BEFORE THE

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

In the Matter of California’s Request for 

Waiver Action Pursuant to Clean Air Act 

Section 209(b) for California’s HeavyDuty Engine On-Board Diagnostic 

System Requirements (HD OBD) and 

On-Board Diagnostic System 

Requirements for Passenger Cars, LightDuty Trucks, and Medium-Duty Vehicles 

and Engines (OBD II)

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CLEAN AIR ACT § 209(b) WAIVER REQUEST

SUPPORT DOCUMENT SUBMITTED BY THE

CALIFORNIA AIR RESOURCES BOARD

January 7, 2014

I. INTRODUCTION AND BACKGROUND

Pursuant to section 209(b) of the Clean Air Act (CAA), the California Air 

Resources Board (CARB or Board) requests that the Administrator of the U.S. 

Environmental Protection Agency (EPA) take the Clean Air Act (CAA) 

section 209(b) waiver actions described below for CARB’s regulatory 

amendments to its on-board diagnostic requirements applicable to 

light-, medium-, and heavy-duty vehicles and engines. This waiver request 

encompasses regulatory amendments to California’s on-board diagnostic 

requirements that were adopted in two separate rulemaking actions.

A. CARB January 6, 2012 Rulemaking

At a public hearing on January 6, 2012, CARB, by Resolution 12-11 (Enclosure 

27), approved the adoption of amendments to the regulation entitled “Malfunction 

and Diagnostic System Requirements -- 2004 and Subsequent Model-Year 

Passenger Cars, Light-Duty Trucks, and Medium-Duty Vehicles and Engines 

(OBD II Requirements),1 and to the regulation entitled “Enforcement of 

Malfunction and Diagnostic System Requirements for 2004 and Subsequent 

Model-Year Passenger Cars, Light-Duty Trucks, and Medium-Duty Vehicles and 

Engines” (OBD II Enforcement Regulation).2

1 Title 13, California Code of Regulations (CCR) section 1968.2

2 Title 13, California Code of Regulations (CCR) section 1968.5
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The Board subsequently adopted the rulemaking in Resolution 12-21 on March 

22, 2012. (Enclosure 28).3 The regulation was submitted to California’s Office of 

Administrative Law (OAL) for review on June 25, 2012 and was approved by 

OAL, filed with California’s Secretary of State, and became operative under state 

law on August 7, 2012.

B. CARB August 23, 2012 Rulemaking

At a public hearing on August 23, 2012, CARB, by Resolution 12-29 (enclosed 

herewith), approved the adoption of amendments to its regulation entitled 

“Malfunction and Diagnostic System Requirements for 2010 and Subsequent 

Model-Year Heavy-Duty Engines” (HD OBD Requirements),4 the regulation 

entitled “Enforcement of Malfunction and Diagnostic System Requirements for 

2010 and Subsequent Model-Year Heavy-Duty Engines” (HD OBD Enforcement 

Regulation),5 and to the OBD II Requirements and the OBD II Enforcement 

Regulation. 

At the direction of the Board, after making modifications to the regulation 

available for supplemental public comment, CARB’s Executive Officer formally 

adopted the rulemaking in Executive Order R-13-005 on June 26, 2013 

(Enclosure 16). The regulation was submitted to California’s Office of 

Administrative Law (OAL) for review on June 27, 2013, and was approved by 

OAL, filed with California’s Secretary of State, and became operative under state 

law on July 31, 2103. 

C. HD OBD Regulatory and Waiver History

CARB initially adopted the HD OBD Requirements in December 2005, and EPA 

issued California a waiver for those requirements under CAA section 209(b) in 

August 2008.6 The regulation, as initially adopted, required manufacturers to 

install fully compliant HD OBD systems in both diesel and gasoline powered 

heavy-duty engines (engines used in vehicles having a gross vehicle weight 

rating greater than 14,000 pounds). The requirements were to be phased in on a 

single engine family for model years 2010 through 2012 before requiring 

manufacturers to incorporate compliant HD OBD systems on all 2013 and later 

model year engines. The phase-in was designed to allow manufacturers to gain 

experience on a smaller number of engines prior to wide scale implementation, 

promoting more effective use of their personnel and testing resources. The 

Board subsequently updated the HD OBD regulation and also adopted HD OBDspecific enforcement requirements (HD OBD Enforcement Regulation) in 2010. 

3 Although this rulemaking contained a supplemental public comment period, no amendments to 

sections 1968.2 or 1968.5 were proposed or made to the versions of the amendments described 

in the 2012 Staff Report. 

4 Title 13, California Code of Regulations (CCR) section 1971.1

5 Title 13, California Code of Regulations (CCR) section 1971.5

6 73 Fed.Reg. 52042 (September 8, 2008).
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The 2010 HD OBD amendments also aligned the HD OBD requirements with the 

OBD II requirements for medium-duty vehicles. EPA issued California a waiver 

for the 2010 HD OBD amendments in December 2012.7

D. OBD II Regulatory and Waiver History

CARB initially adopted the OBD II regulation in July 1990 and subsequently 

adopted amendments to the OBD II regulation in 1992, 1993, 1995.8 EPA

issued California a waiver of the regulation, as last amended in 1995, under CAA 

section 209(b) in October 1996.9 Since the granting of the waiver, CARB has 

adopted further amendments to the OBD II regulation in 1997, 2003, 2007, and 

2010.10 CARB subsequently filed requests on December 24, 1997, October 30, 

2003, January 22, 2008, and December 15, 2010 that the EPA respectively find 

that the 1997, 2003, 2007, and 2010 amendments to the OBD II regulation be 

found to be within the scope of the previously granted OBD II waiver. The 

October 30, 2003 request further requested that the OBD II enforcement 

procedures be found within the scope of the previously granted waiver for 

“California’s Enforcement of New and In-Use Vehicle Standards,” title 13, Cal. 

Code Regs. section 2100 et seq.11 The 1997, 2003, 2007, and 2010 requests 

are still pending.

As waived in 1996, the OBD II regulation requires motor vehicle manufacturers to 

incorporate OBD II systems in all new passenger cars, light-duty trucks, and 

medium-duty vehicles and engines. Specifically, manufacturers are required to 

install OBD II systems that effectively monitor all emission-related components 

and systems on the motor vehicle for proper operation and for deterioration or 

malfunctions that cause emissions to exceed specific thresholds. The regulation 

also requires that OBD II systems provide specific diagnostic information in a 

standardized format through a standardized serial data link on-board the vehicles 

to ensure that service and repair technicians can properly and promptly repair 

identified malfunctions.

Since initially adopting the OBD II requirements in 1990, the Board has 

requested that the staff biennially update it on motor vehicle manufacturers’ 

progress in meeting the amended OBD II requirements and to propose such 

modifications as necessary to achieve maximum compliance with the regulation. 

At a May 28, 2009 rulemaking, staff proposed changes to the OBD II 

Requirements to primarily harmonize the medium-duty diesel vehicle 

7 77 Fed.Reg. 73459 (December 10, 2012).

8 The Board initially approved the regulation and amendments thereto at rulemakings held 

respectively on September 14, 1989, September 12, 1991, July 9, 1993, and December 8, 1994.

9 The decision was signed on October 2, 1996, and published at 61 Fed.Reg. 53371 (October 11, 

1996).

10 The Board initially approved the amendments at rulemakings held respectively on 

December 12, 1996; April 25, 2002; September 28, 2006; and May 28, 2010.

11 See 61 Fed.Reg. 53371 (October 11, 1996); 43 Fed.Reg. 9344 (March 7, 1978); 43 Fed.Reg. 

25729 (June 14, 1978).
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requirements with the amendments to the HD OBD Requirements that apply to 

heavy-duty diesel engines.12 Harmonization would allow manufacturers that 

produce both heavy-duty and medium-duty diesel engines to design to and meet 

essentially the same requirements.

E. Overview of Waiver Request 

Section II of this document describes the 2012 Amendments to the OBD II 

Requirements and OBD II Enforcement Regulation. Section III of this document 

describes the 2013 Amendments to the HD OBD and OBD II Requirements and 

Section IV of this document describes the 2013 Amendments to the HD OBD and 

OBD II Enforcement Regulations. Section V describes the criteria that EPA 

considers in taking waiver actions for California rulemakings that adopt or amend 

standards relating to the control of emissions from new motor vehicles or new 

motor vehicle engines, and Sections VI through VIII demonstrate that EPA must

grant the requested waiver actions for the 2013 Amendments to the HD OBD 

Requirements and HD OBD Enforcement Regulation, the 2013 Amendments to 

the OBD II Requirements and OBD II Enforcement Regulation, and the 2012 

Amendments to the OBD II Requirements and OBD II Enforcement Regulations, 

respectively.

CARB respectively requests that the Administrator grant a new waiver for those 

elements of the 2013 Amendments to the HD OBD Requirements and the HD 

OBD Enforcement regulation that are determined to establish new or more 

stringent standards, and to confirm that those elements of the 2013 HD OBD 

Amendments that relax the stringency or that clarify previously waived 

requirements fall within the scope of the waiver granted in 2012. 

CARB also requests that the Administrator grant a new waiver for those elements 

of the 2012 and 2013 Amendments to the OBD II Requirements and OBD II 

Enforcement Regulation that are determined to establish new or more stringent 

standards, and to confirm that those elements of the 2012 and 2013 

Amendments to the OBD II Requirements and OBD II Enforcement Regulation 

that relax the stringency or that clarify previously waived requirements fall within 

the scope of the previously granted waiver.13

12 EPA granted CARB a waiver for its initially adopted HD OBD Requirements on August 13, 

2008 (73 Fed.Reg. 52042 (September 8, 2008). The Board approved amendments to the HD

OBD Requirements concurrently with the proposed amendments to the OBD II Requirements on 

May 28, 2009, which the Board formally adopted on April 5, 2010 and EPA granted a waiver for 

the 2010 Amendments to the HD OBD Requirements on November 29, 2012. 77 Fed.Reg. 73459 

(December 10, 2012).

13 CARB continues to believe that it is appropriate for EPA to determine that all of the 2012 and 

2013 Amendments to the OBD II Requirements and OBD II Enforcement regulation fall within the 

scope of the OBD II waiver granted in October 1996, for the reasons set forth in CARB’s prior 

OBD II waiver submittals December 24, 1997, October 30, 2003, January 22, 2008, and 

December 15, 2010.
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II. SUMMARY OF 2012 AMENDMENTS TO OBD II MONITORING 

REQUIREMENTS AND OBD II ENFORCEMENT REGULATION14

CARB adopted the 2012 Amendments to the OBD II Requirements to respond to 

manufacturers’ requests to modify the existing OBD II regulation. Manufacturers 

approached staff in 2011 and claimed that the OBD II Requirements needed to 

be immediately modified so that they could produce and certify compliant 2013 

model year vehicles, and CARB responded to the requests by modifying both the

OBD II Requirements and the OBD II Enforcement regulation. The 2012 

Amendments largely relax the implementation of a few requirements in 

recognition of delays in technology development, and additionally clarify existing 

requirements, including requirements applicable to hybrid and plug-in hybrid 

vehicles. 

A summary of the substantive amendments is provided below. All references to 

the Staff Report in this section are to the Staff Report supporting the 2012 

Amendments.

A. Definitions15

1. Section (c): Calculated Load Value

The definition of “calculated load value” was amended to allow diesel engine 

manufacturers to use the definition in Society of Automotive Engineers (SAE) 

J1979 in lieu of the current definition in SAE J1939, which only applies to heavyduty diesels and not medium-duty diesels.16

2. Section (c): Fueled Engine Operation

A new definition of “fueled engine operation”, defined as the state where any fuel 

is introduced into the engine for purposes of combustion, was added to 

supplement the amendments to the in-use monitor performance requirements for 

hybrid vehicles.17

14 A detailed discussion of the adopted OBD II Requirements and the OBD II Enforcement 

Requirements discussed in Section II.F, infra, is set forth in the Staff Report: Initial Statement of 

Reasons For Proposed Rulemaking (Staff Report) issued on December 7, 2011. 

15 All citations to section numbers in section II of this document are to title 13, California Code of 

Regulations section 1968.2, unless indicated otherwise. 

16 Staff Report, at page 62. 17 Staff Report, at pages 63-67.
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3. Section (c): Hybrid Vehicle

A new definition for “hybrid vehicle” was added to supplement the amendments 

to the permanent fault code erasure requirements and the in-use performance 

requirements, where “hybrid vehicle” is used.18

4. Section (c): Plug-in Hybrid Electric Vehicle

A new definition of “plug-in hybrid electric vehicle” was added to supplement the 

amendments to the in-use monitor performance requirements, sections 

(d)(3.2.1), (d)(4.3.2) and (d)(5.5),where this definition is used.19

5. Section (c): Propulsion System Active

A new definition for “propulsion system active” was added to supplement the 

amendments to the permanent fault code erasure requirements and the in-use 

performance requirements, sections (d)(2.5), (d)(4.3.2) and (d)(5.5), the sections 

where “propulsion system active” is used.20

6. Section (c): Warm-up Cycle

The amendments modified the definition for “warm-up cycle” to allow 

manufacturers to use an alternative definition of “warm-up cycle” based on the 

criteria to erase the permanent fault code. The amendment would be applicable 

to vehicles such as hybrid vehicles or vehicles with highly efficient engines that 

are unable to warm up the engine coolant temperature to the defined 

temperatures under the current definition even when they have been sufficiently 

driven to constitute a “warm up cycle”.21

B. General Requirements 

1. Malfunction Indicator Light (MIL) and Fault Code Requirements

a. Section (d)(2.5.2)(B): Erasing a Permanent Fault Code. 

Section (d)(2.5.2), as initially adopted, required manufacturers to erase a 

permanent fault code only if on a single driving cycle, among other conditions, 

the cumulative time since engine start was greater than or equal to 600 seconds 

and the malfunction was not detected again. This ensured that the vehicle was 

operated for a sufficient period of time to reasonably detect a recurrence of the 

malfunction, but did not unnecessarily delay erasure of the permanent fault code.

18 Staff Report, at pages 63-67. 19 Staff Report, at pages 63-67. 20 Staff Report, at pages 63-67. 21 Staff Report, at pages 62-63.
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The amendments clarify that for hybrid vehicles, the equivalent condition is 

“cumulative propulsion system active time since engine start” since hybrid 

engines may not start right after the vehicle is turned on (if at all) in typical drive 

cycles.22

2. In-Use Monitor Performance Ratio Definition

The OBD II regulation requires manufacturers to track monitor performance by 

counting the number of monitoring events and the number of driving events. The 

number of monitoring events is defined as the numerator and the number of 

driving events is defined as the denominator. The ratio of these two numbers is 

referred to as the monitoring frequency and provides an indication of how often 

the monitor is operating relative to vehicle operation.

a. Section (d)(3.2.1)(D)(v): Minimum Acceptable In-Use Monitor 

Performance Ratios

The OBD II regulation previously required manufacturers to meet minimum inuse monitor performance ratios (0.336 for most monitors) through the 2016 

model year. The amendments now allow monitors of components or systems 

that require engine operation on plug-in hybrid electric vehicles to meet a 

reduced in-use monitor performance ratio of 0.100 through the 2016 model year. 

In the 2017 model year, the interim relief ends.

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b. Sections (d)(4.3.2)(D) and (L): Denominator Specifications 

Section (d)(4.3.2)(D), as originally adopted, required the denominator to be 

incremented for the evaporative system monitors only on trips that met a ‘cold 

start’ definition (i.e., if the engine coolant temperature (ECT) and the ambient 

temperature were considered cold and the ECT at engine start was less than or 

equal to 12 degrees Fahrenheit higher than ambient temperature at start). 

The amendments to sections (d)(4.3.2)(D) and (L) require 2015 and subsequent 

model year plug-in hybrid vehicles to use an alternate definition of “cold start” 

(when the soak period immediately preceding the driving cycle is greater than or 

equal to 6 hours) in lieu of requiring the ECT at engine start to be less than or 

equal to 12 degrees Fahrenheit higher than ambient temperature at start. 2014 

and older model year plug-in hybrid electric vehicles can either use the new 

criteria or the existing criteria to increment the evaporative system monitor 

denominator.24

22 Staff Report, at pages 63-64. 23 Staff Report, at page 66. 24 Staff Report, at pages 65-66.
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c. Section (d)(4.3.2)(F): Denominator Specifications

The regulation originally required the PM sensor heater monitor to increment the 

denominator based on the general denominator incrementing criteria in section 

(d)(4.3.2)(B). The amendments modify section (d)(4.3.2)(F) to require the PM 

sensor heater monitor to increment the denominator if the component is 

commanded to function on two or more occasions for greater than two seconds 

or for a cumulative time greater than or equal to 10 seconds, whichever occurs 

first.25

d. Section (d)(4.3.2)(H): Denominator Specifications 

The regulation originally required the PM sensor monitoring capability monitor to 

increment the denominator based on the general denominator incrementing 

criteria. The amendments to section(d)(4.3.2)(H) now allow manufacturers to 

propose alternate criteria (for CARB review and approval) to increment the 

denominator for PM sensor monitoring capability monitors.26

e. Section (d)(4.3.2)(K): Denominator Specifications

The newly added section (d)(4.3.2)(K) specifies the criteria for incrementing the 

general denominator for hybrid vehicles starting with the 2014 model year, and 

bases the incrementing on cumulative propulsion system active time and fueled 

engine operation, since the original general denominator criteria under section 

(d)(4.3.2)(B) was based on time after engine start, and therefore did not account 

for hybrid vehicles in which the engine starts later in the trip.27

3. Sections (d)(5.5.1) and (d)(5.5.2) – Ignition Cycle Counter

Sections (d)(5.5.1) and (d)(5.5.2), as originally adopted, required vehicles to 

report one ignition cycle counter that incremented if the engine exceeded a 

specific engine speed for at least two seconds plus or minus one second. 

Section (d)(5.5.2)(B) was amended for hybrid vehicles, to require the counter to 

be incremented when the propulsion system active definition is met for at least 

two seconds plus or minus one second. Sections (d)(5.5.1) and (d)(5.5.2)(C) 

were also amended for plug-in hybrid electric vehicles, to require 2014 and 

subsequent model year plug-in hybrid electric vehicles to report two ignition cycle 

counters, with the additional counter required to be incremented if the fueled 

engine operation definition has been met for at least two seconds plus or minus 

one second.28

25 Staff Report, at page 69. 26 Staff Report, at pages 67 and 69. 27 Staff Report, at pages 64-65. 28 Staff Report, at pages 66-67.
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C. Monitoring Requirements for Diesel/Compression-Ignition Engines.

