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 On-Board Diagnostic Program

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CLEAN AIR ACT § 209(b) WAIVER REQUEST 

SUPPORT DOCUMENT SUBMITTED BY THE 

CALIFORNIA AIR RESOURCES BOARD

September 27, 2010 

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 appropriate action to grant 

California a waiver from the preemption set forth in CAA section 209(a), which 

prohibits states from adopting and enforcing emission standards relating to the 

control of emissions from new motor vehicles or new motor vehicle engines. At a 

public hearing on May 28, 2010, CARB, by Resolution 09-37 (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) and the adoption of a 

new enforcement regulation entitled “Enforcement of Malfunction and Diagnostic 

System Requirements for 2010 and Subsequent Model-Year Heavy-Duty 

Engines” (HD OBD Enforcement Regulation). The regulations are respectively 

codified at title 13, California Code of Regulations (Cal. Code Regs.) sections 

1971.1 and 1971.5. 1 After, proposing modifications to the regulations on 

October 29, 2009, the Board formally adopted the amended HD OBD 

Requirements and the new HD OBD Enforcement Regulation on April 5, 2010. 

The California Office of Administrative Law approved the amendments and the 

new regulation on May 18, 2010, and they became operative on June 17, 2010, 

after being certified by the California Secretary of State. 

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

issued a waiver under CAA section 209(b) in August 2008.2

 The regulation, as 

initially adopted, required manufacturers to install a fully compliant HD OBD 

 

1

 Unless otherwise noted, all section references are to title 13, CCR section 1971.1. 

2

 The decision was signed on August 13, 2008 and published at 73 Fed.Reg. 52042 (September 

8, 2008). 
Waiver Request Support Document 

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system on 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 are to be phased in on a single engine family for model years 

2010 through 2012 before requiring manufacturers to incorporate fully 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. 

Among other things, the initially adopted regulation requires engine 

manufacturers to do the following on vehicles subject to the 2010 model-year 

phase-in: 

• Implement OBD systems that monitor for engine misfire as well as 

emission-related malfunctions in various systems, including, but not 

limited to, fuel injection, catalyst, turbocharging, exhaust gas recirculation 

(EGR), particulate matter (PM) filter, cooling, and variable valve timing and 

control (VVT). 

• Calibrate major emission control monitors so that malfunctions are 

detected before tailpipe emission levels exceed thresholds correlated to 

certification emission standards. 

• Design the OBD system to monitor other emission-related components 

and systems for proper performance and functionality. 

• Conduct post-assembly testing on a sample of production engines and 

vehicles to ensure that the OBD systems, as built, are able to properly 

detect malfunctions, store the appropriate fault codes, and illuminate the 

MIL. 

• Use a standardized methodology to determine and track whether most 

OBD monitors operate with sufficient frequency during in-use driving. 

Sections II and III of this document respectively describe the amendments to the 

HD OBD Requirements and the new HD OBD Enforcement Regulation. Section 

IV first 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, including the 

criteria it considers in confirming that amendments fall within the scope of 

previously granted waivers. Section IV then presents CARB’s analysis that the 

amendments to the HD OBD Requirements fall within the scope of the HD OBD 

waiver granted in August 2008. Alternatively, CARB requests that the 

Administrator confirm, at a minimum, that those amendments which relax the 

stringency of or clarify previously waived requirements fall within the scope of the 

previously granted waiver and that a new waiver be granted for those 

requirements that are determined to create new, more stringent requirements. 

Finally, CARB requests that the Administrator confirm that the HD OBD 

Enforcement Regulation is within the scope of the previously granted HD OBD 

waiver. 
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II. SUMMARY OF AMENDMENTS TO HD OBD REQUIREMENTS3

In amending the HD OBD regulation, the Board addressed recent developments 

in HD OBD technology. The amendments include revisions to several of the 

monitoring requirements for diesel engines to ensure that the requirements are 

technologically feasible in the lead time provided. These amendments include 

changes that relax the malfunction thresholds until 2013 model year for three 

major emission controls: PM filters, oxides of nitrogen (NOx) catalysts, and NOx 

sensors. The Board also recognized that it was necessary to provide 

manufacturers with greater lead time in several instances to allow for proper 

development of emission control strategies. In this regard, the Board approved 

amendments to delay certain monitoring requirements, including those that apply 

to catalyst-based components, until 2013. With better understanding of 

emission control strategies that manufacturers will be using in 2010 and later 

model-year engines, the Board further amended the regulation to address these 

new strategies. For example, the Board amended the regulation to expand the 

monitoring requirements for EGR and boost control system strategies. Finally, 

the regulation has been amended, as necessary, to provide clarification to the 

initially adopted regulation. A summary of the substantive amendments is 

provided below. 

A. General Requirements. 

1. Malfunction Indicator Light (MIL) and Fault Codes 

a. Sections (d)(2.2.1)(E) and (d)(2.2.2)(E): MIL Illumination and Fault 

Code Storage Protocol. 

The sections were relaxed to allow manufacturers to delay illumination of the MIL 

when the engine has entered a default or “limp home” mode of operation that can 

affect emissions or the performance of the OBD system. Formerly, the OBD 

system was required to illuminate and store a fault code within 10 seconds of 

detecting such a condition. Under the amendments, illumination is not required 

until the condition causing the default or “limp home” mode of operation is again 

detected before the end of the next driving cycle. 

b. Sections (d)(2.3.1)(C) and (d)(2.3.2)(A) and (D): Malfunction 

Indicator Light (MIL) Extinguishing and Fault Code Erasure 

Protocol. 

 

3

 A detailed discussion of the adopted HD OBD Requirements and the HD OBD Enforcement 

Regulation discussed in Section III, infra, is set forth in the Staff Report: Initial Statement of 

Reasons (Staff Report) issued on April 10, 2009, the Notice of Availability of Modified Text issued 

on October 29, 2009 (15-Day Notice), and the Final Statement of Reasons (FSOR), issued on 

April 5, 2009. Copies of the aforementioned documents are enclosed herewith. 
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Sections (d)(2.3.1)(C) and (d)(2.3.2)(D) were amended to clarify the protocol for 

erasing permanent fault codes to ensure consistent implementation by 

manufacturers and consistent methods to be followed by repair technicians in 

preparing vehicles for re-inspection. The proposed amendments would, in 

general, only allow a permanent fault code to be erased once the vehicle has run 

and passed the relevant monitor and has been driven a minimum amount (i.e., 

an amount sufficient to meet the criteria of a general denominator of 

§1971.1(d)(4.3.2)(B)).4

 

The amendments to section (d)(2.3.2)(A) clarify that diesel fuel system monitors 

use a different MIL extinguishing protocol than the standard protocol used by 

other monitors. 

c. Section (d)(2.4.1)(A): Exceptions to MIL and Fault Code 

Requirements 

The amendments eliminate a circular reference and clarify that the exemption 

from MIL illumination for default strategies is not allowed if the engine enters a 

default strategy that is caused by or invoked to protect a component required to 

be monitored by the OBD system. 

2. General Monitoring Requirements – Sections (d)(3.1.3) and (d)(3.2.1): 

Monitoring Conditions for All Engines 

Section (d)(3.1.3), as initially adopted, allowed manufacturers to use monitoring 

conditions that are not encountered on the Federal Test Procedure (FTP) cycle if, 

among other things, they were able to demonstrate that their monitoring 

conditions would meet the minimum acceptable in-use monitor performance ratio 

requirements. The amendments clarify that manufacturers may include in-use 

driving data that meet the minimum requirements. 

The amendments to section (d)(3.2.1) add new requirements for tracking and 

reporting of diesel fuel systems, specifically diesel fuel pressure and secondary 

oxygen sensor monitors starting with the 2013 model year.5

 

3. In-Use Monitor Performance Ratio Definition 

a. Section (d)(4.2.2)(F): Numerator Specifications 

The amendments clarify how monitors that use an exponentially weighted 

moving average (EWMA) strategy for MIL illumination are to increment the 

numerator after a reset or erasure of the EWMA result. Specifically, following 

this reset or erasure, the numerator cannot increment until the requisite number 

of decisions necessary for MIL illumination have been met. Previously, monitors 

 

4

 Staff Report at pages 48-49. 

5

 See Id., at pages 12-14 and 32-35. 
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that used the EWMA strategy had to submit and receive CARB staff approval for 

their plan for incrementing the numerator of the in-use performance monitoring 

ratio. The amendments set forth the criteria that CARB has followed in approving 

such plans. 

b. Section (d)(4.3.2)(B)(ii) and (iv): In-Use Performance Ratio 

Performance Definition. 

Currently, the HD OBD 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. 

To address engine manufacturers concerns regarding the definition of the 

denominator drive cycle for diesel engines, the definition was amended to delete 

the five cumulative minutes above a calculated 15 percent load parameter and 

replace it with a parameter of five cumulative minutes of engine speed at or 

above 1150 rpm. Alternatively, manufacturers could elect to continue to use the 

15 percent load parameter through the 2012 model year. 

c. Sections (d)(4.3.2)(B)(iii), (E), (F), (G), and (H): -- Incrementing the 

Denominator. 

Currently, the HD OBD regulation requires manufacturers to track monitor 

performance by calculating the ratio of the number of monitoring events (the 

numerator) and the number of driving events (the denominator). The definition of 

“idle” operation in section (d)(4.3.2)(B)(iii), which is used in determining the 

denominator in tracking performance of the diesel PM filter/NMHC catalyst was 

relaxed to define idle operation in terms of revolutions per minute as well as 

vehicle speed.6

 

Section (d)(4.3.2)(E) was relaxed overall by adding additional criteria7

 that 

manufacturers must follow in incrementing the denominator and by allowing 

manufacturers to use the denominator criteria of the OBD II regulation.8

 

Section (d)(4.3.2)(F) was relaxed by adding additional components/monitors – 

temperature sensor rationality monitors and PM filter frequent regeneration 

monitors – to the list of components/monitors for which a manufacturer may 

request Executive Officer approval to use alternate or additional criteria for 

incrementing the denominator. 

 

6 Id., at page 66. 7

 Adding additional criteria is a relaxation because it results in the denominator incrementing less 

often with the consequence that the performance ratio will be larger and more likely to be in 

compliance. 

8

 15-Day Notice, at page 5. 
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Section (d)(4.3.2)(G) was relaxed by adding the diesel NMHC converting catalyst 

used for other aftertreatment assistance functions to the list of 

components/monitors that are required to meet the criteria of this section before 

the HD OBD system is required to increment the in-use performance 

denominator.9 Additionally the regulation, as initially adopted, required 

manufacturers to request Executive Officer approval for proposed alternate 

criteria to increment the denominator for PM filters and NMHC converting 

catalysts. The amendments clarify manufacturer obligations by specifically 

setting forth acceptable denominator-incrementing criteria that CARB has 

previously approved under the regulation since initial adoption. Finally, the 

Board amended the section to set forth an additional specific criterion that 

manufacturers must follow in incrementing the denominator for PM filter 

monitors. In the past, manufacturers needed to obtain Executive Officer approval 

for the use of additional criteria beyond the general denominator criteria. The 

amendments replace that provision with a specific requirement that before the 

denominator may be incremented, the denominator of the PM filter monitor must, 

in addition to meeting the general denominator criteria, the engine must have 800 

minutes of cumulative run time.10

Section (d)(4.3.2)(H) was relaxed by requiring additional criteria to be met before 

the HD OBD system needs to increment the in-use monitor performance 

denominators for monitors that rely on regeneration events.11 

 

d. Section (d)(4.5.3): Disablement of Numerators and Denominators 

This section allows the HD OBD system to disable incrementing of the 

numerators and denominators if a fault of a component used to determine the 

incrementing criteria in sections (d)(4.3.2)(B) and (C) is detected. The 

amendments clarify that this is defined as a pending, confirmed, or MIL-on fault 

code being stored for this component. 

5. Standardized Tracking and Reporting of Monitor Performance – 

Section (d)(5.1.2): 

This section lists the specific monitors on gasoline engines that are required to 

track and report the in-use monitor performance data. The amendments clarify 

that “oxygen sensor bank 1 and 2” are referring to the “primary” oxygen sensors. 

 

9

 Staff Report, at pages 65-66 and 15-Day Notice, at pages 5-6. 

