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Attachment E to the Resolution 12-29

Staff’s Suggested Modifications to the Original Proposal

(Distributed at the August 23, 2012 Board hearing)

Amend section 1971.1, title 13, California Code of Regulations, to read as follows: 

Note: The amendments proposed with the 45-day notice are shown in single underline

to indicate additions and single strikeout to indicate deletions from the existing 

regulatory text, while new amendments proposed with these staff suggested 

modifications are shown in double underline to indicate additions and double strikeout to

indicate deletions from the existing regulatory text. Various portions of the regulations 

that are not modified by the proposed amendments are omitted from the text shown and 

indicated by “ * * * * ”. 

§1971.1. On-Board Diagnostic System Requirements--2010 and Subsequent 

Model-Year Heavy-Duty Engines

* * * * 

(e) Monitoring Requirements for Diesel/Compression-Ignition Engines.

(1) Fuel System Monitoring

* * * *

(1.4) MIL Illumination and Fault Code Storage: 

* * * *

(1.4.2) Additionally, for malfunctions identified in section (e)(1.2.1) (i.e., fuel 

pressure control) on all 2013 and subsequent model year vehicles 

engines:

* * * *

(D)Storage of freeze frame conditions.

(i) For 2013 through 2015 model year engines, aA manufacturer shall 

store and erase freeze frame conditions either in conjunction with 

storing and erasing a pending fault code or in conjunction with storing 

and erasing a confirmed/MIL-on fault code. For 2016 and subsequent 

model year engines, a manufacturer shall store freeze frame 

conditions in conjunction with storing and erasing a pending fault code 

in accordance with section (d)(2.2.1)(D)(iii) or (d)(2.2.2)(D).

(ii) If freeze frame conditions are stored for a malfunction other than 

misfire (see section (e)(2)) or fuel system malfunction when a fault 

code is stored as specified in section (e)(1.4.2) above, the stored 

freeze frame information shall be replaced with freeze frame 

information regarding the fuel system malfunction.

* * * *

(2) Misfire Monitoring

* * * *
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(2.3) Monitoring Conditions: 

* * * *

(2.3.3) Additionally, fFor misfires identified in section (e)(2.2.2) 2013 and 

subsequent model year engines equipped with sensors that can detect 

combustion or combustion quality:

(A) The OBD system shall continuously monitor for misfire under the following 

conditions:

(i) For 2013 through 2018 model year engines and 2019 and subsequent 

model year engines that are not included in the phase-in specified in 

section (e)(2.3.3)(A)(ii), all under positive torque conditions between 20 

percent and 75 percent of peak torque with engine speeds up to 75 

percent of the maximum-rated engine speed and engine load up to 75 

percent maximum-rated and load conditions except within the following 

range.: the engine operating region bound by the positive torque line 

(i.e., engine load with transmission in neutral) and the two following 

engine-operating points: engine speed of 50 percent of maximum-rated 

engine speed with the engine load at the positive torque line, and 75 

percent of the maximum-rated engine speed with the engine load 5 

percent above the positive torque line.

(ii) For 20 percent of 2019 model year diesel engines, 50 percent of 2020 

model year diesel engines, and 100 percent of 2021 model year diesel 

engines (percentage based on the manufacturer’s projected California 

sales volume of all diesel engines subject to this regulation), under all 

positive torque engine speed and load conditions except within the 

following range: the engine operating region bound by the positive 

torque line (i.e., engine load with transmission in neutral) and the two 

following engine-operating points: engine speed of 50 percent of 

maximum-rated engine speed with the engine torque at the positive 

torque line, and 100 percent of the maximum-rated engine speed with 

the engine torque 10 percent above the positive torque line.

* * * *

(C)A manufacturer may request Executive Officer approval to disable misfire 

monitoring or employ an alternate malfunction criterion when misfire 

cannot be distinguished from other effects.

(i) Upon determining that the manufacturer has presented documentation 

that demonstrates the disablement interval or period of use of an 

alternate malfunction criterion is limited only to that necessary for 

avoiding false detection, the Executive Officer shall approve the 

disablement or use of the alternate malfunction criterion for conditions 

involving:

a. rough road,

b. fuel cut,

c. gear changes for manual transmission vehicles,
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d. traction control or other vehicle stability control activation such as 

anti-lock braking or other engine torque modifications to enhance 

vehicle stability,

e. off-board control or intrusive activation of vehicle components or 

diagnostics during service or assembly plant testing,

f. intrusive diagnostics during portions that can significantly affect 

engine stability, or

g. infrequent regeneration events during portions that can significantly

affect engine stability.