1. Section (f)(1.2.3)(B): NMHC Converting Catalyst Feedgas Monitoring

Section (f)(1.2.3)(B) previously required 2010 and later model year light-duty 

vehicles and 2013 and later model year medium-duty vehicles to monitor the 

ability of NMHC catalysts to generate a desired feedgas (e.g., nitrogen dioxide 

(NO2)) to promote better performance in a downstream aftertreatment 

component (e.g., for higher NOx conversion efficiency in a selective catalytic 

reduction (SCR) system). The amendments delay this requirement until the 2015 

model year for both light-duty and medium-duty vehicles.29

2. Section (f)(9.2.4): PM Filter NMHC Conversion Monitoring 

Section (f)(9.2.4) previously required 2010 and later model year light-duty 

vehicles and 2013 and later model year medium-duty vehicles to monitor 

catalyzed PM filters for proper NMHC conversion capability. The amendments 

delay this requirement until the 2015 model year for both light-duty and mediumduty vehicles.30

3. Section (f)(15.2.2)(F): Comprehensive Component Output Component 

Monitoring

Section (f)(15.2.2)(F) previously required manufacturers to monitor fuel control 

system components (e.g., injectors, fuel pumps) having tolerance compensation 

features on 2013 and subsequent model year diesel vehicles. The amendments 

delay this requirement to the 2015 model year for both light-duty and mediumduty diesel vehicles.31

4. Section (f)(17.1): Exceptions to Monitoring Requirements – Revision of 

Emission Threshold or Malfunction Criteria

Section (f)(17.1) originally allowed manufacturers to revise the PM filter filtering 

performance malfunction criteria to exclude detection of specific failure modes 

under certain conditions up through the 2009 model year for light-duty vehicles 

and through the 2012 model year for medium-duty vehicles. The amendments 

extend this allowance for both light-duty and medium-duty vehicles through the 

2013 model year.32

D. Standardization Requirements

1. Section (g)(1.4): Reference Documents

29 Staff Report, at pages 67-68. 30 Staff Report, at pages 69-70. 31 Staff Report, at pages 70-71. 32 Staff Report, at page 68.
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The amendments update the list of SAE and ISO documents that are 

incorporated by reference into the OBD II Requirements, specifically adding the 

October 2011 version of SAE J1979-DA: Digital Annex of E/E Diagnostic Test 

Modes. As is common practice with technical standards, industry periodically 

updates the standards to add specification or clarity.33

2. Section (g)(4): Required Emission Related Functions

a. Sections (g)(4.2.6) and (g)(4.2.7): Data Stream Parameters

Section (g)(4.2.6) originally required all 2013 and subsequent model year 

vehicles to report the parameter “type of fuel currently being used.” The 

amendments to sections (g)(4.2.6) and (g)(4.2.7) delay the requirement until the 

2015 model year to provide manufacturers time to implement the latest revisions 

of the format for this parameter and to address interpretations by some 

manufacturers that this parameter was only required on flex fuel vehicles.34

b. Section (g)(4.2.6)(B): Required Emission Related Functions:

The OBD II regulation previously and erroneously specified that the “PM sensor 

output” signal was to be made available starting in both the 2010 model year and 

the 2013 model year. The amendments clarify that access to this signal was 

required in the 2010 model year by deleting the reference to “PM sensor output” 

under the 2013 and subsequent model year language in section 

1968.2(g)(4.2.6)(B)).

E. Deficiencies 

1. Section (k)(4): Carry-over Deficiencies 

The regulation originally allowed manufacturers to carry over deficiencies up to a 

maximum of three model years, provided manufacturers demonstrated that 

substantial hardware changes were needed to correct the deficiency. The 

amendments allow manufacturers to carry over deficiencies for up four model 

years (i.e., deficiencies first granted in the 2010 model year may be carried over 

through the 2013 model year), if they can demonstrate that substantial hardware 

changes, vehicle hardware modifications, and additional lead time are necessary 

to correct the deficiencies.35

33 Staff Report, at page 71. 34 Staff Report, at pages 71-72. 35 Staff Report, at page 68.
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2. Section (k)(7): Exceptions to Fines Requirements 

The amendments to section (k)(7) provide manufacturers free deficiencies for the 

PM filter filtering performance monitor, PM sensor monitor, and PM sensor 

heater monitor on 2013 and 2014 model year light- and medium-duty vehicles.36

F. Amendments to OBD II Enforcement Regulation 

1. Sections 1968.5(b)(6)(B)(i)a. and (c)(3)(A)(i): Finding of Nonconformance 

after Enforcement Testing and Ordered Remedial Action 

Section 1968.5(b)(6)(B)(i)a. specifies the criteria for engines to be included in the 

test sample group for OBD ratio testing while section (c)(3)(A)(i) specifies the 

criteria for mandatory recall for OBD ratio issues. The amendments extend the 

last model year from 2013 to 2016 for vehicles certified to the 0.100 ratio to 

account for the amendments made for plug-in hybrid electric vehicles in section 

1968.2(d)(3.2.1)(D)(v).37

G. Other Amendments

As discussed in the Staff Report, other amendments to the regulation were made 

to clarify existing requirements.

III. SUMMARY OF 2013 AMENDMENTS TO HD OBD and OBD II 

REQUIREMENTS38

In adopting the HD OBD and OBD II regulations, the Board directed the staff to 

continue to follow manufacturers’ progress towards meeting the regulations’ 

requirements and to report back should modifications to the requirements be 

deemed appropriate. In accordance with the Board’s directives, staff met with 

stakeholders and, in conjunction with manufacturers, identified areas in which 

modifications to the HD OBD and OBD II regulations, as the latter regulation

applies to medium-duty diesel vehicles, would be beneficial. 

The 2013 Amendments to the HD OBD Requirements primarily: accelerate the 

start date for OBD system implementation on alternate-fueled engines from the 

2020 model year to the 2018 model year, relax some requirements for OBD 

systems on heavy-duty hybrid vehicles for the 2013 through 2015 model years, 

relax malfunction thresholds for three major emission control systems (particulate 

36 Staff Report, at page 69. 37 Staff Report, at page 66. 38 A detailed discussion of the 2013 Amendments as discussed in Section II of this document is 

set forth in the Staff Report: Initial Statement of Reasons (Staff Report) issued on July 5, 2012, 

the Notice of Availability of Modified Text issued on January 4, 2013 (15-Day Notice), and the 

Final Statement of Reasons (FSOR), issued on June 27, 2013. Copies of the aforementioned 

documents are enclosed herewith. 
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matter (PM) filters, oxides of nitrogen (NOx) catalysts, and NOx sensors) on 

diesel engines until the 2016 model year, delay monitoring requirements for 

some diesel-related components until 2015 to provide further lead time for 

emission control strategies to stabilize, and clarify requirements for several 

monitors and standardization. 

The 2013 Amendments additionally amended the HD OBD Requirements to be 

consistent with the federal definition of “emission standard” as set forth in Engine 

Manufacturers Association v. South Coast Air Quality Management District 

(2004) 541 U.S. 246, 253, 124 S.Ct. 1756, 1762 (EMA).

The 2013 Amendments also include the following amendments to the HD OBD 

regulation:

• Clarifying the purposes and objectives of the OBD regulations 

• Adding definitions of emission standard as it applies to OBD systems 

• Adding definitions for exhaust and evaporative emission standards 

• Adding definitions and revising the permanent fault code storage and 

erasure protocol and in-use monitoring performance requirements 

applicable to hybrid vehicles 

• Revising the freeze frame storage and erasure protocol 

• Revising the in-use monitoring performance requirements for the PM filter 

and PM sensor monitors 

• Revising the diesel misfire monitoring requirements to no longer require 

emission threshold-based malfunction criteria and to require expanded 

monitoring conditions 

• Delaying some monitoring requirements for catalyzed PM filters and diesel 

non-methane hydrocarbon converting catalysts from the 2013 model year 

to the 2015 model year 

• Revising the cooling system monitoring requirements to clarify when monitor 

enablement can occur 

• Updating the Society of Automotive Engineers (SAE) and International 

Standards Organization document references 

• Revising the standardized communication protocol and diagnostic connector 

requirements to account for the new 500 kilobits per second baud rate 

version of SAE J1939 

• Revising the readiness status requirements to clarify which monitors must 

be included in determining readiness 

• Clarifying the calibration verification number requirements 

• Deleting the service information requirements 

• Revising the certification demonstration testing requirements to clarify how 

to perform the testing for gasoline air-fuel ratio cylinder imbalance 

monitoring and exhaust gas sensor monitoring, to clarify the test 

requirements for diesel misfire monitoring, and to clarify the test 

requirements for catalyst faults and other faults where default actions are 

taken 
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• Adding items required to be submitted as part of the certification application 

• Revising the deficiencies section to allow up to two free deficiencies for 

2013 through 2015 model year heavy-duty hybrid vehicles and for PM 

filter and PM sensor monitors

To allow manufacturers of both heavy-duty and medium-duty diesel engines to 

be able to design OBD systems that will operate and be in compliance on 

medium- and heavy-duty engines, the 2013 Amendments concurrently amended 

certain OBD II Requirements that apply to medium-duty diesel engines to align 

where necessary with the aforementioned amendments to the HD OBD 

Requirements.39

A summary of the substantive amendments to the HD OBD and medium-duty 

vehicle OBD II requirements is provided below. The summary references the 

Staff Report: Initial Statement of Reasons for Proposed Rulemaking (Staff 

Report), issued July 5, 2012,and the Notice of Availability of Modified Text, 

39 The 2013 Amendments to the OBD II Requirements for medium-duty engines are less 

extensive than the 2013 Amendments applicable to HD OBD Requirements as the OBD II 

Requirements already incorporate several provisions of the amendments to the HD OBD 

Requirements, as discussed below in this footnote. 

1971.1(d)(7.5.3): Implementation Schedule for Alternate-Fueled Engines. No 

corresponding amendment to the OBD II Requirement is needed because medium-duty alternatefueled engines are currently required to have fully compliant OBD II systems. 

1971.1(d)(7.6), (g)(3.1.4), (g)(3.1.5): 2013 MY Hybrid Vehicles, and Exceptions for Hybrid 

Vehicles. No corresponding amendments to the OBD II Requirements are needed because 

medium-duty vehicle hybrid vehicles are currently required to have fully compliant OBD II 

systems. 

1971.1(d)(2) and (h)(3.2): Diagnostic connector and SAE 1939 protocol. No 

corresponding amendments to the OBD II Requirements are needed since the OBD II 

Requirements already allow medium-duty vehicles to use the diagnostic connector and SAE 

J1939 protocol requirements specified in the 2013 HD OBD amendments,

1971.1(k): Deficiencies for HD Diesels and Hybrids. No corresponding amendments to 

the OBD II Requirements are needed because the OBD II Requirements already incorporate 

deficiencies for hybrid vehicles and additionally incorporates similar, but not identical deficiency 

provisions for diesel-related monitors.

1971.1(l)(2.1): Verification of Monitoring Requirements. No corresponding amendments 

to the OBD II Requirements are needed given the differences between the heavy-duty and 

medium-duty vehicle manufacturing industry. The heavy-duty vehicle industry consists of 

manufacturers that manufacture engines that are installed in vehicles that are generally 

manufactured by separate manufacturers, whereas medium-duty vehicles consist of engines and 

vehicles manufactured by a single manufacturer. The amendments to this section account for the 

non-integrated nature of the heavy-duty engines and heavy-duty vehicle and are not required 

given the integrated nature of the medium-duty vehicle industry. 
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issued January 4, 2013 (15-day Notice) associated with the Board’s 2013 

rulemaking action (Enclosures 9-13 and 15).

A. Purpose [Section 1971.1(a) and 1968.2(a)]

The amendments clarify and reaffirm that the objectives of the HD OBD and the 

OBD II regulations are to ensure that emissions reductions in in-use motor 

vehicles and motor vehicle engines are achieved through improvements of 

emission system durability and performance.

B. Definitions [Section 1971.1(c)]40

1. Alternate-fueled engine

A new definition for “alternate-fueled engine” has been added to clarify which 

engines constitute alternate-fueled engines that are exempted from complying 

with the HD OBD monitoring requirements until the 2018 model year, and 

specifically addresses engines that can utilize more than one type of fuel (i.e.,

engines that can operate on two different types of fuel at the same time or two 

different types of fuel but only one at a time).41

2. Alternate phase-in/[Section 1968.2(c)]

A new definition for “alternate phase-in” has been added that is similar to the

current definition in the OBD II regulation, and provides manufacturers additional 

compliance flexibility in meeting some regulatory requirements subject to 

prescribed phase-in schedules.42

3. Diagnostic or Emission Critical

The amendments modify the definition for “diagnostic or emission critical” 

electronic control unit, and specifically modify the criteria for control units to be 

considered diagnostic or emission critical, which will limit the number of control 

units that are subject to reporting the CAL ID/CVN parameters.43

4. Emission Standard, Exhaust Emission Standards or Tailpipe Emission 

Standards, and Evaporative Emission Standards/[Section 1968.2(c)]

A new definition of “emission standard” was added to clarify that OBD systems,

in general, and OBD design-feature requirements of sections 1971.1 and 1968.2, 

40 The amendments discussed in this section pertain almost exclusively to definitions contained in 

title 13, CCR section 1971.1. In the several instances in which an amended definition also 

applies to medium-duty vehicle OBD II Requirements set forth in title 13, CCR section 1968.2, 

such amended definitions are specifically referenced as well. 

41 Staff Report, at page 17. 42 15-Day Notice, Attachment B. 43 Staff Report at page 19, 15-Day Notice at pages 2-3.
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specifically, are emission standards. The new definition conforms to the U.S. 

Supreme Court’s interpretation of the term in Engine Manufacturers Association 

v. South Coast Air Quality Management District (2004) 541 U.S. 246, which 

defined a “standard relating to the control of emissions” under Title 2 of the Clean 

Air Act as it applies to motor vehicles and motor vehicle engines. The definitions 

of “exhaust emission standards”, “tailpipe emission standards”, and evaporative 

emission standards” were added to specifically identify a subcategory of 

emission standard as opposed to the broader term of emission standard that 

encompasses all standards.44

5. Fueled Engine Operation

A new definition of “fueled engine operation,” defined as the state where any fuel 

is introduced into the engine for purposes of combustion, was added to 

complement the amendments to the in-use monitor performance requirements 

for hybrid vehicles.45

6. Hybrid Vehicle

A new definition for “hybrid vehicle” was added to complement the amendments 

to the permanent fault code erasure requirements and the in-use performance 

requirements, the sections in which “hybrid vehicle” is used.

7. Ignition Cycle

The definition of ignition cycle was amended to be consistent with the 

amendments to section 1971.1(d)(5.5) relating to ignition cycle counter 

requirements for hybrid vehicles. Specifically, for hybrid vehicles, ignition cycle is 

defined as a driving cycle that begins when the propulsion system active 

definition is met for at least two seconds plus or minus one second, and ends 

when the propulsion system active definition is no longer met.

8. Propulsion System Active

A new definition for “propulsion system active” was added to complement the 

amendments to the permanent fault code erasure requirements and the in-use 

performance requirements for hybrid vehicles. Specifically, this is defined as the 

state where the powertrain is enabled by the driver such that the vehicle is ready 

to be used.46

44 Staff Report at page 18-19, 15-Day Notice at p.3. 45 Staff Report, at page 22. 46 Staff Report, at pages 22-24.
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9. Small Volume Manufacturer

A new definition for “small volume manufacturer” was added to complement the 

proposed changes to the exceptions to the monitoring requirements in section 

(g)(5.8.2), which allows small volume manufacturers to meet alternate phase-in 

schedules in lieu of the required phase-in scheduled specified in the regulation.47

10. Warm-up Cycle

The amendments modify the definition for “warm-up cycle” to allow 

manufacturers to use an alternative definition of “warm-up cycle” based on the 

criteria to erase the permanent fault code. This accounts for vehicles with highly 

efficient engines that are unable to warm up the engine coolant temperature to 

the specified temperatures in the current definition even if they have been 

sufficiently driven.48

C. General Requirements49

1. Malfunction Indicator Light (MIL) and Fault Codes

a. Section 1971.1(d)(2.2.1)(D): Storage and erasure of freeze frame 

conditions for ISO 15765-4 protocol.

Section 1971.1(d)(2.2.1)(D) initially required vehicles using the ISO 15765-4

protocol to store and erase freeze frame conditions in conjunction with the 

storage and erasure of either pending or confirmed fault codes. This prior

requirement unintentionally resulted in manufacturers erasing freeze frame 

conditions for pending fault codes that matured to confirmed fault codes and left 

repair technicians without helpful information to diagnose detected faults. This 

section was therefore amended to require most manufacturers to store freeze 

frame conditions in conjunction with storage of pending fault codes, to erase 

freeze frame conditions if the pending fault code is erased when no fault is 

detected, and to either keep the previous freeze frame conditions or to update 

the freeze frame conditions if the pending fault code matures to a confirmed fault 

code starting with the 2016 model year. The section was also amended with the 

addition of section 1971.1(d)(2.2.1)(D)(iv) to clarify the freeze frame requirements 

for monitoring strategies that do not store pending fault codes, requiring 

manufacturers to store and erase freeze frame conditions in conjunction with 

storage and erasure of confirmed fault codes, to better ensure that freeze frame 

47 Staff Report, at page 19. 48 Staff Report, at pages 19-20. 49 The amendments discussed in this section generally pertain only to requirements contained in 

title 13, CCR section 1971.1. Only one amendment (discussed below in section 2a.) applies 

solely to the OBD II Requirements in 1968.2 and is so indicated. 
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information is available under all conditions to aid a technician in diagnosing a 

detected fault.50

b. Section 1971.1(d)(2.2.2)(D): Storage and erasure of freeze frame 

conditions for SAE J1939 Protocol.

Section 1971.1(d)(2.2.2)(D), as initially adopted, required manufacturers to store 

and erase freeze frame conditions in conjunction with the storage and erasure of 

either pending or confirmed fault codes. The section was amended with the 

addition of section 1971.1(d)(2.2.2)(D)(v) to clarify the freeze frame requirements 

for monitoring strategies that do not store pending fault codes, and now requires

manufacturers to store and erase freeze frame conditions in conjunction with the 

storage and erasure of MIL-on fault codes. 

c. Sections 1971.1(d)(2.3.1)(A) and (d)(2.3.2)(A): MIL Extinguishing 

Protocol. 

Section 1971.1(d)(2.3.1)(A), as initially adopted, exempted gasoline monitors that 

had their own protocol for extinguishing the MIL from the MIL extinguishing 

protocol specified in section (d)(2.3.1)(A). The amendments now also exempt 

diesel monitors that have their own MIL extinguishing protocol from the MIL 

extinguishing protocol specified in section (d)(2.3.1)(A). Sections (d)(2.3.1)(A)

and (d)(2.3.2)(A) also originally stated that the MIL “may be extinguished after 

three subsequent sequential driving cycles” with the previously detected 

malfunction no longer present. The amendments to these sections clarify that 

the MIL “shall” be extinguished “after at least” three subsequent sequential 

driving cycles to avoid misinterpretation of the original intent.

d. Sections 1971.1(d)(2.3.1)(B) and (d)(2.3.2)(C): Fault Code Erasure 

Protocol.

Sections 1971.1(d)(2.3.1)(B) and (d)(2.3.2)(C) previously allowed HD OBD 

systems to erase a confirmed fault code if the fault was not detected again for “at 

least 40 engine warm-up cycles.” These sections were amended to delete the 

word “engine” to be consistent with the use of “warm-up cycle” in the definitions 

in section (c) and were also amended to require manufacturers erase the fault 

code if the fault is not detected again for 40 warm-up cycles to ensure consistent 

implementation by manufacturers and to better ensure that repair technicians 

focus on recently detected faults and are not led astray by chasing down faults 

that have long since disappeared.51

50 Staff Report, at page 20. 51 See Id, at pages 20-21.
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e. Sections 1971.1(d)(2.3.1)(C)(ii)b.3 and (d)(2.3.2)(D)(ii)b.3: Erasing a 

Permanent Fault Code.