10 Id., at pages 63-66, and Notice of Availability of Modified Text (15-Day Notice), at page 5. 

Although the specific 800-minute cumulative run-time requirement is a new requirement, this 

requirement is effectively no more stringent than what was previously allowed by the Executive 

Officer. 

11 15-Day Notice, at page 6. 
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6. Section (d)(6.2.3): Malfunction Criteria Determination, Alternatives for 

Calculating Infrequent Regeneration Adjustment Factors (IRAFs) 

The regulation, as initially adopted, required that manufacturers must follow 

certain procedures on engines equipped with emission controls that experience 

infrequent regeneration events. Specifically, they were required to adjust the 

emission test results used to determine the malfunction criterion for those 

monitors that indicate a malfunction before emissions exceed a certain emission 

threshold. The amendments relax these requirements to allow manufacturers to 

use alternative methods to calculate the adjustment factors for determining the 

adjusted emission values in addition to the procedures described in CFR title 40, 

part 86.004-28(i). 

B. Monitoring Requirements for Diesel/Compression-Ignition Engines. 

1. General – Sections (e)(1.2.4), (e)(3.2.4), (e)(4.2.5), (e)(6.2.2)(D), 

(e)(7.2.3), (e)(8.2.7), (e)(9.2.1)(A)(iii),(B)(iii), (e)(9.2.2)(C): Feedforward control 

The amendments clarify that, as used in the regulation, the term feedback control 

also refers to feed-forward control. 

2. Fuel System Monitoring 

a. Section (e)(1.2.7): Determining Malfunction Criteria 

The regulation, as initially adopted, intended that manufacturers determine the 

appropriate malfunction criteria for monitoring fuel pressure, fuel quantify, and 

timing by calibrating the vehicle’s fuel system to both single injector faults and 

faults that affect all cylinders equally. The amendments relax the requirements to 

allow manufacturers in model years 2010-2012 to elect to calibrate for either 

single injector faults or faults that affect all cylinders. They would not be required 

to monitor both types of faults until the 2013 model year.12 

b. Section (e)(1.3.2): Monitoring Fuel Injectors that Build Pressure 

Internally. 

Recognizing that it would be difficult to continuously monitor the fuel pressure on 

fuel injection systems that achieve injection fuel pressure within the injector or 

increase pressure within the injector, the Board amended the regulation to allow 

once per trip monitoring of fuel pressure rather than continuous monitoring.13

c. Section (e)(1.3.4): Disabling of Continuous Monitoring 

 

12 Staff Report, at page 13. 13 Id. 
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The regulation was amended to allow manufacturers, upon Executive Officer 

approval, to temporarily disable continuous monitoring to ensure robust detection 

of malfunctions and to avoid false passes and false indications of malfunctions.14 

d. Section (e)(1.4.2): MIL Illumination and Fault Code Storage for 

Diesel Fuel System Monitoring 

The amendments added a MIL illumination and fault code storage protocol for 

fuel pressure control monitoring that is similar to the current requirements for 

gasoline fuel system monitoring. Specifically, the amendments require fault 

detection to be more robust for failures that occur within specific operating 

conditions by requiring subsequent monitoring in the same operating conditions 

before a fault is confirmed or erased.15 

3. Misfire Monitoring, Section (e)(2.2.4): Multi-cylinder Misfire 

The requirements for misfire monitoring were relaxed when multiple cylinder 

misfire occurs that results in a misfire rate greater than or equal to 50 percent of 

all engine firings. In such situations, the HD OBD system would only be required 

to detect malfunctions caused by a single component failure. 

4. EGR System Monitoring 

 

a. Section (e)(3.1.2): General Requirements 

The intent of HD OBD regulation is that HD OBD systems detect virtually any 

malfunction that leads to an emission increase. The regulation, as initially 

adopted, required manufacturers to monitor faults that disable, prevent, or delay 

EGR from properly operating and faults that cause the strategies to reach 

adaptive or authority limits that make it unable to achieve the desired goal under 

conditions where it should be able to achieve them. The amendments clarify this 

intent by specifically stating that, if there is an emission control strategy being 

used by the engine, manufacturers should, to the extent possible, monitor this 

strategy for proper operation. 

b. Sections (e)(3.2.1) and (3.2.2): Malfunction Criteria for EGR Low 

and High Flow 

The regulation, as initially adopted, required functional monitoring of EGR system 

low flow and high flow faults if faults did not cause emissions to exceed the 

emission malfunction thresholds. Specifically, a malfunction was required to be 

detected if the EGR system had reached its control limits such that it could not 

increase or decrease EGR flow to achieve the commanded flow rate. In 

response to questions from manufacturers as to what is covered under functional 

 

14 Id., at page 47. 15 Id., at page 14. 
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monitoring for non-feedback controlled EGR systems, the requirement was 

clarified to require detection of a malfunction when there is either no detectable 

amount of EGR flow when EGR flow is expected or when there is to much EGR 

flow when little or none is expected. 

c. Section (e)(3.2.3): Malfunction Criteria for EGR Slow Response 

The amendments clarify what an EGR system “slow response” malfunction is. 

Specifically, it is a malfunction if the EGR system cannot achieve the specified 

flow rate within a manufacturer-specified time. The amendments also clarify that 

HD OBD systems are to detect slow response faults under both increasing and 

decreasing EGR flow rate conditions. 

d. Section (e)(3.2.6): Malfunction Criteria for EGR Catalyst 

Performance 

The amendments require that manufacturers monitor EGR catalysts beginning 

with the 2013 model year if such components are used.16

e. Section (e)(3.2.9): Malfunction Criteria for EGR Cooler Performance 

The regulation originally envisioned that systems using an EGR cooler would 

utilize a single EGR cooler and structured the language accordingly. However, 

as manufacturers developed their engines, many started to use configurations 

with multiple individual coolers in series and had several questions on how to 

interpret the requirements (e.g., applying the monitoring requirements to each 

cooler independent of the others or to the collective EGR cooler system). This 

amendment clarifies the requirements for multiple cooler systems. Under the 

amendments, manufacturers are to consider the coolers as a system and present 

monitoring plans for review and approval that consider the typical aging and 

deterioration mechanisms and patterns that will affect the system of coolers. 

f. Section (e)(3.3.4): EGR Monitoring Requirements 

This section, as initially adopted, allowed manufacturers to temporarily disable 

continuous monitoring of EGR system faults under specific conditions in which it 

is difficult to distinguish properly-working EGR systems from failing EGR 

systems. The amendments clarify the situations in which disablement is 

appropriate (e.g., disable EGR low flow monitoring when no or very little flow is 

commanded). 

5. Boost Pressure Control System Monitoring 

a. Section (e)(4.1.2): General Requirements 

 

16 Id., at pages 14-15. 
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See discussion above in section B.4.a. 

b. Sections (e)(4.2.1) and (e)(4.2.2): Under and Over Boost Pressure 

The regulation, as originally adopted, required functional monitoring of under and 

overboost faults of the boost pressure control system if faults did not cause 

emissions to exceed the emission malfunction thresholds. Specifically, a 

malfunction was required to be detected if the boost system had reached its 

control limits such that it could not increase or decrease boost to achieve the 

commanded boost pressure. In response to questions from manufacturers as to 

what is covered under functional monitoring, the Board amended the regulation 

to clarify that for non-feedback controlled boost systems, a malfunction is 

required to be detected when there is either no detectable amount of boost when 

boost is expected or when there too much detectable boost when little or no 

boost is expected. 

c. Section (e)(4.2.3): Boost Pressure Slow Response Rate 

The regulation, as originally adopted, required only boost systems using variable 

geometry turbochargers (VGT) to be monitored for slow response failures. 

CARB staff subsequently determined that malfunctions that delay the boost 

pressure control system from achieving desired boost levels can affect 

emissions, regardless of the boost system architecture. Accordingly, for the 

2013 model year, manufacturers are required to monitor the boost pressure 

control system for slow response failures regardless of whether the system uses 

a VGT. The regulation was further amended to require manufacturers to use 

specific criteria based on the response of the system to achieve the actual boost 

rather than on the response of one of the individual actuators to achieve a certain 

position.17 

d. Section (e)(4.2.8): Boost Pressure Charge Air Cooling Performance 

Identical to the amendment made in section (e)(3.2.9) for EGR coolers listed 

above, this amendment clarifies the requirements for systems utilizing multiple 

charge air coolers in lieu of a single charge air cooler. 

e. Section (e)(4.3.4): Disablement of Continuous Boost Pressure 

Monitoring 

The regulation was amended to allow manufacturers, upon Executive Officer 

approval, to temporarily disable continuous monitoring to ensure robust detection 

of malfunctions and to avoid false passes and false indications of malfunctions.18 

 

17 Id., at page 15. 18 Id. 
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6. NMHC Converting Catalyst Monitoring 

a. General 

To be consistent with the OBD II regulation update in 2006, the amendments add 

specific language detailing the requirements for manufacturers to functionally 

monitor an NMHC-converting catalyst used to prevent ammonia slip downstream 

of an SCR system. Under the regulation, as initially adopted, all NMHCconverting catalysts were to be monitored (under the “Other Emission Control 

System” monitoring requirements) but specific criteria were only provided for the 

most common types of catalysts such as catalysts used to generate an exotherm 

for PM filter regeneration or catalyzed PM filters. 

b. Section (e)(5.2.2)(B): Conversion Efficiency 

The amendments added specific NOx thresholds for detecting malfunctions of 

the NMHC converting catalyst in addition to the preexisting NMHC detection 

thresholds. Specifically, starting with the 2013 model year, manufacturers are to 

detect a fault before NMHC emissions exceed 2.0 times the applicable standard 

or NOx emissions exceed the applicable NOx standard by more than 0.2 gram 

per brake horsepower hour (g/bhp-hr), whichever occurs first.19 

c. Section (e)(5.2.3)(B): Delay Implementation Start Date to 2013. 

The regulation, as initially adopted, provided that, starting in the 2010 model 

year, manufacturers were to monitor catalysts that were used to generate a feedgas constituency to assist SCR systems. The start date for monitoring has been 

delayed until the 2013 model year.20

d. Section (e)(5.2.4)(A) and (B): Aging of NMHC Converting Catalyst 

Monitor 

In order to determine the malfunction criteria for NMHC catalyst monitoring, the 

regulation, as initially adopted, required manufacturers to age catalysts using 

methods representative of catalyst deterioration in-use. The amendments clarify 

that for catalyst systems with catalysts in parallel, the parallel catalysts are to be 

simultaneously deteriorated. 

7. NOx Converting Catalyst Monitoring 

a. Section (e)(6.2.1)(A): Conversion Efficiency Monitoring - Increase 

NOx Threshold 

 

19 Id., at pages 16-21. 20 Id., at pages 19-20. 
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The regulation originally required 2010 through 2012 model year engines to 

detect NOx catalyst conversion efficiency faults before emissions exceeded the 

applicable NOx standard by more than 0.3 g/bhp-hr. The amendments increase 

the threshold to the applicable NOx standard plus 0.4 g/bhp-hr.21

b. Section (e)(6.2.1)(B): Detection of NMHC Emissions Increase 

Section (e)(6.2.1)(B) was amended to add specific NMHC thresholds for 

detection of malfunctions of the NOx converting catalyst in addition to the 

preexisting NOx detection thresholds starting in the 2013 model year. 

Specifically, NOx converting catalyst malfunctions must be detected before NOx 

emissions exceed the applicable NOx standard by more than 0.2 g/bhp-hr or 

NMHC emissions exceed 2.0 times the applicable standard, whichever occurs 

first.22 

c. Section (e)(6.2.2)(A): Detection of Reductant Delivery Malfunctions 

Section (e)(6.2.2)(A) was amended to add specific NMHC emission thresholds 

for detection of malfunctions of the selective catalytic reduction delivery system 

catalyst in addition to the preexisting NOx detection thresholds starting in the 

2013 model year. Specifically, malfunctions of the reductant delivery system 

must be detected before NOx emissions exceed the applicable NOx standard by 

more than 0.2 g/bhp-hr or NMHC emissions exceed 2.0 times the applicable 

standard, whichever happens first.23

d. Section (e)(6.2.2)(A): SCR or Other Active/Intrusive Reductant 

Injection System Performance Monitoring – Increase NOx 

Threshold 

The regulation originally required 2010 through 2012 model year engines to 

detect reductant delivery performance faults before emissions exceeded the 

applicable NOx standard by more than 0.3 g/bhp-hr. The amendments increase 

the threshold to the applicable NOx standard plus 0.4 g/bhp-hr.24

e. Section (e)(6.2.3)(A) and (B): Aging of NOx Converting Catalyst 

Monitor 

In order to determine the malfunction criteria NOx catalyst monitoring, the 

regulation, as initially adopted, required manufacturers to age catalysts using 

methods representative of catalyst deterioration in-use. The amendments clarify 

that for catalyst systems with catalysts in parallel, the parallel catalysts are to be 

simultaneously deteriorated. 

