

Section 86.013–18 includes text that 

specifies requirements that differ from 

§ 86.010–18. Where a paragraph in 

§ 86.010–18 is identical and applicable 

to § 86.013–18, this may be indicated by 

specifying the corresponding paragraph 

and the statement ‘‘[Reserved]. For 

guidance see § 86.010–18.’’ However, 

where a paragraph in § 86.010–18 is 

identical and applicable to § 86.013–18, 

and there appears the statement 

‘‘[Reserved]. For guidance see § 86.010–

18,’’ it shall be understood that any 

referenced tables within § 86.010–18 

shall actually refer to the applicable 

table shown in § 86.013–18. 

(a) General. All heavy-duty engines 

intended for use in a heavy-duty vehicle 

weighing more than 14,000 pounds 

GVWR must be equipped with an onboard diagnostic (OBD) system capable 

of monitoring all emission-related 

engine systems or components during 

the life of the engine. The OBD system 

is required to detect all malfunctions 

specified in paragraphs (g), and (i) of 

this section and paragraph (h) of 

§ 86.010–18 although the OBD system is 

not required to use a unique monitor to 

detect each of those malfunctions. 

(a)(1) [Reserved]. For guidance see 

§ 86.010–18. 

(a)(2) The OBD system must be 

equipped with a standardized data link 

connector to provide access to the 

stored DTCs as specified in paragraph 

(k)(2) of this section. 

(a)(3) and (a)(4) [Reserved]. For 

guidance see § 86.010–18. 

(b) Malfunction indicator light (MIL) 

and Diagnostic Trouble Codes (DTC). 

The OBD system must incorporate a 

malfunction indicator light (MIL) or 

equivalent and must store specific types 

of diagnostic trouble codes (DTC). 

(1) MIL specifications. 

(i) The MIL must be located on the 

driver’s side instrument panel and be of 

sufficient illumination and location to 

be readily visible under all lighting 

conditions. The MIL must be amber 

(yellow) in color; the use of red for the 

OBD-related MIL is prohibited. More 

than one general purpose malfunction 

indicator light for emission-related 

problems shall not be used; separate 

specific purpose warning lights (e.g., 

brake system, fasten seat belt, oil 

pressure, etc.) are permitted. When 

activated, the MIL must display the 

engine symbol designated as F01 by the 

International Standards Organization 

(ISO) in ‘‘Road vehicles—Symbols for 

controls, indicators and tell-tales,’’ ISO 

2575:2004. 

(b)(1)(ii) through (b)(1)(iv) [Reserved]. 

For guidance see § 86.010–18. 

(b)(1)(v) The MIL required by this 

paragraph (b) must not be used in any 

other way than is specified in this 

section. 

(b)(2) [Reserved]. For guidance see 

§ 86.010–18. 

(b)(3) MIL deactivation and DTC 

erasure protocol. 

(i) Deactivating the MIL. Except as 

otherwise provided for in paragraph 

(g)(2)(iv)(E) of this section and § 86.010–

18(g)(6)(iv)(B) for diesel misfire 

malfunctions and empty reductant 

tanks, and paragraphs (h)(1)(iv)(F), 

(h)(2)(viii), and (h)(7)(iv)(B) of § 86.010–

18 for gasoline fuel system, misfire, and 

evaporative system malfunctions, once 

the MIL has been activated, it may be 

deactivated after three subsequent 

sequential drive cycles during which 

the monitoring system responsible for 

activating the MIL functions and the 

previously detected malfunction is no 

longer present and provided no other 

malfunction has been detected that 

would independently activate the MIL 

according to the requirements outlined 

in § 86.010–18(b)(2). 

(b)(3)(ii) through (b)(4) [Reserved.] For 

guidance see § 86.010–18. 

(c) Monitoring conditions. The OBD 

system must monitor and detect the 

malfunctions specified in paragraphs (g) 

and (i) of this section and § 86.010–

18(h) under the following general 

monitoring conditions. The more 

specific monitoring conditions of 

paragraph (d) of this section are 

sometimes required according to the 

provisions of paragraphs (g) and (i) of 

this section and §86.010–18(h). 

(1) As specifically provided for in 

paragraphs (g) and (i) of this section and 

§ 86.010–18(h), the monitoring 

conditions for detecting malfunctions 

must be technically necessary to ensure 

robust detection of malfunctions (e.g. 

avoid false passes and false indications 

of malfunctions); designed to ensure 

monitoring will occur under conditions 

that may reasonably be expected to be 

encountered in normal vehicle 

operation and normal vehicle use; and, 

designed to ensure monitoring will 

occur during the FTP transient test cycle 

contained in Appendix I paragraph (f), 

of this part, or similar drive cycle as 

approved by the Administrator. 

(c)(2) [Reserved]. For guidance see 

§ 86.010–18. 

(c)(3) Manufacturers may request 

approval to define monitoring 

conditions that are not encountered 

during the FTP cycle as required in 

paragraph (c)(1) of this section. In 


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evaluating the manufacturer’s request, 

the Administrator will consider the 

degree to which the requirement to run 

during the FTP transient cycle restricts 

monitoring during in-use operation, the 

technical necessity for defining 

monitoring conditions that are not 

encountered during the FTP cycle, data 

and/or an engineering evaluation 

submitted by the manufacturer that 

demonstrate that the component/system 

does not normally function during the 

FTP, whether monitoring is otherwise 

not feasible during the FTP cycle, and/ 

or the ability of the manufacturer to 

demonstrate that the monitoring 

conditions satisfy the minimum 

acceptable in-use monitor performance 

ratio requirement as defined in 

paragraph (d)(1)(ii) of this section. 

(d) through (d)(1)(i) [Reserved]. For 

guidance see § 86.010–18. 

(d)(1)(ii) Manufacturers must define 

monitoring conditions that, in addition 

to meeting the criteria in paragraph 

(c)(1) of this section and § 86.010–18(d) 

through (d)(1)(i), ensure that the 

monitor yields an in-use performance 

ratio (as defined in § 86.010–18(d)(2) 

that meets or exceeds the minimum 

acceptable in-use monitor performance 

ratio of 0.100 for all monitors 

specifically required in paragraphs (g) 

and (i) of this section and § 86.010–

18(h) to meet the monitoring condition 

requirements in § 86.010–(18)(d)(1)(i). 

(iii) If the most reliable monitoring 

method developed requires a lower ratio 

for a specific monitor than that specified 

in paragraph (d)(1)(ii) of this section, the 

Administrator may lower the minimum 

acceptable in-use monitoring 

performance ratio. 

(d)(2) through (d)(3)(iv) [Reserved]. 

For guidance see § 86.010–18. 

(d)(3)(v) Manufacturers that use 

alternative statistical MIL activation 

protocols as allowed in § 86.010–

18(b)(2)(iii) for any of the monitors 

requiring a numerator, are required to 

increment the numerator(s) 

appropriately. The manufacturer may be 

required to provide supporting data 

and/or engineering analyses 

demonstrating both the equivalence of 

their incrementing approach to the 

incrementing specified in this paragraph 

(d)(3) for monitors using the standard 

MIL activation protocol, and the overall 

equivalence of the incrementing 

approach in determining that the 

minimum acceptable in-use 

performance ratio of paragraph (d)(1)(ii) 

of this section has been satisfied. 

(d)(4) through (f) [Reserved]. For 

guidance see § 86.010–18. 

(g) OBD monitoring requirements for 

diesel-fueled/compression-ignition 

engines. The following table shows the 

thresholds at which point certain 

components or systems, as specified in 

this paragraph (g), are considered 

malfunctioning. 

TABLE 1.—OBD EMISSIONS THRESHOLDS FOR DIESEL-FUELED/COMPRESSION IGNITION ENGINES MEANT FOR ENGINES

PLACED IN APPLICATIONS GREATER THAN 14,000 POUNDS GVWR (G/BHP-HR) 

Component 

§ 86.010–

18 reference NMHC CO NOX PM 

NMHC catalyst system .................................................................................... (g)(5) ........ 2x ............. .................. .................. ....................

NOX aftertreatment system .............................................................................. (g)(6) ........ .................. .................. +0.3 ......... ....................

(g)(7) 

Diesel particulate filter (DPF) system .............................................................. (g)(8) ........ 2x ............. .................. .................. 0.05/+0.04 

Air-fuel ratio sensors upstream of aftertreatment devices .............................. (g)(9) ........ 2x ............. 2x ............. +0.3 ......... 0.03/+0.02 

Air-fuel ratio sensors downstream of aftertreatment devices .......................... (g)(9) ........ 2x ............. .................. +0.3 ......... 0.05/+0.04 

NOX sensors .................................................................................................... (g)(9) ........ .................. .................. +0.3 ......... 0.05/+0.04 

‘‘Other monitors’’ with emissions thresholds ................................................... (g)(1) ........

(g)(2) ........

2x ............. 2x ............. +0.3 ......... 0.03/+0.02 

(g)(3) 

(g)(4) 

(g)(10) 

Notes: FEL=Family Emissions Limit; 2x std means a multiple of 2 times the applicable emissions standard; +0.3 means the standard or FEL 

plus 0.3; 0.05/+0.04 means an absolute level of 0.05 or an additive level of the standard or FEL plus 0.04, whichever level is higher; these emissions thresholds apply to the monitoring requirements of paragraph (g) of this § 86.013–18. 

(1) Fuel system monitoring. 

(g)(1)(i) through (g)(1)(iii)(A) 

[Reserved]. For guidance see § 86.010–

18. 

(g)(1)(iii)(B) The manufacturer must 

define the monitoring conditions for 

malfunctions identified in § 86.010–

18(g)(1)(ii)(B) and (g)(1)(ii)(C) and Table 

1 of paragraph (g) of this section in 

accordance with paragraphs (c) and (d) 

of this section. 

(iv) Fuel system MIL activation and 

DTC storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(2) Engine misfire monitoring. 

(g)(2)(i) [Reserved]. For guidance see 

§ 86.010–18. 

(g)(2)(ii) Engine misfire malfunction 

criteria. 

(A) The OBD system must be capable 

of detecting misfire occurring in one or 

more cylinders. To the extent possible 

without adding hardware for this 

specific purpose, the OBD system must 

also identify the specific misfiring 

cylinder. If more than one cylinder is 

continuously misfiring, a separate DTC 

must be stored indicating that multiple 

cylinders are misfiring. When 

identifying multiple cylinder misfire, 

the OBD system is not required to 

identify individually through separate 

DTCs each of the continuously misfiring 

cylinders. 

(B) On engines equipped with sensors 

that can detect combustion or 

combustion quality (e.g., for use in 

engines with homogeneous charge 

compression ignition (HCCI) control 

systems), the OBD system must detect a 

misfire malfunction causing emissions 

to exceed the applicable thresholds for 

‘‘other monitors’’ shown in Table 1 of 

this paragraph (g). To determine what 

level of misfire would cause emissions 

to exceed the applicable emissions 

thresholds, the manufacturer must 

determine the percentage of misfire 

evaluated in 1,000 revolution 

increments that would cause emissions 

from an emission durability 

demonstration engine to exceed the 

emissions thresholds if the percentage 

of misfire were present from the 

beginning of the test. To establish this 

percentage of misfire, the manufacturer 

must use misfire events occurring at 

equally spaced, complete engine cycle 

intervals, across randomly selected 

cylinders throughout each 1,000- 

revolution increment. If this percentage 


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of misfire is determined to be lower 

than one percent, the manufacturer may 

set the malfunction criteria at one 

percent. Any misfire malfunction must 

be detected if the percentage of misfire 

established via this testing is exceeded 

regardless of the pattern of misfire 

events (e.g., random, equally spaced, 

continuous). The manufacturer may 

employ other revolution increments 

besides the 1,000 revolution increment. 

To do so, the manufacturer must 

demonstrate that the strategy is equally 

effective and timely in detecting misfire. 

(iii) Engine misfire monitoring 

conditions. 

(g)(2)(iii)(A) and (g)(2)(iii)(B) 

[Reserved]. For guidance see § 86.010–

18. 

(g)(2)(iii)(C) For engines equipped 

with sensors that can detect combustion 

or combustion quality the OBD system 

must monitor continuously for engine 

misfire under all positive torque engine 

speed and load conditions. If a 

monitoring system cannot detect all 

misfire patterns under all required 

engine speed and load conditions, the 

manufacturer may request that the 

Administrator approve the monitoring 

system nonetheless. In evaluating the 

manufacturer’s request, the 

Administrator will consider the 

following factors: the magnitude of the 

region(s) in which misfire detection is 

limited; the degree to which misfire 

detection is limited in the region(s) (i.e., 

the probability of detection of misfire 

events); the frequency with which said 

region(s) are expected to be encountered 

in-use; the type of misfire patterns for 

which misfire detection is troublesome; 

and demonstration that the monitoring 

technology employed is not inherently 

incapable of detecting misfire under 

required conditions (i.e., compliance 

can be achieved on other engines). The 

evaluation will be based on the 

following misfire patterns: equally 

spaced misfire occurring on randomly 

selected cylinders; single cylinder 

continuous misfire; and, paired cylinder 

(cylinders firing at the same crank 

angle) continuous misfire. 

(iv) Engine misfire MIL activation and 

DTC storage. 

(A) General requirements for MIL 

activation and DTC storage are set forth 

in paragraph (b) of this section. 