Sections 1971.1(d)(2.3.1)(C) and (d)(2.3.2)(D) require a HD OBD system to 

erase a permanent fault code if, among other conditions, the HD OBD system 

determines, among other conditions, that the malfunction that caused the 

permanent fault code to be stored is no longer present for a cumulative time 

period since engine start that is greater than or equal to 600 seconds during a 

single driving cycle. The amendments clarify that for hybrid vehicles, this criteria 

would be “cumulative propulsion system active time since engine start” since the 

engine may not start right after the vehicle is turned on. The amendments will 

help ensure equivalent vehicle operation time between conventional vehicles and

hybrid vehicles.52

2. In-Use Monitor Performance Ratio Definition

Currently, both the HD OBD and the OBD II regulation require manufacturers to 

track monitor performance by counting the number of monitoring events and the 

number of driving events. The number of monitoring events is defined as the 

numerator and the number of driving events is defined as the denominator. The 

ratio of these two numbers is referred to as the monitoring frequency and 

provides an indication of how often the monitor is operating relative to vehicle 

operation.

a. Section 1968.2(d)(3.2.1: Monitoring Conditions - Diesel PM Filter 

 Performance Monitors and Missing Substrate Monitors 53

The OBD II regulation specifies minimum monitoring ratios for the diesel PM filter 

filtering performance monitor and the missing substrate monitor. The 

amendments now allow 2015 through 2018 model year medium-duty vehicles to 

meet a less stringent minimum in-use performance ratio of 0.100 instead of the 

previously prescribed in-use performance ratio of 0.336. This amendment will

allow manufacturers to gain some experience with these monitors before they

are required to use a higher monitoring ratio starting in 2019.

b. Subsection 1971.1(d)(4.3.2)(B): Denominator Specifications 

Subsection 1971.1(d)(4.3.2)(B) currently describes the specifications for 

incrementing the denominator. The amendments clarify that the requirements of 

subsections 1971.1(d)(4.3.2)(F), (I), and (J) may supersede the requirements of 

subsection 1971.1(d)(4.3.2)(B) for specific monitors/vehicles since they have 

52 See Id, at page 21. 53 This amendment applies solely to the OBD II Requirements. There is no corresponding 

amendment to the HD OBD Requirements because the HD OBD Requirements already specify 

minimum monitoring ratios of 0.100 for the diesel PM filter filtering performance monitor and the 

missing substrate monitor.
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certain characteristics that make the requirements in subsection (d)(4.3.2)(B)

inappropriate to use. 

c. Section 1971.1(d)(4.3.2)(C): Denominator Specifications 

Section 1971.1(d)(4.3.2)(C), as originally adopted, specified the denominator 

incrementing criteria for evaporative system monitors, requiring a cold start 

condition to be met. The amendments allow monitors for the comprehensive 

component input component temperature sensors and the engine cooling system 

input components to use these denominator incrementing criteria as well, since 

these monitors generally require a cold start condition to enable monitoring. 

d. Section 1971.1(d)(4.3.2)(E) and Section 1968.2(d)(4.3.2)(F):

 Denominator Specifications 

The regulation originally required the PM filter active/intrusive injection monitor to 

increment the denominator if, among other conditions, a regeneration event is 

commanded for at least 10 seconds, and required the PM sensor heater monitor 

to increment the denominator if the general denominator criteria are met. The 

amendments modify sections 1971.1(d)(4.3.2)(E) and 1968.2(d)(4.3.2)(F) to now 

require the PM filter active/intrusive injection monitor and the PM sensor heater 

monitor to increment the denominator if, among other conditions, the component 

is commanded to function for at least 10 seconds, which are more appropriate 

criteria.54 Additionally, the amendments allow 2010 through 2015 model year 

engines to use the previously required denominator updating criteria to provide 

manufacturers lead time to meet the amended requirements.

e. Section 1971.1(d)(4.3.2)(F): Denominator Specifications

The regulation originally required the PM sensor monitoring capability monitor to 

increment the denominator based on the general denominator incrementing 

criteria. The amendments to section (d)(4.3.2)(F) now allow the monitor to 

increment the denominator based on manufacturer-proposed alternate criteria, to 

accommodate manufacturer concerns that the current denominator incrementing

criteria may result in the denominator incrementing more often than is 

appropriate for PM sensors that may be regenerated or used infrequently, which 

makes frequent monitoring of such sensors difficult.55

f. Section 1971.1(d)(4.3.2)(G) and Section 1968.2(d)(4.3.2)(G):

 Denominator Specifications 

Sections 1971.1(d)(4.3.2)(G) and 1968.2(d)(4.3.2)(G) currently allow monitors of 

components/emission controls that experience infrequent regeneration events to 

54 Staff Report, at pages 22-23. 55 Id., at page 23.
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increment the denominator if, among other conditions, the cumulative engine

runtime exceeds 800 minutes (section 1971.1(d)(4.3.2)(G)) or 500 miles for 

section 1968.2). The amendments would only allow PM filter performance 

monitors and PM filter missing substrate monitors to use these criteria from the 

2010 through the 2015 model years, after which the PM filter monitor will be 

subject to the general denominator criteria. The restriction is justified based on 

the vital role that PM filters in controlling PM emissions.56

g. Section 1971.1(d)(4.3.2)(J): Denominator Specifications

The newly added section 1971.1(d)(4.3.2)(J) indicates the criteria under which 

the general denominator will increment for hybrid vehicles starting with the 2016 

model year. This criteria is based on cumulative propulsion system active time 

and fueled engine operation, since the original general denominator criteria 

under section 1971.1(d)(4.3.2)(B) requires time after engine start and therefore 

does not account for hybrid vehicles where the engine starts later in the trip.57 In 

addition, this section allows 2010 through 2015 model year hybrid vehicles to use 

the current denominator updating criteria in section 1971.1(d)(4.3.2)(l) to provide 

lead time for hybrid manufacturers to meet the 2016 model year general 

denominator incrementing criteria.

h. Section 1971.1(d)(4.5.3): Disablement of Numerators and 

Denominators.

Section 1971.1(d)(4.5.3) currently allows HD OBD systems to disable 

incrementing all numerators and denominators if any component used to 

determine if the criteria for incrementing the general denominator and 

evaporative system denominator, including engine cold start criteria, are 

malfunctioning. The amendments delete the qualifying criterion of incrementing 

the evaporative system denominator (i.e., the engine cold start criteria), since 

monitors that do not require a code start can and should still accurately 

increment the numerators and denominators even if an “engine cold start” can no 

longer be determined.

3. Section 1971.1(d)(5.1.1) - Standardized Tracking and Reporting of 

Monitor Performance 

This section lists the specific diesel components and systems that are required to 

report in-use monitoring performance data. The amendments delete references

to “bank 1” and “bank 2” for the NMHC catalyst, NOx catalyst, and exhaust gas 

sensor monitors to be consistent with what is required to be reported in SAE 

J1979 and SAE J1939.58

56 Id. at pages 22-23. 57 Id., at page 22. 58 Id. at p.24.
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4. Section 1971.1(d)(5.5.2) – Ignition Cycle Counter

Section 1971.1(d)(5.5.2) specifies that the ignition cycle counter shall increment if 

the engine exceeds a specific engine speed for at least two seconds plus or 

minus one second. The section was amended for hybrid vehicles, requiring the 

counter to be incremented when the propulsion system active definition is met 

(i.e., each time the vehicle is operated, without respect to whether the engine is 

started or used) for at least two seconds plus or minus one second.59

5. Section 1971.1(d)(7.5.3): Implementation Schedule for AlternateFueled Engines

The HD OBD regulation currently allows alternate-fueled engines to delay

implementation of “full” OBD systems until the 2020 model year, with 2013 

through 2019 model year alternate-fueled engines required to comply with the 

less comprehensive EMD requirements and basic monitoring of all NOx 

aftertreatment components. This late start date of 2020 was adopted in 2006 as 

part of the initial HD OBD regulation. The amendments accelerate the start date 

for OBD implementation on alternate-fueled engines from the 2020 model year to 

the 2018 model year based on information that alternate-fueled engine sales are 

not insignificant, and that manufacturers are currently offering alternate-fueled 

engines that utilize more diverse conversion solutions than staff anticipated, 

which can have a much larger impact on the OBD system than simpler

conversions, and can also result in several unmonitored major emission control 

components in addition to the normal impacts of altering correlation to emission 

thresholds and monitoring frequency.60 The amendments also require 

manufacturers to propose a monitoring plan for alternate-fueled engines to 

ensure all emission control components, which may include both diesel and 

gasoline-related components, on the engine are properly monitored.

6. Section 1971.1(d)(7.6): 2013 Model Year Hybrid Vehicles

The newly added section 1971.1(d)(7.6) allows manufacturers of 2013 model 

year hybrid vehicles to meet alternative, less stringent requirements in lieu of the 

requirements of section 1971.161

D. Monitoring Requirements for Diesel/Compression-Ignition Engines62

1. Fuel System Monitoring 

59 Id., at pages 23-24. 60 Id. at pages 16-17. 61 Id., at pages 10, 12-16. 62 The amendments discussed in this section generally pertain only to requirements contained in 

title 13, CCR section 1971.1. Amendments that also apply to medium-duty vehicle OBD II 

Requirements set forth in title 13, CCR section 1968.2 are specifically identified as well.
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a. Section 1971.1(e)(1.4.2)(D): Storage of freeze frame conditions

The amendments align the freeze frame storage requirements for diesel fuel 

system monitors with the amended requirements in section (d)(2.2.1)(D)(iii).

Specifically, starting in the 2016 model year, HD OBD systems are required to 

store and erase freeze frame conditions for fuel system faults in conjunction with 

the storage and erasure of pending fault codes.63

2. Misfire Monitoring

a. Sections 1971.1(e)(2.2) and (e)(2.3.3) and Sections 1968.2(f)(3.2.2) 

and (f)(3.3.3): Malfunction Criteria and Monitoring Conditions

HD OBD systems were previously required to only monitor diesel engines for 

misfire during engine idle conditions and only for faults that cause one or more 

cylinders to be continuously misfiring. In addition, 2013 and subsequent model 

year heavy-duty diesel engines and 2010 and subsequent model year light- and

medium-duty vehicles equipped with sensors that can detect combustion or 

combustion quality were required to continuously monitor for misfire under all 

positive torque engine speeds and load conditions and to detect misfire before 

emissions exceeded specific thresholds (e.g., 2.0 times the applicable 

standards).

The amendments now require all heavy-duty and medium-duty diesel engines to 

continuously monitor for misfire. Heavy-duty diesel engines and light- and 

medium-duty vehicles that are not equipped with sensors capable of detecting 

combustion or combustion quality are subject to continuous misfire detection 

requirements that phase-in beginning with the 2016 model year and require 100

percent of 2018 model year engines to be able to continuously monitor for 

misfire malfunctions.64 The amendments also modify the malfunction criteria from 

an emission threshold-based criterion to a specific misfire percentage criterion

(i.e., five percent) to address manufacturers’ concerns regarding the difficulty in 

establishing a level of misfire that equates to the exceedance of a specific 

tailpipe emissions standard, and further allow manufacturers to request 

Executive Officer approval to detect misfires at higher levels of misfire 

percentage criterion. Further, the continuous misfire monitoring conditions are 

amended to allow for limited monitoring conditions for engines through the 2018 

model year under positive torque conditions up to 75 percent of peak torque (with 

a minimum 20 percent of peak torque for heavy-duty engines) and up to 75 

percent of the maximum engine speed. More comprehensive monitoring 

63 15-Day Notice, at page 3. 64 The phase-in provisions specify minimum percentages of engines that are based on projected 

California sales volumes of all diesel engines and medium-duty vehicles (i.e., engines and 

medium-duty vehicles that are both equipped and that are not equipped with combustion 

sensors). 
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conditions are phased in starting with 2019 model year engines that require 

monitoring across all positive torque engine speed conditions except those 

conditions in a limited disablement area of very low torque and high engine 

speed conditions. Lastly, manufacturers are now allowed to disable continuous 

misfire monitoring under conditions in which robust detection of misfires is at 

issue.65

b. Section 1971.1(e)(2.4.2)(B): Storage of freeze frame conditions

These amendments align the freeze frame storage requirements with the 

amended requirements in section 1971.1(d)(2.2.1)(D)(iii) or (d)(2.2.2)(D).

Specifically, starting in the 2016 model year, the manufacturer is required to store 

and erase freeze frame conditions for fuel system faults in conjunction with the 

storage and erasure of pending fault codes.66

3. EGR System Monitoring

Section 1971.1(e)(3.2.6) and Section 1968.2(f)(6.2.6): Malfunction 

Criteria for EGR Catalyst Performance

HD OBD and OBD II systems are currently required to monitor EGR catalysts

used in EGR systems for all 2013 and subsequent model year engines. Such

catalysts are used to treat the exhaust gas before it is recirculated into the intake 

of the engine to reduce contamination or fouling that might otherwise affect 

durability of the EGR system. Although failures of an EGR catalyst may not 

result in an immediate impact on emissions, they could lead to more aggressive 

deterioration of other EGR system components such as fouling or plugging of the 

EGR cooler.

In response to manufacturer concerns, the amendments now exempt EGR 

catalysts from being monitored provided manufacturers demonstrate that failures 

of EGR catalysts will not cause a measurable emissions impact on the criteria

pollutants (i.e., NMHC, CO, NOx, and PM) during any reasonable driving 

condition in which the catalyst is most likely to affect criteria pollutants.67

4. NMHC Converting Catalyst Monitoring

Section 1971.1(e)(5.2.3)(B) and Section 1968.2(f)(1.2.3)(B): Delay 

Implementation Start Date to 2015.

The HD OBD and OBD II regulations previously required monitoring of NMHC 

catalysts used to generate a feed-gas constituency to assist SCR systems 

beginning in the 2013 model year. The amendments delay this monitoring 

65 Staff Report, at pages 24-26; 15-Day Notice, at pages 3-4. 66 15-Day Notice, at page 4. 67 Staff Report, at page 26.
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requirement until the 2015 model year and further exempt manufacturers from 

this requirement if they can demonstrate that both a complete failure of the 

component or loss of the function results in less than a 15 percent of the 

standard increase for any pollutant over an applicable test cycle (e.g., Federal 

Test Procedure (FTP) or Supplemental Emission Test (SET)) during the engine’s 

useful life, and that tailpipe emissions are below the standards. This will ensure 

that any impact is truly ‘minor.’ 68

5. NOx Converting Catalyst Monitoring

a. Sections 1971.1(e)(6.2.1) and (e)(6.2.2) and Section

1968.2(f)(2.2.2)(A): Conversion Efficiency and Reductant 

Delivery Performance Monitoring

HD OBD and medium-duty OBD II systems in 2013 and subsequent model year 

engines were previously required to detect NOx converting catalyst (typically an 

SCR catalyst) conversion efficiency before NOx emissions exceed the applicable 

NOx standard plus 0.2 g/bhp-hr.

The amendments increase the current HD OBD threshold to the applicable NOx 

standard plus 0.4 g/bhp-hr starting in the 2013 model year. Beginning with the 

2014 model year, manufacturers must phase in a tighter threshold of the 

applicable NOx standard plus 0.3 g/bhp-hr for 20 percent of 2014 model year 

diesel engines and 50 percent of 2015 model year diesel engines, with the 

percentages based on a manufacturer’s projected California sales volume of all 

heavy-duty diesel engines. For the 2016 model year, manufacturers must meet 

the applicable NOx standard plus 0.2 g/bhp-hr with the exception that any 

engines that were phased-in during 2014 or 2015 to the ‘+0.3’ threshold would be

able to remain at that threshold in 2016 and would not have to meet the ‘+0.2’ 

threshold until the 2017 model year.

For medium-duty OBD II systems the amendments increase the threshold to the 

applicable NOx standard plus 0.3 g/bhp-hr from 2013 through 2015. For chassis 

dynamometer-certified applications, the threshold is 2.0 times the applicable 

standard.69

b. Section 1971.1(e)(6.3) and Section 1968.2(f)(2.3.1): Monitoring 

Conditions for Reductant Delivery Performance Monitoring

The regulation previously required continuous monitoring for reductant delivery 

faults. The amendments now allow HD OBD and OBD II systems to monitor for 

such faults once per trip. 

68 Id., at pages 28-29. 69 Staff Report, pages 29-31.
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6. PM Filter Performance Monitoring

a. Section 1971.1(e)(8.2.1) and Section 1968.2(f)(9.2.1): Increasing 

PM Threshold

2013 through 2015 model year heavy-duty engines subject to full OBD and all 

2016 and subsequent model year engines were previously required to detect PM 

filter performance faults before emissions exceeded either 0.03 g/bhp-hr from an 

applicable emission-test cycle or the applicable PM standard plus 0.02 g/bhp-hr. 

The amendments increase these thresholds to either 0.05 g/bhp-hr from an 

applicable emission test cycle or the applicable PM standard plus 0.04 g/bhp-hr

starting in the 2013 model year engines. The amendments also allow 

manufacturers to either (1) use a threshold of 0.05 g/bhp-hr or the applicable PM 

standard plus 0.04 g/bhp-hr for 20 percent of 2014 and 2015 model year engines 

without the provisions to exclude specific failure modes, or (2) use a threshold of 

0.03 g/bhp-hr or the applicable PM standard plus 0.02 g/bhp-hr for 50 percent of 

2015 model year engines without the provisions to exclude specific failure 

modes.70 The amendments also add new section1971.1 (e)(8.2.1)(F), which 

prohibits manufacturers from using an alternate phase-in schedule for these 

monitoring requirements.

2013 and subsequent model year medium-duty vehicles and engines subject to 

the OBD II regulation were previously required to detect PM filter performance 

faults before emissions exceeded 0.03 g/bhp-hr from an applicable emission-test 

cycle.

For the OBD II regulation, the amendments to section 1968.2(f)(9.2.1) retain the 

0.03 g/bhp-hr PM threshold, but with amendments previously approved in

January 2012, manufacturers are eligible to receive ARB approval to exclude 

specific failure modes. For the 2014 and 2015 model years, medium-duty 

manufacturers can either: (1) implement monitoring to a PM threshold of 0.03

g/bhp-hr without the failure mode exemptions on at least 20 percent of their 2014 

and 2015 annual model year medium-duty diesel vehicle volumes, and certify the 

remaining vehicles to the 0.03 g/bhp-hr threshold with the failure mode 

exemption or (2) elect to continue complying with the 2013 threshold with the 

failure mode exemption in the 2014 model year. However, for the 2015 model 

year, manufacturers need to certify at least 50 percent of their 2015 model year 

medium-duty diesel volume to the threshold of 0.03 without the failure mode 

exemption. 

70 Staff Report, at pages 32-34.
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b. Section 1971.1(e)(8.2.4) and Section 1968.2(f)(9.2.4)(A): NMHC

Conversion Monitoring

The HD OBD regulation previously required manufacturers to monitor the NMHC 

conversion capability of catalyzed PM filters starting with the 2013 model year. 

OBD II systems were required to monitor the NMHC conversion capability of 

catalyzed PM filters starting with the 2015 model year. 

The amendments delay the 2013 model year HD OBD monitoring requirement 

until the 2015 model year. The amendments to section 1971.1(e)(8.2.4) and 

section 1968.2(f)(9.2.4)(A) also allow manufacturers to be exempt from this

monitoring requirement if a malfunction cannot cause emissions to exceed 

certain criteria.71 The amendments also require that 2016 and subsequent 

model year engines that use catalyzed PM filters to generate feedgas 

constituency (e.g., NO2 to assist SCR systems), be monitored for the capability of 

the system to generate desired feedgas, but allow manufacturers to be exempt 

from this monitoring requirement if a malfunction cannot cause emissions to 

exceed certain criteria.72

7. Exhaust Gas Sensor Monitoring

a. Section 1971.1(e)(9.2.2)(A) and Section 1968.2(f)(5.2.2)(A): NOx 

and PM Sensor Malfunction Criteria

The HD OBD and medium-duty OBD II regulations originally required 2013 and 

subsequent model year engines to detect NOx sensor performance faults before 

emissions exceeded the applicable NOx standard by more than 0.2 g/bhp-hr,

instead of the previous threshold of ‘+0.4’ g/bhp-hr. The amendments delay 

implementing the ‘+0.2 g/bhp-hr 2013 model year threshold until the 2014 model 

year, at which time manufacturers are required to phase in a tighter threshold of 

‘+0.3’ on 20 percent of their 2014 model year heavy-duty engine volumes and 50 

percent of their 2015 model year heavy-duty engine volumes. For the 2016 

model year, manufacturers are required to meet the ‘+0.2’ threshold with the 

exception that any products that were phased-in during 2014 or 2015 to the ‘+0.3’ 

threshold would be able to remain at that threshold in 2016 and would not have 

to meet the ‘+0.2’ threshold until the 2017 model year. The amendments also 

add an NMHC threshold to the HD OBD regulation starting in the 2016 model 

year, requiring manufacturers to detect a fault before emissions exceed two 

times the applicable NMHC standard.73

71 If no malfunction of the catalyzed PM filter’s NMHC conversion capability causes emissions to 

increase by 15 percent or more of the applicable standard over an applicable test cycle (e.g., 

Federal Test Procedure (FTP) or Supplemental Emission Test (SET)) during the engine’s useful 

life or exceeds the applicable full useful life standard as measured from an applicable emission 

test.