 

21 Id., at page 22. 22 Id., at page 24 23 Id., at pages 21-24. 24 Id.
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d. Section (e)(6.3.1): Once Per Trip Monitoring for Improper Reductant 

Recognizing that it would be difficult to continuously monitor for faults where an 

improper reductant is being used, the regulation was amended to allow once per 

trip monitoring of this fault. 

e. Section (e)(6.3.3): Disablement of Continuous Monitoring 

In addition to specifically providing that reductant monitoring need only occur 

once per trip, the regulation was amended to allow manufacturers, upon 

Executive Officer approval, to temporarily disable continuous monitoring of other 

malfunctions to ensure robust detection of malfunctions and to avoid false 

passes and false indications of malfunctions. 25

8. NOx Adsorber Monitoring 

 

a. Section (e)(7.2.1)(B): NMHC Thresholds 

The section was amended to add specific NMHC thresholds for detection of 

malfunctions of the NOx adsorbers in addition to the preexisting NOx detection 

thresholds starting in the 2013 model year. Specifically, NOx converting catalyst 

malfunctions must be detected before NOx emissions exceed the applicable NOx 

standard by more than 0.2 g/bhp-hr or NMHC emissions exceed 2.0 times the 

applicable standard, whichever occurs first. 26 

b. Section (e)(7.2.6): Multiple NOx Adsorber System Aging 

The regulation, as initially adopted, required monitoring of the NOx adsorber 

capability. The amendments clarify that manufacturers must submit their aging 

and monitoring plans to CARB for approval to make sure that they are calibrating 

the malfunction criteria correctly, that the aging of the adsorber is representative 

of aging in-use, and that the monitor is able to pinpoint the adsorber at fault. 

c. Section (e)(7.3.3): Disablement of Continuous Monitoring 

The regulation was amended to allow manufacturers, upon Executive Officer 

approval, to temporarily disable continuous monitoring to ensure robust detection 

of malfunctions and to avoid false passes and false failures.27 

9. PM Filter Performance Monitoring 

a. Section (e)(8.2.1)(A): Increasing PM Threshold 

 

25 Id., at page 47. 26 Id., at page 25. 27 Id. 
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The regulation originally required 2010 through 2012 model year engines to 

detect PM filter performance faults before emissions exceeded either 

0.05 g/bhp-hr from an applicable emission-test cycle or the applicable PM 

standard plus 0.04 g/bhp-hr. The amendments increase the threshold to either 

0.07 g/bhp-hr or the applicable PM standard plus 0.06 g/bhp-hr.28

b. Section (e)(8.2.2)(B): NMHC and NOx Monitoring. 

The amendments added specific oxides of nitrogen (NOx) thresholds for 

detection of malfunctions of the PM filter in addition to the preexisting NMHC 

detection thresholds. Specifically, starting with the 2013 model year, 

manufacturers are required to detect a fault before NMHC emissions exceed 2.0 

times the applicable standard or NOx emissions exceed the applicable NOx 

standard by more than 0.2 g/bhp-hr, whichever occurs first.29

c. Section (e)(8.2.4): NMHC Conversion Monitoring – Delay 

Implementation Start Date to 2013 

The regulation had provided that starting in the 2010 model year manufacturers 

were to monitor catalyzed PM filters for proper NMHC conversion capability. The 

start date for monitoring has been delayed until the 2013 model year.30 

d. Section (e)(8.3.2): Continuous Monitoring 

The regulation, as originally adopted, required that PM filter feedback control 

faults be monitored whenever the conditions for monitoring were met during the 

driving cycle. However, by definition, monitoring of feedback control faults can 

only be achieved if the monitor runs continuously. The amendments clarify that 

these faults must be monitored continuously. 

e. Section (e)(8.3.3): Disablement of Continuous Monitoring 

The regulation was amended to allow manufacturers, upon Executive Officer 

approval, to temporarily disable continuous monitoring to ensure robust detection 

of malfunctions and to avoid false passes and false indications of malfunctions.31 

10. Exhaust Gas Sensor Monitoring – Section (e)(9.2.2): NOx and PM 

Sensors 

The regulation, as originally adopted, required manufacturers to establish specific 

monitoring requirements for NOx sensors while PM sensors were covered under 

 

28 Id., at page 26. 29 Id., at pages 28-29. 30 Id., at pages 18-19. 31 Id., at page 47. 
Waiver Request Support Document 

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section (e)(9.2.3). The latter section required manufacturers to submit a 

monitoring plan for approval. Staff subsequently determined that the monitoring 

requirements for NOx sensors were also applicable to PM sensors, so the 

amendments clarify that the monitoring requirements of section (e)(9.2.2) apply 

to both NOx and PM sensors. Additionally, the regulation originally required 

2010 through 2012 model year engines to detect NOx sensor performance faults 

before emissions exceeded the applicable NOx standard by more than 0.3 g/bhphr. The amendments increase the threshold to the applicable NOx standard plus 

0.4 g/bhp-hr.32

11. Cold Start Emission Reduction Strategy Monitoring – Section (e)(11) 

The amendments added section (e)(11), which requires manufacturers to monitor 

cold start emission reduction strategies starting with the 2013 model year. If an 

engine incorporates such strategies, the OBD system must be capable of 

monitoring the system to verify that the selected strategy achieves its desired 

goals (e.g., accelerated catalyst light-off temperature) and that the strategy’s 

commands to required elements of implementation of the strategy (e.g., engine 

speed or ignition timing) are carried out as directed. Malfunction criteria include 

the inability of a required element to respond to a command and a failure or 

deterioration of the strategy that causes NMHC, NOx, or carbon monoxide (CO) 

emissions to exceed 2.0 times the applicable standards or the PM emissions to 

exceed the applicable standard plus 0.02 g/bhp-hr.33 

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

1. Fuel System Monitoring 

a. Section (f)(1.2.1)(B): Malfunctions of Feedback Control System 

The regulation, as initially adopted, section (f)(1.2.1) required that manufacturers 

detect malfunctions of the fuel delivery system, including malfunctions of 

feedback control based on the performance of secondary oxygen sensors. The 

amendments separately list secondary feedback control faults, but the 

malfunction threshold for determining a fault remains at 1.5 times the applicable 

standard. 

b. Sections (f)(1.2.1)(C): Malfunctions Caused by Air-Fuel Ratio 

Cylinder Imbalance 

The amendments require that manufacturers detect air-fuel cylinder imbalances 

that cause the fuel delivery system to be unable to maintain tailpipe emissions 

below a specified emission level. To provide manufacturers sufficient lead time 

to comply with the new requirements, section (f)(1.2.1)(C) allows manufacturers 

 

32 Id., at page 22. 33 Id., at pages 35-37. 
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to phase-in the requirement during the 2014-2016 model years with a 

malfunction threshold of 3.0 times the standards. All engines covered by the 

section are required to meet the final threshold of 1.5 times the standards in the 

2017 model year.34 

c. Sections (f)(1.2.5): Engine Shut-Off Strategies Not Requiring 

Restart (Hybrids) 

The originally adopted regulation requires manufacturers to detect a malfunction 

whenever the fuel system fails to enter closed-loop operation within a certain 

amount of time after “engine start.” For hybrid vehicles with engine shutoff 

strategies that do not require the driver to restart the engine to continue driving 

(e.g., a vehicle that turns off the engine at idle and restarts the engine when the 

vehicle starts to move again), it wasn’t clear as to whether this requirement 

applied to these engine restarts. The amendments clarify that manufacturers are 

required to detect faults that occur after such restarts.35

d. Sections (f)(1.3.1) to (1.3.4): Monitoring Conditions 

The regulation, as initially adopted, had a general provision requiring that the fuel 

system was to be monitored continuously. The amendments specifically identify 

different types of malfunctions that must now be monitored, and the regulation 

now specifically identifies specific monitoring conditions for each type of 

malfunction. 

e. Section (f)(1.3.5): Disablement of Continuous Monitoring 

The regulation was amended to allow manufacturers, upon Executive Officer 

approval, to temporarily disable continuous monitoring to ensure robust detection 

of malfunctions and to avoid false passes and false failures.36 

f. Section (f)(1.4.5)(B): Similar Conditions Definition for Secondary 

Feedback Control Faults 

The regulation was amended to allow manufacturers to use an alternate 

definition of “similar conditions” in lieu of the definition in section (c) for fuel 

system faults detected using feedback control based on a secondary oxygen (or 

equivalent) sensor.37 

2. Misfire Monitoring 

a. Section (f)(2.2.1)(C): Multi-cylinder Misfire 

 

34 Id., at page 30. 35 Id. 

36 Id., at page 47. 37 Id., at page 14. 
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The requirements for misfire monitoring were relaxed when multiple-cylinder 

misfire occurs that results in a misfire rate greater than or equal to 50 percent of 

all engine firings. In those situations, the amendments require the HD OBD 

system to detect only those malfunctions caused by a single component failure. 

b. Section (f)(2.3.1)(B): Monitoring While Under Positive-Torque 

Conditions 

The regulation originally required the HD OBD system to monitor for misfire at all 

times while engine speed rises and settles before the engine reaches the desired 

idle engine speed at engine start-up. The amendments limit this to just positivetorque conditions.38

c. Section (f)(2.3.5): Hybrid Vehicle Misfire Monitoring 

Under the regulation, as originally adopted, manufacturers were required to start 

misfire monitoring no later than the end of the second crankshaft revolution after 

“engine start.” For hybrid vehicles with engine shutoff strategies that don’t 

require the driver to restart the engine to continue driving (e.g., a vehicle that 

turns off the engine at idle and restarts the engine when the vehicle starts to 

move again), it wasn’t clear whether this requirement applied to these engine 

restarts. The amendments clarify that the manufacturer must design the HD 

OBD system to start misfire monitoring no later than the end of the second 

crankshaft revolution after each these engine restarts. 

3. Cold Start Emission Reduction Strategy Monitoring – Section (f)(4.2.2) 

The section was amended to add more specific requirements starting with the 

2013 model year. The changes parallel those discussed above in section 

II.B.11.39 

4. Secondary Air System Monitoring – Section (f)(5.1.2): Exemption from 

Monitoring: 

For engines using secondary air systems with multiple air flow paths, the 

amendments would exempt monitoring of air flow to each bank if complete 

blockage of air delivery to one bank does not cause a measurable emissions 

increase.40

5. Evaporative System Monitoring 

a. Section (f)(7.1): General Requirements 

 

38 Id., at page 31. 39 Id., at pages 35-37. 40 Id., at page 32. 
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The amendments clarify that vehicles without evaporative systems are not 

subject to this section. 

b. Section (f)(7.2.5): Multiple Purge Flow Paths 

The regulation, as initially adopted, required monitoring of the purge flow from the 

evaporative system to the engine. The amendments clarify that manufacturers 

must monitor all purge flow paths. 

6. Exhaust Gas Sensor Monitoring – Sections (f)(8.2.1)(A) and (f)(8.2.2): 

Malfunction Criteria for Primary and Secondary Sensors 

The HD OBD regulation, as initially adopted, detailed specific monitoring 

requirements that applied to all “exhaust gas sensors,” with monitoring 

requirements split for exhaust gas sensors that are considered “primary” sensors 

and those considered “secondary” sensors. Since gasoline engines are 

generally not expected to utilize other exhaust gas sensors as much as oxygen 

sensors, the section was amended to set forth specific requirements for primary 

and secondary oxygen sensors and require manufacturers to submit a plan to the 

Executive Officer for other exhaust gas sensors. 