(B) For engines equipped with sensors 

that can detect combustion or 

combustion quality, upon detection of 

the percentage of misfire specified in 

paragraph (g)(2)(ii)(B) of this section, the 

following criteria shall apply for MIL 

activation and DTC storage: A pending 

DTC must be stored no later than after 

the fourth exceedance of the percentage 

of misfire specified in paragraph 

(g)(2)(ii) of this section during a single 

drive cycle; if a pending fault code has 

been stored, the OBD system must 

activate the MIL and store a MIL-on 

DTC within 10 seconds if the percentage 

of misfire specified in paragraph 

(g)(2)(ii) of this section is again 

exceeded four times during the drive 

cycle immediately following storage of 

the pending DTC, regardless of the 

conditions encountered during the drive 

cycle, or on the next drive cycle in 

which similar conditions are 

encountered to those that were 

occurring when the pending DTC was 

stored. Similar conditions means an 

engine speed within 375 rpm, engine 

load within 20 percent, and the same 

warm up status (i.e., cold or hot). The 

Administrator may approve other 

definitions of similar conditions based 

on comparable timeliness and reliability 

in detecting similar engine operation. 

The pending DTC may be erased at the 

end of the next drive cycle in which 

similar conditions are encountered to 

those that were occurring when the 

pending DTC was stored provided the 

specified percentage of misfire was not 

again exceeded. The pending DTC may 

also be erased if similar conditions are 

not encountered during the 80 drive 

cycles immediately following initial 

detection of the malfunction. 

(C) For engines equipped with sensors 

that can detect combustion or 

combustion quality, the OBD system 

must store and erase freeze frame 

conditions either in conjunction with 

storing and erasing a pending DTC or in 

conjunction with storing and erasing a 

MIL-on DTC. If freeze frame conditions 

are stored for a malfunction other than 

a misfire malfunction when a DTC is 

stored as specified in paragraph 

(g)(2)(iv)(B) of this section, the stored 

freeze frame information must be 

replaced with the freeze frame 

information regarding the misfire 

malfunction. 

(D) For engines equipped with sensors 

that can detect combustion or 

combustion quality, upon detection of 

misfire according to paragraph 

(g)(2)(iv)(B) of this section, the OBD 

system must also store the following 

engine conditions: engine speed, load, 

and warm up status of the first misfire 

event that resulted in the storage of the 

pending DTC. 

(E) For engines equipped with sensors 

that can detect combustion or 

combustion quality, the MIL may be 

deactivated after three sequential drive 

cycles in which similar conditions have 

been encountered without an 

exceedance of the specified percentage 

of misfire. 

(3) EGR system monitoring. 

(g)(3)(i) and (g)(3)(ii) [Reserved]. For 

guidance see § 86.010–18. 

(g)(3)(iii) EGR system monitoring 

conditions. 

(g)(3)(iii)(A) [Reserved]. For guidance 

see § 86.010–18. 

(g)(3)(iii)(B) The manufacturer must 

define the monitoring conditions for 

malfunctions identified in § 86.010–

18(g)(3)(ii)(C) and Table 1 of paragragh 

(g) of this section in accordance with 

paragraphs (c) and (d) of this section, 

with the exception that monitoring must 

occur every time the monitoring 

conditions are met during the drive 

cycle rather than once per drive cycle as 

required in § 86.010–18(c)(2). For 

purposes of tracking and reporting as 

required in § 86.010–18(d) through 

(d)(1)(i), all monitors used to detect 

malfunctions identified in § 86.010–

18(g)(3)(ii)(C) and Table 1 of paragraph 

(g) of this section must be tracked 

separately but reported as a single set of 

values as specified in § 86.010–

18(e)(1)(iii). 

(C) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(g)(3)(ii)(E) and 

Table 1 of paragraph (g) of this section 

in accordance with paragraphs (c) and 

(d) of this section. For purposes of 

tracking and reporting as required in 

§ 86.010–18(d) through (d)(1)(i), all 

monitors used to detect malfunctions 

identified in § 86.010–18(g)(3)(ii)(E) and 

Table 1 of paragraph (g) of this section 

must be tracked separately but reported 

as a single set of values as specified in 

§ 86.010–18(e)(1)(iii). 

(g)(3)(iii)(D) [Reserved]. For guidance 

see § 86.010–18. 

(g)(3)(iv) EGR system MIL activation 

and DTC storage. The MIL must activate 

and DTCs must be stored according to 

the provisions of paragraph (b) of this 

section. 

(4) Turbo boost control system 

monitoring. 

(g)(4)(i) and (g)(4)(ii) [Reserved]. For 

guidance see § 86.010–18. 

(g)(4)(iii) Turbo boost control system 

monitoring conditions. 

(g)(4)(iii)(A) [Reserved]. For guidance 

see § 86.010–18. 

(g)(iii)(3)(B) The manufacturer must 

define the monitoring conditions for 

malfunctions identified in § 86.010–

18(g)(4)(ii)(C) and Table 1 of paragraph 

(g) of this section in accordance with 

paragraphs (c) and (d) of this section, 

with the exception that monitoring must 

occur every time the monitoring 

conditions are met during the drive 

cycle rather than once per drive cycle as 

required in § 86.010–18(c)(2). For 

purposes of tracking and reporting as 

required in § 86.010–18(d) through 

(d)(1)(i), all monitors used to detect 


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malfunctions identified in § 86.010–

18(g)(4)(ii)(C) and Table 1 of paragraph 

(g) of this section must be tracked 

separately but reported as a single set of 

values as specified in § 86.010–

18(e)(1)(iii). 

(C) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(g)(4)(ii)(E) and 

Table 1 of paragraph (g) of this section 

in accordance with paragraphs (c) and 

(d) of this section. For purposes of 

tracking and reporting as required in 

§ 86.010–18(d) through (d)(1)(i), all 

monitors used to detect malfunctions 

identified in § 86.010–18(g)(4)(ii)(E) and 

Table 1 of paragraph (g) of this section 

must be tracked separately but reported 

as a single set of values as specified in 

§ 86.010–18(e)(1)(iii). 

(iv) Turbo boost system MIL activation 

and DTC storage. The MIL must activate 

and DTCs must be stored according to 

the provisions of paragraph (b) of this 

section. 

(5) NMHC converting catalyst 

monitoring. 

(g)(5)(i) and (g)(5)(ii) [Reserved]. For 

guidance see § 86.010–18. 

(g)(5)(iii) NMHC converting catalyst 

monitoring conditions. The 

manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(g)(5)(ii)(A) and 

(g)(5)(ii)(B) and Table 1 of paragraph (g) 

of this section in accordance with 

paragraphs (c) and (d) of this section. 

For purposes of tracking and reporting 

as required in § 86.010–18(d) through 

(d)(1)(i), all monitors used to detect 

malfunctions identified in § 86.010–

18(g)(5)(ii)(A) and (g)(5)(ii)(B) and Table 

1 of paragraph (g) of this section must 

be tracked separately but reported as a 

single set of values as specified in 

§ 86.010–18(e)(1)(iii). 

(iv) NMHC converting catalyst MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. The monitoring 

method for the NMHC converting 

catalyst(s) must be capable of detecting 

all instances, except diagnostic selfclearing, when a catalyst DTC has been 

erased but the catalyst has not been 

replaced (e.g., catalyst over-temperature 

histogram approaches are not 

acceptable). 

(6) Selective catalytic reduction (SCR) 

and lean NOX catalyst monitoring. 

(g)(6)(i) and (g)(6)(ii) [Reserved]. For 

guidance see § 86.010–18 

(g)(6)(iii) SCR and lean NOX catalyst 

monitoring conditions. 

(A) The manufacturers must define 

the monitoring conditions for 

malfunctions identified in § 86.010–

18(g)(6)(ii)(A) and Table 1 of paragraph 

(g) of this section in accordance with 

paragraphs (c) and (d) of this section. 

For purposes of tracking and reporting 

as required in § 86.010–18(d) through 

(d)(1)(i), all monitors used to detect 

malfunctions identified in § 86.010–

18(g)(6)(ii)(A) and Table 1 of paragraph 

(g) of this section must be tracked 

separately but reported as a single set of 

values as specified in § 86.010–

18(e)(1)(iii). 

(g)(6)(iii)(B) [Reserved]. For guidance 

see § 86.010–18. 

(g)(6)(iv) SCR and lean NOX catalyst 

MIL activation and DTC storage. 

(A) For malfunctions identified in 

§ 86.010–18(g)(6)(ii)(A) and Table 1 of 

paragraph (g) of this section, the MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. 

(g)(6)(iv)(B) and (g)(6)(iv)(C) 

[Reserved]. For guidance see § 86.010–

18. 

(g)(7) NOX adsorber system 

monitoring. 

(g)(7)(i) and (g)(7)(ii) [Reserved]. For 

guidance see § 86.010–18. 

(g)(7)(iii) NOX adsorber system 

monitoring conditions. 

(A) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(g)(7)(ii)(A) and 

Table 1 of paragraph (g) of this section 

in accordance with paragraphs (c) and 

(d) of this section. For purposes of 

tracking and reporting as required in 

§ 86.010–18(d) through (d)(1)(i), all 

monitors used to detect malfunctions 

identified in § 86.010–18(g)(7)(ii)(A) and 

Table 1 of paragraph (g) of this section 

must be tracked separately but reported 

as a single set of values as specified in 

of § 86.010–18(e)(1)(iii). 

(g)(7)(iii)(B) [Reserved]. For guidance 

see § 86.010–18. 

(g)(7)(iv) NOX adsorber system MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. 

(8) Diesel particulate filter (DPF) 

system monitoring. 

(g)(8)(i) and (g)(8)(ii) [Reserved]. For 

guidance see § 86.010–18. 

(g)(8)(iii) DPF monitoring conditions. 

The manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(g)(8)(ii) and 

Table 1 of paragraph (g) of this section 

in accordance with paragraphs (c) and 

(d) of this section, with the exception 

that monitoring must occur every time 

the monitoring conditions are met 

during the drive cycle rather than once 

per drive cycle as required in § 86.010–

18(c)(2). For purposes of tracking and 

reporting as required in § 86.010–18(d) 

through (d)(1)(i), all monitors used to 

detect malfunctions identified in 

§ 86.010–18(g)(8)(ii) and Table 1 of 

paragraph (g) of this section must be 

tracked separately but reported as a 

single set of values as specified in 

§ 86.010–18(e)(1)(iii). 

(iv) DPF system MIL activation and 

DTC storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(9) Exhaust gas sensor and sensor 

heater monitoring. 

(g)(9)(i) through (g)(9)(vi) [Reserved]. 

For guidance see § 86.010–18. 

(g)(9)(vii) Monitoring conditions for 

exhaust gas sensors. 

(A) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(g)(9)(ii)(A), 

(g)(9)(iii)(A), and (g)(9)(iv)(A) (i.e., 

sensor performance) and Table 1 of 

paragraph (g) of this section in 

accordance with paragraphs (c) and (d) 

of this section. For purposes of tracking 

and reporting as required in § 86.010–

18(d) through (d)(1)(i), all monitors used 

to detect malfunctions identified in 

§ 86.010–18(g)(9)(ii)(A), (g)(9)(iii)(A), 

and(g)(9)(iv)(A) and Table 1 of 

paragraph (g) of this section must be 

tracked separately but reported as a 

single set of values as specified in 

§ 86.010–18(e)(1)(iii). 

(B) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(g)(9)(ii)(D), 

(g)(9)(iii)(D), and (g)(9)(iv)(D) (i.e., 

monitoring function) and Table 1 of 

paragraph (g) of this section in 

accordance with paragraphs (c) and (d) 

of this section with the exception that 

monitoring must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in § 86.010–

18(c)(2). 

(g)(9)(vii)(C) and (g)(9)(vii)(D) 

[Reserved]. For guidance see § 86.010–

18. 

(g)(9)(viii) Monitoring conditions for 

exhaust gas sensor heaters. 

(A) The manufacturer must define 

monitoring conditions for malfunctions 

identified in § 86.010–18(g)(9)(A) (i.e., 

sensor heater performance) and Table 1 

of paragraph (g) of this section in 

accordance with paragraphs (c) and (d) 

of this section. 

(g)(9)(viii)(B) [Reserved]. For guidance 

see § 86.010–18. 

(g)(9)(ix) Exhaust gas sensor and 

sensor heater MIL activation and DTC 

storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(10) Variable valve timing (VVT) 

system monitoring. 


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(g)(10)(i) and (g)(10)(vii) [Reserved]. 

For guidance see § 86.010–18. 

(g)(10)(iii) VVT system monitoring 

conditions. Manufacturers must define 

the monitoring conditions for VVT 

system malfunctions identified in 

§ 86.010–18(g)(10)(ii) and Table 1 of 

paragraph (g) of this section in 

accordance with paragraphs (c) and (d) 

of this section, with the exception that 

monitoring must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in § 86.010–

18(c)(2). For purposes of tracking and 

reporting as required in § 86.010–18(d) 

through (d)(1)(i), all monitors used to 

detect malfunctions identified in 

§ 86.010–18(g)(10)(ii) and Table 1 of 

paragraph (g) of this section must be 

tracked separately but reported as a 

single set of values as specified in 

§ 86.010–18(d)(1)(iii). 

(iv) VVT MIL activation and DTC 

storage. The MIL must activate and 

DTCs must be stored according to the 

provisions of paragraph (b) of this 

section. 

(h) [Reserved]. For guidance see 

§ 86.010–18. 

(i) OBD monitoring requirements for 

all engines. 

(1) Engine cooling system monitoring. 

(i)(1)(i) through (i)(1)(iii) [Reserved]. 

For guidance see § 86.010–18. 

(i)(1)(iv) Monitoring conditions for the 

thermostat. 

(A) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in paragraph § 86.010–

18(i)(1)(ii)(A) and Table 1 of paragraph 

(g) of this section in accordance with 

paragraph (c) of this section. 