72 See fn. 42; Staff Report at pp. 34-35. 73 Id., at pages 35-37.
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The amendments to section 1968.2(f)(5.2.2)(A) now require 2013 through 2015 

model year medium-duty vehicles to meet a threshold of ‘+0.3’ (i.e., the 

applicable NOx standard + 0.3 g/bhp-hr) instead of the ‘+0.2’ current threshold. 

b. Section 1971.1(e)(9.3.1) and Section 1968.2(f)(5.3.1)(A): NOx and 

PM Sensor Monitoring Conditions

The regulation originally required the NOx sensor monitoring capability monitor to 

run every time the monitoring conditions were met. The amendments now 

require the monitor to run once per driving cycle, since some monitors would not 

be able to meet the prior requirements if they were intrusive monitors. The 

regulation was also amended to now require the NOx sensor monitoring 

capability monitor to track and report the in-use monitor performance data

starting with the 2016 model year.74

Both the HD OBD and medium-duty OBD II regulations previously did not 

require manufacturers to track and report the diesel NOx/PM sensor “monitoring

capability” monitors (sections 1971.1(e)(9.2.2)(D) and 1968.2(f)(5.2.2)(D)), but 

instead only required manufacturers to track and report diesel NOx/PM sensor 

performance monitors that were emission threshold-based (sections 

1971.1(e)(9.2.2)(A) and 1968.2(f)(5.2.2)(A)). However, because many of these 

sensors do not have emission-threshold based monitors, and thus would only be 

subject to monitoring if a malfunction causes the sensor to no longer be sufficient 

for use as an OBD system monitoring device, and because NOx and PM sensors 

are important for monitoring major aftertreatment emission control devices, the 

amendments now require HD OBD and OBD II systems to track and report the 

diesel NOx/PM sensor “monitoring capability” monitors for 2016 and subsequent 

model year heavy-duty engines and medium-duty vehicles.

E. Monitoring Requirements for Gasoline/Spark-Ignited Engines.

1. Section 1971.1(f)(2.3.6): Misfire Monitoring 

The regulation originally required engines that employ engine shutoff strategies 

that do not require the vehicle operator to restart the engine to continue driving to 

monitor for misfire no later than the end of the second crankshaft revolution “after 

each engine restart”. The amendments now require monitoring no later than the 

end of the second crankshaft revolution “after engine fueling begins for the initial 

start and after each time fueling resumes.”75

2. Section 1971.1 (f)(5.2.4): Secondary Air System Monitoring 

The regulation originally required manufacturers to monitor the secondary air

74 Id., at page 24. 75 Staff Report, at page 37.
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system for malfunctions prior to either a decrease or an increase from the 

specified air flow that would cause emissions to exceed 1.5 times the standards.

Further, if no fault that caused a decrease or an increase in air flow could cause

emissions to exceed 1.5 times the standards, the manufacturer was required to 

detect a fault when “no detectable amount of air flow is delivered during normal 

operation of the secondary air system.” Manufacturers were not required to 

functionally monitor for increases in air flow that do not cause emissions to 

exceed 1.5 times the standards.

The amendments now require manufacturers to detect a fault when no 

detectable amount of air flow is delivered only if no fault that causes a decrease 

in air flow could cause emissions to exceed the threshold. The amendments also 

require that if no fault that causes an increase in air flow could also cause 

emissions to exceed the threshold (1.5 times the standard), that manufacturers 

are required to detect a fault when the system has reached its control limits such 

that it cannot reduce air flow during normal operation of the secondary air system

beginning in the 2016 model year.76

3. Section 1971.1 (f)(7.1): Evaporative System Monitoring

The amendments clarify that manufacturers of alternate-fueled engines that are 

subject to evaporative emission standards and evaporative system monitoring 

requirements are required to submit a plan for Executive Officer approval 

regarding what monitoring they would do and its equivalence to the type of 

evaporative system monitoring required for gasoline applications.77

F. Monitoring Requirements for All Engines.

1. Comprehensive Component Monitoring

a. Sections 1971.1(g)(3.1.4) and (g)(3.1.5): Exceptions for Hybrid 

Vehicles

The amendments incorporate newly added section 1971.1(d)(7.6), which allows 

manufacturers of 2013 model year hybrid vehicles to meet the alternative 

requirements set forth in sections 1971.1(d)(7.6.1) through (d)(7.6.5) in lieu of 

meeting all other requirements of section 1971.1.

b. Section 1971.1(g)(3.2.2)(B)(ii)d.: Diesel Idle Control System 

Monitoring 

The regulation originally required manufacturers to detect diesel idle control 

system faults if the system could not achieve target idle speed with a fuel 

injection quantity within +/- 50 percent of the fuel quantity necessary to achieve 

76 Id., at pages 37-38. 77 Id. at page 18.
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the target speed for a properly functioning engine and the “given” operating 

conditions. The amendments now require the manufacturer to consider the 

“known”, not “given”, operating conditions.78

c. Section 1971.1(g)(3.2.2)(F) and Section 1968.2(f)(15.2.2)(F)(ii):

Malfunction Criteria for Certain Output Components

Section 1971.1(g)(3.2.2)(F) originally required manufacturers to monitor fuel 

system components for proper compensation starting with the 2013 model year.

The amendments delay this requirement until the 2015 model year. The 

amendments to section 1971.1(g)(3.2.2)(F) and section 1968.2(f)(15.2.2)(F)(ii) 

also added language to allow manufacturers to be exempt from this monitoring 

requirement if a malfunction cannot cause emissions to exceed certain criteria.79

2. Exceptions to Monitoring Requirements

a. Section 1971.1(g)(5.1) and Section 1968.2(f)(17.1): Revision of 

Emission Threshold or Malfunction Criteria

Section 1971.1(g)(5.1) originally allowed manufacturers to indefinitely revise the 

PM filter filtering performance malfunction criteria to exclude detection of specific 

failure modes under certain conditions. The amendments limit this allowance to 

the 2010 through 2015 model years, since the allowance provides an unknown 

risk for failures that can cause high PM emissions to go undetected, which 

should not be allowed on all future engines and is not needed based on new 

monitoring techniques being developed for future engines.80

Section 1968.2(f)(17.1) allows manufacturers to revise the required malfunction 

criteria if certain conditions are met. The amendments extend the allowance for 

medium-duty vehicles to not detect specific failure modes of the PM filter from 

the 2013 to the 2015 model year.81

78 Id., at pages 38-39. 79 Id., at pages 39-40. 80 Id., at pages 33-34. 81 The amendments to section 1971.1(g)(5) and 1968.2(f)(17.1) are consistent although they 

apply to different model years of engines and vehicles. The initial OBD II Requirements applied 

to 2004 and newer model year medium-duty engines and vehicles, and CARB amended the OBD 

II Requirements in 2007 to first allow manufacturers to revise malfunction criteria for specific PM 

filter failure modes for 2007 through 2012 MY medium-duty vehicles. The amendments to section 

1968.2(f)(17.1) now extend that exemption to 2007 through 2015 MY medium-duty vehicles. 

When CARB adopted the initial HD OBD Requirements in 2005 that apply to 2010 and newer MY 

HD engines and vehicles, it incorporated the same provisions of section 1968.2(f)(17.1) 

that allow manufacturers to indefinitely revise malfunction criteria for specific PM filter failure 

modes. However, for the reasons set forth in the Staff Report for the 2013 Amendments, CARB 

decided to limit manufacturers’ ability to utilize this provision and has accordingly limited this 

provision to only apply to 2010 through 2015 MY engines. This limitation did not include the 2007 
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Sections 1968.2(f)(17.1.5) and (f)(17.1.6) describe the monitoring requirements 

and malfunction criteria for medium-duty diesel vehicles certified to a chassisdynamometer tailpipe emission standard. 

The OBD II regulation previously required manufacturers of medium-duty diesel 

vehicles certified on a chassis dynamometer to request CARB’s approval

of the emission-based malfunction criteria in lieu of the engine dynamometerbased malfunction criteria (e.g., 2.0 times the applicable standards) for each

applicable diesel monitor in section 1968.2(f). Increasingly more medium-duty 

diesel vehicles are being certified on chassis dynamometers, and the 

amendments in section 1968.2(f)(17.1.6) specify that, with a few exceptions,

monitors on 2016 and subsequent model year medium-duty diesel vehicles 

certified to a chassis dynamometer tailpipe emission standard are required to use 

the same malfunction criteria as those applicable to passenger cars, light-duty 

trucks, and medium-duty passenger vehicles certified to a chassis dynamometer 

tailpipe emissions standard. The exceptions include the following. Since the 

light-duty malfunction criteria lack a NOx malfunction threshold (unlike the 

medium-duty engine dynamometer-based criteria, which does), manufacturers 

must detect NMHC catalyst conversion efficiency monitoring faults before 

emissions exceed 1.75 times the applicable FTP, NMHC, or NOx standards. 

Similarly, for diesel misfire monitoring, since the OBD II regulation currently 

requires continuous monitoring of light-duty emission threshold-based 

malfunction criteria while the medium-duty engine dynamometer-based criteria 

do not require continuous monitoring, the amendments require manufacturers to 

detect a malfunction based on the medium-duty engine dynamometer-based

malfunction criteria and monitoring requirements. The amendments eliminate the 

requirement for manufacturers to individually propose chassis-based thresholds 

and seek Executive Officer approval and would instead provide clear monitoring 

thresholds for all manufacturers.82 Due to these new requirements, the 

amendments now limit the current requirements in section 1968.2(f)(17.1.5) to 

the 2004 through 2015 model years

b. Section 1971.1(g)(5.7): Monitor Disablement at Low Temperatures

The amendments add new section 1971.1(g)(5.7), which exempts manufacturers 

from monitoring an electronic powertrain component/system if a malfunction of 

the component does not affect emissions during any reasonable driving condition

and does not affect the diagnostic strategy for any other monitored component or 

system when the ambient temperature is above 20 degrees Fahrenheit. The 

through the 2009 MY engines and vehicles because the HD OBD Requirements only apply to 

2010 and newer model year engines and vehicles. 

82 Id. at pages 47-48.
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ambient temperature in this case is determined based on a temperature sensor 

monitored by the OBD system (e.g., IAT sensor).83

c. Section 1971.1(g)(5.8) and Section 1968.2(f)(17.2.3): Alternate 

Phase-in Schedules for Small Volume Manufacturers

The amendments add new section 1971.1(g)(5.8), which allows small volume 

manufacturers to use alternate phase-in schedules in lieu of the specified phasein schedules in the regulation. Such phase-in schedules provide manufacturers 

more lead-time to meet regulatory requirements compared to originally 

prescribed phase-in schedules. The amendments define the allowed alternate 

phase-in schedules for small volume manufacturers and the allowed 

manufacturer-defined phase-in schedules for diesel NOx converting catalyst and 

NOx and PM sensor monitors.84 The amendments to section 1968.2(f)(17.2.3) 

define alternate phase-in schedule for the diesel PM filter monitor that can be 

used in lieu of the required phase-in schedule. 

G. Standardization Requirements

1. Section 1971.1(h)(1): Reference Documents

The amendments update the list of SAE and ISO documents that are 

incorporated by reference into the HD OBD regulation. It is a common industry 

practice to update technical standards to provide greater specificity and clarity.85

2. Section 1971.1(h)(2): Diagnostic Connector

The amendments to section 1971.1(h)(2.5), which were made to account for the 

new 500 kbps baud rate variant of SAE J1939, requires the diagnostic connector 

to meet the Type 1 or Type SAE 1939-13 specifications if the 250 kbps baud rate 

of J1939 is used and to meet the Type 2 specifications if the 500 kbps baud rate 

of J1939 is used. The amendments to section 1971.1(h)(2.6), which originally 

allowed manufacturers to have an additional non-OBD connector that conforms

to the same specifications as the OBD diagnostic connector, now prohibits the 

additional non-OBD connector from being located in the same area as the OBD 

diagnostic connector starting in the 2016 model year.86

3. Section 1971.1(h)(3.2): SAE J1939 Communication Protocol

The amendments clarify that for engines using the SAE J1939 communication 

protocol, the manufacturer may use either the 250 or 500 kbps baud rate 

83 15-Day Notice, at page 5. 84 15-Day Notice, at pages 5-6 85 Staff Report at page 40. 86 Staff Report at pages 40-41.
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versions up through the 2015 model year, but would be prohibited from using the 

250 kbps baud rate version starting in the 2016 model year.87

4. Section 1971.1(h)(4): Required Emission Related Functions

a. Section 1971.1(h)(4.1): Readiness Status

Under the pre-amended regulation, manufacturers were required to incorporate 

readiness status of several major emission control systems and components into 

their OBD systems, which helps determine if the OBD monitors have performed 

their system evaluations. The amendments clarify which monitors are required to 

be included in the determination of readiness status to ensure consistency in 

implementation among all manufacturers. The amendments also delete the 

allowance in section 1971.1(h)(4.1.1) that allowed manufacturers to request 

Executive Officer approval to set the readiness status to “complete” without 

monitoring actually having been completed if monitoring is disabled on multiple 

driving cycles due to extreme operating conditions (e.g., cold ambient 

temperatures, high altitudes).88

b. Sections 1971.1(h)(4.2.2) and (h)(4.2.3)(E): Data Stream

Sections 1971.1(h)(4.2.2) and (h)(4.2.3) were amended as they apply to 2016 

and subsequent model year engines to require manufacturers to provide some 

additional data stream information. The HD OBD system on diesel engines must 

now provide information on the fuel rate (mg/stroke), engine torque, and modeled 

exhaust flow (mass/time). The HD OBD system on both diesel and gasoline 

engines are required, if so equipped, to report data stream information on such 

things as reductant quality sensor output and corrected NOx sensor output.89

c. Sections 1971.1(h)(4.4.1)(F)(iv) and (4.4.2)(F)(iv): Erasing of 

Permanent Fault Codes

The regulation previously allowed permanent fault codes to be erased if the 

individual control module containing the permanent fault code was 

reprogrammed and the vehicle/engine readiness status for all monitors (in all 

emission-related modules) indicated “not complete”. 

The amendments now allow manufacturers to limit the resetting of readiness bits 

if a permanent fault code is erased in a certain control module to only those 

modules that support readiness for major components (i.e., any readiness bits 

other than comprehensive components). While this does still require some form 

of ‘coordinated’ code clearing, it limits the number of involved modules. For 

example, if a vehicle has an engine control unit (ECU) that supports readiness for 

87 Id., at page 40. 88 Staff Report, at pages 41-42; 15-Day Notice, at pages 6-7. 89 Staff Report, at page 42.
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major components and five auxiliary emission-related modules that don’t support 

readiness for any major components, and if one of the auxiliary modules has a 

permanent fault code stored and that module is reprogrammed and erases the 

permanent fault code, the OBD system would only need to ensure that the 

engine ECU resets all readiness bits and not that all five of the auxiliary modules 

also reset readiness.90

d. Section 1971.1(h)(4.5.5): Test Results when Fault Memory Cleared

The regulation, as initially adopted, required test results and limits to report 

values of zero after the OBD system fault memory was cleared. The 

amendments require 2016 and subsequent model year vehicles using the SAE 

J1939 protocol to report non-zero values corresponding to “test not complete” for 

the test results and limits.91

e. Section 1971.1(h)(4.7.5): Software Calibration Verification Number 

(CVN)

The regulation, as originally adopted, required the CVN information to be made 

available through the data link connector to a generic scan tool in accordance 

with SAE specifications except for the following: immediately after a 

reprogramming event; a non-volatile memory clearance; or the first 30 seconds 

of engine operation after a volatile memory clearance. The amendments extend 

the timeframes after a memory clear to 120 seconds and clarify when it is 

acceptable and not acceptable for the on-board computer to send a message 

directing the scan tool to wait or resend the request message after the delay.92

f. Section 1971.1(h)(4.8.3): Reprogrammable Vehicle Identification 

Number (VIN) and Engine Serial Numbers (ESN)

The regulation originally specified that when the VIN or ESN was reprogrammed, 

the OBD system was required to erase all emission-related diagnostic 

information. The amendments now limit the erasure to control modules that 

reported supported readiness for a readiness bit other than the bit for the 

comprehensive component monitors.93

5. Section 1971.1(h)(6): Service Information 

The regulation originally described specific service information requirements to 

apply to HD OBD systems. The amendments delete these requirements since 

90 Id., at page 43. 91 15-Day Notice, at page 7. 92 Staff Report, at pages 43-44. 93 Id., at page 43.
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the requirements are prescribed in a separate ARB regulation, section 1969 of 

title 13, CCR.94

H. Certification Demonstration Testing

1. Required Testing of Components 

a. Section 1971.1(i)(3.1.2) and Section 1968.2(h)(4.3): Diesel Misfire 

Monitor

The amendments to section 1971.1(e)(2.2) and section 1968.2(f)(3.2) require 

continuous misfire monitoring for all diesel engines starting in 2016, and change 

the malfunction criterion from an emission threshold-based criterion to a specific 

misfire percentage. However, section 1971.1(e)(2.2.5) and section 

1968.2(f)(3.2.5) allow manufacturers to increase the misfire percentage 

malfunction criterion if a misfire cannot cause emissions to exceed specific 

thresholds. The amendments to section 1971.1(i)(3.1.2) and section 

1968.2(h)(4.3) require manufacturers to conduct demonstration testing of the 

diesel misfire monitor to verify manufacturer requests to increase the misfire 

percentage malfunction criterion under section 1971.1(e)(2.2.5) or section 

1968.2(f)(3.2.5).95

b. Section 1971.1(i)(3.2.1): Gasoline Fuel System

The amendments add section 1971.1(i)(3.2.1)(C), which requires manufacturers 

to conduct demonstration testing of the air-fuel cylinder imbalance monitor.96

c. Section 1971.1(i)(3.2.7): Exhaust Gas Sensors

The regulation, as originally adopted, specified demonstration testing 

requirements for “exhaust gas sensors” on gasoline engines. The amendments 

limit the amount of testing manufacturers are required to perform by requiring 

that testing be done on only certain response rate malfunctions (e.g., worst case 

malfunctions) rather than all six response rate malfunctions.97

2. Section 1971.1(i)(5.1.3): Testing Evaluation Protocol

The amendments clarify the requirements for evaluating demonstration tests. 

Specifically, the regulation originally listed evaluation provisions for catalyst and 

PM filter systems. The amendments clarify the test procedures for catalyst faults 

and other faults where default actions are taken subsequent to fault detection.98

9415-Day Notice, at page 7. 95 Staff Report, at page 44; 15-Day Notice, at page 7-8. 96 Staff Report, at page 44. 97 Id., at page 44-45. 98 Staff Report, at page 45.
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I. Certification Documentation

1. Certification Application

a. Section 1971.1(j)(2.6) and Section 1968.2(i)(2.5.2): Diesel Misfire 

Monitor Data

The amendments now require manufacturers to provide misfire monitor data for

the newly required continuous diesel misfire monitors prescribed in section 

1971.1 (e)(2) and in section 1968.2(f)(3).99

b. Section 1971.1(j)(2.16): Cover Letter

The amendments now require manufacturers to include in the cover letter 

information about all other issues that apply to the engine to assist staff in 

reviewing the application.

c. Section 1971.1(j)(2.18): In-Use Monitor Performance 

To assist staff in reviewing applications, the amendments now require 

manufacturers to provide information about the components/systems required to 

track and report in-use monitor performance, the corresponding diagnostics used

to increment the numerator for each component/system, and a description of the 

numerator and denominator incrementing specifications.

d. Section 1971.1(j)(2.19): Test Results

The amendments now require manufacturers to include a list of the test results 

and the corresponding diagnostics for each test result to assist staff in reviewing 

the application.

e. Section 1971.1(j)(2.20): Timeline

The amendments now require manufacturers to include a timeline showing the 

start of engine and vehicle production for each engine family and the required 

deadlines for production engine/vehicle evaluation testing required under 

section (l) to assist staff in reviewing the application.