CARB amended section (f)(8.2.1)(A) to also clarify the regulation’s existing 

requirement that manufacturers are required to monitor a primary oxygen 

sensor’s response rate for both asymmetric and symmetric malfunctions. The 

amendments identify the six types of response rate fault conditions that the HD 

OBD system must detect. Under the initially adopted regulation, manufacturers 

were to determine an appropriate response monitor threshold(s) to ensure that all 

response failures are detected prior to exceeding 1.5 times the standards. 

Beginning in the 2013 model year, manufacturers are required to submit data 

and/or documentation demonstrating that they have used a calibration method 

that ensures that these criteria have been satisfied.41

Section (f)(8.2.2)(C) was amended to clarify the monitoring requirements of 

secondary oxygen sensors and what is meant by the previously adopted 

requirement that the OBD system “detect a malfunction of the exhaust sensor 

when the sensor [is] no longer sufficient for use as an OBD system monitoring 

device [for other monitoring systems] (e.g., for catalyst monitoring.” The 

amendment clarifies that the OBD system must be designed to detect failures of 

the secondary sensor, with failure being defined as the secondary sensor not 

able to detect the best-performing unacceptable system or component (e.g., a 

catalyst deteriorated right to the emission detection threshold).42 

 

41 Id., at pages 32-33. 42 Id., at pages 33-35. Arguably, this clarification is not a new more stringent requirement, but just 

an explanation of the previously adopted language that was subsequently waived by EPA. This 

is especially true given the new “relaxed provisions of subparagraphs (f)(8.2.2)(C)(ii) and (iii). 
Waiver Request Support Document 

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D. Monitoring Requirements for All Engines. 

1. Engine Cooling System Monitoring 

a. Section (g)(1.2.1)(B) and (D): Malfunction Criteria for Thermostat 

Monitoring 

Under the amendment to section (g)(1.2.1)(B), starting with the 2016 model year, 

manufacturers must additionally have the OBD system monitor the engine 

coolant temperature (ECT) for failures that cause the ECT to drop below 

diagnostic enablement temperatures after they have initially been reached.43

To address manufacturers’ concerns about truck cabin heat or other sources 

affecting coolant warm-up at lower temperatures, section (g)(1.2.1)(D) was 

amended to allow manufacturers to desensitize the thermostat monitor on engine 

starts when temperatures are below 50 degrees Fahrenheit.44 

b. Section (g)(1.3.1)(B) and (E): Monitoring Conditions for Thermostat 

Monitoring 

Section(g)(1.3.1)(B) was added to address monitoring conditions that 

manufacturers are to follow consistent with ECT monitoring. See subparagraph 

a. above. 

Section (g)(1.3.1)(E), as initially adopted, required the thermostat to be monitored 

during conditions defined according to section (d)(3.1), which included 

requirements that ensured that monitoring occur under conditions that may 

reasonably be expected to be encountered during normal vehicle operation and 

during the FTP cycle. The amendments clarify that for thermostat monitoring the 

conditions that may be expected to occur during the FTP cycle, refers to on-road 

driving following the FTP cycle and does not refer to testing on an engine 

dynamometer. 

2. Crankcase Ventilation (CV) System Monitoring 

a. Section (g)(2.2.3): Exemption from Monitoring 

The amendments exempt manufacturers from monitoring a disconnection in the 

CV system if the disconnection results in a rapid loss of oil or any other overt 

indication of a CV system malfunction.45 

b. Section (g)(2.2.7): Malfunction Criteria 

 

43 Id., at page 39. 44 Id., at page 38. 45 Id., at pages 40-41. 
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The regulation originally required manufacturers of diesel engines to submit a 

monitoring plan for Executive Officer approval for their CV systems. Upon further 

review, staff determined that the requirements in this section, which were initially 

specific to gasoline engines, are also appropriate for most diesel engine CV 

systems. Thus, the regulation was amended to clarify that the criteria for 

gasoline engines also apply to all diesels engines, except those certified on an 

engine dynamometer with an open CV system. 

3. Comprehensive Component Monitoring 

a. Sections (g)(3.1.3) and (g)(3.1.4): Exemptions from Monitoring 

The amendments exempt manufacturers from having to monitor electronic 

components that are not related to fuel or emission control of the engine; 

specifically, those components that either are driven by the engine or can 

increase emissions only by increasing electrical demand or load on the engine 

are exempt from monitoring.46 

b. Section (g)(3.1.6): Vehicle Speed Information Monitoring 

Under the original requirements, if the engine manufacturer used vehicle speed 

information for another OBD monitor, they were required to comprehensively 

monitor this information. In response to engine manufacturers’ concerns about 

having to perform comprehensive monitoring of vehicle speed sensors located in 

the transmission over which they have no control, the amendments relaxed the 

regulation to require monitoring of vehicle speed information only to the extent 

that the engine manufacturer requires the OBD system to indicate a fault if the 

vehicle speed information was identified as faulty by diagnostics outside of the 

engine manufacturer’s OBD system (e.g., by the transmission supplier’s 

diagnostics).47 

c. Section (g)(3.2.1)(D): Malfunction Criteria for Input Components 

Not Otherwise Covered 

The intent of HD OBD regulation is that HD OBD systems detect virtually any 

malfunction that leads to an emission increase, so it would be inappropriate for 

systems to be certified with emission controls that are not monitored. Leading up 

to the 2009 Board hearing, staff had concerns that some manufacturers were 

designing OBD systems without monitoring certain aspects of the emission 

control system solely because those emission controls or aspects were not 

“specifically” identified in the regulation. Further, some manufacturers were not 

readily disclosing to ARB the presence of these controls or even considering 

OBD monitors for these emission controls or strategies. The amendments clarify 

the obligations of manufacturers by specifically stating that if there is an emission 

 

46 Id., at page 42. 47 Id., at pages 43-44 and 15-Day Notice, at pages 6-7. 
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control strategy being used by the engine, manufacturers are required, to the 

extent possible, to monitor the strategy for proper operation. 

 

d. Section (g)(3.2.2)(B)(ii): Malfunction Criteria for Diesel Idle Fuel 

Control Monitoring – Delay Implementation Start Date to 2013 - 

The regulation had provided that starting in the 2010 model year manufacturers 

were to monitor the diesel idle control for faults related to fuel injection quantity. 

The start date for monitoring has been delayed until the 2013 model year. 

e. Section (g)(3.2.2)(C): Malfunction Criteria for Glow Plug Monitoring 

– Delay Fault Code Implementation Start Date to 2013 

The amendments delay the start date for requiring manufacturers to store a fault 

code identifying the malfunctioning glow plug until the 2013 model year. 

f. Section (g)(3.2.2)(D): Deletion of Malfunction Criteria for MIL Circuit 

Monitoring Requirement 

Based on engine manufacturers’ concerns that they do not have control over the 

location of the MIL on the instrument panel, which is under the control of the 

heavy-duty vehicle manufacturer, and given the minimal additional benefit of 

monitoring the MIL during roadside inspections, the amendments deleted the 

monitoring requirement for MIL circuit faults.48 

g. Section (g)(3.2.2)(E): Malfunction Criteria for Output Components 

Not Otherwise Covered 

See subparagraph c. above. 

h. Section (g)(3.2.2)(F): Malfunction Criteria for Certain Output 

Components 

Finding that fuel control system components (e.g., injectors, fuel pumps) that 

have tolerance compensation features implemented in hardware or software 

during production or repair procedures are prone to erroneous or incomplete 

repairs, which can result in undetected increases in emission levels, the Board 

amended section (g)(3.2.2)(F) to ensure that the components are properly 

monitored. Under the amendment, manufacturers must start to monitor the fuel 

system components for proper compensation with the 2013 model year.49 

The regulation was further amended as it applies to engines manufactured in 

2013 and later model years to specify where diagnostic connectors on the 

vehicle must be located. The amendments additionally require the engine 

 

48 Id., at page 43. 49 Id., at page 44. 
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manufacturer to ensure that the vehicle can be operated while the diagnostic 

scan tool is connected to the connector. 

 4. Other Emission Control System Monitoring – Section 4.3: Malfunction 

Criteria for Components Not Otherwise Covered 

See subparagraph D.3.c. above. 

5. Comprehensive Component Monitoring. 

a. Section (g)(5.6): Disabling of Power Take-Off (PTO) 

Section (g)(5.6), as originally adopted, allowed manufacturers to disable affected 

monitoring systems in vehicles equipped with PTO while the PTO unit was active 

so long as the OBD readiness status was set to incomplete/not ready during the 

activation. The section was amended to require Executive Officer approval to 

disable affected monitors and to alter the handling of readiness status during and 

after the activation. Specifically, the Executive Officer approval is to be granted if 

disablement occurs only while the PTO unit is active, the manufacturer can show 

that the affected monitors cannot robustly operate while the PTO unit is active, 

and the OBD readiness status is retained/erased based on cumulative PTO 

operation of 750 minutes.50 

b. Section (g)(5.7): Exceptions to Monitoring Requirements 

Several sections in the regulation, as originally adopted, required manufacturers 

to monitor a component/system for a specific fault “to the extent feasible.” The 

amendments to section (g)(5.7) clarify and codify CARB’s practice in determining 

feasibility, which is based on “best available monitoring technology.” By 

definition, this does not include software or hardware technologies that are 

considered proprietary or confidential and known or able to be used only by a 

competitor. This has been CARB’s practice for almost a decade and ensures 

that equity is maintained among the manufacturers in meeting the requirements. 

E. Standardization Requirements 

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

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

incorporated by reference into the HD OBD regulation. As is common practice 

with technical standards, industry periodically updates the standards to add 

specification or clarity. 

2. Section (h)(2.2): Diagnostic Connector. 

 

50 15-Day Notice, at pages 3 and 7. 
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The regulation was amended as it applies to engines manufactured in 2013 and 

later model years to further specify where diagnostic connectors on the vehicle 

must be located. The amendments additionally require the engine manufacturer 

to ensure that the vehicle can be operated while the diagnostic scan tool is 

connected to the connector. 

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

a. Sections (h)(4.1) and (h)(4.1.4): Readiness Status 

The amendments clarify which monitors (e.g., circuit/out-of-range monitors, 

feedback control monitors) can be excluded from the determination of readiness 

status because they run continuously. 

b. Sections (h)(4.2.2)(E) and (F) and (h)(4.2.3)(B) and (D): Data 

Stream through Data Link Connector. 

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

manufactured in 2013 and later model years to require manufacturers to provide 

some additional data stream information. The HD OBD system on diesel 

vehicles would be required to provide information on such events as the status of 

PM filter regeneration, when regeneration is triggered, and how far a vehicle 

travels between regeneration events. The OBD system on both diesel and 

gasoline engines would be required, if so equipped, to report data stream 

information on such things as EGR temperature, reductant level, and NOx 

adsorber regeneration and desulfurization status. 51 

c. Section (h)(4.3.1): Freeze Frame 

This section refers to specific sections that contain requirements for freeze frame 

storage. The amendments add two sections (for diesel fuel system and diesel 

misfire monitoring) that were intended to be included, but mistakenly left out, 

when the regulation was initially adopted. 

d. Sections (h)(4.4.1)(D), (4.4.2)(D): Fault Code Storage and 

Availability on Scan Tool 

The regulation, as initially adopted, required a permanent fault code to be stored 

and made available to an SAE J1978 scan tool no later than the end of an 

ignition cycle in which the corresponding confirmed fault code had been stored. 

The amendments clarify that the “end of an ignition cycle” includes electronic 

control unit shutdown. 

e. Sections (h)(4.4.1)(F)(iv) and (4.4.2)(F)(iv): Erasing of Permanent 

Fault Codes 

 

51 Staff Report, at page 50. 
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The regulation, as initially adopted, prohibited a permanent fault code being 

erased when the control module with the permanent fault code is reprogrammed 

unless the readiness status of all control modules has been reset to “not 

complete” when the control module is reprogrammed. The amendments clarify 

but do not substantively change the requirement. 

f. Section (h)(4.5): Test Results 

The regulation, as initially adopted, contained specific requirements for test 

results. The amendments clarify and specifically identify the continuous monitors 

covered by the section. 

g. Section (h)(4.6.3): Software Calibration Identification -- Multiple CAL 

IDs per Control Unit 

The amendments allow manufacturers to request Executive Officer approval to 

respond with more than one CAL ID per diagnostic or emission critical control 

unit.52

h. Sections (h)(4.7.2) and (h)(4.7.5): Software Calibration Verification 

The regulation, as initially adopted, required OBD systems to support parameters 

identifying the current software “version” or calibration (CAL ID) and an internal 

calibration verification number (CVN), the calculation verifying the integrity of the 

software. These two parameters are intended to be used to help verify that valid 

software is installed in the on-board computer and that the software has not been 

corrupted or tampered. With the relaxation allowing manufacturers to use 

multiple CAL IDs, the Board clarified that a CVN shall be made available for each 

CAL ID.. 