Additionally, except as provided for in 

§ 86.010–18(i)(1)(iv)(B) and (i)(1)(iv)(C), 

monitoring for malfunctions identified 

in § 86.010–18(i)(1)(ii)(A) and Table 1 of 

paragraph (g) of this section must be 

conducted once per drive cycle on every 

drive cycle in which the ECT sensor 

indicates, at engine start, a temperature 

lower than the temperature established 

as the malfunction criteria in § 86.010–

18(i)(1)(ii)(A) and Table 1 of paragraph 

(g) of this section. 

(i)(1)(iv)(B) and (i)(1)(iv)(C) 

[Reserved]. For guidance see § 86.010–

18. 

(i)(1)(v) Monitoring conditions for the 

ECT sensor. 

(i)(1)(v)(A) [Reserved]. For guidance 

see § 86.010–18. 

(i)(1)(v)(B) The manufacturer must 

define the monitoring conditions for 

malfunctions identified in § 86.010–

18(i)(1)(iii)(B) and Table 1 of paragraph 

(g) of this section in accordance with 

paragraph (c) of this section. 

Additionally, except as provided for in 

§ 86.010–18(i)(1)(v)(D), monitoring for 

malfunctions identified in § 86.010–

18(i)(1)(iii)(B) and Table 1 of paragraph 

(g) of this section must be conducted 

once per drive cycle on every drive 

cycle in which the ECT sensor indicates 

a temperature lower than the closedloop enable temperature at engine start 

(i.e., all engine start temperatures 

greater than the ECT sensor out-of-range 

low temperature and less than the 

closed-loop enable temperature). 

(C) The manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(i)(1)(iii)(C) and 

(i)(1)(iii)(D) and Table 1 of paragraph (g) 

of this section in accordance with 

paragraphs (c) and (d) of this section. 

(i)(1)(v)(D) and (i)(1)(v)(E) [Reserved]. 

For guidance see § 86.010–18. 

(i)(1)(vi) Engine cooling system MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. 

(2) Crankcase ventilation (CV) system 

monitoring. 

(i)(2)(i) and (i)(2)(ii) [Reserved]. For 

guidance see § 86.010–18. 

(i)(2)(iii) Crankcase ventilation system 

monitoring conditions. The 

manufacturer must define the 

monitoring conditions for malfunctions 

identified in § 86.010–18(i)(2)(ii) and 

Table 1 of paragraph (g) of this section 

in accordance with paragraphs (c) and 

(d) of this section. 

(iv) Crankcase ventilation system MIL 

activation and DTC storage. The MIL 

must activate and DTCs must be stored 

according to the provisions of paragraph 

(b) of this section. The stored DTC need 

not identify specifically the CV system 

(e.g., a DTC for idle speed control or fuel 

system monitoring can be stored) if the 

manufacturer can demonstrate that 

additional monitoring hardware would 

be necessary to make such an 

identification and provided the 

manufacturer’s diagnostic and repair 

procedures for the detected malfunction 

include directions to check the integrity 

of the CV system. 

(3) Comprehensive component 

monitoring. 

(i) General. Except as provided for in 

paragraph (i)(4) of this section, the OBD 

system must detect a malfunction of any 

electronic engine component or system 

not otherwise described in paragraphs 

(g), (i)(1), and (i)(2) of this section and 

§ 86.010–18(h) that either provides 

input to (directly or indirectly, such 

components may include the crank 

angle sensor, knock sensor, throttle 

position sensor, cam position sensor, 

intake air temperature sensor, boost 

pressure sensor, manifold pressure 

sensor, mass air flow sensor, exhaust 

temperature sensor, exhaust pressure 

sensor, fuel pressure sensor, fuel 

composition sensor of a flexible fuel 

vehicle, etc.) or receives commands 

from (such components or systems may 

include the idle speed control system, 

glow plug system, variable length intake 

manifold runner systems, supercharger 

or turbocharger electronic components, 

heated fuel preparation systems, the 

wait-to-start lamp on diesel 

applications, the MIL, etc.) the onboard 

computer(s) and meets either of the 

criteria described in § 86.010–

18(i)(3)(i)(A) and/or (i)(3)(i)(B). Note 

that, for the purposes of this paragraph 

(i)(3), ‘‘electronic engine component or 

system’’ does not include components 

that are driven by the engine and are not 

related to the control of the fueling, air 

handling, or emissions of the engine 

(e.g., PTO components, air conditioning 

system components, and power steering 

components). 

(i)(3)(i)(A) through (i)(3)(iii) 

[Reserved]. For guidance see § 86.010–

18. 

(i)(3)(iv) Monitoring conditions for 

input components. 

(i)(3)(iv)(A) [Reserved]. For guidance 

see § 86.010–18. 

(i)(3)(iv)(B) For input component 

rationality checks (where applicable), 

the manufacturer must define the 

monitoring conditions for detecting 

malfunctions in accordance with 

paragraphs (c) and (d) of this section, 

with the exception that rationality 

checks must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in § 86.010–

18(c)(2). 

(v) Monitoring conditions for output 

components/systems. 

(i)(3)(v)(A) [Reserved]. For guidance 

see § 86.010–18. 

(i)(3)(v)(B) For output component/ 

system functional checks, the 

manufacturer must define the 

monitoring conditions for detecting 

malfunctions in accordance with 

paragraphs (c) and (d) of this section. 

Specifically for the idle control system, 

the manufacturer must define the 

monitoring conditions for detecting 

malfunctions in accordance with 

paragraphs (c) and (d) of this section, 

with the exception that functional 

checks must occur every time the 

monitoring conditions are met during 

the drive cycle rather than once per 

drive cycle as required in § 86.010–

18(c)(2). 

(vi) Comprehensive component MIL 

activation and DTC storage. 

(A) Except as provided for in 

§ 86.010–18(i)(3)(vi)(B) and (i)(3)(vi)(C), 

the MIL must activate and DTCs must be 


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stored according to the provisions of 

paragraph (b) of this section. 

(i)(3)(vi)(B) and (i)(3)(vi)(C) 

[Reserved]. For guidance see § 86.010–

18. 

(i)(4) Other emission control system 

monitoring. 

(i) General. For other emission control 

systems that are either not addressed in 

§ 86.010–18(h) and paragraphs (g) and 

(i)(1) through (i)(3) of this section (e.g., 

hydrocarbon traps, homogeneous charge 

compression ignition control systems), 

or addressed in paragraph (i)(3) of this 

section but not corrected or 

compensated for by an adaptive control 

system (e.g., swirl control valves), the 

manufacturer must submit a plan for 

Administrator approval of the 

monitoring strategy, malfunction 

criteria, and monitoring conditions prior 

to introduction on a production engine. 

The plan must demonstrate the 

effectiveness of the monitoring strategy, 

the malfunction criteria used, the 

monitoring conditions required by the 

monitor, and, if applicable, the 

determination that the requirements of 

§ 86.010–18(i)(4)(ii) are satisfied. 

(i)(4)(ii) through (i)(5)(v) [Reserved]. 

For guidance see § 86.010–18. 

(i)(6) Feedback control system 

monitoring. If the engine is equipped 

with feedback control of any of the 

systems covered in paragraphs (g) and 

(i) of this section and § 86.010–18(h), 

then the OBD system must detect as 

malfunctions the conditions specified in 

this paragraph (i)(6) for each of the 

individual feedback controls. 

(i)(6)(i) through (i)(6)(iv) [Reserved]. 

For guidance see § 86.010–18. 

(j) Production evaluation testing. 

(1) Verification of standardization 

requirements. 

(i) The manufacturer must perform 

testing to verify that production vehicles 

meet the requirements of paragraphs 

(k)(3) and (k)(4) of this section relevant 

to the proper communication of 

required emissions-related messages to a 

SAE J1978/J1939 scan tool. 

(ii) Selection of test vehicles. 

(A) The manufacturer must perform 

this testing every model year on ten 

unique production vehicles (i.e., engine 

rating and chassis application 

combination) per engine family. If there 

are less than ten unique production 

vehicles for a certain engine family, the 

manufacturer must test each unique 

production vehicle in that engine 

family. The manufacturer must perform 

this testing within either three months 

of the start of engine production or one 

month of the start of vehicle production, 

whichever is later. The manufacturer 

may request approval to group multiple 

production vehicles together and test 

one representative vehicle per group. To 

do so, the software and hardware 

designed to comply with the 

standardization requirements of 

paragraph (k) of this section (e.g., 

communication protocol message 

timing, number of supported data 

stream parameters, engine and vehicle 

communication network architecture) in 

the representative vehicle must be 

identical to all others in the group and 

any differences in the production 

vehicles cannot be relevant with respect 

to meeting the criteria of paragraph 

(j)(1)(iv) of this section. 

(B) For 2016 and subsequent model 

years, the required number of vehicles 

to be tested shall be reduced to five per 

engine family provided zero vehicles 

fail the testing required by paragraph 

(j)(1) of this section for two consecutive 

years. 

(C) For 2019 and subsequent model 

years, the required number of vehicles 

to be tested shall be reduced to three per 

engine family provided zero vehicles 

fail the testing required by paragraph 

(j)(1) of this section for three 

consecutive years. 

(D) The requirement for submittal of 

data from one or more of the production 

vehicles shall be waived if data have 

been submitted previously for all of the 

production vehicles. The manufacturer 

may request approval to carry over data 

collected in previous model years. To 

do so, the software and hardware 

designed to comply with the 

standardization requirements of 

paragraph (k) of this section must be 

identical to the previous model year and 

there must not have been other 

hardware or software changes that affect 

compliance with the standardization 

requirements. 

(iii) Test equipment. For the testing 

required by paragraph (j)(1) of this 

section, the manufacturer shall use an 

off-board device to conduct the testing. 

The manufacturer must be able to show 

that the off-board device is able to verify 

that the vehicles tested using the device 

are able to perform all of the required 

functions in paragraph (j)(1)(iv) of this 

section with any other off-board device 

designed and built in accordance with 

the SAE J1978/J1939 generic scan tool 

specifications. 

(iv) Required testing. The testing must 

verify that communication can be 

established properly between all 

emission-related on-board computers 

and any SAE J1978/J1939 scan tool 

designed to adhere strictly to the 

communication protocols allowed in 

paragraph (k)(3) of this section. The 

testing must also verify that all 

emission-related information is 

communicated properly between all 

emission-related on-board computers 

and any SAE J1978/J1939 scan tool in 

accordance with the requirements of 

paragraph (k) of this section and the 

applicable ISO and SAE specifications 

including specifications for physical 

layer, network layer, message structure, 

and message content. The testing must 

also verify that the onboard computer(s) 

can properly respond to any SAE J1978/ 

J1939 scan tool request to clear 

emissions-related DTCs and reset the 

ready status in accordance with 

paragraph (k)(4)(ix) of this section. The 

testing must further verify that the 

following information can be properly 

communicated to any SAE J1978/J1939 

scan tool: 

(A) The current ready status from all 

onboard computers required to support 

ready status in accordance with SAE 

J1978/J1939–73 and paragraph (k)(4)(i) 

of this section in the key-on, engine-off 

position and while the engine is 

running. 

(B) The MIL command status while a 

deactivated MIL is commanded and 

while an activated MIL is commanded 

in accordance with SAE J1979/J1939 

and paragraph (k)(4)(ii) of this section in 

the key-on, engine-off position and 

while the engine is running, and in 

accordance with SAE J1979/J1939 and 

§ 86.010–18(b)(1)(ii) during the MIL 

functional check and, if applicable, 

(k)(4)(i)(C) of this section during the 

MIL ready status check while the engine 

is off. 

(C) All data stream parameters 

required in paragraph (k)(4)(ii) of this 

section in accordance with SAE J1979/ 

J1939 including, if applicable, the 

proper identification of each data stream 

parameter as supported in SAE J1979 

(e.g., Mode/Service $01, PID $00). 

(D) The CAL ID, CVN, and VIN as 

required by paragraphs (k)(4)(vi), 

(k)(4)(vii), and (k)(4)(viii) of this section 

and in accordance with SAE J1979/ 

J1939. 

(E) An emissions-related DTC 

(permanent, pending, MIL-on, previousMIL-on) in accordance with SAE J1979/ 

J1939–73 (including the correct 

indication of the number of stored DTCs 

(e.g., Mode/Service $01, PID $01, Data A 

for SAE J1979)) and paragraph (k)(4)(iv) 

of this section. 

(v) Reporting of results. The 

manufacturer must submit to the 

Administrator the following, based on 

the results of the testing required by 

paragraph (j)(1)(iv) of this section: 

(A) If a variant meets all the 

requirements of paragraph (j)(1)(iv) of 

this section, a statement specifying that 

the variant passed all the tests. Upon 

request from the Administrator, the 


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detailed results of any such testing may 

have to be submitted. 

(B) If any variant does not meet the 

requirements of paragraph (j)(1)(iv) of 

this section, a written report detailing 

the problem(s) identified and the 

manufacturer’s proposed corrective 

action (if any) to remedy the problem(s). 

This report must be submitted within 

one month of testing the specific 

variant. The Administrator will consider 

the proposed remedy and, if in 

disagreement, will work with the 

manufacturer to propose an alternative 

remedy. Factors to be considered by the 

Administrator in considering the 

proposed remedy will include the 

severity of the problem(s), the ability of 

service technicians to access the 

required diagnostic information, the 

impact on equipment and tool 

manufacturers, and the amount of time 

prior to implementation of the proposed 

corrective action. 

(vi) Alternative testing protocols. 