* * * *

(2.4) MIL Illumination and Fault Code Storage:

* * * *

(2.4.2) Additionally, for 2013 and subsequent model year engines misfires 

identified in section (e)(2.2.2)equipped with sensors that can detect 

combustion or combustion quality:

* * * *

(B) Storage of freeze frame conditions.

(i) For 2013 through 2015 model year engines, tThe OBD system shall 

store and erase freeze frame conditions either in conjunction with 

storing and erasing a pending fault code or in conjunction with storing 

a confirmed/MIL-on fault code and erasing a confirmed/previously MILon fault code. For 2016 and subsequent model year engines, a 

manufacturer shall store freeze frame conditions in conjunction with 

storing and erasing a pending fault code in accordance with section 

(d)(2.2.1)(D)(iii) or (d)(2.2.2)(D).

(ii) If freeze frame conditions are stored for a malfunction other than a 

misfire malfunction when a fault code is stored as specified in section 

(e)(2.4.2), the stored freeze frame information shall be replaced with 

freeze frame information regarding the misfire malfunction.

* * * *

(5) Non-Methane Hydrocarbon (NMHC) Converting Catalyst Monitoring

* * * *

(5.2) Malfunction Criteria:

* * * *

(5.2.3) Other Aftertreatment Assistance Functions:

* * * *

(B) For 2013 2015 and subsequent model year engines, for catalysts used to 

generate a feedgas constituency to assist SCR systems (e.g., to increase 

NO2 concentration upstream of an SCR system), the OBD system shall 

detect a malfunction when the catalyst is unable to generate the 

necessary feedgas constituents for proper SCR system operation. 

Catalysts are exempt from feedgas generation this monitoring if both of 

the following criteria are satisfied: (1) no malfunction of the catalyst’s 

feedgas generation ability can cause emissions to (1) increase by 15 
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percent or more of the applicable full useful life standard as measured 

from an applicable emission test cycle; or and (2) no malfunction of the 

catalyst’s feedgas generation ability can cause emissions to exceed the 

applicable full useful life standard as measured from an applicable 

emission test cycle.

* * * *

(8) Particulate Matter (PM) Filter Monitoring

* * * *

(8.2) Malfunction Criteria:

* * * *

(8.2.4) Catalyzed PM Filter:

(A) NMHC conversion: For 2013 2015 and subsequent model year engines,

for with catalyzed PM filters that convert NMHC emissions,:

(i) tThe OBD system shall monitor the catalyst function of the PM filter 

and detect a malfunction when the NMHC conversion capability 

decreases to the point that NMHC emissions exceed 2.0 times the 

applicable standards. 

(ii) If no failure or deterioration of the NMHC conversion capability could 

result in an engine’s NMHC emissions exceeding 2.0 times the 

applicable standards, the OBD system shall detect a malfunction when 

the system has no detectable amount of NMHC conversion capability.

(iii) Catalyzed PM filters are exempt from NMHC conversion capabilitythis

monitoring if both of the following criteria are satisfied: (1) no

malfunction of the catalyzed PM filter’s NMHC conversion capability 

can cause emissions to (1) increase by 15 percent or more of the 

applicable full useful life standard as measured from an applicable 

emission test cycle; or and (2) no malfunction of the catalyzed PM 

filter’s NMHC conversion capability can cause emissions to exceed the 

applicable full useful life standard as measured from an applicable 

emission test cycle.

(B) Feedgas generation: For 2016 and subsequent model year engines with 

catalyzed PM filters used to generate a feedgas constituency to assist 

SCR systems (e.g., to increase NO2 concentration upstream of an SCR 

system), the OBD system shall detect a malfunction when the system is 

unable to generate the necessary feedgas constituents for proper SCR 

system operation. Catalyzed PM filters are exempt from feedgas 

generation this monitoring if both of the following criteria are satisfied: (1) 

no malfunction of the catalyzed PM filter’s feedgas generation ability can 

cause emissions to (1) increase by 15 percent or more of the applicable 

full useful life standard as measured from an applicable emission test 

cycle; or and (2) no malfunction of the catalyzed PM filter’s feedgas 

generation ability can cause emissions to exceed the applicable full useful 

life standard as measured from an applicable emission test cycle.

* * * *
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(g) Monitoring Requirements For All Engines.