The regulation, as originally adopted, required the CVN and CAL ID information 

to be reported in a “standardized electronic format” but did not provide any 

information on what the standardized format entailed. Staff has since developed 

such a standardized template and sent it out to industry in a CARB mail-out, 

specifically CARB Mail-Out MSC#09-22, “Guidelines for Heavy-Duty On-Board 

Diagnostic (HD OBD) Certification Data,” July 7, 2009. The amendments to 

section (h)(4.75) specifically reference this document. 

i Sections (h)(4.8) and (h)(4.9)(B) and (D): Engine Serial Number 

(ESN) and Electronic Control Unit (ECU) Number. 

 

The regulation was amended to require that starting with the 2013 model year 

manufacturers are required to have the ESN of an engine available in a 

standardized format that can be accessed through a standardized data link 

 

52 Id., at page 51. 
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connector. Also, starting with the 2013 model year, manufacturers are required 

for each ECU that responds to a Society of Automotive Engineers J1978/J1939 

scan tool to have a unique address or identifier that communicates the name 

and/or function of the ECU (e.g., transmission control unit) in a standardized 

format.53 

4. Tracking Requirements 

a. Section (h)(5.2.1)(B) and (D): Engine Run Time Tracking 

Requirements 

The regulation, as initially adopted, required manufacturers to track and report 

engine run time and identify engine operating conditions, including “idle run time,” 

that constitute engine run time. The amendments clarified the definition of “idle 

run time,” and added engine operation while emission increasing auxiliary 

emission control devices (EI-AECDs) are active to the conditions covered by the 

term engine run time. 

b. Section (h)(5.2.2)(A): Numerical Value Specifications 

The regulation, as originally adopted, detailed the specifications for engine runtime values (e.g., four-byte values with a minimum value of zero, a resolution of 

one second per bit, etc.). These specifications have since been incorporated into 

SAE J1979/J1939, so the amendments now reference the SAE documents 

instead of detailing the specifications. 

c. Section (5.2.3): Specifications of EI-AECDs 

The Board amended the regulation to require the tracking of EI-AECDs starting 

with the 2013 model year. The amendments describe the actions, parameters, 

and conditions of EI-AECDs that the HD OBD system must track. 54 

6. Section (h)(6.4.2): Service Information – Alternative to Repair 

Procedure Requirements 

The regulation had required engine manufacturers to make readily available, at a 

fair and reasonable price to the automotive service repair industry, vehicle repair 

procedures which allow for effective emission-related repairs to be made using 

the Society of Automotive Engineers (SAE) J1978/J1939 scan tool and 

commonly available, non-microprocessor based tools. The amendments allow 

manufacturers to meet an alternative requirement based on what is presently 

required in title 13, CCR, section 1969, California’s Motor Vehicle Service 

Information rule. Specifically, manufacturers could make available for purchase, 

 

53 Id., at page 51. 54 Id., at pages 52-54. 
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at a fair and reasonable price, a manufacturer-specific or enhanced tool to 

perform the repair procedures.55 

H. Certification Demonstration 

1. Sections (i)(2.3.1), (2.3.2), (2.3.3), and (2.4): Selection of Test 

Engines – Aging and data collection of diesel test engines and Aging of 

gasoline engines. 

The regulation’s requirements for aging and data collection of diesel engine 

demonstration test vehicles were amended as they applied to 2013 and later 

model year vehicles. The amendments to section (j)(2.3.1) clarify that the 

original aging requirements apply only to 2010 through 2012 model-year diesel 

engines. The amendments also clarify that for 2010 through 2012 model-year 

engines, the exhaust aftertreatment emission controls are to be aged by an 

accelerated aging process that is representative of full useful life, that 

manufacturers are not required to provide data validating their aging process for 

these engines, and that the aging requirements applicable to gasoline engines 

should be consistent with what gasoline engine manufacturers have been doing 

for medium-duty gasoline engines. 

For 2013 to 2015 model year engines subject to 110,000 or 185,000 mile useful 

life periods, a manufacturer is now required to use the knowledge gained from 

data collected on in-use engines prior to 2013 to modify (if necessary), validate, 

and obtain CARB approval of its accelerated aging processes and use that 

improved aging process going forward. For engines subject to a 435,000 mile 

useful life period, a manufacturer must obtain similar approval as above but 

would still use its best estimates for full useful life aging as the collected data 

would only allow validation of the aging process up to 185,000 miles and not to 

the full useful life of 435,000 miles.56 

For 2016 and subsequent model year engines subject to a 435,000 mile useful 

life period, the manufacturer is required, among other things, to use the 

knowledge gained from data collected on in-use engines prior to 2016 to similarly 

modify (if necessary), validate, and obtain CARB approval of its accelerated 

aging process to full useful life and use that improved aging process going 

forward.57 

2. Required Testing of Components 

a. Sections (i)(3.1.3) and (3.1.4): EGR and Boost Pressure Control 

 

55 Id., at pages 54-56. 56 Id., at page 59-60. 57 Id. 
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The amendments require manufacturers to use components that are aged 

consistent with the aging and monitoring plans that they have submitted per the 

monitoring requirements. 

b. Sections (i)(3.1.5) and (3.1.6): NMHC and NOx Catalysts 

The regulation, as initially adopted, required testing of “each monitored NMHC 

catalyst(s)” and “each monitored NOx catalyst(s).” The amendments clarify that 

this manufacturers must monitor each catalyst that is used for a different 

purpose. 

c. Section (i)(3.2.7): Exhaust Gas Sensors 

The regulation, as originally adopted, set forth demonstration testing 

requirements that applied to “exhaust gas sensors” on gasoline engines. As 

mentioned above, amendments were made to the gasoline exhaust gas sensor 

monitoring requirements that included specific language requiring manufacturers 

to develop a monitoring plan for exhaust gas sensors other than oxygen sensors 

(e.g., hydrocarbon sensors), which CARB must approve. The amendments to 

section (i)(3.2.7) separate out the requirements for oxygen sensors from other 

exhaust gas sensors. The original requirements apply to oxygen sensors, while 

manufacturers are required to submit a demonstration test plan for other exhaust 

gas sensors. 

d. Section (i)(3.4): Gasoline Engines – Electronic Simulation of 

Components 

The regulation, as initially adopted, allowed manufacturers to electronically 

simulate deteriorated components for demonstration testing purposes. The 

amendments clarify that this will only be allowed if the manufacturer can 

demonstrate that the modifications produce test results equivalent to an induced 

hardware malfunction. 

The regulation also allowed manufacturers to electronically simulate (e.g., using 

an external simulator) malfunctions but did not allow them to make internal 

modifications to the electronic control unit (on-board computer) except for a few 

limited monitors. Given the wide variety of technologies and complexity of 

strategies being implemented, the Board amended the regulation to allow 

manufacturers to request Executive Officer approval to use internal computer 

modifications to simulate additional faults for demonstration testing when 

manufacturers can demonstrate that implanting a fault externally is technically 

infeasible, very difficult to implement, or too resource intensive.58 

e. Section (i)(3.5): Components or Systems Used in Parallel 

 

58 Id., at page 61. 
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The regulation, as initially adopted, required all monitored components and 

systems to be tested. The amendments clarify that components or systems used 

in parallel for the same purpose are to be simultaneously deteriorated to the 

malfunction criteria limit for demonstration testing. The amendments also clarify 

that components or systems used for different purposes are not to be 

simultaneously deteriorated for demonstration testing. 

3. Testing Protocol 

a. Section (i)(4.1): Preconditioning 

The regulation, as initially adopted, allowed manufacturers to request the use of 

preconditioning cycles if they provide data showing that they are necessary to 

stabilize the emission control system. The amendments clarify these 

requirements. 

b. Section (i)(4.2): Test Sequence 

The emission test requirements in the HD OBD regulation were primarily copied 

from the test procedures used for testing light-duty vehicles; however, recent 

discussions with manufacturers revealed some fundamental differences in how 

heavy-duty emission tests are run. Unlike light-duty, the heavy-duty emissiontest procedure does not include a ‘preconditioning’ cycle the day before the 

emission test. To be consistent with the current heavy-duty emission-test 

procedures and to eliminate unnecessary extra testing, the amendments 

eliminate the preconditioning cycle and require manufacturers to implant the fault 

and immediately perform the emission test. Further, because the previous test 

procedures anticipated the use of a preconditioning cycle, the procedure 

expected that the HD OBD fault would be detected once during the 

preconditioning cycle and a second time during the first engine start of the 

emission test. In conjunction with eliminating the preconditioning, the language 

of the HD OBD regulation was modified to expect the fault to be first detected on 

the first engine start of the emission test and detected a second time during the 

second engine start of the emission test. The HD OBD regulation still allows a 

manufacturer to request approval to use preconditioning cycles if technically 

justified to stabilize the emission control system. 

c. Section (i)(4.3): Test Data Collection 

As initially adopted, the provisions requiring manufacturers to collect specific fault 

information (i.e., time after start when the MIL illuminated, fault code(s), freeze 

frame information, test results) were in section (j) covering certification 

documentation. The amendments move the requirements to section (i), which 

covers certification demonstration testing. 

d. Section (i)(5): Evaluation Protocol 
Waiver Request Support Document 

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The amendments are intended to make clearer the requirements for evaluating 

the demonstration tests. Specifically, the current regulation lists evaluation 

provisions for catalyst and PM filter systems. The amendments include section 

references to the specific catalyst and PM filter monitors for which the evaluation 

protocol applies. 

I. Certification Documentation 

1. Certification Application 

a. Section (j)(2.2): Summary Table 

The regulation, as originally adopted, required the summary table for the OBD 

application to be reported in a “standardized electronic format” according to 

CARB Mail-Out #95-20, May 22, 1995. Staff has since developed an updated 

standardized template that applies specifically to heavy-duty engines and sent it 

out to industry in a CARB mail-out, specifically CARB Mail-Out MSC#09-22, 

“Guidelines for Heavy-Duty On-Board Diagnostic (HD OBD) Certification Data,” 

July 7, 2009. The amendments specifically reference this document. 

b. Section (j)(2.7): Data Supporting Fuel System Criteria 

The regulation, as initially adopted, required manufacturers to adjust emission 

results for each applicable monitor with an adjustment factor when determining 

the malfunction criteria (section (d)(6.2)). The amendments clarify that 

manufacturers are to include this information in the certification documentation 

provided to CARB. 

c. Section (j)(2.13): EI-AECDs 

The regulation, as initially adopted, required manufacturers to provide, provide 

among other things, a written description of each auxiliary emission control 

device (AECD) used by a manufacturer, the need for the AECD, and the values 

used to invoke operation of the AECD. The regulation has been amended to 

require manufacturers to provide information for each EI-AECD that is required to 

be tracked and reported. 

d. Sections (j)(2.16) and (j)(2.17): Cover Letter and Check List 

Section (i)(2.16), as initially adopted, required manufacturers to provide any 

information, other than that listed in section (i)(2), that it determined was 

necessary to demonstrate compliance with the regulation. The amendments 

clarify that a cover letter should accompany each OBD application and include 

information identifying the deficiencies and concerns (if any exist) that apply to 

the equivalent engine family or OBD group in the previous model year and the 
Waiver Request Support Document 

30

changes and/or resolution of each concern or deficiency as it applies to the 

current model year. The amendments also clarify that the certification application 

information should be summarized in a checklist of all the malfunction criteria for 

all monitors and the corresponding diagnostic noted by fault code for each 

malfunction criterion in the standardized format to help speed up certification. 