Manufacturers may request approval to 

use other testing protocols. To do so, the 

manufacturer must demonstrate that the 

alternative testing methods and 

equipment will provide an equivalent 

level of verification of compliance with 

the standardization requirements as is 

required by paragraph (j)(1) of this 

section. 

(2) Verification of monitoring 

requirements. 

(j)(2)(i) through (j)(2)(ii)(C) [Reserved]. 

For guidance see § 86.010–18. 

(j)(2)(iii) Evaluation requirements. 

(A) The evaluation must demonstrate 

the ability of the OBD system on the 

selected test vehicle to detect a 

malfunction, activate the MIL, and, 

where applicable, store an appropriate 

DTC readable by a SAE J1978/J1939 

scan tool when a malfunction is present 

and the monitoring conditions have 

been satisfied for each individual 

monitor required by this section. 

(j)(2)(iii)(B) through (j)(2)(iv) 

[Reserved]. For guidance see § 86.010–

18. 

(j)(3) Verification of in-use monitoring 

performance ratios. 

(j)(3)(i) through (j)(3)(iii) [Reserved]. 

For guidance see § 86.010–18. 

(j)(3)(iv) For each monitoring 

performance group, the data must 

include all of the in-use performance 

tracking data reported through SAE 

J1979/J1939 (i.e., all numerators, 

denominators, the general denominator, 

and the ignition cycle counter), the date 

the data were collected, the odometer 

reading, the VIN, and the calibration ID. 

(j)(3)(v) and (j)(3)(vi) [Reserved]. For 

guidance see § 86.010–18. 

(k) Standardization requirements. 

(k)(1) through (k)(1)(i)(B) [Reserved]. 

For guidance see § 86.010–18. 

(k)(1)(i)(C) SAE J1962 ‘‘Diagnostic 

Connector—;Equivalent to ISO/DIS 

15031–3: December 14, 2001,’’ April 

2002. 

(k)(1)(i)(D) through (k)(1)(ii)(A) 

[Reserved]. For guidance see § 86.010–

18. 

(k)(2) Diagnostic connector. A 

standard data link connector 

conforming to SAE J1962 or SAE J1939–

13 specifications (except as provided for 

in paragraph (k)(2)(iii) of this section) 

must be included in each vehicle. 

(i) The connector must be located in 

the driver’s side foot-well region of the 

vehicle interior in the area bound by the 

driver’s side of the vehicle and the 

driver’s side edge of the center console 

(or the vehicle centerline if the vehicle 

does not have a center console) and at 

a location no higher than the bottom of 

the steering wheel when in the lowest 

adjustable position. The connector shall 

not be located on or in the center 

console (i.e., neither on the horizontal 

faces near the floor-mounted gear 

selector, parking brake lever, or cupholders nor on the vertical faces near 

the car stereo, climate system, or 

navigation system controls). The 

location of the connector shall be 

capable of being easily identified and 

accessed (e.g., to connect an off-board 

tool). For vehicles equipped with a 

driver’s side door, the connector must 

be identified and accessed easily by 

someone standing (or ‘‘crouched’’) on 

the ground outside the driver’s side of 

the vehicle with the driver’s side door 

open. The Administrator may approve 

an alternative location upon request 

from the manufacturer. In all cases, the 

installation position of the connector 

must be both identified and accessed 

easily by someone standing outside the 

vehicle and protected from accidental 

damage during normal vehicle use. 

(ii) If the connector is covered, the 

cover must be removable by hand 

without the use of any tools and be 

labeled ‘‘OBD’’ to aid technicians in 

identifying the location of the 

connector. Access to the diagnostic 

connector shall not require opening or 

the removal of any storage accessory 

(e.g., ashtray, coinbox). The label must 

clearly identify that the connector is 

located behind the cover and is 

consistent with language and/or 

symbols commonly used in the 

automobile and/or heavy truck industry. 

(iii) If the ISO 15765–4 

communication protocol is used for the 

required OBD standardized functions, 

the connector must meet the ‘‘Type A’’

specifications of SAE J1962. Any pins in 

the connector that provide electrical 

power must be properly fused to protect 

the integrity and usefulness of the 

connector for diagnostic purposes and 

shall not exceed 20.0 Volts DC 

regardless of the nominal vehicle system 

or battery voltage (e.g., 12V, 24V, 42V). 

(iv) If the SAE J1939 protocol is used 

for the required OBD standardized 

functions, the connector must meet the 

specifications of SAE J1939–13. Any 

pins in the connector that provide 

electrical power must be properly fused 

to protect the integrity and usefulness of 

the connector for diagnostic purposes. 

(v) The manufacturer may equip 

engines/vehicles with additional 

diagnostic connectors for manufacturerspecific purposes (i.e., purposes other 

than the required OBD functions). 

However, if the additional connector 

conforms to the ‘‘Type A’’ specifications 

of SAE J1962 or the specifications of 

SAE J1939–13 and is located in the 

vehicle interior near the required 

connector as described in this paragraph 

(k)(2) of this section, the connector(s) 

must be labeled clearly to identify 

which connector is used to access the 

standardized OBD information required 

by paragraph (k) of this section. 

(3) Communications to a scan tool. 

All OBD control modules (e.g., engine, 

auxiliary emission control module) on a 

single vehicle must use the same 

protocol for communication of required 

emission-related messages from onboard to off-board network 

communications to a scan tool meeting 

SAE J1978 specifications or designed to 

communicate with an SAE J1939 

network. Engine manufacturers shall not 

alter normal operation of the engine 

emission control system due to the 

presence of off-board test equipment 

accessing information required by this 

paragraph (k). The OBD system must 

use one of the following standardized 

protocols: 

(i) ISO 15765–4. All required 

emission-related messages using this 

protocol must use a 500 kbps baud rate. 

(ii) SAE J1939. This protocol may 

only be used on vehicles with diesel 

engines. 

(4) Required emission related 

functions. The following standardized 

functions must be implemented in 

accordance with the specifications in 

SAE J1979 or SAE J1939 to allow for 

access to the required information by a 

scan tool meeting SAE J1978 

specifications or designed to 

communicate with an SAE J1939 

network: 

(i) Ready status. In accordance with 

SAE J1979/J1939–73 specifications, the 

OBD system must indicate ‘‘complete’’

or ‘‘not complete’’ for each of the 

installed monitored components and 


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systems identified in paragraphs (g), and 

(i)(3) of this section, and paragraph (h) 

with the exception of § 86.010–18(h)(4). 

All components or systems identified in 

§ 86.010–18(h)(1) or (h)(2), or (i)(3) of 

this section that are monitored 

continuously must always indicate 

‘‘complete.’’ Components or systems 

that are not subject to being monitored 

continuously must immediately indicate 

‘‘complete’’ upon the respective 

monitor(s) being executed fully and 

determining that the component or 

system is not malfunctioning. A 

component or system must also indicate 

‘‘complete’’ if, after the requisite 

number of decisions necessary for 

determining MIL status has been 

executed fully, the monitor indicates a 

malfunction of the component or 

system. The status for each of the 

monitored components or systems must 

indicate ‘‘not complete’’ whenever 

diagnostic memory has been cleared or 

erased by a means other than that 

allowed in paragraph (b) of this section. 

Normal vehicle shut down (i.e., key-off/ 

engine-off) shall not cause the status to 

indicate ‘‘not complete.’’

(k)(4)(i)(A) [Reserved]. For guidance 

see § 86.010–18. 

(k)(4)(i)(B) For the evaporative system 

monitor, the ready status must be set in 

accordance with this paragraph (k)(4)(i) 

when both the functional check of the 

purge valve and, if applicable, the leak 

detection monitor of the hole size 

specified in § 86.010–18(h)(7)(ii)(B) 

indicate that they are complete. 

(C) If the manufacturer elects to 

indicate ready status through the MIL in 

the key-on/engine-off position as 

provided for in § 86.010–18(b)(1)(iii), 

the ready status must be indicated in the 

following manner: If the ready status for 

all monitored components or systems is 

‘‘complete,’’ the MIL shall remain 

continuously activated in the key-on/ 

engine-off position for at least 10–20 

seconds. If the ready status for one or 

more of the monitored components or 

systems is ‘‘not complete,’’ after at least 

5 seconds of operation in the key-on/ 

engine-off position with the MIL 

activated continuously, the MIL shall 

blink once per second for 5–10 seconds. 

The data stream value for MIL status as 

required in paragraph (k)(4)(ii) of this 

section must indicate ‘‘commanded off’’

during this sequence unless the MIL has 

also been ‘‘commanded on’’ for a 

detected malfunction. 

(ii) Data stream. The following signals 

must be made available on demand 

through the standardized data link 

connector in accordance with SAE 

J1979/J1939 specifications. The actual 

signal value must always be used 

instead of a limp home value. 

(k)(4)(ii)(A) through (k)(4)(ii)(C) 

[Reserved]. For guidance see § 86.010–

18. 

(k)(4)(iii) Freeze frame. 

(A) ‘‘Freeze frame’’ information 

required to be stored pursuant to 

§ 86.010–18(b)(2)(iv), (h)(1)(iv)(D), and 

(h)(2)(vi) must be made available on 

demand through the standardized data 

link connector in accordance with SAE 

J1979/J1939–73 specifications. 

(k)(4)(iii)(B) [Reserved]. For guidance 

see § 86.010–18. 

(k)(4)(iii)(C) Only one frame of data is 

required to be recorded. The 

manufacturer may choose to store 

additional frames provided that at least 

the required frame can be read by a scan 

tool meeting SAE J1978 specifications or 

designed to communicate with an SAE 

J1939 network. 

(iv) Diagnostic trouble codes. 

(A) For all monitored components and 

systems, any stored pending, MIL-on, 

and previous-MIL-on DTCs must be 

made available through the diagnostic 

connector in a standardized format in 

accordance with SAE J1939 or ISO 

15765–4 specifications. Standardized 

DTCs conforming to the applicable 

standardized specifications must be 

employed. 

(k)(4)(iv)(B) and (k)(4)(iv)(C) 

[Reserved]. For guidance see § 86.010–

18. 

(k)(4)(iv)(D) A pending or MIL-on 

DTC (as required in paragraphs (g) and 

(i) of this section and § 86.010–18(h)) 

must be stored and available to an SAE 

J1978 or SAE J1939 scan tool within 10 

seconds after a monitor has determined 

that a malfunction or potential 

malfunction has occurred. A permanent 

DTC must be stored and available to an 

SAE J1978 or SAE J1939 scan tool no 

later than the end of an ignition cycle 

in which the corresponding MIL-on 

DTC that caused MIL activation has 

been stored. 

(E) Pending DTCs for all components 

and systems (including those monitored 

continuously and non-continuously) 

must be made available through the 

diagnostic connector in accordance with 

the applicable standard’s specifications. 

A manufacturer using alternative 

statistical protocols for MIL activation 

as allowed in § 86.010–18(b)(2)(iii) must 

submit the details of their protocol for 

setting pending DTCs. The protocol 

must be, overall, equivalent to the 

requirements of this paragraph 

(k)(4)(iv)(E) and provide service 

technicians with a quick and accurate 

indication of a potential malfunction. 

(F) Permanent DTC for all 

components and systems must be made 

available through the diagnostic 

connector in a standardized format that 

distinguishes permanent DTCs from 

pending DTCs, MIL-on DTCs, and 

previous-MIL-on DTCs. A MIL-on DTC 

must be stored as a permanent DTC no 

later than the end of the ignition cycle 

and subsequently at all times that the 

MIL-on DTC is commanding the MIL on. 

Permanent DTCs must be stored in nonvolatile random access memory 

(NVRAM) and shall not be erasable by 

any scan tool command or by 

disconnecting power to the on-board 

computer. Permanent DTCs must be 

erasable if the engine control module is 

reprogrammed and the ready status 

described in paragraph (k)(4)(i) of this 

section for all monitored components 

and systems are set to ‘‘not complete.’’

The OBD system must have the ability 

to store a minimum of four current MILon DTCs as permanent DTCs in 

NVRAM. If the number of MIL-on DTCs 

currently commanding activation of the 

MIL exceeds the maximum number of 

permanent DTCs that can be stored, the 

OBD system must store the earliest 

detected MIL-on DTC as permanent 

DTC. If additional MIL-on DTCs are 

stored when the maximum number of 

permanent DTCs is already stored in 

NVRAM, the OBD system shall not 

replace any existing permanent DTC 

with the additional MIL-on DTCs. 

(v) Test results. 

(A) Except as provided for in 

§ 86.010–18(k)(4)(v)(G), for all 

monitored components and systems 

identified in paragraph (g) of this 

section and § 86.010–18(h), results of 

the most recent monitoring of the 

components and systems and the test 

limits established for monitoring the 

respective components and systems 

must be stored and available through 

the data link in accordance with the 

standardized format specified in SAE 

J1979 (for engines using the ISO 15765–

4 protocol) or SAE J1939. 

(k)(4)(v)(B) [Reserved]. For guidance 

see § 86.010–18. 

(k)(4)(v)(C) The test results must be 

standardized such that the name of the 

monitored component (e.g., catalyst 

bank 1) can be identified by a generic 

scan tool and the test results and limits 

can be scaled and reported by a generic 

scan tool with the appropriate 

engineering units. 

(k)(4)(v)(D) through (k)(4)(v)(G) 

[Reserved]. For guidance see § 86.010–

18. 