J. Deficiencies 

1. Section 1971.1(k)(4): Carry-Over Deficiencies

The regulation originally allowed manufacturers to only carry over deficiencies up 

to a maximum of three model years, provided the manufacturers demonstrated 

99 Staff Report, at pages 25-26; and page 83.
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that substantial hardware changes were needed to correct the deficiency. The 

amendments allow manufacturers to carry over deficiencies for up to four model 

years (i.e., deficiencies first granted in the 2010 model year may be carried over 

through the 2013 model year), provided the manufacturer can demonstrate that 

substantial hardware changes are needed to correct the deficiency. The 

amendments also allow manufacturers to carry over deficiencies first granted in 

the 2011 model year into the 2014 model year without demonstrating the need 

for hardware changes.100

2. Section 1971.1(k)(6.1): Retroactive Deficiencies

The regulation originally only allowed manufacturers to be granted a retroactive 

deficiency during either the first six months after the start of engine production or 

the first three months after the start of vehicle production, whichever is later. The 

amendments increase the criteria from three months to six months after the start 

of vehicle production.101

3. Section 1971.1(k)(7): Deficiencies for PM Filter and PM Sensor 

Monitors

For engines with PM filter filtering performance monitors that utilize the PM 

sensor in the 2013 through 2015 model years, the amendments now allow 

manufacturers to be granted free deficiencies for the PM filter monitor, PM 

sensor monitor, and PM sensor heater monitor.102

4. Section 1971.1(k)(8): Deficiencies for Hybrid Vehicles

For hybrid vehicles, the amendments allow 2014 model year vehicles previously 

certified with deficiencies in 2013 to have the 2014 model year be considered the 

first model year for the deficiencies with regards to the carry-over provisions.

The amendments provide manufacturers with two additional free deficiencies 

during the 2013 through 2015 model years.103

K. Production Engine/Vehicle Evaluation Testing

1. Sections 1971.1(l)(1.4) and (1.5): Verification of Standardized

Requirements

Section 1971.1(l)(1.4.3)(E) was amended to require that the standardization 

testing verify that the MIL command status can be properly communicated to a 

scan tool in conjunction with emission-related fault code and that this information 

100 15-Day Notice, at page 8. 101 Staff Report, at pages 45-46. 102 Id., at page 9. 103 Id., at page 46.
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be made available from each diagnostic and emission critical electronic 

powertrain control unit to ensure the correct information is made available and 

that the OBD system as a whole is working as certified. Section 1971.1(l)(1.5.1) 

was amended to require manufacturers to submit the test results to ARB.

2. Section 1971.1(l)(2.1): Verification of Monitoring Requirements

The regulation originally required manufacturers to verify the monitoring 

requirements on an engine no later than either six months after the start of 

engine production or three months after the start of vehicle production, whichever 

is later. The amendments increase the criteria from three months after the start 

of vehicle production to six months after the start of vehicle production.104

3. Section 1971.1(l)(2.3.6): Exemption from Testing of Specific 

Diagnostics

The regulation originally exempted manufacturers from testing specific 

diagnostics if the testing would cause physical damage to the vehicle. The

amendments now also exempt manufacturers from testing specific diagnostics if 

the testing cannot be done without jeopardizing the safety of the tester.

III. SUMMARY OF HD OBD AND OBD II ENFORCEMENT REGULATIONS

A summary of the substantive amendments to the HD OBD Enforcement and 

OBD II Enforcement regulations is provided below.105

A. Section 1971.5(a)(3) and Section 1968.5(a)(3): Definitions of 

“Nonconforming OBD System” 

The HD OBD and OBD II enforcement regulations establish procedures to 

ensure that vehicles and engines certified for sale in California are equipped with 

OBD systems that properly function and meet the purposes and requirements of 

sections 1971.1 and 1968.2, respectively, and that OBD systems that fail to meet 

those requirements are nonconforming and subject to remedial action, including 

recall. The amendments to the HD and OBD II regulations include a specific 

definition of “emission standard.” The amendments to the HD OBD and OBD II 

enforcement regulations now modify the preexisting term “nonconforming OBD 

system” to reference the new definition of emission standard. Specifically, the 

amendments now define a nonconforming OBD system as an OBD system on a 

production engine/vehicle that has been determined not to meet the emission 

standards of sections 1971.1 and 1968.2. Additionally, for purposes of clarity, the 

reference in the definitions to tailpipe emission standards has been replaced with 

104 Staff Report, at page 48. 105 Staff Report, at pages 48-51.
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the term “exhaust emission standards,” a term that is more generally used but 

has the same meaning.106

B. Section 1971.5(b)(3)(D)(ii)b and Section 1968.5(b)(3)(D)(ii)b: Engines 

to be Included in a Test Sample Group:

The HD OBD and OBD II enforcement regulations specify criteria for

procuring engines/vehicles for the test sample group used to evaluate if a 

monitor is in compliance with the in-use monitoring performance

requirements, and require the test sample group to include engines/vehicles

with denominators for that monitor meeting a minimum required value. The 

regulations previously required many PM filter-related monitors and PM sensor 

monitors to have denominator values of at least 150 or 300, depending on the 

denominator incrementing criteria being used. Many of these monitors, however, 

required a PM filter regeneration event to occur, which would have required such 

engines/vehicles to have accumulated very high mileage in order to be

acceptable as a test sample group. In light of the recent trend in industry to 

further lengthen intervals between regeneration events, this criterion will become 

even more restrictive in the future. The amendments therefore decrease the 

minimum denominator needed for the diesel PM filter, PM sensor, and NMHC 

converting catalyst monitors.107

C. Section 1971.5(b)(6)(B) and Sections 1968.5(b)(6)(A) and (b)(6)(B): 

Finding of Nonconformance after Enforcement Testing

As previously discussed, the amendments modify the denominator incrementing 

criteria for the PM filter filtering performance monitor and PM filter missing 

substrate monitor in both the HD OBD and OBD II regulations. Specifically, the

amendments now require these monitors to increment the denominators using 

only the general denominator criteria starting in the 2016 model year. In addition, 

the OBD II regulation allows manufacturers to certify these monitors to a lower 

interim in-use ratio of 0.100 on 2016 through 2018 model year medium-duty 

vehicles. Because the new denominator will be incremented more often than the 

previous denominator, the amendments relax the nonconformance criteria and 

mandatory recall enforcement provisions in the first few years that the monitors 

start using this new denominator.

The OBD II enforcement regulation already has nonconformance criteria for 

monitors certified to an in-use ratio of 0.100 and do not subject these monitors to 

mandatory recall, so minimal changes are needed to address such amendments. 

The amendments to the HD OBD enforcement regulation allow the PM filter 

filtering performance monitor and PM filter missing substrate monitor on 2016 

through 2018 model year engines to use less stringent criteria to determine 

nonconformance. Specifically, while other monitors on 2016 and subsequent 

106 15-Day Notice at page 11. 107 Staff Report at page 49.
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model year engines would be considered nonconforming if the average in-use 

monitor performance ratio of engines in the test sample group is less than 0.088 

or if at least 66 percent of the engines have an in-use ratio of less than 0.100, the 

PM filter filtering performance monitor and PM filter missing substrate monitor

would be considered nonconforming if the average in-use ratio is less than 0.050 

or if at least 66 percent of the engines have an in-use ratio of less than 0.050. 

Further, these monitors will not be subject to mandatory recall for the 2016 

through the 2018 model years.108

The amendments to section 1968.5(b)(6)(A) modify the existing nonconformance 

criteria for OBD II emission testing of intermediate and final diesel thresholds to 

account for the new interim thresholds for the NOx converting catalyst monitor,

NOx sensor monitor, and PM filter monitor in sections 1968.2(f)(2), (f)(5), and 

(f)(9).

D. Ordered Remedial Action – Mandatory Recall

1. Section 1971.5(d)(3)(A)(i) and Section 1968.5(c)(3)(A)(i)

The amendments allow PM filter filtering performance and missing substrate 

monitors on 2016 through 2018 model year engines to be exempt from 

mandatory recall based on in-use performance ratios.109

2. Section 1971.5(d)(3)(A)(iii) and Section 1968.5(c)(3)(A)(iii):

The amendments add mandatory recall criteria for diesel misfire monitors, setting 

the recall level at more than 10 percentage points above the misfire malfunction 

criteria starting in the 2019 model year.110

3. Section 1971.5(d)(3)(A)(vi) and Section 1968.5(c)(3)(A)(vi)

The amendments add mandatory recall criteria for the PM filter monitor, requiring 

recall if the PM filter monitor cannot detect a missing substrate fault or cannot 

detect a fault that causes emissions to exceed the emission level of the engine 

with the PM filter substrate completely removed.111

E. Other Amendments

As discussed in the Staff Report and 15-Day Notice, other amendments to the 

HD OBD and OBD II Enforcement regulations were made to clarify existing 

requirements.

108 Staff Report at pages 49-50. 109 Staff Report at pages 49-50. 110 Staff Report at page 50. 111 Staff Report at page 50.
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V. WAIVER ANALYSIS

A. Criteria for Granting Waivers of Preemption under CAA Section 

209(b) and Confirmations that Amendments are Within the Scope of 

Previous Waivers

Section 209(b) of the CAA sets forth the protocol for granting California112

waivers from the general preemption of section 209(a), which prohibits states 

from adopting and enforcing standards and other requirements relating to the 

control of emissions from motor vehicles. Under section 209(b), the 

Administrator must grant a waiver to California if the state has determined that its 

standards will be, in the aggregate, at least as protective of public health and 

welfare as applicable federal standards, unless the Administrator finds that (1) 

the state’s protectiveness determination is arbitrary and capricious, (2) California 

does not need separate state standards to meet compelling and extraordinary 

conditions, or (3) the state standards and accompanying enforcement 

procedures are not consistent with section 202(a) of the CAA. In granting the 

initial waiver for the OBD II regulation in 1995, and for both the initial HD OBD 

regulation and for the 2010 HD OBD amendments applicable to 2013 and later 

model year HD OBD systems, the Administrator concluded that the record was 

devoid of sufficient evidence to support denial of the waiver.113

In considering whether to grant waivers for accompanying enforcement 

procedures tied to standards for which a waiver has already been granted, the

Administrator will only address questions as to (1) whether the enforcement 

procedures are so lax that they threaten the validity of California’s determination 

that its standards are as protective of public health and welfare as applicable 

federal standards and (2) whether the enforcement procedures are consistent 

with section 202(a).114

The Administrator has applied a similar analysis in finding that amendments to a 

standard or regulation are within the scope of a previously granted waiver.

If California acts to amend a previously waived standard or 

accompanying enforcement procedure, the change may be 

included within the scope of the previous waiver if it does not 

112 CAA section 209(b) provides for granting a waiver to “any State that has adopted standards 

(other than crankcase emission standards) for the control of emissions from new motor vehicles 

or new motor vehicle engines prior to March 30, 1966.” California is the only State that meets this 

eligibility criterion for granting waivers. See, e.g., S. Rep. No. 90-403, at 632 (1967) and Motor 

and Equipment Manufacturers Association v. EPA (MEMA I) (D.C. Cir. 1979) 627 F.2d 1095, 

1101 fn. 1.

113 61 Fed.Reg. 53371 (October 11, 1996), 73 Fed.Reg. 52042 (Sept, 8, 2008), 77 Fed.Reg. 

73459 (December 10, 2012).

114 Motor and Equipment Manufacturers Association v. EPA (MEMA) (D.C. Cir. 1979) 627 F.2. 

1095, 1111, 1113.
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undermine California’s determination that its standards, in the 

aggregate, are as protective of public health and welfare as 

comparable Federal standards, does not affect the consistency of 

California’s requirements with section 202(a) of the [CAA], and 

raises no new issues affecting the Administrator’s previous waiver 

determination.115

B. Principles Followed in Granting CAA Section 209(b) Waivers

1. The Opponents of a Waiver Bear the Burden of Opposing the 

Waiver Request 

In considering a waiver or a within the scope waiver request, California’s 

regulations are presumed to satisfy the criteria for granting a waiver, and the 

burden to show otherwise is on those persons challenging the waiver request.116

As held by the court in MEMA and long followed by EPA:

The language of the statute and its legislative history indicate that 

California’s regulations, and California’s determination that they 

comply with the statute, when presented to the Administrator are 

presumed to satisfy the waiver requirements and that the burden of 

proving otherwise is on whoever attacks them.117

2. The Scope of a Waiver Hearing Should Be Limited

The scope of the Administrator’s inquiry in determining whether to deny a waiver 

request is limited by the express terms of CAA section 209(b)(1). Once 

California determines that its standards are, in the aggregate, at least as 

protective of public health and welfare as applicable federal standards, the 

Administrator must grant the waiver unless one of the three specified findings 

can be made.

This reading of the statute is consistent with the decision in MEMA I and prior 

EPA waiver decisions interpreting CAA section 209(b), which hold that the review 

of California’s decision to adopt separate standards is a narrow one.118 In 

granting the waiver for the OBD II regulation in 1996, Administrator Carol 

Browner concluded that she must grant a waiver if she could not find sufficient 

evidence in the record to support any of the above listed criteria that would 

dictate not granting the waiver.119 Much earlier Administrator William D. 

Ruckleshaus stated:

115 Decision Document accompanying scope of waiver determination in 51 Fed.Reg. 12391 (April 

10, 1986), at p. 2 (footnotes omitted); see also 46 Fed.Reg. 36742 (July 15, 1981).

116 Manufacturers Association v. EPA (MEMA) (D.C. Cir. 1979) 627 F.2d 1095, 1121. 117 Id.; See also Decision Document accompanying OBD II Waiver Determination, 61 Fed.Reg. 

53371 (October 11, 1996), at pages. 15-16.

118 See 40 Fed.Reg. 23102, 23103 (May 28, 1975). 119 61 Fed.Reg. 53371 (October 11, 1996).
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The law makes it clear that the waiver request cannot be denied unless 

the specific findings designated in the statute can properly be made. The 

issue of whether a proposed California requirement is likely to result in 

only marginal improvement in air quality not commensurate with its cost or 

is otherwise an arguably unwise exercise of regulatory power is not legally 

pertinent to my decision under section 209 . . . . 120

3. Deference Must Be Accorded to California’s Policy Judgments

As indicated in the waiver decisions cited above, in granting waivers to 

California’s motor vehicle program, EPA has routinely deferred to the policy 

judgments of California’s decision-makers. EPA has recognized that the intent of 

Congress in creating a limited review of California’s determinations regarding its 

need for separate standards was to ensure that the federal government did not 

second-guess the wisdom of state policy.121

In 2009 EPA reiterated its recognition that Congress intended EPA to show great 

deference to California’s decision making when analyzing a waiver request for 

California’s greenhouse gas standards for new vehicles.122 In that decision, the 

Administrator recognized that Congress has had the opportunity to restrict 

California’s ability to obtain a waiver and has had instead elected to highlight the 

utility of California’s flexibility to adopt a complete program of motor vehicle 

emission controls as the state saw fit. The Administrator found that Congress 

has intended “to afford California the broadest possible discretion in selecting the 

best means to protect the health of its citizens and the public welfare.”123

VI. THE 2013 AMENDMENTS TO THE HD OBD MONITORING 

REQUIREMENTS IN SECTION 1971.1 AND TO THE HD OBD 

ENFORCEMENT REGULATION IN SECTION 1975.1 EITHER MEET THE 

CRITERIA FOR A NEW WAIVER OR FALL WITHIN THE SCOPE OF THE 

PREVIOUSLY GRANTED WAIVER.

CARB submits that for the reasons set forth below in section VI, and in the 

rulemaking documents associated with the 2013 Amendments to the HD OBD 

and OBD II Requirements and Enforcement regulations, the Administrator must 

grant California the requested waiver actions as the Administrator has no basis 

under the criteria of CAA section 209(b) to deny California’s request.

A. A New Waiver Should Be Granted for Those 2013 Amendments to 

120 36 Fed.Reg. 17158 (August 31, 1971). See also 40 Fed.Reg. 23102, 23104; 58 Fed.Reg. 

4166 (January 7, 1993), Decision Document, at p. 20, 74 Fed.Reg. 32744, 32748 (July 8, 2009).

121 74 Fed.Reg. 32744, 32748 (July 8, 2009). 122 74 Fed.Reg. 32744 (July 8, 2009). 123 Id. at p. 32748; MEMA I, 627 F.2d at 1110.
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the HD OBD Requirements Set Forth in Section 1971.1 that Establish 

New, More Stringent Requirements.

As described in Section II of this document, certain of the 2013 Amendments

arguably establish new or more stringent standards which require a new waiver 

under section 209(a) of the CAA.124 These amendments are listed in Attachment 

1 of this waiver support document. The remainder of the 2013 Amendments

either relax the regulation’s requirements, and thereby provide engine 

manufacturers with greater compliance flexibility, or clarify previously waived 

provisions of the HD OBD Requirements. Such amendments are listed in 

Attachment 2 and 3 to this document, respectively, and fall within the scope of 

the previously waived HD OBD Requirements.

1. CARB’s Protectiveness Determinations for the 2013 Amendments 

to the HD OBD Requirements Are Neither Arbitrary Nor 

Capricious

In adopting Resolution 12-29, the Board expressly found that the 2013 

Amendments to the HD OBD Requirements and related enforcement provisions 

(sections 1971.1, and 1971.5) do not undermine California’s previous 

determinations that its standards are, in the aggregate, at least as protective of 

the public health and welfare as applicable federal standards. 

In reviewing California’s protectiveness findings for the above-identified 2013 

Amendments to the HD OBD regulations, those challenging the waiver must 

present clear and convincing evidence to show that the protectiveness finding by 

California is arbitrary and capricious.125 This standard is in accord with 

“Congressional intent to provide California with the broadest possible discretion 

in setting regulations it finds protective of the public health and welfare”.126

Moreover, in reviewing CARB’s protectiveness determination, EPA traditionally 

evaluates the stringency of California’s newly adopted standards to comparable 

applicable EPA emission standards, and that comparison has been undertaken 

in the broader context of the previously waived California program, which relies 

upon protectiveness determinations that EPA has previously determined were 

not arbitrary and capricious.127 EPA’s recognition of its previous protectiveness 

determinations is especially pertinent here because in granting California 

waivers for its emission standards and related test procedures for 2007 and

124 “EPA has stated in prior waiver and authorization determinations that increases in the

stringency of standards are ‘‘new issues’’ for which full waiver or authorization is required.” 77 

Fed.Reg. 73459, 73460 (December 10, 2012).

125 MEMA, 627 F.2d at 1122, Decision Document accompanying OBD II Waiver Determination, at 

p. 14.

126 Id.

127 74 Fed. Reg. 32744, 32749 (July 8, 2009); 78 Fed. Reg. 2112, 2121-2122 (Jan. 9. 2013).
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subsequent model year heavy-duty diesel engines and vehicles 128 and for 2008

and subsequent model year Otto-cycle engines and vehicles,129 EPA found that 

California’s heavy-duty diesel and heavy-duty Otto-cycle exhaust emission 

standards, in the aggregate, were not less protective than applicable federal 

standards, and given that the purpose of the OBD requirements is to ensure that 

heavy-duty engines and vehicles maintain their emissions performance 

throughout their useful lives. In granting California the waiver for the initial HD 

OBD regulation and again for the 2010 Amendments to the HD OBD regulation, 

the Administrator was unable to find that CARB’s protectiveness determinations

were arbitrary or capricious.130

The 2013 Amendments to the HD OBD and the HD OBD Enforcement regulation 

do not disturb these findings. The amendments that increase the stringency of 

previously waived standards establish more stringent requirements than 

comparable federal regulations. The amendments that relax previously waived 

HD OBD requirements for the 2013-2015 model years continue to be more 

stringent than EPA’s requirements for those model year engines, and the HD 

OBD requirements for 2016 and subsequent model years continue to be more 

stringent than comparable federal requirements. Overall, CARB’s heavy duty 

engine emissions control program, including the HD OBD requirements and 

enforcement regulations as amended in 2013, continues to be more stringent 

than the federal heavy-duty regulations for vehicles greater than 14,000 pounds. 