J. Deficiencies – Section (k)(6.1): Request for Retroactive Deficiencies 

In response to questions from industry regarding various possible interpretations 

of the language initially adopted, the amendments delete the reference to 

“normal production” and replace it with “start of engine production.” The 

amendments also modify the timeline in section (k) for when the Executive 

Officer may issue retroactive deficiencies so that it is consistent with the timeline 

for manufacturers to perform verification of monitoring requirements under 

section (l)(2); specifically, during either the first six months after commencement 

of the start of engine production or the first three months after commencement of 

the start of vehicle production, whichever ends later. This change is consistent 

with other parts of section (k), which already provide that retroactive deficiencies 

may be granted for problems found during verification testing. Further, section 

(k) currently states that deficiencies would be “retroactive to the start of 

production.” The amendments also clarify that identified deficiencies are 

retroactive to “all affected engines within the engine family.” 

L. Production Engine/Vehicle Evaluation Testing 

1. Sections (l)(1.2.1) and (2.1): Verification of Standardized/Monitoring 

Requirements 

The regulation, as originally adopted, stated that production engine/vehicle 

testing of standardized requirements and monitoring requirements is required to 

be done “within” a number of months after the start of engine or vehicle 

production. However, a manufacturer interpreted this to mean that testing could 

not be done on engines/vehicles built “before” the defined start of production (i.e., 

before the two percent mark), which was not staff’s intention. The amendments 

clarify that testing may be done at any point before the specified number of 

months since start of production. 

2. Section (l)(1.3): Test Equipment 

The regulation, as initially adopted, required manufacturers to request Executive 

Officer approval of the testing equipment used to conduct the verification of the 

standardization requirements. The amendments specifically detail what is 

required now for vehicles that use the ISO 15765-4 protocol. 

3. Section (l)(4): Agree to Conduct Self Testing of Engines 
Waiver Request Support Document 

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As a condition for certification, manufacturers would be required to perform inuse compliance testing on their own engines pursuant to the newly adopted HDOBD enforcement procedures set forth at title 13, Cal. Code Regs., 

section1971.5.59

III. SUMMARY OF HD OBD ENFORCEMENT REGULATION 

The HD OBD requirements, as initially adopted in 2005, included detailed 

certification requirements and production engine/vehicle evaluation testing. To 

help ensure that post-production OBD-equipped vehicles meet the many 

monitoring and standardized requirements of section 1971.1, the amended 

regulation includes additional in-use enforcement provisions as set forth in 

section 1971.5. 

In section 1971.5, CARB adopted an HD-OBD specific in-use enforcement 

testing protocol and remedial provisions. The new provisions establish detailed 

in-use testing procedures for HD OBD systems installed on 2010 and 

subsequent model year vehicles. Among other things, the procedures provide 

that CARB can directly test or have manufacturers self-test a limited number of 

in-use engines to ensure that engines remain in compliance with the 

requirements of section 1971.1 through their useful life. Manufacturers are not 

required to begin self-testing of 2010 model-year engines until 3013.60 

The enforcement regulation sets forth detailed protocol for procuring, selecting 

and testing of engines for compliance enforcement.61 The regulation also 

includes the criteria that CARB will consider in determining compliance and 

appropriate remedies for noncompliance. Finally, the regulation includes 

requirements and procedures to be followed by engine manufacturers in 

implementing either a voluntary, influenced, or ordered remedial action if 

engines, as a class, are determined to be out of compliance. Among other 

things, the regulation contains specific provisions requiring manufacturers to 

establish remedial action plans, provide notice to owners of vehicles and engines 

affected by the remedial action, and maintain and make available specific 

information regarding the remedial action. 

The proposed enforcement procedures are similar in comprehensiveness to 

those currently required for light-duty and medium-duty OBD II systems. As 

under the OBD II enforcement protocol, HD OBD systems may be tested for a 

monitor’s compliance with the HD OBD emission threshold requirements (i.e., 

does the MIL illuminate prior to the emissions exceeding a certain level above 

the malfunction threshold), the in-use performance ratio requirements (i.e., the 

 

59 Id., at page 62. For discussion of section 60 See title 13, CCR, section 1971.5(c)(3). 61 To a large extent, the proposed procurement and selection process parallels the recently 

established procedures that EPA, CARB, and manufacturers agreed to for manufacturer selftesting for tailpipe emission compliance using portable emission measurement systems. 
Waiver Request Support Document 

32

ratio measuring the number of monitoring events compared to the number of 

driving events), and other requirements. However, because heavy-duty vehicles 

are typically manufactured in a horizontally-integrated manner– heavy-duty 

engines are manufactured and certified by engine manufacturers; vehicle 

manufacturers subsequently purchase and install certified engines in heavy-duty 

vehicles – emission testing for HD OBD systems is necessarily different than 

emission testing for OBD II equipped passenger vehicles, light-duty trucks, and 

for some medium-duty vehicles, which are manufactured by vertically-integrated 

manufacturers.62 At this time, in-use compliance testing of HD OBD systems for 

emission threshold requirements entails testing the heavy-duty engine outside of 

the vehicle on an engine dynamometer. In contrast, emission testing of most 

OBD II systems can be done with the engine installed on the vehicle and tested 

on a chassis dynamometer. 

The proposed regulation provides that CARB may conduct enforcement testing 

for emission threshold noncompliance by procuring engines from in-use vehicles 

and testing them on an engine dynamometer in accordance with the 

procurement, selection, and testing criteria noted above. The regulation also 

provides that CARB may direct manufacturers to perform self-testing on a limited 

number of engines each year to determine whether the engines’ HD OBD 

systems properly detect malfunctions of emission-related components before 

emissions exceed specified malfunction thresholds. Specifically, if so directed, 

manufacturers would be required to perform enforcement testing on one to three 

engine families per year, depending on the size of the manufacturer. For each 

engine family, they would be required to procure a single representative in-use 

engine with approximately 75 percent of full useful life mileage and remove it 

from the vehicle for engine dynamometer testing. For each tested engine, the 

manufacturer would run the same sequence of tests that CARB would run – 

testing each threshold component one after the other and determining the 

emission level at which the fault is detected. Given the mileage for procurement, 

such testing would occur approximately three years after introduction of the 

engine into the marketplace so 2010 model year engines would first be tested in 

2013 calendar year. 

For both testing done by CARB and by manufacturers, for each engine tested, if 

the faults are detected prior to the prescribed emission levels being exceeded, 

the testing is completed. However, if one or more faults result in excessive 

emissions before the fault is detected, four more engines from the same engine 

family must be procured and tested for that specific monitor. And, if two or more 

of the additional four engines fail, an additional five more engines are to be 

procured for testing of the failing monitor. At most, a manufacturer would have to 

test 10 engines from the same engine family. The monitor would be judged 

noncompliant if five or more of the 10 tested engines failed to detect the fault 

before the appropriate emission threshold is exceeded. 

 

62 The vehicle manufacturer also manufactures the engine and is the manufacturer responsible 

for certifying the vehicle with the engine installed 
Waiver Request Support Document 

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CARB staff intends to perform testing to determine compliance with the in-use 

performance monitoring ratios and other non-emission-threshold-related issues. 

This testing can be done with the engine installed in the vehicle, and staff will be 

able to download needed data or implant malfunctions and add data loggers to 

determine noncompliance. 

If the Executive Officer determines that a substantial number of vehicles of an 

identified test-engine class are found not to be in nonconformance with engines 

as certified, he may order engine manufacturers to recall the nonconforming 

engines or take other appropriate remedial action. 

IV. WAIVER ANALYSIS 

A. Introduction 

Section 209(b) of the CAA sets forth the protocol for granting California waivers 

to the general preemption of section 209(a), which prohibits the states from 

adopting and enforcing standards and other requirements relating to the control 

of emissions from motor vehicles. Under section 209(b), the Administrator shall 

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 waiver for the HD OBD 

regulation in 2008, the Administrator concluded that the record was devoid of 

sufficient evidence to support denial of the waiver.63 

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).64

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 

 

63 61 Fed.Reg. 53371 (October 11, 1996). 64 Motor and Equipment Manufacturers Association v. EPA (MEMA) (D.C. Cir. 1979) 627 F.2. 

1095, 1111, 1113. 
Waiver Request Support Document 

34

included within the scope of the previous waiver if it does not 

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.65

In considering a waiver or a within the scope waiver request, California’s 

regulations and protectiveness determination are presumed to satisfy the criteria 

for granting a waiver, and the burden to show otherwise is on those persons 

challenging the waiver request.66 As held by the court in MEMA and long 

followed by U.S. EPA: 

The language of the statute and its legislative history indicate that 

California’s regulations, and California’ 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.67

B. The Amendments to the OBD Monitoring Requirements Set Forth in 

Section 1968.2 Are within the Scope of the Previously Granted Waiver 

1. The Amendments Do Not Require a New Waiver 

As set forth above, 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 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.68 

The recently adopted amendments to the HD OBD monitoring requirements 

should be found within the scope of the existing waiver for several reasons. As 

stated, the previously granted waiver permits California to require HD OBD 

systems in all 2010 and subsequent model year heavy-duty engines certified for 

sale in California. The HD OBD requirements, taken as a whole, establish a 

single monitoring system, which, under California law, may only be certified if it 

fully complies with all requirements. Thus, even though there are numerous 

 

65 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). 

66 Manufacturers Association v. EPA (MEMA) (D.C. Cir. 1979) 627 F.2d 1095, 1121. 67 Id.; See also Decision Document accompanying OBD II Waiver Determination, 61 Fed.Reg. 

53371 (October 11, 1996), at pages. 15-16. 

68 See page 6, supra. 
Waiver Request Support Document 

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monitoring requirements and diagnostics that must be met, they should for 

purposes of a waiver effectively be considered as just one standard. EPA 

recognized this in granting its waiver for OBD II systems in 1996: 

[U.S.] EPA agrees . . . that CARB’s OBD II regulation should be 

treated as a standard under section 209 . . . . EPA believes that the 

classification of CARB’s OBD II requirements as a standard for 

purposes of section 209 is consistent with statutory language, case 

law, and with past waiver practice.69 (Emphasis added.) 

The most recent modifications to the HD OBD regulation were intended to adjust 

and upgrade the HD OBD systems, for which the waiver was granted in 2008. 

They do not mandate a new system or even appreciable hardware changes. 

Instead, the upgrades and modifications required under section 1971.1 for the 

most part require recalibration of software for some of the existing monitors and, 

in the case of new monitors, new diagnostic strategies. To the extent that new 

hardware is required, the amendments provide additional lead time for 

manufacturer compliance. 

Finally, it should be kept in mind, that the analysis for granting a new 

waiver and a within the scope waiver request are very similar. Under 

both, CARB must submit to the Administrator its determination that it 

meets the protectiveness and consistency criteria of CAA section 209(b). 

The only difference being that California does not need to again 

demonstrate that compelling and extraordinary conditions exist within the 

state when making a “within the scope” request.70 This is really not an 

issue. It is beyond dispute that “compelling and extraordinary conditions” 

continue to exist in California.71

 

69 61 Fed.Reg. 53371 (October 11, 1996), waiver decision document, p. 20. See also p. 20, in 

which the Administrator concludes that “OBD II requirements are indeed a standard.” 

70 In issuing the October 11, 1996 waiver, the Administrator reaffirmed that U.S. EPA’s 

inquiry into the “compelling and extraordinary conditions” criterion “is limited to whether 

California needs its own motor vehicle program to meet compelling and extraordinary 

conditions and not whether any given standards are necessary to meet such conditions. 

(Decision Document accompanying OBD II Waiver Determination, at pp. 39-40.) In 

granting the waiver, the Administrator found that the ARB has repeatedly demonstrated 

the existence of compelling and extraordinary conditions in California justifying its need 

for its own motor vehicle pollution control program. (Id., at p.42). 71 See 74 Fed.Reg. 32744, 32762 (July 8, 2009); see also 49 Fed.Reg. 18887, 18890, in which 

the Administrator determined that the phrase “compelling and extraordinary conditions” refers 

“primarily to the factors that tend to produce [high levels of pollution]: geographical and climatic 

conditions that, when combined with large numbers and high concentrations of automobiles, 

create serious air pollution problems.” These conditions continue to exist in California. The 

South Coast Air Basin and the San Joaquin Valley Air Basin, in particular, continue to be plagued 

by the worst air quality in the nation. 
Waiver Request Support Document 

36

2. Protectiveness 

In adopting Resolution 09-37, the Board expressly found that amendments to the 

HD OBD requirements set forth in section 1971.1 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 finding accompanying the newly adopted 

amendments to the HD OBD regulation, those challenging the waiver, must 

present clear and convincing evidence to show that the protectiveness finding by 

California is arbitrary and capricious.72 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”.73

In adopting the initial HD OBD regulation in 2006, 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, 

which at the time were nonexistent for heavy-duty engines used in vehicles over 

14,000 pounds. In granting the 2008 waiver, the Administrator of U.S. EPA held 

that he could not find that CARB’s determination was arbitrary and capricious.74 

The amendments do not disturb this finding even though EPA has since adopted 

OBD requirements for heavy-duty engines greater than 14,000 pounds.75 Even 

considering the provisions that were relaxed for 2010-2012 model years, HD 

OBD 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 continue to be more stringent than comparable 

federal regulations. 