(1) Engine Cooling System Monitoring

* * * *

(1.3) Monitoring Conditions:

(1.3.1) Thermostat

* * * *

(D) Manufacturers may request Executive Officer approval to suspend or 

disable thermostat monitoring if the vehicle is subjected to conditions 

which could lead to false diagnosis (e.g., vehicle operation at idle for more 

than 50 percent of the warm-up time, hot restart conditions engine block 

heater operation). In general, the Executive Officer shall not approve 

disablement of the monitor on engine starts where the ECT at engine start 

is more than 35 degrees Fahrenheit lower than the thermostat malfunction 

threshold temperature determined under section (g)(1.2.1)(A). The 

Executive Officer shall approve the request upon determining that the 

manufacturer has provided data and/or engineering analysis that 

demonstrate the need for the request. With respect to disablement on 

driving cycles solely due to warm ECT at engine start conditions, the 

manufacturer shall disable the monitor during driving cycles where the 

ECT at engine start is within 35 degrees Fahrenheit of the thermostat 

malfunction threshold temperature determined under section (g)(1.2.1)(A) 

(e.g., if the malfunction threshold temperature is 160 degrees Fahrenheit, 

the monitor shall be disabled if the ECT at engine start is between above

125 and 160 degrees Fahrenheit).

* * * *

(3) Comprehensive Component Monitoring

* * * *

(3.2) Malfunction Criteria:

* * * *

(3.2.2) Output Components/Systems:

* * * *

(F) For 2013 2015 and subsequent model year engines that utilize fuel control 

system components (e.g., injectors, fuel pump) that have tolerance 

compensation features implemented in hardware or software during 

production or repair procedures (e.g., individually coded injectors for flow 

characteristics that are programmed into an electronic control unit to 

compensate for injector to injector tolerances, fuel pumps that use in-line 

resistors to correct for differences in fuel pump volume output), the 

components shall be monitored to ensure the proper compensation is 

being used. 

* * * *

(ii) Monitoring of the fuel control system components under section 

(g)(3.2.2)(F)(i) is not required if the manufacturer demonstrates that 

both of the following criteria are satisfied: (1) no fault of the 
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components’ tolerance compensation features (e.g., wrong 

compensation being used) could cause emissions to (1) increase by 15 

percent or more of the applicable full useful life standard as measured 

from an applicable emission test cycle; or and (2) no fault of the 

components’ tolerance compensation features can cause emissions to 

exceed the applicable full useful life standard as measured from an 

applicable emission test cycle. For purposes of determining if the 

emission criteria above are met, the manufacturers shall request 

Executive Officer approval of the test plan for which the emission 

impact will be determined. The test plan shall include the combination 

of failed components and the degree of mismatch (e.g., wrong 

compensation) used as well as the test procedure and emission test 

cycles used to demonstrate the emission impact, including the 

necessary preconditioning cycles used by the system to correct or 

adapt for any mismatch and mitigate the emission impact. Executive 

Officer approval shall be granted upon determining that the 

manufacturer has submitted data and/or engineering analysis that 

demonstrate that the conditions necessary for the system to correct or 

adapt will readily occur in a timely manner during in-use operation and 

that the test conditions represent worst case emissions from typical inuse service actions when considering the distribution and variance of 

the compensation values and parts (e.g., replacement of one or more 

plus-one-sigma injectors with minus-one-sigma injectors without 

updating of the compensation value). 

* * * *

(5) Exceptions to Monitoring Requirements

* * * *

(5.7) A manufacturer may request Executive Officer approval to be exempt from 

monitoring a component if both of The OBD system is not required to monitor 

an electronic powertrain component/system if the following criteria are met 

when the ambient temperature is above 20 degrees Fahrenheit: (1) a 

malfunction of the component does not affect emissions during any 

reasonable driving condition, and (2) a malfunction of the component does 

not affect the diagnostic strategy for any other monitored component or 

system,. and (3) tThe ambient temperature shall be is determined based on 

a temperature sensor monitored by the OBD system (e.g., IAT sensor). The 

manufacturer shall determine whether a component/system meets these 

criteria. If the Executive Officer reasonably believes that a manufacturer has 

incorrectly determined that a component/system meets these criteria, the 

Executive Officer shall require the manufacturer to provide emission and/or 

other diagnostic data showing that the component/system, when 

malfunctioning and installed in a suitable test vehicle, does not have an effect 

on emissions or other diagnostic strategies. The Executive Officer may 

request emission data for any reasonable driving condition at ambient 

temperatures above 20 degrees Fahrenheit. The Executive Officer shall 
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approve the request upon determining that the manufacturer has submitted 

data and/or engineering evaluation that support these criteria.

(5.8) Whenever the requirements in section (e) or (f) of this regulation require a 

manufacturer to meet a specific phase-in schedule, manufacturers may use 

an alternate phase-in schedule in lieu of the required phase-in schedule if the 

alternate phase-in schedule provides for equivalent compliance volume as 

defined in section (c) except as specifically noted for the phase-in for the PM 

filter monitor in section (e)(8.2.1) 

(5.8.1) Manufacturers may use an alternate phase-in schedule in lieu of the 

required phase-in schedule if the alternate phase-in schedule provides for 

equivalent compliance volume as defined in section (c) except as 

specifically noted for the phase-in for the PM filter monitor in section 

(e)(8.2.1).