(k)(4)(vi) Software calibration 

identification (CAL ID). On all engines, 

a single software calibration 

identification number (CAL ID) for each 

monitor or emission critical control 

unit(s) must be made available through 

the standardized data link connector in 

accordance with the SAE J1979/J1939 


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specifications. A unique CAL ID must 

be used for every emission-related 

calibration and/or software set having at 

least one bit of different data from any 

other emission-related calibration and/ 

or software set. Control units coded 

with multiple emission or diagnostic 

calibrations and/or software sets must 

indicate a unique CAL ID for each 

variant in a manner that enables an offboard device to determine which variant 

is being used by the vehicle. Control 

units that use a strategy that will result 

in MIL activation if the incorrect variant 

is used (e.g., control units that contain 

variants for manual and automatic 

transmissions but will activate the MIL 

if the selected variant does not match 

the type of transmission mated to the 

engine) are not required to use unique 

CAL IDs. 

(vii) Software calibration verification 

number (CVN). 

(A) All engines must use an algorithm 

to calculate a single calibration 

verification number (CVN) that verifies 

the on-board computer software 

integrity for each monitor or emission 

critical control unit that is electronically 

reprogrammable. The CVN must be 

made available through the 

standardized data link connector in 

accordance with the SAE J1979/J1939 

specifications. The CVN must indicate 

whether the emission-related software 

and/or calibration data are valid and 

applicable for the given vehicle and 

CAL ID. 

(k)(4)(vii)(B) [Reserved]. For guidance 

see § 86.010–18. 

(k)(4)(vii)(C) The CVN must be 

calculated at least once per drive cycle 

and stored until the CVN is 

subsequently updated. Except for 

immediately after a reprogramming 

event or a non-volatile memory clear or 

for the first 30 seconds of engine 

operation after a volatile memory clear 

or battery disconnect, the stored value 

must be made available through the data 

link connector to a generic scan tool in 

accordance with SAE J1979/J1939 

specifications. The stored CVN value 

shall not be erased when DTC memory 

is erased by a generic scan tool in 

accordance with SAE J1979/J1939 

specifications or during normal vehicle 

shut down (i.e., key-off/engine-off). 

(D) The CVN and CAL ID combination 

information must be available for all 

engines/vehicles in a standardized 

electronic format that allows for offboard verification that the CVN is valid 

and appropriate for a specific vehicle 

and CAL ID. 

(viii) Vehicle identification number 

(VIN). 

(A) All vehicles must have the vehicle 

identification number (VIN) available in 

a standardized format through the 

standardized data link connector in 

accordance with SAE J1979/J1939 

specifications. Only one electronic 

control unit per vehicle may report the 

VIN to an SAE J1978/J1939 scan tool. 

(k)(4)(viii)(B) [Reserved]. For guidance 

see § 86.010–18. 

(k)(4)(ix) Erasure of diagnostic 

information. 

(A) For purposes of this paragraph 

(k)(4)(ix), ‘‘emission-related diagnostic 

information’’ includes all of the 

following: ready status as required by 

paragraph (k)(4)(i) of this section; data 

stream information as required by 

paragraph (k)(4)(ii) of this section 

including the number of stored MIL-on 

DTCs, distance traveled while MIL 

activated, number of warm-up cycles 

since DTC memory last erased, and 

distance traveled since DTC memory 

last erased; freeze frame information as 

required by paragraph (k)(4)(iii) of this 

section; pending, MIL-on, and previousMIL-on DTCs as required by paragraph 

(k)(4)(iv) of this section; and, test results 

as required by paragraph (k)(4)(v) of this 

section. 

(k)(4)(ix)(B) [Reserved]. For guidance 

see § 86.010–18. 

(k)(5) In-use performance ratio 

tracking requirements. 

(i) For each monitor required in 

paragraphs (g) and (i) of this section and 

§ 86.010–18(h) to separately report an 

in-use performance ratio, manufacturers 

must implement software algorithms to 

report a numerator and denominator in 

the standardized format specified in this 

paragraph (k)(5) in accordance with the 

SAE J1979/J1939 specifications. 

(ii) For the numerator, denominator, 

general denominator, and ignition cycle 

counters required by § 86.010–18(e), the 

following numerical value 

specifications apply: 

(A) Each number shall have a 

minimum value of zero and a maximum 

value of 65,535 with a resolution of one. 

(B) Each number shall be reset to zero 

only when a non-volatile random access 

memory (NVRAM) reset occurs (e.g., 

reprogramming event) or, if the numbers 

are stored in keep-alive memory (KAM), 

when KAM is lost due to an 

interruption in electrical power to the 

control unit (e.g., battery disconnect). 

Numbers shall not be reset to zero under 

any other circumstances including 

when a scan tool command to clear 

DTCs or reset KAM is received. 

(C) To avoid overflow problems, if 

either the numerator or denominator for 

a specific component reaches the 

maximum value of 65,535 ±2, both 

numbers shall be divided by two before 

either is incremented again. 

(D) To avoid overflow problems, if the 

ignition cycle counter reaches the 

maximum value of 65,535 ±2, the 

ignition cycle counter shall rollover and 

increment to zero on the next ignition 

cycle. 

(E) To avoid overflow problems, if the 

general denominator reaches the 

maximum value of 65,535 ±2, the 

general denominator shall rollover and 

increment to zero on the next drive 

cycle that meets the general 

denominator definition. 

(F) If a vehicle is not equipped with 

a component (e.g., oxygen sensor bank 

2, secondary air system), the 

corresponding numerator and 

denominator for that specific 

component shall always be reported as 

zero. 

(iii) For the ratio required by 

§ 86.010–18(e), the following numerical 

value specifications apply: 

(A) The ratio shall have a minimum 

value of zero and a maximum value of 

7.99527 with a resolution of 0.000122. 

(B) The ratio for a specific component 

shall be considered to be zero whenever 

the corresponding numerator is equal to 

zero and the corresponding 

denominator is not zero. 

(C) The ratio for a specific component 

shall be considered to be the maximum 

value of 7.99527 if the corresponding 

denominator is zero or if the actual 

value of the numerator divided by the 

denominator exceeds the maximum 

value of 7.99527. 

(6) Engine run time tracking 

requirements. 

(i) For all gasoline and diesel engines, 

the manufacturer must implement 

software algorithms to track and report 

individually in a standardized format 

the amount of time the engine has been 

operated in the following conditions: 

(A) Total engine run time. 

(B) Total idle run time (with ‘‘idle’’

defined as accelerator pedal released by 

the driver, vehicle speed less than or 

equal to one mile per hour, engine 

speed greater than or equal to 50 to 150 

rpm below the normal, warmed-up idle 

speed (as determined in the drive 

position for vehicles equipped with an 

automatic transmission), and power 

take-off not active). 

(C) Total run time with power take off 

active. 

(ii) For each counter specified in 

paragraph (k)(6)(i) of this section, the 

following numerical value 

specifications apply: 

(A) Each number shall be a four-byte 

value with a minimum value of zero, a 

resolution of one second per bit, and an 

accuracy of ± ten seconds per drive 

cycle. 


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(B) Each number shall be reset to zero 

only when a non-volatile memory reset 

occurs (e.g., reprogramming event). 

Numbers shall not be reset to zero under 

any other circumstances including 

when a scan tool (generic or enhanced) 

command to clear fault codes or reset 

KAM is received. 

(C) To avoid overflow problems, if 

any of the individual counters reach the 

maximum value, all counters shall be 

divided by two before any are 

incremented again. 

(D) The counters shall be made 

available to a generic scan tool in 

accordance with the SAE J1979/J1939 

specifications and may be rescaled 

when transmitted, if required by the 

SAE specifications, from a resolution of 

one second per bit to no more than three 

minutes per bit. 

(l) Monitoring system demonstration 

requirements for certification. 

(1) General. 

(l)(1)(i) through (l)(1)(iii) [Reserved]. 

For guidance see § 86.010–18. 

(l)(2) Selection of test engines. 

(l)(2)(i) [Reserved]. For guidance see 

§ 86.010–18. 

(l)(2)(ii) A manufacturer certifying one 

to five engine families in a given model 

year must provide emissions test data 

for a single test engine from one engine 

rating. A manufacturer certifying six to 

ten engine families in a given model 

year must provide emissions test data 

for a single test engine from two 

different engine ratings. A manufacturer 

certifying eleven or more engine 

families in a given model year must 

provide emissions test data for a single 

test engine from three different engine 

ratings. A manufacturer may forego 

submittal of test data for one or more of 

these test engines if data have been 

submitted previously for all of the 

engine ratings and/or if all requirements 

for certification carry-over from one 

model year to the next are satisfied. 

(iii) For a given model year, a 

manufacturer may elect to provide 

emissions data for test engines from 

more engine ratings than required by 

paragraph (l)(2)(ii) of this section. For 

each additional engine rating tested in 

that given model year, the number of 

engine ratings required for testing in one 

future model year will be reduced by 

one. 

(iv) For the test engine, the 

manufacturer must use an engine aged 

for a minimum of 125 hours fitted with 

exhaust aftertreatment emission controls 

aged to be representative of useful life 

aging. The manufacturer is required to 

submit a description of the accelerated 

aging process and/or supporting data. 

The process and/or data must 

demonstrate assurance that 

deterioration of the exhaust 

aftertreatment emission controls is 

stabilized sufficiently such that it 

represents emission control 

performance at the end of the useful life. 

(3) Required testing. Except as 

otherwise described in this paragraph 

(l)(3) of this section, the manufacturer 

must perform single malfunction testing 

based on the applicable test with the 

components/systems set at their 

malfunction criteria limits as 

determined by the manufacturer for 

meeting the emissions thresholds 

required in paragraphs (g) and (i) of this 

section and § 86.010–18(h). 

(i) Required testing for diesel-fueled/ 

compression ignition engines. 

(l)(3)(i)(A) [Reserved]. For guidance 

see § 86.010–18. 

(l)(3)(i)(B) Engine misfire. The 

manufacturer must perform a test at the 

malfunction limit established by the 

manufacturer for the monitoring 

required by paragraph (g)(2)(ii)(B) of this 

section. 

(l)(3)(i)(C) through (l)(3)(i)(K) 

[Reserved]. For guidance see § 86.010–

18. 

(l)(3)(ii) Required testing for gasolinefueled/spark-ignition engines. 

(l)(3)(ii)(A) through (l)(3)(ii)(I) 

[Reserved]. For guidance see § 86.010–

18. 

(l)(3)(iii) Required testing for all 

engines. 

(l)(3)(iii)(A) and (l)(3)(iii)(B) 

[Reserved]. For guidance see § 86.010–

18. 

(l)(3)(iv) [Reserved]. For guidance see 

§ 86.010–18. 

(l)(4) Testing protocol. 

(l)(4)(i) [Reserved]. For guidance see 

§ 86.010–18. 

(l)(4)(ii) Test sequence. 

(l)(4)(ii)(A) through (l)(4)(ii)(C) 

[Reserved]. For guidance see § 86.010–

18. 

(l)(4)(iii) A manufacturer required to 

test more than one test engine according 

to paragraph (l)(2)(ii) of this section may 

use internal calibration sign-off test 

procedures (e.g., forced cool downs, less 

frequently calibrated emission 

analyzers) instead of official test 

procedures to obtain the emission test 

data required by this paragraph (l) of 

this section for all but one of the 

required test engines. The manufacturer 

may elect this option if the data from 

the alternative test procedure are 

representative of official emissions test 

results. A manufacturer using this 

option is still responsible for meeting 

the malfunction criteria specified in 

paragraphs (g) and (i) of this section and 

§ 86.010–18(h) if and when emissions 

tests are performed in accordance with 

official test procedures. 

(l)(4)(iv) [Reserved]. For guidance see 

§ 86.010–18. 

(l)(5) Evaluation protocol. 

(l)(5)(i) [Reserved]. For guidance see 

§ 86.010–18. 

(l)(5)(ii) If the MIL activates prior to 

emissions exceeding the applicable 

malfunction criteria limits specified in 

paragraphs (g) and (i) of this section and 

§ 86.010–18(h), no further 

demonstration is required. With respect 

to the misfire monitor demonstration 

test, if the manufacturer has elected to 

use the minimum misfire malfunction 

criteria of one percent as allowed in 

paragraphs (g)(2)(ii)(B) of this section 

and § 86.010–18(h)(2)(ii)(B), no further 

demonstration is required provided the 

MIL activates with engine misfire 

occurring at the malfunction criteria 

limit. 

(l)(5)(iii) through (l)(5)(iv) [Reserved]. 

For guidance see § 86.010–18. 

(l)(6) Confirmatory testing. 

(i) The Administrator may perform 

confirmatory testing to verify the 

emission test data submitted by the 

manufacturer as required by paragraph 

(l) of this section comply with its 

requirements and the malfunction 

criteria set forth in paragraphs (g) and (i) 

of this section and § 86.010–18(h). Such 

confirmatory testing is limited to the 

test engine(s) required by paragraph 

(l)(2) of this section. 

(l)(6)(ii) through (l)(7) [Reserved]. For 

guidance see § 86.010–18. 

(m) Certification documentation 

requirements. 

(m)(1) through (m)(2)(iv) [Reserved]. 

For guidance see § 86.010–18. 

(m)(2)(v) Emissions test data, a 

description of the testing sequence (e.g., 

the number and types of 

preconditioning cycles), approximate 

time (in seconds) of MIL activation 

during the test, diagnostic trouble 

code(s) and freeze frame information 

stored at the time of detection, 

corresponding test results (e.g. SAE 

J1979 Mode/Service $06, SAE J1939 

Diagnostic Message 8 (DM8)) stored 

during the test, and a description of the 

modified or deteriorated components 

used for malfunction simulation with 

respect to the demonstration tests 

specified in paragraph (l) of this section. 

The freeze frame data are not required 

for engines subject to paragraph (o)(3) of 

this section. 