3. Consistency 

For the reasons set forth in the Staff Report, 15-Day Notice, and FSOR,76 the HD 

OBD requirements, as amended, remain consistent with section 202(a) of the 

CAA. The U.S. EPA has historically interpreted consistency with section 202(a) 

under a two-prong 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 

 

72 MEMA, 627 F.2d at 1122, Decision Document accompanying OBD II Waiver Determination, at 

p. 14. 

73 Id. 

74 73 Fed.Reg. 52042 (September 8, 2008), Decision Document accompanying HD OBD Waiver 

Determination, at page 7. 

75 74 Fed.Reg. 8310 (February 24, 2009). 76 See Section II. above summarizing the amended requirements and the and the references to 

the Staff Report and 15-Day Notice; see also FSOR (a copy of which is enclosed), at pages 9-35. 
Waiver Request Support Document 

37

sufficiently compatible to permit manufacturers to meet both the state and federal 

test requirements with one test vehicle or engine.77 

a. Technical Feasibility of Amended Monitoring Requirements 

In the short term – the 2010 through 2012 model years – to the extent that the 

Board has amended requirements that have been previously waived, the 

amendments only relax the requirements, providing manufacturers with greater 

compliance flexibility. For example, section (e)(6.2.1)(A) increases the NOx 

malfunction emission threshold for 2010-2012 model-year diesel NOx converting 

catalysts; sections (e)(1.3.4), and (e)(4.3.4) respectively allow manufacturers to 

disable continuous monitoring of fuel and boost control systems; section 

(d)(6.2.3) allows manufacturers to use alternate compliance options for 

calculating adjustment factors; and sections (e)(8.2.4) and (g)(3.2.2)(C) 

respectively allow manufacturers to delay compliance until the 2013 model year. 

This is not to say that CARB provided engine manufacturers with insufficient lead 

time when initially adopting the regulation. Rather, as stated in the FSOR: 

[T]hese changes were not made because the initially adopted requirements 

were technically infeasible. In all cases, at least one or two manufacturers 

appeared to be on track to meet the existing requirement without the need for 

relaxation. However, staff recommended interim relief due to the complexity 

of the 2010 emission control solutions being pursued by several 

manufacturers—including some configurations that appear to be negatively 

impacting OBD monitoring capability.78 

With regard to amended requirements that manufacturers must meet in 2013 and 

subsequent model years, manufacturers have been provided with at least three 

years of lead time. In some cases, like those identified above, in which 

compliance has been delayed from model year 2010 to 2013, manufacturers 

have been provided with up to seven years of lead time. As stated, during the 

course of the rulemaking, CARB provided reasoned explanations and responses 

to objections raised by industry to support the basis for development and 

application of the requisite technological in the lead time provided.79 

b. Test Procedures 

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. 

 

77 See 61 Fed.Reg. 53371, 53372 (October 11, 1996); Decision Document at p.2 (OBD II Waiver 

Decision). 78 FSOR, at pages 10-11. 79 See National Resource Defense Council v. EPA (D.C. Cir. 1981) 655 F.2d 318, 328; see Staff 

Report and FSOR. 
Waiver Request Support Document 

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4. 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 waiver. 

For the above reasons, EPA should find that the HD OBD amendments 

fall within the scope of the 2008 waiver. 

C. Alternatively, the Amendments that Relax and Clarify the HD OBD 

Monitoring Requirements Are Within the Scope of the Previously Granted 

Waiver 

If EPA cannot find that the full spectrum of amendments fall within the 

scope of the previously granted HD OBD waiver, ARB respectfully 

requests that EPA confirm that at least those changes that either relax the 

regulation’s requirements, and thereby provide engine manufacturers with 

greater compliance flexibility, or clarify previously existing provisions be 

found to be within the scope of the 2008 waiver. A listing of amendments 

that relax or clarify previously waived provisions of the HD OBD regulation 

is attached hereto. 

1. Protectiveness 

The amendments that relax and clarify the requirements previously waived in 

2008 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. The amended regulation, 

considered as a whole, continues to be more stringent than the federal OBD 

regulation for vehicles greater than 14,000 pounds. The Board affirmed this 

determination in Resolution 09-37, a copy of which is enclosed herewith. 

2. Consistency with CAA Section 202(a) 

a. Lead Time 

The first prong of the two-part consistency criteria requires those opposed to 

California obtaining a favorable within-the-scope determination to show that the 

regulation, as amended, provides insufficient lead time to permit the development 

of technology to meet those requirements, giving appropriate consideration to the 

cost of compliance within the time provided for compliance.80 It is 

incontrovertible that amendments providing for greater compliance flexibility and 

clarifying the requirements that manufacturers must follow make the regulation 

more feasible. 

 

80 See pp. 21-22, supra. 
Waiver Request Support Document 

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The HD OBD regulation, as initially adopted by CARB and subsequently 

waived by EPA, required engines manufacturers to meet certain 

requirements staring with the 2010 model year. To the extent that these 

requirements have been amended and still require compliance in 2010 

through 2012 model years, the amendments have relaxed the 

requirements by, among other things, providing for higher emission 

malfunction thresholds and changing many of the continuous monitoring 

requirements to either once-per-trip monitoring or disablement of 

continuous monitoring under certain driving conditions.81 Other 

amendments delayed initial compliance scheduled for the 2010 model 

year to the 2013 model year;82 while still others provided greater flexibility 

for compliance with the in-use performance ratio requirements (e.g., 

providing additional criteria that must be met before incrementing the 

number of driving trips – the denominator used in the ratio.)83 

The amendments that clarify existing provisions have not added any new 

requirements and have not affected the lead time initially provided when the 

regulation was first adopted. In granting the 2008 waiver, EPA found the 

provided lead time not to be inconsistent with CAA section 202(a). 

b. Test Procedures 

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 vehicles and addresses the same 

pollutants covered in the initially granted waiver. 

For the above reasons, EPA must find that the HD OBD amendments that 

relax or clarify the HD OBD requirements fall within the scope of the 2008 

waiver. 

C. Alternatively, EPA Must Grant a New Waiver for Amendments Creating 

New, More Stringent HD OBD Requirements 

 If EPA determines that it cannot confirm that any of the amendments 

summarized above in Section II fall within the scope of the August 2008 waiver, 

EPA must grant California a new waiver for those amendments. As set forth 

 

81 See e.g., sections (e)(6.2.1(A), (e)(6.2.2)(A), (e)(8.2.1)(A), (e)(1.3.2), and (e)(1.3.4). 82 See e.g., sections (e)(5.2.3)(B) and (e)(8.2.4). 83 See e.g., sections (d)(4.3.2)(F) and (H) 
Waiver Request Support Document 

40

above, the Board’s determination that the regulation, as amended, continues to 

be more protective of public health and welfare as applicable federal regulations 

is neither arbitrary nor capricious, California continues to need its motor vehicle 

program to meet and compelling and extraordinary conditions, and the 

amendments are consistent with CAA section 202(a).84 

D. The Administrator Should Grant California’s Request that HD OBD 

Enforcement Regulations Be Granted a Waiver as an Accompanying 

Enforcement Provisions 

As stated, the U.S. EPA has previously granted a waiver for the HD OBD 

regulation.85 Sections 1971.1 (i), certification demonstration testing, and (l), 

production engine/vehicle evaluation testing, were initially adopted in 2006 and 

covered by the 2008 HD OBD waiver. To the extent that the amendments to 

these sections merely clarify the previously waived provisions, they should be 

found to be within the scope of the previously granted waiver. Although the 

amendment to section 1971.1(l)(4), requiring manufacturers to conduct 

compliance testing under section 1971.5 as a condition precedent to certification, 

is a new provision, such a requirement does not require a new waiver separate 

and apart from consideration of the accompanying enforcement provision of 

section 1971.5, to which the condition precedent specifically refers.86 

Although codified in a different location of title 13, CCR, the HD OBD 

enforcement provisions of section 1971.5, like those previously adopted for 

OBD II at title 13, CCR, section 1968.5, are in point of fact amendments to the 

general in-use enforcement requirements of section 2100 et seq., which have 

previously been granted waivers or found to be within the scope of existing 

waivers.87 The amendments establishing section 1971.5 are necessary to 

address the uniqueness of HD OBD systems and the special circumstances 

surrounding in-use compliance testing of such systems. 

For the reasons set forth above and those that follow, the Administrator should 

find that the amendments to sections 1971.1(i) and (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 waiver for the accompanying enforcement provision. 

1. Protectiveness 

As stated, in adopting Resolution 09-37, the Board resolved that the 

amendments to sections 1971.1 and 1971.5 do not undermine its previous 

 

84 See Staff Report and 15-Day Notice, at the pages identified in Section II and FSOR. 85 See 61 Fed.Reg. 53371 (October 11, 1996). 86 See 43 Fed.Reg. 36679 (August 18, 1978). 87 43 Fed.Reg. 9344 (March 7, 1978); 43 Fed.Reg. 25729 (June 14, 1978), 49 Fed.Reg. 43502 

(October 29, 1984). 
Waiver Request Support Document 

41

determinations that the HD OBD regulation, in the aggregate, is at least as 

protective of public health and welfare as applicable federal regulations. Indeed, 

the enforcement provisions are intended to ensure greater compliance with the 

adopted HD OBD monitoring, standardization, and certification requirements by 

establishing defined and HD OBD-specific protocols for manufacturer verification 

and in-use compliance testing. As stated the requirements that manufacturers 

conduct testing to verify that the HD OBD system in post-production vehicles 

properly communicates with scan tools, evaluate proper performance of HD OBD 

monitoring systems, and collect and report data on frequency of in-use 

monitoring performance were all adopted in 2006 and covered by the 2008 

waiver. The amendments merely clarify several of the requirements and do not 

negatively impact the stringency of the requirements. 

With adoption of section 1971.5 and an HD OBD-specific in-use compliancetesting protocol, CARB has helped ensure that HD OBD systems operate as 

certified throughout their useful life, and, if found to be out of compliance, that the 

non-compliance will be quickly remedied. As more fully set forth in the Staff 

Report, the new in-use compliance-enforcement procedures establish specific 

provisions for testing HD OBD system requirements and criteria for determining 

compliance. Additionally, the enforcement regulation sets forth specific criteria 

that the ARB will follow in determining appropriate remedies for those vehicles 

found to be nonconforming. The regulation has been drafted to provide 

manufacturers with clear notice of what the ARB considers to be a compliant 

system. This will ensure that manufacturers design and manufacture complying, 

more durable HD OBD systems and emission-related components and that 

emission reductions forecasted to be achieved by new engines will, in fact, be 

achieved. 

. 

Based on the foregoing, CARB reconfirms the Board’s protectiveness 

determination. Far from undermining the Board’s previous determination that the 

HD OBD regulation, in the aggregate, is more protective than applicable federal 

regulations, the adopted enforcement provisions bolster the previous findings. 

2. Consistency

(a) Technical Feasibility 

No technical feasibility issues exist for the adopted HD OBD enforcement 

provisions independent of the technical feasibility of the underlying HD OBD 

monitoring requirements.88 Regarding the issue of manufacturer self-testing – 

 

88 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 

Fed.Reg. 53371 (October 11, 1996), decision document at p.3, fn. 5.88 61 Fed.Reg. 53371 

(October 11, 1996). 