2. Compelling and Extraordinary Circumstances

In adopting Resolution 12-29 (Enclosure 14), the Board confirmed CARB’s 

longstanding position that California continues to need its own motor vehicle 

program to meet serious air pollution problems. The Administrator has 

previously and consistently recognized that California meets the compelling and 

extraordinary criterion when granting waivers for motor vehicles under section 

209(b). The relevant inquiry under section 209(b)(1)(B) is whether California 

needs its own emission control program to meet compelling and extraordinary 

conditions, not whether any given standard is necessary to meet such 

conditions.131 In approving waivers under section 209(b), the Administrator has 

determined that: 

128 70 Fed. Reg. 50322 (August 26, 2005). 129 75 Fed. Reg. 70237 (Nov. 17, 2010). 130 73 Fed.Reg. 52042 (September 8, 2008), Decision Document accompanying HD OBD Waiver 

Determination, at page 7; 77 Fed.Reg. 73459,73460 (December 10, 2012), Decision Document 

accompanying 2010 HD OBD Amendments Waiver Determination at pages 10 and 14.

131 The Administrator has recognized that even if such a standard by standard test were applied 

to California, it "would not be applicable to its fullest stringency due to the degree of discretion 

given to California in dealing with its mobile source pollution problems." 41 Fed.Reg. 44209, 

44213, (October 7, 1976); 49 Fed.Reg. 18887, 18892 (May 3, 1984) (finding Congressional intent 

precludes EPA from viewing adopted California vehicular particulate matter standard in isolation).
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“[C]ompelling and extraordinary conditions” does not refer to levels of 

pollution directly, but primarily to the factors that tend to produce them: 

geographical and climatic conditions that, when combined with large 

numbers and high concentrations of automobiles, create serious air 

pollution problems.132

In the California Clean Air Act of 1988, the California Legislature found that: 

“[D]espite the significant reductions in vehicle emissions which have been 

achieved in recent years, continued growth in population and vehicle miles 

traveled throughout California have the potential not only to prevent 

attainment of the state standards, but in some cases, to result in 

worsening of air quality.”133

The geographical and climatic conditions and the tremendous growth in vehicle 

population and use that moved Congress to authorize California to establish 

separate vehicle standards in 1967 still exist today. EPA has long confirmed the 

ARB’s judgment, on behalf of the State of California, on this matter.134

Nothing in these conditions has changed to warrant a change in EPA’s 

confirmation, and therefore there can be no doubt of the continuing existence of 

compelling and extraordinary conditions justifying California’s need for its own 

motor vehicle emissions control program.

3. Consistency with Clean Air Act Section 202(a)

EPA has historically interpreted consistency with CAA section 202(a) using a 

two-pronged test: (1) that there is sufficient lead time to permit the development 

of technology necessary to meet the standards and other requirements, giving 

appropriate consideration to the cost of compliance in the time frame provided, 

and (2) that the California and federal test procedures are sufficiently compatible 

to permit manufacturers to meet both the state and federal test requirements with 

one test vehicle or engine.135 The reference to “cost of compliance” in CAA 

section 202(a) refers to the economic costs of emission standards and 

132 49 Fed. Reg. 18887, 18890 (May 3, 1984). There the Administrator found that California need 

not demonstrate its particulate problem (or diesel vehicles’ contribution to it) is the worst in the 

country in order to adopt a particulate matter standard affecting diesel vehicles. Id. at 18891-

1892. 

133 California Health and Safety Code section 43000.5. 134 California State Motor Vehicle Pollution Control Standards; Waiver of Federal Preemption –

Notice of Decision, 70 Fed.Reg. 50322, 50323 (August 26, 2005); 77 Fed. Reg. 73459, 73461 

(December 10, 2012).

135 See 61 Fed.Reg. 53371, 53372 (October 11, 1996); Decision Document at p.2 (OBD II Waiver 

Decision). Even where there is incompatibility between the California and federal test 

procedures, EPA has granted a waiver under circumstances where EPA accepts a demonstration 

of federal compliance based on California test results, thus obviating the need for two separate 

tests. (43 Fed.Reg. 1829, 1830 (January 12, 1978); 40 Fed.Reg. 30311, 30314 (July 18, 1975).) 
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46

accompanying enforcement procedures and the timing of a particular emission 

control regulation rather than to its social implications.136 As demonstrated 

below, the 2013 Amendments are fully consistent with section 202(a) of the CAA.

a. Technical Feasibility and Lead Time Considerations of 

Amendments that Establish New, More Stringent HD OBD 

Requirements

The 2013 Amendments to the HD OBD Requirements primarily relax the 

requirements applicable to 2013 and subsequent model year engines in order to 

provide manufacturers additional time to develop and refine monitoring strategies 

for certain components or emission control systems. However, a limited number 

of the 2013 Amendments (identified in Attachment 1), arguably establish new or 

more stringent standards than the previously waived standards applicable to 

2013 and subsequent model year HD OBD systems. These additional and more 

stringent requirements are consistent with section 202(a) in that manufacturers 

have been provided sufficient lead time, and do not require appreciable hardware 

changes beyond those considered by staff and the Board in the original and 

amended HD OBD rulemakings. Instead, the upgrades and modifications largely 

only require recalibration of software for existing monitors and, in the case of new 

monitors, the development of new diagnostic strategies. To the extent that new 

hardware is required, the amendments provide additional lead time for 

manufacturer compliance.

i) diesel misfire monitoring

The amendments establishing more stringent misfire monitoring requirements for 

diesel engines phase-in those requirements beginning in the 2016 model year,

and require all 2018 and subsequent model year engines to continually detect a 

misfire malfunction.137 Manufacturers should not need new hardware to comply 

with these new requirements, but to the extent that such new hardware is 

required, manufacturers have been provided adequate lead time. The 

amendments further accommodate manufacturers’ concerns regarding the 

difficulty of identifying a level of misfire that equates to the exceedance of a 

specific tailpipe emissions standard by allowing the detection of a fixed misfire 

rate of 5 percent in lieu of a detection rate based on emissions exceeding 

specific thresholds (e.g., 2.0 times the applicable standards), and further allow 

manufacturers to request Executive Officer approval to detect misfires at a higher 

level of misfire percentage criterion. In addition, 2013 through 2018 model year 

engines may limit misfire monitoring to limited conditions (positive torque 

conditions between 20 and 75 percent of peak torque and up to 75 percent of the 

maximum engine speed) with 2019 and subsequent model year engines required

136 Id., referencing See S. Rep. No. 192, 89th Cong., 1st Sess. 5-8 (1965); H.R. Rep. No. 728, 

90th Cong., 1st Sess. 23 (1967), U.S. Code Cong. & Admin.News 1967, p. 1938; see also 74 

Fed.Reg. 3030 (January 16, 2009), Decision Document at p. 49. 137 Sections 1971.1(e)(2.2) and (e)(2.3.3) and 1968.2(f)(3.2.2) and (f)(3.3.3)
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to monitor for misfire across all positive torque engine speed conditions except 

conditions in a limited disablement area of very low torque and high engine 

speed conditions. Finally, the amendments allow manufacturers to disable 

continuous misfire monitoring under conditions that prevent the robust detection 

of misfires.

ii) alternate fueled engines

The amendments require manufacturers to fully implement HD OBD systems on 

alternate-fueled engines beginning with 2018 model year engines, which is two 

years earlier than previously required.138 This amendment does not present any 

issue regarding technical feasibility, as the requirement to implement HD OBD 

systems on alternate fueled engines was initially established by the original HD 

OBD regulation, and in any event this amendment provides alternate fueled 

engine manufacturers 5 years of lead time.

iii) secondary air flow monitor and PM filter feedgas generation 

The amendments that establish more stringent monitoring requirements for 

secondary air systems in gasoline engines,139 and require monitoring of 

catalyzed PM filters for feedgas generation (e.g., NO2 to assist SCR systems),140

likewise present no issue regarding technical feasibility. These amendments 

provide manufacturers three years of lead time, and should only require the 

recalibration of software for existing monitors instead of requiring any 

modifications to hardware. Moreover, the PM filter feedgas generation 

monitoring requirement provides additional flexibility by exempting manufacturers 

from this requirement if manufacturers can demonstrate that complete failure of 

the component or loss of the function results in both: (1) less than a 15 percent 

increase of the standard of any pollutant over an applicable test cycle (e.g., FTP 

or SET) and (2) tailpipe emissions remain below the standard.

iv) NMHC threshold for NOx Sensor

The amendments that require 2016 and subsequent model year HD OBD 

systems to monitor the NOx sensor in diesel engines for performance faults 

before NMHC emissions exceed 2.0 times the standards141 are technically 

feasible because manufacturers have been provided 3 years of leadtime, 

no additional hardware should be required, the NMHC thresholds are consistent 

with the thresholds currently required for diesel NOx catalyst monitoring, and in 

virtually all cases, CARB does not expect this new requirement to alter the 

current calibration or sensitivity of NOx or PM sensor diagnostics.

138 Section (d)(7.5.3) 139 Section (f)(5.2.4) 140 Section (e)(8.2.4) 141 Section (e)(9.2.2.)(A). 
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v) freeze frame and fault code erasure criteria, incrementing 

monitoring numerators and denominators

The amendments that effectively restrict the conditions applicable to the erasure 

of freeze frame conditions142 and fault codes,143 and that require monitors that do 

not require a cold start to increment their numerators and denominators

even if an “engine cold start” cannot be determined144 are technically feasible in 

that they apply to 2016 and subsequent model year engines, which provide

manufacturers three years of leadtime, and can be implemented by modifying 

existing software. 

The amendments that restrict the criteria for incrementing the denominator for 

monitoring the PM filter performance monitor and PM filter missing substrate 

monitor145 are technically feasible. CARB staff explained in the ISOR146that 

advances in monitoring technology have resulted in newly developed PM 

sensors that are estimated to be available in the 2014 and 2015 model years. 

Such sensors are capable of evaluating the performance of the PM filter on 

virtually every driving cycle and have little or no connection to PM filter 

regeneration events. 

vi) PM filter monitoring – more extensive monitoring required

The amendment that now limits the previously unrestricted allowance to exclude

specific PM filter failure modes from the malfunction criteria of section (e)(8.2.1) 

to just the 2010 through 2015 model years147 is technically feasible, because 

technology is presently available to permit more comprehensive and reliable 

detection of PM filter failure modes.148 Specifically, at least one light-duty 

manufacturer is implementing a PM sensor in the 2013 model year, several 

heavy-duty manufacturers were, until very recently, also scheduled to implement 

PM sensors in 2013 engines, and manufacturers have indicated that PM sensors 

can be implemented in their 2014 or 2015 model year products. Furthermore, 

other manufacturers that have elected not to use PM sensors are using 

techniques such as further refining delta pressure-based approaches and 

concepts such as a downstream secondary filter optimized for monitoring 

capability. Such techniques have already achieved the emission level of the 

2016 threshold on medium-duty vehicles when used in conjunction with the 

relaxed provisions provided in the OBD II regulation to exclude certain failure 

modes such as a partially melted and partially cracked filter that results in the 

identical delta pressure characteristics of a good filter. The HD OBD regulation 

contains similar provisions that allow the exclusion of specific PM filter failure 

142 Sections (d)(2.2.1)(D), (e)(1.4.2)(D), and (e)(2.4.2)(B). 143 Sections (d)(2.3.1)(B) and (d)(2.3.2)(C) 144 Section (d)(4.5.3) 145 Section (d)(4.3.2)(G)/ Section 1968.2(d)(4.3.2)(G) 146 Staff Report at pages 22-23. 147 Section (g)(5.1) 148 This amendment is effective beginning with the 2014 model year.
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modes in section 1971.1(g)(5.1). . Moreover, the amendments allow 

manufacturers to certify to less stringent thresholds during the 2014 and 2015 

model years.

vii) diagnostic connector and communication protocol

The amendments affecting the diagnostic connector149 do not present any issues 

regarding technical feasibility as SAE J1939 now includes specifications 

regarding the new “Type 2” connector, the new connector is “backwards 

compatible” with previous specified baud rates, industry has supported the new 

connector, and several J1939 committee members have committed to ensuring 

that the J1939 specification contains enough direction to tool manufacturers on 

how to accurately determine the appropriate baud rate

Several of the amendments under this section are technically feasible by 

modifications to existing software. They include the amendments that remove 

the allowance to set the readiness status to “complete” before monitoring is 

actually completed; require information on diesel engines and reductant quality 

sensor output and corrected NOx sensor output;150 and that require tracking and 

reporting of in-use monitor performance data for the NOx sensor.151

b. Consideration of Costs

CARB appropriately considered the cost of compliance of the 2013 Amendments.

As stated in Section V.B of the 2013 ISOR and Appendix B to the 15-day Notice 

of Availability of Modified Text, CARB staff reasoned that the only elements of 

the 2013 Amendments that would result in increased costs would be the 

amendments establishing more comprehensive misfire monitoring requirements 

(beginning in the 2016 model year) and the amendments requiring alternatefueled engines to incorporate fully compliant HD OBD systems beginning with the 

2018 model year, instead of the previously specified 2020 model year. CARB 

staff performed a cost analysis that is applicable to both the 2013 HD OBD and 

the 2013 OBD II Requirements; however, that analysis was focused on the costs 

attributable to the HD OBD amendments as those costs would represent the 

highest costs to manufacturers and consumers.152

Staff estimated that the amendments requiring more comprehensive misfire

monitoring requirements for heavy-duty diesel engines would result in an

149 Sections (h)(2) and (h)(3.2) 150 Sections (h)(4.1.1), (4.2.2), and (4.2.3.)(E), respectively. 151 Section (e)(9.3.1) and Section 1968.2(f)(5.3.1) 152 Staff reasoned that over 90 percent of all new vehicles in the heavy-duty sector consist of

diesel and alternate-fueled engines, while the light-duty and medium-duty sector primarily 

consists of gasoline-powered vehicles. Staff’s analysis estimated the long-term “learned-out” 

costs of the program to a heavy-duty engine purchaser for a “typical” engine, and the analysis 

also estimated the incremental costs of implementing the proposed amendments. (Section V.B, 

2013 ISOR). 
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incremental retail cost of $0.59 per vehicle, which is less than a 0.01

percent increase in the retail price of a typical heavy duty vehicle.153 These costs 

are expected to be passed onto the purchasers of new engines and vehicles.

Staff further estimated that the incremental retail costs associated with requiring 

manufacturers to incorporate fully compliant HD OBD systems in 2018 model 

year alternate-fueled engines range from $23 to $228 per vehicle, which 

represents less than a 1.0 percent increase in the retail price of the

smallest vehicles and far less than a 0.1 percent increase for larger vehicles.154

These costs are also expected to be passed onto the purchasers of new engines 

and vehicles. 

In conclusion, the 2013 Amendments to the HD OBD Requirements that arguably 

establish new or more stringent standards than the previously waived standards

are technologically feasible, considering the cost of compliance within the lead 

time provided.

c. Test Procedure Consistency

California and federal test procedures for HD OBD systems are not incompatible. 

In fact, federal regulations provide that engines certified to California’s HD OBD 

regulation are deemed to comply with federal standards.

B. The 2013 Amendments that Relax and Clarify the HD OBD 

Requirements Fall Within the Scope of the Previously Granted 

Waiver

The 2013 Amendments to the HD OBD Requirements that relax the regulation’s 

requirements, and thereby provide engine manufacturers with greater 

compliance flexibility, or that clarify previously waived provisions of the HD OBD 

Requirements are listed in Attachment 2 and 3 to this document, respectively, 

and fall within the scope of the previously waived HD OBD Requirements.

1. Protectiveness 

153 Appendix B to 15-Day Notice of Public Availability of Modified Text for 2013 Amendments 

(Attachment 15)

154 Ibid. Staff reasoned that because this amendment would require manufacturers to implement 

fully-complaint OBD systems two years earlier than previously required, the majority of costs 

were already accounted for in the 2009 HD OBD biennial review rulemaking, and therefore the 

only additional costs would be those costs associated with the amendments to the misfire 

monitoring requirement described above and the time value of money that is incurred due to 

using money two years earlier instead of earning investment returns. Specifically, this would 

include the earlier hiring of additional staff or purchasing of equipment needed for compliance and 

some annual costs for recalibration within this earlier compliance timeframe. Also, since alternatefueled engines will have OBD systems on them two years earlier, the purchasers of such engines 

in these two years will experience an incremental price increase that they would not have 

incurred until later.
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51

For the reasons set forth in Section VI.A.1 of this document, the amendments 

that relax and clarify the HD OBD Requirements that EPA previously waived in 

2012 do not undermine California’s previous determination that its motor vehicle 

standards, in the aggregate, are at least as protective of public health and 

welfare as the comparable federal standards. 

2. Consistency with Clean Air Act Section 202(a)

a. Technical Feasibility and Lead Time Considerations of 

Amendments that Relax and Clarify Existing HD OBD 

Requirements

The amendments that either relax or clarify previously waived provisions of the 

HD OBD regulation are clearly technically feasible because they provide 

manufacturers additional flexibility to comply with provisions that the 

Administrator has already determined are not inconsistent with section 202(a).

The HD OBD regulation, as initially adopted and subsequently amended in 2010, 

requires engine manufacturers to incorporate HD OBD systems on 2013 and 

subsequent model year later engines that comply with specified requirements. 

In her 1012 HD OBD waiver determination, the Administrator confirmed that the 

2010 amendments that relaxed and clarified requirements applicable to 2010 

through 2012 model year engines were within the scope of the waiver for the 

original HD OBD regulation, and alternatively, issued California a full waiver for 

the amendments affecting 2010-2012 model year engines. The Administrator 

issued California a full waiver for the 2010 amendments that created new, more 

stringent requirements for 2013 and subsequent model year engines and for the 

amendments that created new in-use testing procedures.

To the extent that the 2013 Amendments amend previously waived provisions,

those amendments have only relaxed those provisions to provide manufacturers 

additional compliance flexibility. For instance, for certain emission control 

systems on diesel engines (NOx converting catalysts, SCR reductant delivery 

systems, PM filter monitoring, and NOx sensors) the 2013 Amendments relax 

malfunction emission thresholds for 2013 through 2015 model year engines, 

delay the final stringent emission thresholds until the 2016 model year, and 

further exempt those 2014 and 2015 model year engines that were certified to 

interim higher emission thresholds from the 2016 emission thresholds until the 

2017 model year. The 2013 Amendments also allow manufacturers to reduce 

the monitoring frequency of the SCR reductant delivery performance system and 

the NOx sensor; delay monitoring NMHC catalyst feedgas generation capability, 

catalyzed PM filter NMHC conversion capability, and fuel system component 

compensation capability until the 2015 model year, and alternatively exempt

manufacturers from such monitoring if malfunctions do not cause emissions to 

exceed certain criteria; exempt manufacturers from monitoring EGR catalysts if 
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52

manufacturers can demonstrate that failures in those catalysts will not result in 

measurable emissions impacts; and allow manufacturers to carryover 

deficiencies first granted in the 2010 model year up through the 2014 model year 

and to carryover deficiencies first granted in 2011 model year through the 2014 

model year.

“[S]taff has identified methods that are already in-use or could be used

to meet each proposed monitoring requirement, determined that such 

methods will likely succeed in getting there, and addressed all technical 

issues regarding the monitoring requirements raised by industry.

[¶]

Further, for monitoring requirements where staff relaxed the thresholds, 

some manufacturers were on track to meet the previous, tighter 

thresholds, which demonstrates that the thresholds were technically 

feasible to achieve, but several manufacturers had not been as 

successful. Thus, in reviewing the industry status as a whole and taking 

into account that manufacturers were substantially expanding from OBD 

systems on one engine family to OBD systems on all engine families in 

the 2013 model year, staff felt that relief for a few specific monitors was 

warranted. Considering these modifications and relaxations only affected 

a small number of the total individual monitoring requirements, staff’s 

original assessment of what was technically feasible in the scheduled 

implementation time frame was predominantly on target.”155

The amendments that clarify existing provisions have not added any new 

requirements and have not affected the lead time provided when the regulation 

was last amended in 2010. In granting the 2010 waiver, EPA found that the 

provided lead time was not inconsistent with CAA section 202(a).

b. Test Procedure Consistency

As stated above in Section VI.A.3.c, California and federal test procedures for 

HD OBD systems are not incompatible. In fact, federal regulations provide that 

engines certified to California’s HD OBD regulation are deemed to comply with 

federal standards.