(m)(2)(vi) through (m)(2)(x) 

[Reserved]. For guidance see § 86.010–

18. 

(m)(2)(xi) A written identification of 

the communication protocol utilized by 

each engine for communication with a 

SAE J1978/J1939 scan tool. 

(xii) A pictorial representation or 

written description of the diagnostic 


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connector location including any covers 

or labels. 

(m)(2)(xiii) [Reserved]. For guidance 

see § 86.010–18. 

(m)(2)(xiv) Build specifications 

provided to engine purchasers or 

chassis manufacturers detailing all 

specifications or limitations imposed on 

the engine purchaser relevant to OBD 

requirements or emissions compliance 

(e.g., allowable MIL locations, connector 

location specifications, cooling system 

heat rejection rates). A description of 

the method or copies of agreements 

used to ensure engine purchasers or 

chassis manufacturers will comply with 

the OBD and emissions relevant build 

specifications (e.g., signed agreements, 

required audit/evaluation procedures). 

(m)(2)(xv) [Reserved]. For guidance 

see § 86.010–18. 

(n) [Reserved]. For guidance see 

§ 86.010–18. 

(o) Implementation schedule. Except 

as provided for in paragraph (o)(4) of 

this section, the requirements of this 

section must be met according to the 

following provisions: 

(1) OBD groups. The manufacturer 

shall define one or more OBD groups to 

cover all engine ratings in all engine 

families. The manufacturer must submit 

a grouping plan for Administrator 

review and approval detailing the OBD 

groups and the engine families and 

engine ratings within each group for a 

given model year. 

(2) Full OBD. 

(i) For all engine ratings subject to 

§ 86.010–18, the manufacturer must 

implement an OBD system meeting the 

requirements of this section. 

(ii) On one engine rating within each 

of the manufacturer’s OBD groups, the 

manufacturer must implement an OBD 

system meeting the requirements of this 

section. These ‘‘full OBD’’ ratings will 

be known as the ‘‘OBD parent’’ ratings. 

The OBD parent rating for each OBD 

group must be chosen as the rating 

having the highest weighted projected 

U.S. sales within the OBD group, with 

U.S. sales being weighted by the useful 

life of the engine rating. 

(3) Extrapolated OBD. For all other 

engine ratings within each OBD group, 

the manufacturer must implement an 

OBD system meeting the requirements 

of this section except that the OBD 

system is not required to detect a 

malfunction prior to exceeding the 

emission thresholds shown in Table 1 of 

paragraph (g) of this section and Table 

2 of § 86.010–18(h). These extrapolated 

OBD engines will be known as the 

‘‘OBD child’’ ratings. On these OBD 

child ratings, rather than detecting a 

malfunction prior to exceeding the 

emission thresholds, the manufacturer 

must submit a plan for Administrator 

review and approval that details the 

engineering evaluation the manufacturer 

will use to establish the malfunction 

criteria for the OBD child ratings. The 

plan must demonstrate both the use of 

good engineering judgment in 

establishing the malfunction criteria, 

and robust detection of malfunctions, 

including consideration of differences of 

base engine, calibration, emission 

control components, and emission 

control strategies. 

(4) Engines certified as alternative 

fueled engines shall meet the following 

requirements: 

(i) To the extent feasible, those 

specified in paragraph (i)(3) of this 

section. 

(ii) Monitor the NOX aftertreatment 

system on engines so equipped. A 

malfunction must be detected if: 

(A) The NOX aftertreatment system 

has no detectable amount of NOX

aftertreatment capability (i.e., NOX

catalyst conversion or NOX adsorption). 

(B) The NOX aftertreatment substrate 

is completely destroyed, removed, or 

missing. 

(C) The NOX aftertreatment assembly 

is replaced with a straight pipe. 

(p) In-use compliance standards. For 

monitors required to indicate a 

malfunction before emissions exceed a 

certain emission threshold (e.g., 2 times 

any of the applicable standards): 

(1) On the full OBD ratings as defined 

in paragraph (o)(2) of this section, 

separate in-use emissions thresholds 

shall apply. These thresholds are 

determined by doubling the applicable 

thresholds as shown in Table 1 of 

paragraph (g) of this section and Table 

2 of § 86.010–18(h). The resultant 

thresholds apply only in-use and do not 

apply for certification or selective 

enforcement auditing. 

(2) The extrapolated OBD ratings as 

defined in paragraph (o)(3) of this 

section shall not be evaluated against 

emissions levels for purposes of OBD 

compliance in-use. 

(3) Only the test cycle and standard 

determined and identified by the 

manufacturer at the time of certification 

in accordance with § 86.010–18(f) as the 

most stringent shall be used for the 

purpose of determining OBD system 

noncompliance in-use. 

(4) For monitors subject to meeting 

the minimum in-use monitor 

performance ratio of 0.100 in paragraph 

(d)(1)(ii) of this section, the OBD system 

shall not be considered noncompliant 

unless a representative sample indicates 

the in-use ratio is below 0.050. 

(5) An OBD system shall not be 

considered noncompliant solely due to 

a failure or deterioration mode of a 

monitored component or system that 

could not have been reasonably foreseen 

to occur by the manufacturer. 

13. Section 86.013–30 is added to 

Subpart A to read as follows: 

§ 86.013–30 Certification. 

Section 86.013–30 includes text that 

specifies requirements that differ from 

§ 86.010–30. Where a paragraph in 

§ 86.010–30 is identical and applicable 

to § 86.013–30, this may be indicated by 

specifying the corresponding paragraph 

and the statement ‘‘[Reserved]. For 

guidance see § 86.010–30.’’

(a) introductory text through (f)(1)(i) 

[Reserved]. For guidance see § 86.010–

30. 

(f)(1)(ii) Diesel. 

(A) If monitored for emissions 

performance—a reduction catalyst is 

replaced with a deteriorated or defective 

catalyst, or an electronic simulation of 

such, resulting in exhaust NOX

emissions exceeding the applicable NOX

FEL+0.3 g/bhp-hr. Also if monitored for 

emissions performance—an oxidation 

catalyst is replaced with a deteriorated 

or defective catalyst, or an electronic 

simulation of such, resulting in exhaust 

NMHC emissions exceeding 2 times the 

applicable NMHC standard. 

(B) If monitored for performance—a 

particulate trap is replaced with a 

deteriorated or defective trap, or an 

electronic simulation of such, resulting 

in either exhaust PM emissions 

exceeding the applicable FEL+0.04 g/ 

bhp-hr or 0.05 g/bhp-hr PM, whichever 

is higher; or, exhaust NMHC emissions 

exceeding 2 times the applicable NMHC 

standard. Also, if monitored for 

performance—a particulate trap is 

replaced with a catastrophically failed 

trap or a simulation of such. 

(f)(2) [Reserved]. For guidance see 

§ 86.004–30. 

(f)(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. 

(f)(3)(i)(A) [Reserved]. For guidance 

see § 86.007–30. 

(f)(3)(i)(B) Diesel. If so equipped, any 

oxygen sensor or air-fuel ratio sensor 

located downstream of aftertreatment 

devices is replaced with a deteriorated 

or defective sensor, or an electronic 

simulation of such, resulting in exhaust 

emissions exceeding any of the 

following levels: The applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2 times the 

applicable NMHC standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. 

(f)(3)(ii)(A) [Reserved]. For guidance 

see § 86.007–30. 


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(f)(3)(ii)(B) Diesel. If so equipped, any 

oxygen sensor or air-fuel ratio sensor 

located upstream of aftertreatment 

devices is replaced with a deteriorated 

or defective sensor, or an electronic 

simulation of such, resulting in exhaust 

emissions exceeding any of the 

following levels: The applicable PM 

FEL+0.02 g/bhp-hr or 0.03 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2 times the 

applicable NMHC standard; or, 2 times 

the applicable CO standard. 

(iii) NOX sensors. 

(f)(3)(iii)(A) [Reserved]. For guidance 

see § 86.007–30. 

(f)(3)(iii)(B) Diesel. If so equipped, any 

NOX sensor is replaced with a 

deteriorated or defective sensor, or an 

electronic simulation of such, resulting 

in exhaust emissions exceeding any of 

the following levels: The applicable PM 

FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr. 

(f)(4) [Reserved]. For guidance see 

§ 86.010–30. 

(f)(5)(i) [Reserved]. For guidance see 

§ 86.007–30. 

(f)(5)(ii) Diesel. A malfunction 

condition is induced in any emissionrelated engine system or component, 

including but not necessarily limited to, 

the exhaust gas recirculation (EGR) 

system, if equipped, and the fuel control 

system, singularly resulting in exhaust 

emissions exceeding any of the 

following levels: The applicable PM 

FEL+0.02 g/bhp-hr or 0.03 g/bhp-hr PM, 

whichever is higher; or, the applicable 

NOX FEL+0.3 g/bhp-hr; or, 2 times the 

applicable NMHC standard; or, 2 times 

the applicable CO standard. 

(f)(6) [Reserved]. For guidance see 

§ 86.010–30. 

14. Section 86.016–18 is added to 

Subpart A to read as follows: 

§ 86.016–18 On-board Diagnostics for 

engines used in applications greater than 

14,000 pounds GVWR. 

Section 86.016–18 includes text that 

specifies requirements that differ from 

§ 86.013–18. Where a paragraph in 

§ 86.013–18 is identical and applicable 

to § 86.016–18, this may be indicated by 

specifying the corresponding paragraph 

and the statement ‘‘[Reserved]. For 

guidance see § 86.013–18.’’

(a) through (n) [Reserved]. For 

guidance see § 86.013–18. 

(o) Implementation schedule. Except 

as provided for in paragraph (o)(3) of 

this section, the requirements of this 

section must be met according to the 

following provisions: 

(1) OBD groups. The manufacturer 

shall define one or more OBD groups to 

cover all engine ratings in all engine 

families. The manufacturer must submit 

a grouping plan for Administrator 

review and approval detailing the OBD 

groups and the engine families and 

engine ratings within each group for a 

given model year. 

(2) Full OBD. The manufacturer must 

implement an OBD system meeting the 

requirements of this section on all 

engine ratings in all engine families. 

(3) Engines certified as alternative 

fueled engines shall meet the following 

requirements: 

(i) To the extent feasible, those 

specified in § 86.013–18(i)(3). 

(ii) Monitor the NOX aftertreatment 

system on engines so equipped. A 

malfunction must be detected if: 

(A) The NOX aftertreatment system 

has no detectable amount of NOX

aftertreatment capability (i.e., NOX

catalyst conversion or NOX adsorption). 

(B) The NOX aftertreatment substrate 

is completely destroyed, removed, or 

missing. 

(C) The NOX aftertreatment assembly 

is replaced with a straight pipe. 

(p) In-use compliance standards. For 

monitors required to indicate a 

malfunction before emissions exceed a 

certain emission threshold (e.g., 2 times 

any of the applicable standards): 

(1) On the engine ratings tested 

according to § 86.013–18(l)(2)(ii), the 

certification emissions thresholds shall 

apply in-use. 

(2) On the manufacturer’s remaining 

engine ratings, separate in-use 

emissions thresholds shall apply. These 

thresholds are determined by doubling 

the applicable thresholds as shown in 

Table 1 of § 86.013–18(g) and Table 2 of 

§ 86.010–18(h). The resultant thresholds 

apply only in-use and do not apply for 

certification or selective enforcement 

auditing. 

(3) An OBD system shall not be 

considered noncompliant solely due to 

a failure or deterioration mode of a 

monitored component or system that 

could not have been reasonably foreseen 

to occur by the manufacturer. 

15. Section 86.019–18 is added to 

subpart A to read as follows: 

§ 86.019–18 On-board diagnostics for 

engines used in applications greater than 

14,000 pounds GVWR. 

Section 86.019–18 includes text that 

specifies requirements that differ from 

§§ 86.013–18 and 86.016–18. Where a 

paragraph in § 86.013–18 is identical 

and applicable to § 86.019–18, this may 

be indicated by specifying the 

corresponding paragraph and the 

statement ‘‘[Reserved]. For guidance see 

§ 86.013–18.’’

(a) through (k)(6) [Reserved]. For 

guidance see § 86.013–18. 

(k)(7) For 2019 and subsequent model 

year alternative-fueled engines derived 

from a diesel-cycle engine, a 

manufacturer may meet the 

standardization requirements of 

§ 86.013–18(k) that are applicable to 

diesel engines rather than the 

requirements applicable to gasoline 

engines. 

(l) through (n) [Reserved]. For 

guidance see § 86.013–18. 

(o) Implementation schedule. The 

manufacturer must implement an OBD 

system meeting the requirements of this 

section on all engines. 

(p) In-use compliance. An OBD 

system shall not be considered 

noncompliant solely due to a failure or 

deterioration mode of a monitored 

component or system that could not 

have been reasonably foreseen to occur 

by the manufacturer. 

16. Section 86.1806–07 is added to 

Subpart S to read as follows: 

§ 86.1806–07 On-board diagnostics for 

vehicles less than or equal to 14,000 

pounds GVWR. 

Section 86.1806–07 includes text that 

specifies requirements that differ from 

§ 86.1806–05. Where a paragraph in 

§ 86.1806–05 is identical and applicable 

to § 86.1806–07, this may be indicated 

by specifying the corresponding 

paragraph and the statement 

‘‘[Reserved]. For guidance see 

§ 86.1806–05.’’

(a) through (a)(2) [Reserved]. For 

guidance see § 86.1806–05. 

(a)(3) An OBD system demonstrated to 

fully meet the requirements in § 86.007–

17 may be used to meet the 

requirements of this section, provided 

that such an OBD system also 

incorporates appropriate transmission 

diagnostics as may be required under 

this section, and provided that the 

Administrator finds that a 

manufacturer’s decision to use the 

flexibility in this paragraph (a)(3) is 

based on good engineering judgement. 