88 Id., at 53372 
Waiver Request Support Document 

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probably the most contentious issue – there is no question that manufacturers 

have the technical know how and the resources to conduct the limited self-testing 

required by the regulation. Manufacturers are required to do no more than what 

they must do when initially conducting demonstration testing to certify engines. It 

is expected that manufacturers continue to have in their possession all necessary 

facilities and components that they used for certification testing and that will be 

used in conducting compliance testing.89 Staff has determined that the 

incremental cost to manufacturers for testing a limited number of engines – when 

spread out over all engines sold in California for a specific model year – to be 

minimal, approximately $1.97 per engine sold.90 

(b) Compatible Test Procedures 

For the reasons stated above, 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. Additionally, in granting California a waiver for OBD II, the 

Administrator found that California’s OBD II certification test procedures to be 

compatible with the federal OBD test procedures for light-duty vehicle 

certification.91 The same should be held for HD OBD. 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. 

 

2. New Issues 

As stated, the ARB is not aware of any new issues affecting the previously 

granted authorization determination for the HD OBD regulation. 

V. CONCLUSION 

For the reasons set forth above, California respectfully requests that EPA in the 

first instance confirm that all of the above HD OBD amendments fall within the 

scope of the previously issued waiver granted in August 2008. Alternatively, 

ARB requests that if EPA is unable to find the full array of amendments to fall 

within the scope of the August 8, 2008 waiver that it confirm that all amendments 

that either relax or clarify requirements be found to be within the scope of the 

initial HD OBD waiver. Finally, to the extent that EPA cannot make a within the 

scope determination for certain amendments, ARB requests that a new waiver be 

granted. 

 

89 Staff Report, at page 70. 90 Id., at page 72. 91 Id., at 53372. 
Waiver Request Support Document 

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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. Notice of Public Hearing to Consider Malfunction and Diagnostic 

System Requirements for 2010 and Subsequent Model Year Heavy 

Duty Engines (HD OBD), issued April 10, 2009. 

2. Staff Report: Initial Statement of Reasons for Proposed 

Rulemaking, issued April 10, 2009, with Appendices. 

3. Resolution 09-37, dated May 28, 2009. 

4. Notice of Availability of Modified Text, issued October 20, 2009 

5. Executive Order R-10-005, dated April 5, 2010. 

6. Final Statement of Reasons for Rulemaking Including Summary of 

Comments and Agency Response, issued April 9, 2010 . 

7. Final Regulation Order for title 13, California Code of Regulations, 

section 1971.1. 

8. Final Regulation Order for title 13, California Code of Regulations, 

section 1971.5. 

If you should require additional technical information on this item, please have 

your staff contact Mike McCarthy, Manager, Advanced Engineering Section, 

Engineering Studies Branch, Mobile Source Control Division, at (626) 771-3614 

or by email at mmccarth@arb.ca.gov. They should address legal questions to 

Michael L Terris, at (916) 445-9815, or by email at mterris@arb.ca.gov. 
Waiver Request Support Document 

44

ATTACHMENT 

Relaxed Requirements

A. Section (c): Definitions. 

1. “Continuously” 

2. “Diagnostic or Emission Critical Electronic Control Unit 

B. General Requirements 

1. Sections (d)(2.2.1)(E) and (d)(2.2.2)(E): MIL Illumination and Fault 

Code Storage Protocol. 

2. 2. Sections (d)(4.3.2)(B)(iii), (E), (F), (G), and (H): Tracking In-Use 

Monitor Ratio – Incrementing the Denominator. 

3. Section (d)(6.2.3): Malfunction Criteria Determination, Alternatives for 

Calculating Infrequent Regeneration Adjustment Factors (IRAFs) 

C. Monitoring Requirements for Diesel/Compression-Ignition Engines. 

1. Fuel System Monitoring 

a. Section (e)(1.2.7): Determining Malfunction Criteria 

b. Section (e)(1.3.2): Monitoring Fuel Injectors that Build Pressure 

Internally. 

c. Section (e)(1.3.4): Disabling of Continuous Monitoring 

2. Section (e)(2.2.4): Misfire Monitoring – Multi-cylinder Misfire 

3. Section (e)(4.3.4): Boost Pressure Control System Monitoring – 

Disablement of Continuous Monitoring. 

4. Section (e)(5.2.3)(B): NMHC Converting Catalyst Monitoring – Delay 

Implementation Start Date to 2013. 

5. NOx Converting Catalyst Monitoring 

a. Section (e)(6.2.1)(A): Conversion Efficiency Monitoring - Increase 

NOx Threshold 

b. Section (e)(6.2.2)(A): SCR or Other Active/Intrusive Reductant 

Injection System Performance Monitoring – Increase NOx 

Threshold 

c. Section (e)(6.3.1): Monitoring for Improper Reductant 

d. Section (e)(6.3.3): Disablement of Continuous Monitoring 

6. Section (e)(7.3.3): NOx Adsorber Monitoring – Disablement of 

Continuous Monitoring 

7. PM Filter Monitoring 

a. Section (e)(8.2.1)(A): Filtering Performance Monitoring – Increase 

PM Threshold 

b. Section (e)(8.2.4): NMHC Conversion Monitoring – Delay 

Implementation Start Date to 2013 

c. Section (e)(8.3.3): Disablement of Continuous Monitoring 

8. Section (e)(9.2.2): Exhaust Gas Sensor Monitoring 

D. Monitoring Requirements for Gasoline/Spark-Ignited Engines 

1. Fuel System Monitoring 

a. Section (f)(1.3.5): Disablement of Continuous Monitoring 
Waiver Request Support Document 

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b. Section (f)(1.4.5)(B): Similar Conditions Definition for Secondary 

Feedback Control Faults 

2. Misfire Monitoring – Multi-cylinder Misfire 

c. Section (f)(2.2.1)(C): Multi-cylinder Misfire 

d. Section (f)(2.3.1)(B): Monitoring Conditions 

3. Section (f)(5.1.2): Secondary Air System Monitoring – Exemption from 

Monitoring 

E. Monitoring Requirements for All Engines 

1. Section (g)(1.2.1)(D): Engine Cooling System 

2. Section (g)(2.2.3) – Crankcase Ventilation (CV) System Monitoring – 

Exemption from Monitoring 

3. Comprehensive Component Monitoring 

c. Sections (g)(3.1.3) and (g)(3.1.4): Exemptions from Monitoring 

d. Section (g)(3.1.6): Vehicle Speed Information Monitoring 

e. Section (g)(3.2.2)(B)(ii): Diesel Idle Fuel Control Monitoring - Delay 

Implementation Start Date to 2013 

f. Section (g)(3.2.2)(C): Glow Plug Monitoring - Delay Fault Code 

Implementation Start Date to 2013 

g. Section (g)(3.2.2)(D): MIL Circuit Monitoring – Delete Monitoring 

Requirement 

F. Standardization Requirements 

1. Section (h)(4.6.3): Software Calibration Identification: Allow Multiple 

CAL ID per Control Unit 

2. Section (h)(6.4.2): Service Information – Alternative to Repair 

Procedure Requirements 

G. Monitoring System Demonstration Requirements for Certification 

1. Section (i)(3.4): Required Testing Fault Simulation 
Waiver Request Support Document 

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Technical Clarifications to Pre-Existing Requirements

A. Definitions 

1. Section (c) “Calculated load value” 

2. Section (c) “Response rate” 

3. Section (c) “Weighted sales number” 

B. General Requirements 

1. Section (d)(2.3.2)(A): MIL Extinguishing and Fault Code Erasure 

Protocol 

2. Section (d)(2.4.1)(A): Exceptions to MIL and Fault Code 

Requirements 

3. Section (d)(3.1.3): Monitoring Conditions 

4. Section (d)(4.2.2)(F): In-Use Monitor Performance Ratio Definition 

5. Section (d)(4.3.2)(G): In-Use Monitor Performance Ratio Definition 

6. Section (d)(4.5.3): Disablement of Numerators and Denominators 

7. Section (d)(5.1.2): Standardized tracking and reporting of monitor 

performance 

C. Monitoring Requirements for Diesel/Compression-Ignition Engines 

1. Sections (e)(1.2.4), (e)(3.2.4), (e)(4.2.5), (e)(6.2.2)(D), (e)(7.2.3), 

(e)(8.2.7), (e)(9.2.1)(A)(iii),(B)(iii), (e)(9.2.2)(C): Feed-forward 

control 

2. Sections (e)(3.1.2), (e)(4.1.2): Exhaust Gas Recirculation (EGR) 

System Monitoring and Boost Pressure Control System Monitoring 

3. Sections (e)(3.2.1) and (3.2.2): EGR System Monitoring 

4. Section (e)(3.2.3): EGR System Monitoring 

5. Section (e)(3.2.9): EGR System Monitoring 

6. Section (e)(3.3.4): EGR System Monitoring 

7. Sections (e)(4.2.1) and (4.2.2): Boost Pressure System Monitoring 

8. Section (e)(4.2.8): Boost Pressure System Monitoring 

9. Section (e)(5.2.3): NMHC Converting Catalyst Monitoring 

10. Section (e)(5.2.4)(A),(B) and (e)(6.2.3)(A),(B): NMHC Converting 

Catalyst Monitoring and NOx Converting Catalyst Monitoring 

11. Section (e)(7.2.6): NOx Adsorber Monitoring 

12. Section (e)(8.3.2): Particulate Matter (PM) Filter Monitoring 

13. Section (e)(9.2.2): Exhaust Gas Sensor Monitoring 

D. Monitoring Requirements for Gasoline/Spark-Ignited Engines 

1. Section (f)(1.2.1)(B): Fuel System Monitoring 

2. Sections (f)(1.2.5),(1.3.3),(1.3.4): Fuel System Monitoring 

3. Section (f)(2.3.5): Misfire Monitoring 

4. Section (f)(7.1): Evaporative System Monitoring 

5. Section (f)(7.2.5): Evaporative System Monitoring 

6. Section (f)(8.1.4): Exhaust Gas Sensor Monitoring 

7. Section (f)(8.2.1)(A): Exhaust Gas Sensor Monitoring 

8. Section (f)(8.2.2)(C): Exhaust Gas Sensor Monitoring 

E. Monitoring Requirements for All Engines 

1. Section (g)(1.3.1)(E): Engine Cooling System Monitoring 
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2. Section (g)(2.2.7): Crankcase Ventilation (CV) System Monitoring 

3. Section (g)(3.1.5): Comprehensive Component Monitoring 

4. Sections (g)(3.2.1)(D), (g)(3.2.2)(E), (g)(4.3): Comprehensive 

Component Monitoring and Other Emission Controls System 

Monitoring 

5. Section (g)(3.4.3): Comprehensive Component Monitoring 

6. Section (g)(5.7): Exceptions to Monitoring Requirements 

F. Standardization Requirements 

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

2. Section (h)(4.1), (4.1.4): Readiness Status 

3. Section (h)(4.3.1): Required Emission Related Functions 

4. Sections (h)(4.4.1)(D), (4.4.2)(D): Required Emission Related 

Functions 

5. Sections (h)(4.4.1)(F)(iv), (4.4.2)(F)(iv): Required Emission Related 

Functions 

6. Section (h)(4.5): Required Emission Related Functions 

7. Section (h)(4.7.2): Required Emission Related Functions 

8. Section (h)(4.7.5): Required Emission Related Functions 

9. Section (h)(5.2.1)(B): Tracking Requirements 

10. Section (h)(5.2.2)(A): Tracking Requirements 

G. Monitoring System Demonstration Requirements for Certification 

1. Section (i)(2.3.1),(2.4): Aging and data collection of diesel test 

engines and Aging of gasoline engines. 

2. Section (i)(3.1.3),(3.1.4): Required Testing 

3. Section (i)(3.1.5),(3.1.6): Required Testing 

4. Section (i)(3.2.7): Required Testing 

5. Section (i)(3.4): Required Testing 

6. Section (i)(3.5): Required Testing 

7. Section (i)(4.1): Testing Protocol 

8. Section (i)(4.2): Test Sequence 

9. Section (i)(4.3): Test Data Collection 

10. Section (i)(5): Evaluation Protocol 

H. Certification Documentation 

1. Section (j)(2.2) 

2. Section (j)(2.7) 

3. Section (j)(2.16), (2.17) 

I. Deficiencies – Section (k)(6.1): Request for Retroactive Deficiencies 

J. Production Engine/Vehicle Evaluation Testing 

1. Sections (l)(1.2.1), (2.1) 

2. Section (l)(1.3): Test Equipment