3. No New Issues

CARB is not aware of any new issues affecting the previously granted waiver 

determination for the HD OBD regulation. The regulation continues to apply to all 

2010 and subsequent model year heavy-duty engines and addresses the same 

pollutants covered in the initially granted and 2010 waiver. 

155 2013 FSOR at pages 17-18.
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For the above reasons, the Administrator should find that those 2013 

Amendments to the HD OBD Requirements that establish new or more 

stringent standards meet the criteria for a new waiver, and that the 

remaining 2013 Amendments to the HD OBD Requirements fall within the 

scope of the 2010 waiver.

C. The 2013 Amendments to the HD OBD Enforcement Regulation Are

Within the Scope of the 2012 Waiver

As previously discussed, the Administrator granted California a full waiver for the 

initial HD OBD regulation in 2008.156 In 2012, the Administrator granted

California a waiver for the 2010 amendments to the HD OBD regulation. The

Administrator confirmed that those elements of the 2010 amendments that 

relaxed and clarified the section 1971.1 requirements applicable to 2010 through 

2012 model year engines were within the scope of the 2008 waiver, and 

alternatively issued California a full waiver for such amendments. The 

Administrator additionally issued a full waiver for those elements of the 2010 

amendments that applied to 2013 and later model year engines and for the HDOBD specific enforcement provisions of section 1971.5. Therefore, the 2012 HD 

OBD waiver encompassed the HD OBD Enforcement regulation as well as the 

enforcement-related provisions of section 1971.1 (including the provisions 

applicable to certification demonstration testing in section 1971.1(i) and

production engine/vehicle evaluation testing in section 1971.1(l)).157

For the reasons set forth above and those that follow, the Administrator should 

confirm that the 2013 Amendments to sections 1971.1(i), (l), and section 1971.5 

fall within the scope of the previously granted HD OBD waiver. To the extent that 

the Administrator cannot make such a determination, the Administrator must 

grant California a new waiver for such amendments. 

1. Protectiveness

For the reasons set forth in Section VI.A.1 of this document, the 2013 

Amendments to sections 1971.1(i), (l), and section 1971.5 do not undermine 

California’s previous determinations that its standards are, in the aggregate, at 

least as protective of the public health and welfare as applicable federal 

standards. Those amendments primarily align the enforcement related 

provisions to the diesel-related amendments to the HD OBD and OBD II 

Requirements; specifically the selection criteria of engines/vehicles for the test 

sample group and the mandatory recall provisions for diesel engines.

2. Consistency with Clean Air Act Section 209

156 73 Fed.Reg. 52042 (September 8, 2008). 157 77 Fed. Reg. 73459 (December 10, 2012).
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a. Technical Feasibility and Lead Time Considerations

No technical feasibility issues exist for the amended HD OBD enforcement 

provisions independent of the technical feasibility of the underlying HD OBD 

monitoring requirements,158 and the technical feasibility of the underlying HD 

OBD monitoring requirements has been demonstrated above in Section VI.A.3 of 

this document. 

b. Test Procedure Consistency

California and federal test procedures for HD OBD systems are not incompatible. 

In fact, federal regulations provide that engines certified to California’s HD OBD 

regulation are deemed to comply with federal standards. In granting the 2012

waiver, the Administrator found that the HD OBD test procedures were not 

incompatible with federal test procedures,159 and the amended enforcement 

provisions do not establish any new testing requirements that would affect the 

Administrator’s previous determination. 

3. New Issues

As stated, the ARB is not aware of any new issues affecting the previously 

granted authorization determination for the HD OBD regulation.

D. Alternatively, the Administrator Must Grant a New Waiver for those

2013 Amendments to the HD OBD Requirements that CARB Has 

Asserted Relax and Clarify Previously Waived Requirements and 

those Amendments to the Enforcement Procedures of the HD OBD 

Regulations That Do Not Fall Within the Scope of Previously Granted

Waivers

Should the Administrator determine that any of the 2013 Amendments to the HD 

OBD Requirements and Enforcement Regulation do not fall within the scope of 

the 2010 waiver, CARB requests that a new waiver be granted for such 

amendments. No basis exists to deny such a waiver as the amendments satisfy 

the protectiveness and consistency criteria, and as demonstrated in section 

VI.A.2, California meets the compelling and extraordinary criterion.

VII. THE 2013 AMENDMENTS TO THE OBD II REQUIREMENTS SET FORTH 

158 1996 Waiver Decision, 61 Fed.Reg. 53371 (October 11, 1996). In granting the 1996 OBD II 

waiver, the Administrator said the primary aspect of consistency with CAA section 202(a) that is 

applicable to accompanying enforcement procedures is whether there is test procedure 

consistency. Decision document accompanying 1996 Waiver Decision at p.3, fn. 5.

159 Decision Document accompanying 2010 HD OBD Amendments Waiver Determination at page 

17
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IN SECTION 1968.2 AND TO THE OBD II ENFORCEMENT REGULATION 

IN SECTION 1968.5 EITHER MEET THE CRITERIA FOR A NEW WAIVER 

OR FALL WITHIN THE SCOPE OF THE PREVIOUSLY GRANTED 

WAIVER.

CARB submits that for the reasons set forth below in section VII, and in the 

rulemaking documents associated with the 2013 Amendments to the HD OBD 

and OBD II Requirements and Enforcement regulations, the Administrator must 

grant California the requested waiver actions as the Administrator has no basis 

under the criteria of CAA section 209(b) to deny California’s request:

A. A New Waiver Should Be Granted for Those 2013 Amendments to the 

OBD II Requirements Set Forth in Section 1968.2 that Establish New, 

More Stringent Requirements.

As described in Section III of this document, certain of the 2013 Amendments

arguably establish new or more stringent standards which require a new waiver 

under section 209(a) of the CAA. Those amendments are listed in Attachment 1

of this waiver support document. The remainder of the 2013 Amendments either 

relax the regulation’s requirements, and thereby provide engine manufacturers 

with greater compliance flexibility, or clarify previously waived provisions of the 

OBD II Requirements. Such amendments are listed in Attachment 2 and 3 to this 

document, respectively, and fall within the scope of the previously waived OBD II

Requirements.

1. CARB’s Protectiveness Determinations for the 2013 Amendments 

to the OBD II Requirements Are Neither Arbitrary Nor Capricious

In adopting Resolution 12-29, the Board expressly found that the 2013 

Amendments to the OBD II Requirements and related enforcement regulations 

(sections 1968.2 and 1968.5) do not undermine California’s previous 

determinations that its standards are, in the aggregate, at least as protective of 

the public health and welfare as applicable federal standards. In reviewing 

California’s protectiveness findings for the 2013 Amendments to the OBD II 

Requirements and related enforcement regulations, those challenging the waiver

must present clear and convincing evidence to show that the protectiveness 

finding by California is arbitrary and capricious.160 This standard is in accord with 

“Congressional intent to provide California with the broadest possible discretion 

in setting regulations it finds protective of the public health and welfare”.161

In adopting the initial OBD II Requirements and subsequent amendments thereto 

in 1989 through 1994, CARB resolved that its standards, in the aggregate, were 

at least as protective of public health and welfare as the applicable federal 

160 MEMA, 627 F.2d at 1122, Decision Document accompanying OBD II Waiver Determination, at 

p. 14.

161 Id.
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standards, including federal OBD standards. In granting the 1996 waiver, the 

Administrator held that she could not find that CARB’s determination was 

arbitrary and capricious.162

The 2013 Amendments do not disturb this finding even though EPA has since 

adopted amendments to its federal OBD requirements. Even considering the 

provisions that were relaxed for 2013 and subsequent model year medium-duty 

vehicles and engines, the OBD II Requirements continue to be more stringent 

than EPA’s adopted requirements for those model year engines. Similarly, the 

requirements for 2013 and subsequent model years and for all model year

passenger cars and light-duty trucks continue to be more stringent than 

comparable federal regulations.163

The amended OBD II requirements, considered as a whole, continue to be more 

stringent than the federal OBD regulation for light-duty vehicles and trucks and 

heavy-duty trucks (under the federal regulation) of the same vehicle weight rating 

as the California medium-duty vehicle category. The Board affirmed this 

determination in Resolution 12-29. 

2. Compelling and Extraordinary Circumstances

As set forth in Section VI.A.2 of this document, the Board confirmed CARB’s 

longstanding position that California continues to need its own motor vehicle 

program to meet serious air pollution problems in adopting Resolution 12-29, and 

there can be no doubt of the continuing existence of compelling and 

extraordinary conditions justifying California’s need for its own motor vehicle 

emissions control program.

3. Consistency with Clean Air Act Section 202(a)

As discussed above in Section VI.A.3, EPA has historically interpreted 

consistency with CAA section 202(a) using a two-pronged test: (1) that there is 

sufficient lead time to permit the development of technology necessary to meet 

the standards and other requirements, giving appropriate consideration to the 

cost of compliance in the time frame provided, and (2) that the California and 

federal test procedures are sufficiently compatible to permit manufacturers to 

meet both the state and federal test requirements with one test vehicle or 

engine.164 The reference to “cost of compliance” in CAA section 202(a) refers to

the economic costs of emission standards and accompanying enforcement 

procedures and the timing of a particular emission control regulation rather than 

162 OBD II Waiver Decision Document, at page 34. 163 See discussion in CARB’s 2003 and 2007 OBD II waiver request submissions. 164 See 61 Fed.Reg. 53371, 53372 (October 11, 1996); Decision Document at p.2 (OBD II Waiver 

Decision). Even where there is incompatibility between the California and federal test 

procedures, EPA has granted a waiver under circumstances where EPA accepts a demonstration 

of federal compliance based on California test results, thus obviating the need for two separate 

tests. (43 Fed.Reg. 1829, 1830 (January 12, 1978); 40 Fed.Reg. 30311, 30314 (July 18, 1975).) 
Waiver Request Support Document

57

to its social implications.165 As demonstrated below, the 2013 Amendments are 

fully consistent with section 202(a) of the CAA.

a. Technical Feasibility and Lead Time Considerations of 2013 

Amendments that Establish New, More Stringent OBD II 

Requirements

Although the 2013 Amendments to the OBD II Requirements primarily relax 

requirements applicable to 2013 and subsequent model year medium-duty 

vehicles and engines in order to provide manufacturers additional time to develop 

and refine monitoring strategies for certain components or emission control 

systems, a limited number of the 2013 Amendments (identified in Attachment 1)

could be found to establish new or more stringent standards than the previously 

waived standards. Such amendments are consistent with section 202(a) in that 

manufacturers have been provided sufficient lead time, and do not require 

appreciable hardware changes beyond those considered by staff and the Board 

in the original and subsequent OBD II rulemakings. Instead, the upgrades and 

modifications largely only require recalibration of software for existing monitors 

and, in the case of new monitors, the development of new diagnostic strategies.

To the extent that new hardware is required, the amendments provide additional 

lead time for manufacturer compliance.

As previously discussed in Section VI of this document, the amendments that 

could be construed to establish new or more stringent standards for monitoring 

diesel misfire [sections 1968.2(f)(3.2.2) and (f)(3.3.3)], that restrict the criteria for 

incrementing the denominator for monitoring the PM filter performance monitor 

and PM filter missing substrate monitor [section 1968.2(d)(4.3.2)(G)]; and that 

require tracking and reporting of in-use monitor performance data for the NOx 

sensor [section 1968.2(f)(5.3.1)], are technically feasible.166 The amendments 

that specify the monitoring criteria for 2016 and subsequent model year mediumduty diesel vehicles certified to a chassis dynamometer tailpipe emission

standard [sections 1968.2(f)(17.1.5) and (17.1.6)] present no issues of technical 

infeasibility as they essentially align those criteria with existing monitoring criteria 

for light-duty vehicles and with the monitoring criteria for medium-duty engines 

certified on engine dynamometers. 

b. Consideration of Costs

For the reasons set forth in Section VI.A.3.b, CARB appropriately considered the 

cost of compliance of the 2013 Amendments and estimated that the amendments 

requiring more comprehensive misfire monitoring requirements would result in an

165 Id., referencing See S. Rep. No. 192, 89th Cong., 1st Sess. 5-8 (1965); H.R. Rep. No. 728, 

90th Cong., 1st Sess. 23 (1967), U.S. Code Cong. & Admin.News 1967, p. 1938; see also 74 

Fed.Reg. 3030 (January 16, 2009), Decision Document at p. 49. 166 Sections VI.A.3.a(i), VI.A.3.a(v), and VI.A.3.a (vii), respectively. 
Waiver Request Support Document

58

incremental retail cost of $0.59 per vehicle.

c. Test Procedure Consistency

California and federal test procedures for light- and medium-duty OBD systems 

are not incompatible. In fact, federal regulations provide that engines certified to 

California’s OBD II Requirements are deemed to comply with federal standards.

B. The 2013 Amendments that Relax and Clarify the OBD II

Requirements Fall Within the Scope of the Previously Granted 

Waiver

The 2013 Amendments to the OBD II Requirements that relax the regulation’s 

requirements, and thereby provide engine manufacturers with greater 

compliance flexibility, or that clarify previously waived provisions of the OBD II

Requirements are listed in Attachment 2 and 3 to this document, respectively, 

and fall within the scope of the previously waived OBD II Requirements

1. Protectiveness 

For the reasons set forth in Section VII.A.1 of this document, the amendments 

that relax and clarify the OBD II Requirements that EPA previously waived in 

1996 do not undermine California’s previous determination that its motor vehicle 

standards, in the aggregate, are at least as protective of public health and 

welfare as the comparable federal standards. 

2. Consistency with Clean Air Act Section 202(a)

a. Technical Feasibility and Lead Time Considerations of 

Amendments that Relax and Clarify Existing OBD II

Requirements

In the short term – the 2013 through the 2015 model years – to the extent that 

the Board has amended requirements, the amendments only relax the 

requirements, providing manufacturers with greater compliance flexibility. For 

instance, for certain emission control systems on diesel engines (NOx converting 

catalysts, PM filter monitoring, and NOx sensors) the 2013 Amendments relax 

malfunction emission thresholds for 2013 through 2015 model year engines and 

delay the final stringent emission thresholds until the 2016 model year. The 

2013 Amendments also allow manufacturers to reduce the monitoring frequency 

of the SCR reductant delivery performance system; exempt manufacturers from 

monitoring NMHC catalyst feedgas generation capability, catalyzed PM filter 

NMHC conversion capability, and fuel system component compensation 

capability if malfunctions do not cause emissions to exceed certain criteria; and 

exempt manufacturers from monitoring EGR catalysts if manufacturers can 
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demonstrate that failures in those catalysts will not result in measurable 

emissions impacts. 

“[S]taff has identified methods that are already in-use or could be used

to meet each proposed monitoring requirement, determined that such 

methods will likely succeed in getting there, and addressed all technical 

issues regarding the monitoring requirements raised by industry.

[¶]

Further, for monitoring requirements where staff relaxed the thresholds, 

some manufacturers were on track to meet the previous, tighter 

thresholds, which demonstrates that the thresholds were technically 

feasible to achieve, but several manufacturers had not been as 

successful. ...”

167

The amendments that clarify existing provisions have not added any new 

requirements and have not affected the lead time provided when the regulation 

was last amended. In granting the 1996 waiver, EPA found that the provided 

lead time was not inconsistent with CAA section 202(a).

b. Test Procedure Consistency.

California and federal test procedures for OBD II systems are not incompatible. 

In fact, federal regulations provide that engines certified to California’s OBD II 

Requirements are deemed to comply with federal standards. 

3. No New Issues.

CARB is not aware of any new issues affecting the previously granted waiver for 

the OBD II Requirements. The requirements continue to apply to all new 1996 

and subsequent model year passenger cars, light-duty trucks, medium-duty 

vehicles, and engines and addresses the same pollutants covered in the initially 

granted waiver. 

For the above reasons, the Administrator should find that those 2013 

Amendments to the OBD II Requirements that establish new or more 

stringent standards meet the criteria for a new waiver, and that the 

remaining 2013 Amendments to the OBD II Requirements fall within the 

scope of the 1996 waiver.

C. The 2013 Amendments to the OBD II Enforcement Regulation Are 

Accompanying Enforcement Provisions That Fall Within the Scope of 

Previously Granted Waivers Within the Scope of the 1996 Waiver

167 2013 FSOR at pages 17-18.
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For the reasons set forth below, the Administrator should find that the 

amendments to sections 1968.2(j) and section 1968.5 fall within the scope of the 

previously granted OBD II waiver. To the extent that the Administrator cannot 

make such a determination, the Administrator must grant California a waiver for 

the accompanying enforcement provision. 

1. The Amendments Do Not Require a New Waiver

EPA has previously granted waivers for the OBD II regulation and for California’s 

regulations for Enforcement of New and In-Use Vehicle Standards, as set forth in 

title 13, CCR, section 2100 et. seq.168 The enforcement provisions of section 

1968.2 and 1968.5, as modified by the 2013 Amendments, are accompanying 

enforcement provisions of the OBD II regulation and should be found to be within 

the scope of these previously granted waivers. The 1996 waiver covered 

accompanying enforcement provisions, including detailed certification 

requirements. The reason for adopting the post-production testing amendments 

is to ensure that certified OBD II systems are in compliance at the time of 

production. The accompanying enforcement provisions of section 1968.2(j) 

apply to all monitoring requirements of section 1968.2 – both the provisions 

carried over from section 1968.1 and newly added monitoring requirements. 

Although codified in a different location of title 13, CCR, the enforcement 

provisions of section 1968.5 are in point of fact amendments to the general inuse enforcement requirements of section 2100 et seq. The amendments were 

necessary to address the uniqueness of OBD II systems and the special 

circumstances surrounding in-use compliance testing of such systems.

2. Protectiveness

For the reasons set forth above in Section VII.A.1, the 2013 amendments to 

sections 1968.2(j), and section 1968.5 do not undermine California’s previous 

determinations that its standards are, in the aggregate, at least as protective of 

the public health and welfare as applicable federal standards. 

3. Consistency with Clean Air Act section 202(a)

a. Technical Feasibility and Lead Time Considerations

No technical feasibility issues exist for the amended OBD II enforcement 

provisions independent of the technical feasibility of the underlying OBD II 

monitoring requirements,169 and the technical feasibility of the underlying OBD II 

168 See 61 Fed.Reg. 53371 (October 11, 1996); 43 Fed.Reg. 9344 (March 7, 1978); 43 Fed.Reg. 

25729 (June 14, 1978).

169 1996 Waiver Decision, 61 Fed.Reg. 53371. In granting the 1996 OBD II waiver, the 

Administrator said the primary aspect of consistency with CAA section 202(a) that is applicable to 

accompanying enforcement procedures is whether there is test procedure consistency. 61 
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61

monitoring requirements has been demonstrated above in Sections VII.A.3.a.

and VII.B.2.a of this document. 

b. Test Procedure Consistency

In the 1996 waiver the Administrator did not find the California OBD II certification 

test procedures to be incompatible with the federal OBD test procedures for 

certification.170 The adopted enforcement provisions do not establish any new 

testing requirements that would affect the Administrator’s previous determination. 

Accordingly, manufacturers should be able to continue to use only one test to 

certify an engine family to both the federal and California requirements. 

4. New Issues

CARB is not aware of any new issues affecting the previously granted waiver 

determination for the OBD II regulation.

D. Alternatively, the Administrator Must Grant a New Waiver for those 

2013 Amendments to the OBD II Requirements that CARB Has 

Asserted Relax and Clarify Previously Waived Requirements and 

those Amendments to the Enforcement Procedures of the OBD II 

Regulations That Do Not Fall Within the Scope of Previously Granted

Waivers

Should the Administrator determine that any of the 2013 Amendments to the 

OBD II Requirements and Enforcement Regulation do not fall within the scope of 

previously granted waivers, CARB requests that a new waiver be granted for 

such amendments. No basis exists to deny such waivers as the amendments 

satisfy the protectiveness and consistency criteria, and as demonstrated in 

section VI.A.2, California meets the compelling and extraordinary criterion.