(b) through (h) [Reserved]. For 

guidance see § 86.1806–05. 

(i) Deficiencies and alternative fueled 

vehicles. Upon application by the 

manufacturer, the Administrator may 

accept an OBD system as compliant 

even though specific requirements are 

not fully met. Such compliances 

without meeting specific requirements, 

or deficiencies, will be granted only if 

compliance would be infeasible or 

unreasonable considering such factors 

as, but not limited to: technical 

feasibility of the given monitor and lead 

time and production cycles including 

phase-in or phase-out of vehicle designs 

and programmed upgrades of 

computers. Unmet requirements should 


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not be carried over from the previous 

model year except where unreasonable 

hardware or software modifications 

would be necessary to correct the 

deficiency, and the manufacturer has 

demonstrated an acceptable level of 

effort toward compliance as determined 

by the Administrator. Furthermore, EPA 

will not accept any deficiency requests 

that include the complete lack of a 

major diagnostic monitor (‘‘major’’

diagnostic monitors being those for 

exhaust aftertreatment devices, oxygen 

sensor, air-fuel ratio sensor, NOX sensor, 

engine misfire, evaporative leaks, and 

diesel EGR, if equipped), with the 

possible exception of the special 

provisions for alternative fueled 

engines. For alternative fueled vehicles 

(e.g., natural gas, liquefied petroleum 

gas, methanol, ethanol), manufacturers 

may request the Administrator to waive 

specific monitoring requirements of this 

section for which monitoring may not 

be reliable with respect to the use of the 

alternative fuel. At a minimum, 

alternative fuel engines must be 

equipped with an OBD system meeting 

OBD requirements to the extent feasible 

as approved by the Administrator. 

(j) California OBDII compliance 

option. For light-duty vehicles, lightduty trucks, and heavy-duty vehicles 

weighing 14,000 pounds GVWR or less, 

demonstration of compliance with 

California OBD II requirements (Title 13 

California Code of Regulations § 1968.2 

(13 CCR 1968.2)), as modified and 

released on August 11, 2006, shall 

satisfy the requirements of this section, 

except that compliance with 13 CCR 

1968.2(e)(4.2.2)(C), pertaining to 0.02- 

inch evaporative leak detection, and 13 

CCR 1968.2(d)(1.4), pertaining to 

tampering protection, are not required 

to satisfy the requirements of this 

section. Also, the deficiency provisions 

of 13 CCR 1968.2(k) do not apply. The 

deficiency provisions of paragraph (i) of 

this section and the evaporative leak 

detection requirement of § 86.1806–

05(b)(4) apply to manufacturers 

selecting this paragraph for 

demonstrating compliance. In addition, 

demonstration of compliance with 13 

CCR 1968.2(e)(15.2.1)(C), to the extent it 

applies to the verification of proper 

alignment between the camshaft and 

crankshaft, applies only to vehicles 

equipped with variable valve timing. 

(k) through (m) [Reserved]. For 

guidance see § 86.1806–05. 

(n) For diesel complete heavy-duty 

vehicles, in lieu of the malfunction 

descriptions of § 86.1806–05(b), the 

malfunction descriptions of this 

paragraph (n) shall apply. The OBD 

system must detect and identify 

malfunctions in all monitored emissionrelated powertrain systems or 

components according to the following 

malfunction definitions as measured 

and calculated in accordance with test 

procedures set forth in subpart B of this 

part (chassis-based test procedures), 

excluding those test procedures defined 

as ‘‘Supplemental’’ test procedures in 

§ 86.004–2 and codified in §§ 86.158, 

86.159, and 86.160. 

(1) Catalysts and particulate traps. 

(i) If equipped, catalyst deterioration 

or malfunction before it results in 

exhaust emissions exceeding 3 times the 

applicable NOX standard. This 

requirement applies only to reduction 

catalysts; monitoring of oxidation 

catalysts is not required. This 

monitoring need not be done if the 

manufacturer can demonstrate that 

deterioration or malfunction of the 

system will not result in exceedance of 

the threshold. 

(ii) If equipped with a particulate trap, 

catastrophic failure of the device must 

be detected. Any particulate trap whose 

complete failure results in exhaust 

emissions exceeding 1.5 times the 

applicable standard or FEL for NOX or 

PM must be monitored for such 

catastrophic failure. This monitoring 

need not be done if the manufacturer 

can demonstrate that a catastrophic 

failure of the system will not result in 

exceedance of the threshold. 

(2) Engine misfire. Lack of cylinder 

combustion must be detected. 

(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. If equipped, 

sensor deterioration or malfunction 

resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 3 

times the applicable NOX standard; or, 

2.5 times the applicable NMHC 

standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: 4 times the applicable 

PM standard; or, 3 times the applicable 

NOX standard; or, 2.5 times the 

applicable NMHC standard; or, 2.5 

times the applicable CO standard. 

(iii) NOX sensors. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: 5 times the applicable 

PM standard; or, 4 times the applicable 

NOX standard. 

(4) [Reserved.] 

(5) Other emission control systems 

and components. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 3 

times the applicable NOX standard; or, 

2.5 times the applicable NMHC 

standard; or, 2.5 times the applicable 

CO standard. A functional check, as 

described in paragraph (n)(6) of this 

section, may satisfy the requirements of 

this paragraph (n)(5) provided the 

manufacturer can demonstrate that a 

malfunction would not cause emissions 

to exceed the applicable levels. This 

demonstration is subject to 

Administrator approval. For engines 

equipped with crankcase ventilation 

(CV), monitoring of the CV system is not 

necessary provided the manufacturer 

can demonstrate to the Administrator’s 

satisfaction that the CV system is 

unlikely to fail. 

(6) Other emission-related powertrain 

components. Any other deterioration or 

malfunction occurring in an electronic 

emission-related powertrain system or 

component not otherwise described in 

paragraphs (n)(1) through (n)(5) of this 

section that either provides input to or 

receives commands from the on-board 

computer and has a measurable impact 

on emissions; monitoring of 

components required by this paragraph 

(n)(6) must be satisfied by employing 

electrical circuit continuity checks and 

rationality checks for computer input 

components (input values within 

manufacturer specified ranges based on 

other available operating parameters), 

and functionality checks for computer 

output components (proper functional 

response to computer commands) 

except that the Administrator may 

waive such a rationality or functionality 

check where the manufacturer has 

demonstrated infeasibility. 

Malfunctions are defined as a failure of 

the system or component to meet the 

electrical circuit continuity checks or 

the rationality or functionality checks. 

(7) Performance of OBD functions. 

Any sensor or other component 

deterioration or malfunction which 

renders that sensor or component 

incapable of performing its function as 

part of the OBD system must be detected 

and identified on engines so equipped. 

(o) For diesel complete heavy-duty 

vehicles, in lieu of the certification 

provisions of § 86.1806–05(k), the 

certificate provisions of this paragraph 

(o) shall apply. For test groups required 

to have an OBD system, certification 

will not be granted if, for any test 

vehicle approved by the Administrator 

in consultation with the manufacturer, 

the malfunction indicator light does not 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3341 

illuminate under any of the following 

circumstances, unless the manufacturer 

can demonstrate that any identified 

OBD problems discovered during the 

Administrator’s evaluation will be 

corrected on production vehicles. 

(1)(i) If monitored for emissions 

performance—a catalyst is replaced 

with a deteriorated or defective catalyst, 

or an electronic simulation of such, 

resulting in exhaust emissions 

exceeding 3 times the applicable NOX

standard. This requirement applies only 

to reduction catalysts. 

(ii) If monitored for performance—a 

particulate trap is replaced with a trap 

that has catastrophically failed, or an 

electronic simulation of such. 

(2) An engine misfire condition is 

induced and is not detected. 

(3)(i) If so equipped, any oxygen 

sensor or air-fuel ratio sensor located 

downstream of aftertreatment devices is 

replaced with a deteriorated or defective 

sensor, or an electronic simulation of 

such, resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 3 

times the applicable NOX standard; or, 

2.5 times the applicable NMHC 

standard. 

(ii) If so equipped, any oxygen sensor 

or air-fuel ratio sensor located upstream 

of aftertreatment devices is replaced 

with a deteriorated or defective sensor, 

or an electronic simulation of such, 

resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 3 

times the applicable NOX standard; or, 

2.5 times the applicable NMHC 

standard; or, 2.5 times the applicable 

CO standard. 

(iii) If so equipped, any NOX sensor is 

replaced with a deteriorated or defective 

sensor, or an electronic simulation of 

such, resulting in exhaust emissions 

exceeding any of the following levels: 5 

times the applicable PM standard; or, 4 

times the applicable NOX standard. 

(4) [Reserved.] 

(5) A malfunction condition is 

induced in any emission-related engine 

system or component, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 3 

times the applicable NOX standard; or, 

2.5 times the applicable NMHC 

standard; or, 2.5 times the applicable 

CO standard. 

(6) A malfunction condition is 

induced in an electronic emissionrelated powertrain system or component 

not otherwise described in this 

paragraph (o) that either provides input 

to or receives commands from the onboard computer resulting in a 

measurable impact on emissions. 

17. Section 86.1806–10 is added to 

Subpart S to read as follows: 

§ 86.1806–10 On-board diagnostics for 

vehicles less than or equal to 14,000 

pounds GVWR. 

Section 86.1806–10 includes text that 

specifies requirements that differ from 

§ 86.1806–05 and § 86.1806–07. Where a 

paragraph in § 86.1806–05 or § 86.1806–

07 is identical and applicable to 

§ 86.1806–10, this may be indicated by 

specifying the corresponding paragraph 

and the statement ‘‘[Reserved]. For 

guidance see § 86.1806–05.’’ or 

‘‘[Reserved]. For guidance see 

§ 86.1806–07.’’

(a) General. 

(1) All light-duty vehicles, light-duty 

trucks and complete heavy-duty 

vehicles weighing 14,000 pounds 

GVWR or less (including MDPVs) must 

be equipped with an onboard diagnostic 

(OBD) system capable of monitoring all 

emission-related powertrain systems or 

components during the applicable 

useful life of the vehicle. All systems 

and components required to be 

monitored by these regulations must be 

evaluated periodically, but no less 

frequently than once per applicable 

certification test cycle as defined in 

paragraphs (a) and (d) of Appendix I of 

this part, or similar trip as approved by 

the Administrator. 

(2) [Reserved.] 

(3) An OBD system demonstrated to 

fully meet the requirements in § 86.010–

17 may be used to meet the 

requirements of this section, provided 

that such an OBD system also 

incorporates appropriate transmission 

diagnostics as may be required under 

this section, and provided that the 

Administrator finds that a 

manufacturer’s decision to use the 

flexibility in this paragraph (a)(3) is 

based on good engineering judgement. 

(b) through (m) [Reserved]. For 

guidance see § 86.1806–07. 

(n) For diesel complete heavy-duty 

vehicles, in lieu of the malfunction 

descriptions of § 86.1806–05(b), the 

malfunction descriptions of this 

paragraph (n) shall apply. The OBD 

system must detect and identify 

malfunctions in all monitored emissionrelated powertrain systems or 

components according to the following 

malfunction definitions as measured 

and calculated in accordance with test 

procedures set forth in subpart B of this 

part (chassis-based test procedures), 

excluding those test procedures defined 

as ‘‘Supplemental’’ test procedures in 

§ 86.004–2 and codified in §§ 86.158, 

86.159, and 86.160. 

(1) Catalysts and particulate traps. 

(i) If equipped, reduction catalyst 

deterioration or malfunction before it 

results in exhaust NOX emissions 

exceeding the applicable NOX

standard+0.3 g/mi. If equipped, 

oxidation catalyst deterioration or 

malfunction before it results in exhaust 

NMHC emissions exceeding 2.5 times 

the applicable NMHC standard. These 

catalyst monitoring requirements need 

not be done if the manufacturer can 

demonstrate that deterioration or 

malfunction of the system will not 

result in exceedance of the threshold. 

(ii) If equipped, diesel particulate trap 

deterioration or malfunction before it 

results in exhaust emissions exceeding 

any of the following levels: 4 times the 

applicable PM standard; or, exhaust 

NMHC emissions exceeding 2.5 times 

the applicable NMHC standard. 

Catastrophic failure of the particulate 

trap must also be detected. In addition, 

the absence of the particulate trap or the 

trapping substrate must be detected. 

(2) Engine misfire. Lack of cylinder 

combustion must be detected. 

(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. If equipped, 

sensor deterioration or malfunction 

resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 

the applicable NOX standard+0.3 g/mi; 

or, 2.5 times the applicable NMHC 

standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: The applicable PM 

standard+0.02 g/mi; or, the applicable 

NOX standard+0.3 g/mi; or, 2.5 times 

the applicable NMHC standard; or, 2.5 

times the applicable CO standard. 

(iii) NOX sensors. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: 4 times the applicable 

PM standard; or, the applicable NOX

standard+0.3 g/mi. 

(4) [Reserved.] 

(5) Other emission control systems 

and components. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 

the applicable NOX standard+0.3 g/mi; 


sroberts on PROD1PC70 with PROPOSALS
3342 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

or, 2.5 times the applicable NMHC 

standard; or, 2.5 times the applicable 

CO standard. A functional check, as 

described in paragraph (n)(6) of this 

section, may satisfy the requirements of 

this paragraph (n)(5) provided the 

manufacturer can demonstrate that a 

malfunction would not cause emissions 

to exceed the applicable levels. This 

demonstration is subject to 

Administrator approval. For engines 

equipped with crankcase ventilation 

(CV), monitoring of the CV system is not 

necessary provided the manufacturer 

can demonstrate to the Administrator’s 

satisfaction that the CV system is 

unlikely to fail. 