Fed.Reg. 53371 (October 11, 1996), decision document at p.3, fn. 5.169 61 Fed.Reg. 53371 

(October 11, 1996).

169 Id., at 53372

170 Id., at 53372.
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VIII. THE 2012 AMENDMENTS TO THE OBD II MONITORING

REQUIREMENTS SET FORTH IN SECTION 1968.2 AND TO THE OBD 

II ENFORCEMENT PROVISIONS SET FORTH IN SECTION 1968.5 

EITHER MEET THE CRITERIA FOR A NEW WAIVER OR FALL WITHIN 

THE SCOPE OF THE PREVIOUSLY GRANTED WAIVER.

For the reasons set forth below in section VIII, and in the rulemaking documents 

associated with the 2012 Amendments to the OBD II Requirements and 

Enforcement regulations, the Administrator must grant California the requested 

waiver actions as the Administrator has no basis under the criteria of CAA 

section 209(b) to deny California’s request.

The 2012 Amendments were enacted to address manufacturers’ concerns that 

modifications were needed immediately to allow them to certify compliant 2013 

model year vehicles. The 2012 Amendments do not mandate a new system or 

appreciable hardware changes; instead, as explained in Section VIII.A of this 

document, the modifications required under section 1968.2 for light- and

medium-duty vehicles and engines for the most part only require recalibration of

software for some of the existing monitors.

A. A New Waiver Should Be Granted for Those 2012 Amendments to the 

OBD II Requirements Set Forth in Section 1968.2 that Establish New, 

More Stringent Requirements.

As described in Section II of this document, only one of the 2012 Amendments to 

the OBD II regulation arguably establishes a new or additional requirement which 

requires a new waiver. This amendment is listed in Attachment 6 of this waiver 

support document. The remainder of the 2012 Amendments either relax the 

regulation’s requirements, and thereby provide engine manufacturers with 

greater compliance flexibility, or clarify previously waived provisions of the OBD II 

Requirements. Such amendments are listed in Attachments 5 and 7 to this 

document, respectively, and fall within the scope of the previously waived OBD II 

Requirements.

1. CARB’s Protectiveness Determinations for the 2012 Amendments 

to the OBD II Requirements and to the OBD II Enforcement 

Regulation Are Neither Arbitrary Nor Capricious

In adopting Resolutions 12-11 and 12-21, the Board expressly found that the 

2012 Amendments to the OBD II Requirements and related enforcement 

regulation (sections 1968.2 and 1968.5) did not undermine California’s previous 

determinations that its standards are, in the aggregate, at least as protective of 
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63

the public health and welfare as applicable federal standards.171 In reviewing 

California’s protectiveness findings for the 2012 Amendments to the OBD II 

Requirements and related enforcement regulation, those challenging the waiver

must present clear and convincing evidence to show that the protectiveness 

finding by California is arbitrary and capricious.172 This standard is in accord with 

“Congressional intent to provide California with the broadest possible discretion 

in setting regulations it finds protective of the public health and welfare”.173

In adopting the initial OBD II Requirements and subsequent amendments thereto 

in 1989 through 1994, CARB resolved that its standards, in the aggregate, were 

at least as protective of public health and welfare as the applicable federal 

standards, including federal OBD standards. In granting the 1996 waiver, the 

Administrator held that she could not find that CARB’s determination was 

arbitrary and capricious.174

The 2012 Amendments do not disturb this finding even though EPA has since 

adopted amendments to its federal OBD requirements. Even considering the 

provisions that were relaxed for 2010 and subsequent model year light- duty 

vehicles and 2013 and subsequent model year medium-duty vehicles, the OBD II 

Requirements continue to be more stringent than comparable federal 

regulations.175

The 2012 amended OBD II requirements, considered as a whole, continue to be 

more stringent than the federal OBD regulation for light-duty vehicles and trucks 

and heavy-duty trucks (under the federal regulation) of the same vehicle weight 

rating as the California medium-duty vehicle category. The Board affirmed this 

determination in Resolutions 12-11 and 12-21.

2. Compelling and Extraordinary Circumstances

In adopting Resolutions 12-11 and 12-21, the Board confirmed CARB’s 

longstanding position that California continues to need its own motor vehicle 

program to meet serious air pollution problems. The Administrator has 

previously and consistently recognized that California meets the compelling and 

extraordinary criterion when granting waivers for motor vehicles under section 

209(b). The relevant inquiry under section 209(b)(1)(B) is whether California 

171 “BE IT FURTHER RESOLVED that the Board hereby determines that the proposed 

regulations approved for adoption herein will not cause California motor vehicle emission 

standards, in the aggregate, to be less protective of public health and welfare than applicable 

federal standards”; Resolution 12-11 at p. 22; “NOW, THEREFORE, BE IT RESOLVED that the 

recitals and findings contained in Resolution 12-11, are incorporated by reference herein.”

Resolution 12-21 at p.10.

172 MEMA, 627 F.2d at 1122, Decision Document accompanying OBD II Waiver Determination, at 

p. 14.

173 Id.

174 OBD II Waiver Decision Document, at page 34. 175 See discussion in CARB’s 2003 and 2007 OBD II waiver request submissions. 
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needs its own emission control program to meet compelling and extraordinary 

conditions, not whether any given standard is necessary to meet such 

conditions.176 In approving waivers under section 209(b), the Administrator has 

determined that: 

“[C]ompelling and extraordinary conditions” does not refer to levels of 

pollution directly, but primarily to the factors that tend to produce them: 

geographical and climatic conditions that, when combined with large 

numbers and high concentrations of automobiles, create serious air 

pollution problems.177

In the California Clean Air Act of 1988, the California Legislature found that: 

“[D]espite the significant reductions in vehicle emissions which have been 

achieved in recent years, continued growth in population and vehicle miles 

traveled throughout California have the potential not only to prevent 

attainment of the state standards, but in some cases, to result in 

worsening of air quality.”178

The geographical and climatic conditions and the tremendous growth in vehicle 

population and use that moved Congress to authorize California to establish 

separate vehicle standards in 1967 still exist today. EPA has long confirmed the 

ARB’s judgment, on behalf of the State of California, on this matter.179

Nothing in these conditions has changed to warrant a change in EPA’s 

confirmation, and therefore there can be no doubt of the continuing existence of 

compelling and extraordinary conditions justifying California’s need for its own 

motor vehicle emissions control program.

3. Consistency with Clean Air Act section 202(a)

a. Technical Feasibility and Lead Time Considerations

176 The Administrator has recognized that even if such a standard by standard test were applied 

to California, it "would not be applicable to its fullest stringency due to the degree of discretion 

given to California in dealing with its mobile source pollution problems." 41 Fed.Reg. 44209, 

44213, (October 7, 1976); 49 Fed.Reg. 18887, 18892 (May 3, 1984) (finding Congressional intent 

precludes EPA from viewing adopted California vehicular particulate matter standard in isolation).

177 49 Fed. Reg. 18887, 18890 (May 3, 1984). There the Administrator found that California need 

not demonstrate its particulate problem (or diesel vehicles’ contribution to it) is the worst in the 

country in order to adopt a particulate matter standard affecting diesel vehicles. Id. at 18891-

1892. 

178 California Health and Safety Code section 43000.5. 179 California State Motor Vehicle Pollution Control Standards; Waiver of Federal Preemption –

Notice of Decision, 70 Fed.Reg. 50322, 50323 (August 26, 2005); 77 Fed. Reg. 73459, 73461 

(December 10, 2012).
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Only one of the 2012 Amendments to the OBD II regulation arguably establishes 

a new or additional requirement. As described in above, sections (d)(5.5.1) and 

(d)(5.5.2)(C) now require 2014 and subsequent model year plug-in hybrid electric 

vehicles to report a newly required ignition cycle counter that must be 

incremented if the “fueled engine operation” definition has been met for at least 

two seconds plus or minus one second. The technical feasibility of this 

requirement is beyond dispute given that manufacturers were provided 2 years of 

leadtime and given that the amendment can be implemented by only minor 

software changes and is consistent with how industry has either been 

implementing or planning to implement this counter.180

b. Consideration of Costs

CARB appropriately considered the cost of compliance of the 2012 Amendments. 

Staff determined that the costs associated with amendment described above in 

section VIII.A.3.a would be negligible, given that: the amendment could be 

implemented by only software changes, manufacturers have been provided two 

years of leadtime to implement the software changes, and because plug-in hybrid 

manufacturers must necessarily modify software to comply with existing 

requirements, they would not incur any significant costs in modifying their 

software to incorporate the amendment.181

c. Test Procedure Consistency

California and federal test procedures for light- and medium-duty OBD systems 

are not incompatible. In fact, federal regulations provide that engines certified to 

California’s OBD II Requirements are deemed to comply with federal standards.

B. The 2012 Amendments that Relax and Clarify the OBD II 

Requirements Fall Within the Scope of the Previously Granted 

Waiver 

The 2012 Amendments to the OBD II Requirements that relax the regulation’s 

requirements, and thereby provide engine manufacturers with greater 

compliance flexibility, or that clarify previously waived provisions of the OBD II 

Requirements are listed in Attachment 5 and 7 to this document, respectively, 

and fall within the scope of the previously waived OBD II Requirements

1. Protectiveness 

For the reasons set forth in Section VIII.A.1 of this document, the amendments 

that relax and clarify the OBD II Requirements that EPA previously waived in 

1996 do not undermine California’s previous determination that its motor vehicle 

180 Staff Report at p.72. 181 Ibid.
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66

standards, in the aggregate, are at least as protective of public health and 

welfare as the comparable federal standards. 

2. Consistency with Clean Air Act Section 202(a)

a. Technical Feasibility and Lead Time Considerations of 

Amendments that Relax and Clarify Existing OBD II

Requirements

As discussed in Section II, to the extent that the 2012 Amendments modified 

monitoring requirements, all but one of those amendments either relaxed those 

requirements to provide manufacturers greater compliance flexibility or clarified 

existing provisions. For instance, the 2012 Amendments delayed requirements 

for 2010 and subsequent model year light-duty vehicles and 2013 and 

subsequent model year medium-duty vehicles to monitor the ability of NMHC 

catalysts to generate a desired feedgas and to monitor catalyzed PM filters for 

proper NMHC conversion capability until the 2015 model year. The 2012 

Amendments also allow manufacturers to meet a reduced in-use monitor 

performance ratio of 0.100 in lieu of previously specified minimum performance 

ratios (0.336 for most monitors) through the 2016 model year for monitors of 

components or systems that require engine operation on plug-in hybrid electric 

vehicles.

These amendments were not necessitated because the pre-existing OBD 

requirements did not provide manufacturers sufficient lead time. Rather, as 

stated in the Staff Report, “[m]ost of the proposed amendments would either 

relax or clarify the current requirements in the OBD II regulation. Thus, the 

technological feasibility of the proposed amendments has already been 

determined and discussed above and in the staff reports for the previous OBD II 

rulemakings.182

b. Consideration of Costs

CARB staff determined that the costs associated with the amendments are 

negligible, given that such amendments either relax or clarify the current 

requirements.

c. Test Procedure Consistency

California and federal test procedures for light- and medium-duty OBD systems 

are not incompatible. In fact, federal regulations provide that engines certified to 

California’s OBD II Requirements are deemed to comply with federal standards.

3. No New Issues

182 Staff Report at p.72.
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CARB is not aware of any new issues affecting the previously granted waiver for 

the OBD II Requirements. The requirements continue to apply to all new 1996 

and subsequent model year passenger cars, light-duty trucks, medium-duty 

vehicles, and engines and addresses the same pollutants covered in the initially 

granted waiver. 

C. The 2012 Amendments to the OBD II Enforcement Regulation Are 

Accompanying Enforcement Provisions That Fall Within the Scope of 

Previously Granted Waivers 

For the reasons set forth below, the Administrator should find that the 

amendments to section 1968.5 fall within the scope of the previously granted 

OBD II waiver. To the extent that the Administrator cannot make such a 

determination, the Administrator must grant California a waiver for the 

accompanying enforcement provision. 

1. The Amendments Do Not Require a New Waiver

EPA has previously granted waivers for the OBD II regulation and for California’s 

regulations for Enforcement of New and In-Use Vehicle Standards, as set forth in 

title 13, CCR, section 2100 et. seq.183 The enforcement provisions of section 

1968.2 and 1968.5, as modified by the 2012 Amendments, are accompanying 

enforcement provisions of the OBD II regulation and should be found to be within 

the scope of these previously granted waivers. The 1996 waiver covered 

accompanying enforcement provisions, including detailed certification 

requirements. The reason for adopting the post-production testing amendments 

is to ensure that certified OBD II systems are in compliance at the time of 

production. The accompanying enforcement provisions of section 1968.2(j) 

apply to all monitoring requirements of section 1968.2 – both the provisions 

carried over from section 1968.1 and newly added monitoring requirements. 

Although codified in a different location of title 13, CCR, the enforcement 

provisions of section 1968.5 are in point of fact amendments to the general inuse enforcement requirements of section 2100 et seq. The amendments were 

necessary to address the uniqueness of OBD II systems and the special 

circumstances surrounding in-use compliance testing of such systems.

2. Protectiveness

For the reasons set forth above in Section VIII.A.1, the 2012 amendments to 

section 1968.5 do not undermine California’s previous determinations that its 

standards are, in the aggregate, at least as protective of the public health and 

welfare as applicable federal standards. 

183 See 61 Fed.Reg. 53371 (October 11, 1996); 43 Fed.Reg. 9344 (March 7, 1978); 43 Fed.Reg. 

25729 (June 14, 1978).
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3. Consistency with Clean Air Act section 202(a)

a. Technical Feasibility and Lead Time Considerations

No technical feasibility issues exist for the amended OBD II enforcement 

provisions independent of the technical feasibility of the underlying OBD II 

monitoring requirements,184 and the technical feasibility of the underlying OBD II 

monitoring requirements has been demonstrated above in Sections VIII.A.3.a. 

and VIII.B.2.a. of this document. 

b. Test Procedure Consistency

In the 1996 waiver the Administrator did not find the California OBD II certification 

test procedures to be incompatible with the federal OBD test procedures for 

certification.185 The adopted enforcement provisions do not establish any new 

testing requirements that would affect the Administrator’s previous determination. 

Accordingly, manufacturers should be able to continue to use only one test to 

certify an engine family to both the federal and California requirements. 

4. New Issues

As stated, the ARB is not aware of any new issues affecting the previously 

granted authorization determination for the OBD II regulation.

D. Alternatively, the Administrator Must Grant a New Waiver for those 

2012 Amendments to the OBD II Requirements that CARB Has 

Asserted Relax and Clarify Previously Waived Requirements and 

those Amendments to the Enforcement Procedures of the OBD II 

Regulations That Do Not Fall Within the Scope of Previously Granted

Waivers

Should the Administrator determine that any of the 2012 Amendments to the 

OBD II Requirements and Enforcement Regulation do not fall within the scope of 

previously granted waivers, CARB requests that a new waiver be granted for 

such amendments. No basis exists to deny such waivers as the amendments 

satisfy the protectiveness and consistency criteria, and as demonstrated in 

section VIII.A.2, California meets the compelling and extraordinary criterion.

184 1996 Waiver Decision, 61 Fed.Reg. 53371 (October 11, 1996). In granting the 1996 OBD II 

waiver, the Administrator said the primary aspect of consistency with CAA section 202(a) that is 

applicable to accompanying enforcement procedures is whether there is test procedure 

consistency. Decision document at p.3, fn. 5. 

185 Id., at 53372.
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IX. CONCLUSION

For the reasons set forth above, California respectfully requests that EPA in the 

first instance grant a waiver for those 2013 Amendments to the HD OBD 

Requirements that establish new or more stringent standards, and confirm that 

the remaining 2013 Amendments to the HD OBD Requirements and to the HD 

OBD Enforcement regulation fall within the scope of the previously issued waiver 

granted in 2010. Should the Administrator determine that any of the 2013 

Amendments to the HD OBD Requirements and Enforcement Regulation do not 

fall within the scope of the 2010 waiver, CARB requests that a new waiver be 

granted for such amendments.

California is also requesting that EPA grant a waiver for those 2012 and 2013 

Amendments to the OBD II Requirements and OBD II Enforcement regulation 

that establish new or more stringent standards, and confirm that the remaining 

2012 and 2013 Amendments to the OBD II Requirements and OBD II 

Enforcement regulation fall within the scope of the previously issued OBD II 

waiver granted in 1996. Should the Administrator determine that any of the 2012 

and 2013 Amendments do not fall within the scope of the 1996 waiver, CARB 

requests that a new waiver be granted for such amendments.

To assist you in reviewing the regulation, ARB is enclosing the following 

documents that it is incorporating into the record of this waiver proceeding.

1. 2013 Amendments to HD OBD and OBD II Requirements 

That Potentially Establish New or More Stringent Requirements

2. 2013 Amendments to HD OBD and OBD II Requirements That 

Relax Existing Requirements

3. 2013 Amendments to HD OBD and OBD II Requirements That 

Clarify Existing Requirements

4. 2013 Amendments to HD OBD and OBD II Enforcement Regulations 

5. 2012 Amendments to OBD II Requirements and Enforcement 

Regulation that Relax Pre-Existing Requirements

6. 2012 Amendments to OBD II Monitoring Requirements That 

Potentially Establish More Stringent Requirements

7. 2012 Amendments to OBD II Monitoring Requirements That Clarify 

Pre-Existing Requirements
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8. Notice of Public Hearing to Consider Technical Status and Proposed 

Revisions to On-Board Diagnostic System Requirements for HeavyDuty Engines, Passenger Cars, Light-Duty Trucks, Medium-Duty 

Vehicles and Engines, issued July 5, 2012.

9. Staff Report: Initial Statement of Reasons for Proposed 

Rulemaking, issued July 5, 2012.

10. Appendix A to Staff Report; 

11. Appendix B to Staff Report;

12. Appendix C to Staff Report;

13. Appendix D to Staff Report;

14. Resolution 12-29, dated August 23, 2012 and Attachment D to 

Resolution 12-29.

15. Notice of Availability of Modified Text, issued January 4, 2013

16. Executive Order R-13-005, dated June 26, 2013.

17. Final Statement of Reasons for Rulemaking Including Summary of 

Comments and Agency Response, issued June 27, 2013.

18. Addendum to Final Statement of Reasons

19. Request for Early Effective Date

20. Final Regulation Order for title 13, California Code of Regulations, 

section 1971.1

21. Final Regulation Order for title 13, California Code of Regulations, 

section 1968.2

22. Final Regulation Order for title 13, California Code of Regulations, 

section 1971.5

23. Final Regulation Order for title 13, California Code of Regulations, 

section 1968.5

24. Notice of Public Hearing to Consider the “LEV III” Amendments to 

the California Greenhouse Gas and Criteria Pollutant Exhaust and 

Evaporative Emission Standards and Test Procedures and to the 
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On-Board Diagnostic System Requirements for Passenger Cars, 

Light-Duty Trucks, and Medium-Duty Vehicles, and to the 

Evaporative Emission Requirements for Heavy-Duty Vehicles, 

issued December 7, 2011.

25. Staff Report: Initial Statement of Reasons for Proposed Rulemaking, 

issued December 7, 2011.

26. Appendix A to Staff Report: Initial Statement of Reasons for 

Proposed Rulemaking, issued December 7, 2011.

27. Resolution 12-11, dated January 26, 2012 and Attachment D to 

Resolution 12-29.

28. Resolution 12-21, dated March 22, 2012 and Attachment E to 

Resolution 12-21.

29. Final Statement of Reasons for Rulemaking Including Summary of 

Comments and Agency Response, issued June 25, 2012.

30. Addendum to Final Statement of Reasons

31. Request for Early Effective Date

32. Final Regulation Order.

If you require additional technical information on this item, please contact Mike 

Regenfuss, Chief, Engineering Studies Branch, Mobile Source Control Division, 

at (626) 575-7004 or by email at mregenfu@arb.ca.gov. Legal questions should 

be directed to Alexander Wang, Senior Staff Counsel at (916) 323-9610, or by 

email at awang@arb.ca.gov.