(6) Other emission-related powertrain 

components. Any other deterioration or 

malfunction occurring in an electronic 

emission-related powertrain system or 

component not otherwise described in 

paragraphs (n)(1) through (n)(5) of this 

section that either provides input to or 

receives commands from the on-board 

computer and has a measurable impact 

on emissions; monitoring of 

components required by this paragraph 

(n)(6) must be satisfied by employing 

electrical circuit continuity checks and 

rationality checks for computer input 

components (input values within 

manufacturer specified ranges based on 

other available operating parameters), 

and functionality checks for computer 

output components (proper functional 

response to computer commands) 

except that the Administrator may 

waive such a rationality or functionality 

check where the manufacturer has 

demonstrated infeasibility. 

Malfunctions are defined as a failure of 

the system or component to meet the 

electrical circuit continuity checks or 

the rationality or functionality checks. 

(7) Performance of OBD functions. 

Any sensor or other component 

deterioration or malfunction which 

renders that sensor or component 

incapable of performing its function as 

part of the OBD system must be detected 

and identified on engines so equipped. 

(o) For diesel complete heavy-duty 

vehicles, in lieu of the certification 

provisions of § 86.1806–5(k), the 

certification provisions of this 

paragraph (o) shall apply. For test 

groups required to have an OBD system, 

certification will not be granted if, for 

any test vehicle approved by the 

Administrator in consultation with the 

manufacturer, the malfunction indicator 

light does not illuminate under any of 

the following circumstances, unless the 

manufacturer can demonstrate that any 

identified OBD problems discovered 

during the Administrator’s evaluation 

will be corrected on production 

vehicles. 

(1)(i) If monitored for emissions 

performance—a reduction catalyst is 

replaced with a deteriorated or defective 

catalyst, or an electronic simulation of 

such, resulting in exhaust NOX

emissions exceeding the applicable NOX

standard+0.3 g/mi. Also if monitored for 

emissions performance—an oxidation 

catalyst is replaced with a deteriorated 

or defective catalyst, or an electronic 

simulation of such, resulting in exhaust 

NMHC emissions exceeding 2.5 times 

the applicable NMHC standard. 

(ii) If monitored for performance—a 

particulate trap is replaced with a 

deteriorated or defective trap, or an 

electronic simulation of such, resulting 

in exhaust PM emissions exceeding 4 

times the applicable PM standard or 

exhaust NMHC emissions exceeding 2.5 

times the applicable NMHC standard. 

Also, if monitored for performance—a 

particulate trap is replaced with a 

catastrophically failed trap or a 

simulation of such. 

(2) An engine misfire condition is 

induced and is not detected. 

(3)(i) If so equipped, any oxygen 

sensor or air-fuel ratio sensor located 

downstream of aftertreatment devices is 

replaced with a deteriorated or defective 

sensor, or an electronic simulation of 

such, resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 

the applicable NOX standard+0.3 g/mi; 

or, 2.5 times the applicable NMHC 

standard. 

(ii) If so equipped, any oxygen sensor 

or air-fuel ratio sensor located upstream 

of aftertreatment devices is replaced 

with a deteriorated or defective sensor, 

or an electronic simulation of such, 

resulting in exhaust emissions 

exceeding any of the following levels: 

The applicable PM standard+0.02 g/mi; 

or, the applicable NOX standard+0.3 g/ 

mi; or, 2.5 times the applicable NMHC 

standard; or, 2.5 times the applicable 

CO standard. 

(iii) If so equipped, any NOX sensor is 

replaced with a deteriorated or defective 

sensor, or an electronic simulation of 

such, resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 

the applicable NOX standard+0.3 g/mi. 

(4) [Reserved.] 

(5) A malfunction condition is 

induced in any emission-related engine 

system or component, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 4 

times the applicable PM standard; or, 

the applicable NOX standard+0.3 g/mi; 

or, 2.5 times the applicable NMHC 

standard; or, 2.5 times the applicable 

CO standard. 

(6) A malfunction condition is 

induced in an electronic emissionrelated powertrain system or component 

not otherwise described in this 

paragraph (o) that either provides input 

to or receives commands from the onboard computer resulting in a 

measurable impact on emissions. 

18. Section 86.1806–13 is added to 

Subpart S to read as follows: 

§ 86.1806–13 On-board diagnostics for 

vehicles less than or equal to 14,000 

pounds GVWR. 

Section 86.1806–13 includes text that 

specifies requirements that differ from 

§ 86.1806–05, § 86.1806–07 and 

§ 86.1806–10. Where a paragraph in 

§ 86.1806–05 or § 86.1806–07 or 

§ 86.1806–10 is identical and applicable 

to § 86.1806–13 this may be indicated 

by specifying the corresponding 

paragraph and the statement 

‘‘[Reserved]. For guidance see 

§ 86.1806–05.’’ or ‘‘[Reserved]. For 

guidance see § 86.1806–07.’’ or 

‘‘[Reserved]. For guidance see 

§ 86.1806–10.’’

(a)(1) [Reserved]. For guidance see 

§ 86.1806–10. 

(a)(2) [Reserved.] 

(3) An OBD system demonstrated to 

fully meet the requirements in § 86.013–

17 may be used to meet the 

requirements of this section, provided 

that such an OBD system also 

incorporates appropriate transmission 

diagnostics as may be required under 

this section, and provided that the 

Administrator finds that a 

manufacturer’s decision to use the 

flexibility in this paragraph (a)(3) is 

based on good engineering judgement. 

(b) through (m) [Reserved]. For 

guidance see § 86.1806–07. 

(n) For diesel complete heavy-duty 

vehicles, in lieu of the malfunction 

descriptions of § 86.1806–05(b), the 

malfunction descriptions of this 

paragraph (n) shall apply. The OBD 

system must detect and identify 

malfunctions in all monitored emissionrelated powertrain systems or 

components according to the following 

malfunction definitions as measured 

and calculated in accordance with test 

procedures set forth in subpart B of this 

part (chassis-based test procedures), 

excluding those test procedures defined 

as ‘‘Supplemental’’ test procedures in 

§ 86.004–2 and codified in §§ 86.158, 

86.159, and 86.160. 

(1) Catalysts and particulate traps. 

(i) If equipped, reduction catalyst 

deterioration or malfunction before it 

results in exhaust NOX emissions 

exceeding the applicable NOX


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 3343 

standard+0.3 g/mi. If equipped, 

oxidation catalyst deterioration or 

malfunction before it results in exhaust 

NMHC emissions exceeding 2 times the 

applicable NMHC standard. These 

catalyst monitoring requirements need 

not be done if the manufacturer can 

demonstrate that deterioration or 

malfunction of the system will not 

result in exceedance of the threshold. 

(ii) If equipped, diesel particulate trap 

deterioration or malfunction before it 

results in exhaust emissions exceeding 

any of the following levels: the 

applicable PM standard+0.04 g/mi; or, 

exhaust NMHC emissions exceeding 2 

times the applicable NMHC standard. 

Catastrophic failure of the particulate 

trap must also be detected. In addition, 

the absence of the particulate trap or the 

trapping substrate must be detected. 

(2) Engine misfire. Lack of cylinder 

combustion must be detected. 

(3)(i) Oxygen sensors and air-fuel 

ratio sensors downstream of 

aftertreatment devices. If equipped, 

sensor deterioration or malfunction 

resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM standard+0.04 g/mi; 

or, the applicable NOX standard+0.3 g/ 

mi; or, 2 times the applicable NMHC 

standard. 

(ii) Oxygen sensors and air-fuel ratio 

sensors upstream of aftertreatment 

devices. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

standard+0.02 g/mi; or, the applicable 

NOX standard+0.3 g/mi; or, 2 times the 

applicable NMHC standard; or, 2 times 

the applicable CO standard. 

(iii) NOX sensors. If equipped, sensor 

deterioration or malfunction resulting in 

exhaust emissions exceeding any of the 

following levels: the applicable PM 

standard+0.04 g/mi; or, the applicable 

NOX standard+0.3 g/mi. 

(4) [Reserved.] 

(5) Other emission control systems 

and components. Any deterioration or 

malfunction occurring in an engine 

system or component directly intended 

to control emissions, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM standard+0.02 g/mi; 

or, the applicable NOX standard+0.3 g/ 

mi; or, 2 times the applicable NMHC 

standard; or, 2 times the applicable CO 

standard. A functional check, as 

described in paragraph (n)(6) of this 

section, may satisfy the requirements of 

this paragraph (n)(5) provided the 

manufacturer can demonstrate that a 

malfunction would not cause emissions 

to exceed the applicable levels. This 

demonstration is subject to 

Administrator approval. For engines 

equipped with crankcase ventilation 

(CV), monitoring of the CV system is not 

necessary provided the manufacturer 

can demonstrate to the Administrator’s 

satisfaction that the CV system is 

unlikely to fail. 

(6) Other emission-related powertrain 

components. Any other deterioration or 

malfunction occurring in an electronic 

emission-related powertrain system or 

component not otherwise described in 

paragraphs (n)(1) through (n)(5) of this 

section that either provides input to or 

receives commands from the on-board 

computer and has a measurable impact 

on emissions; monitoring of 

components required by this paragraph 

(n)(6) must be satisfied by employing 

electrical circuit continuity checks and 

rationality checks for computer input 

components (input values within 

manufacturer specified ranges based on 

other available operating parameters), 

and functionality checks for computer 

output components (proper functional 

response to computer commands) 

except that the Administrator may 

waive such a rationality or functionality 

check where the manufacturer has 

demonstrated infeasibility. 

Malfunctions are defined as a failure of 

the system or component to meet the 

electrical circuit continuity checks or 

the rationality or functionality checks. 

(7) Performance of OBD functions. 

Any sensor or other component 

deterioration or malfunction which 

renders that sensor or component 

incapable of performing its function as 

part of the OBD system must be detected 

and identified on engines so equipped. 

(o) For diesel complete heavy-duty 

vehicles, in lieu of the certification 

provisions of paragraph (k) of this 

section, the certification provisions of 

this paragraph (o) shall apply. For test 

groups required to have an OBD system, 

certification will not be granted if, for 

any test vehicle approved by the 

Administrator in consultation with the 

manufacturer, the malfunction indicator 

light does not illuminate under any of 

the following circumstances, unless the 

manufacturer can demonstrate that any 

identified OBD problems discovered 

during the Administrator’s evaluation 

will be corrected on production 

vehicles. 

(1)(i) If monitored for emissions 

performance—a reduction catalyst is 

replaced with a deteriorated or defective 

catalyst, or an electronic simulation of 

such, resulting in exhaust NOX

emissions exceeding the applicable NOX

standard+0.3 g/mi. Also if monitored for 

emissions performance—an oxidation 

catalyst is replaced with a deteriorated 

or defective catalyst, or an electronic 

simulation of such, resulting in exhaust 

NMHC emissions exceeding 2 times the 

applicable NMHC standard. 

(ii) If monitored for performance—a 

particulate trap is replaced with a 

deteriorated or defective trap, or an 

electronic simulation of such, resulting 

in exhaust PM emissions exceeding the 

applicable standard+0.04 g/mi or 

exhaust NMHC emissions exceeding 2 

times the applicable NMHC standard. 

Also, if monitored for performance—a 

particulate trap is replaced with a 

catastrophically failed trap or a 

simulation of such. 

(2) An engine misfire condition is 

induced and is not detected. 

(3)(i) If so equipped, any oxygen 

sensor or air-fuel ratio sensor located 

downstream of aftertreatment devices is 

replaced with a deteriorated or defective 

sensor, or an electronic simulation of 

such, resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM standard+0.04 g/mi; 

or, the applicable NOX standard+0.3 g/ 

mi; or, 2 times the applicable NMHC 

standard. 

(ii) If so equipped, any oxygen sensor 

or air-fuel ratio sensor located upstream 

of aftertreatment devices is replaced 

with a deteriorated or defective sensor, 

or an electronic simulation of such, 

resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM standard+0.02 g/mi; 

or, the applicable NOX standard+0.3 g/ 

mi; or, 2 times the applicable NMHC 

standard; or, 2 times the applicable CO 

standard. 

(iii) If so equipped, any NOX sensor is 

replaced with a deteriorated or defective 

sensor, or an electronic simulation of 

such, resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM standard+0.04 g/mi; 

or, the applicable NOX standard+0.3 g/ 

mi. 

(4) [Reserved.] 

(5) A malfunction condition is 

induced in any emission-related engine 

system or component, including but not 

necessarily limited to, the exhaust gas 

recirculation (EGR) system, if equipped, 

and the fuel control system, singularly 

resulting in exhaust emissions 

exceeding any of the following levels: 

the applicable PM standard+0.02 g/mi; 

or, the applicable NOX standard+0.3 g/ 

mi; or, 2 times the applicable NMHC 

standard; or, 2 times the applicable CO 

standard. 

(6) A malfunction condition is 

induced in an electronic emissionrelated powertrain system or component 

not otherwise described in this 


sroberts on PROD1PC70 with PROPOSALS
3344 Federal Register / Vol. 72, No. 15 / Wednesday, January 24, 2007 / Proposed Rules 

paragraph (o) that either provides input 

to or receives commands from the onboard computer resulting in a 

measurable impact on emissions. 

[FR Doc. 07–110 Filed 1–23–07; 8:45 am] 

BILLING CODE 6560–50–P 


sroberts on PROD1PC70 with PROPOSALS