* * * *

(h) Standardization Requirements.

* * * *

(4) Required Emission Related Functions:

The following standardized functions shall be implemented in accordance with 

the specifications in SAE J1979 or SAE J1939 to allow for access to the required 

information by a scan tool meeting SAE J1978 specifications or designed to 

communicate with an SAE J1939 network: 

(4.1) Readiness Status: In accordance with SAE J1979/J1939-73 specifications, 

the OBD system shall indicate “complete” or “not complete” since the fault 

memory was last cleared for each of the installed monitored components and 

systems identified in sections (e)(1) through (f)(9), and (g)(3) except (e)(11) 

and (f)(4). The readiness status for all components or systems identified in 

(f)(2) and (g)(3) shall always indicate “complete”. The readiness status for all 

other components or systems shall immediately indicate “complete” upon the 

respective monitor(s) (except those monitors specified under section 

(h)(4.1.4) below) determining that the component or system is not 

malfunctioning. The readiness status for a component or system shall also 

indicate “complete” if after the requisite number of decisions necessary for 

determining MIL status has been fully executed, the monitor indicates a 

malfunction for the component or system. The readiness status for each of 

the monitored components or systems shall indicate “not complete” whenever 

fault memory has been cleared or erased by a means other than that allowed 

in section (d)(2). Normal vehicle shut down (i.e., key off, engine off) may not 

cause the readiness status to indicate “not complete”.

(4.1.1) Subject to Executive Officer approval, a manufacturer may request that 

the readiness status for a monitor be set to indicate “complete” without 

monitoring having been completed if monitoring is disabled for a multiple 

number of driving cycles due to the continued presence of extreme 

operating conditions (e.g., cold ambient temperatures, high altitudes). 

Executive Officer approval shall be based on the conditions for monitoring 

system disablement and the number of driving cycles specified without 
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completion of monitoring before readiness is indicated as “complete”. The 

readiness status for the following component/system readiness bits shall 

always indicate “complete”:

(A) Diesel misfire (section (e)(2)) for engines without a separate monitor 

designed to detect misfires identified in section (e)(2.2.1) and subject to 

the monitoring conditions of sections (e)(2.3.1) and (e)(2.3.2)

(AB) Gasoline misfire (section (f)(2))

(BC) Diesel and gasoline comprehensive component (section (g)(3))

* * * *

(4.1.3) For 2016 and subsequent model year engines, for components and 

systems not listed in section (h)(4.1.1) above, the readiness status for 

each component/system readiness bit listed below shall immediately 

indicate “complete” if any of the following conditions occur: (1) all the 

respective supported monitors listed below for each component/system 

have fully executed and determined that the component or system is not 

malfunctioning, or (2) at least one of the monitors listed below for each 

component/system has determined that the component or system is 

malfunctioning after the requisite number of decisions necessary for 

determining the MIL status have been fully executed, regardless of 

whether or not the other monitors listed have been fully executed:

(A) Diesel Fuel System: sections (e)(1.2.1), (e)(1.2.2), and (e)(1.2.3)

(B) Diesel Misfire: section (e)(2.2.1) for engines with a separate monitor 

designed to detect misfires identified in section (e)(2.2.1) and subject to 

the monitoring conditions of sections (e)(2.3.1) and (e)(2.3.2)

* * * *

(6) Service Information:

(6.1) Engine manufacturers shall provide the aftermarket service and repair 

industry emission-related service information as set forth in sections (h)(6.3) 

through (6.5).

(6.2) The Executive Officer shall waive the requirements of sections (h)(6.3) 

through (6.5) upon determining that ARB or U.S. EPA has adopted a service 

information regulation or rule that is in effect and operative and requires 

engine manufacturers to provide emission-related service information:

(A) of comparable or greater scope than required under these provisions;

(B) in an easily accessible format and in a timeframe that is equivalent to or 

exceeds the timeframes set forth below; and

(C)at fair and reasonable cost.

(6.3) Manufacturers shall make readily available, at a fair and reasonable price to 

the automotive repair industry, vehicle repair procedures which allow effective 

emission-related diagnosis and repairs to be performed using only the SAE 

J1978/J1939 generic scan tool and commonly available, non-microprocessor 

based tools.

(6.4) As an alternative to publishing repair procedures required under section 

(h)(6.3), a manufacturer may publish repair procedures referencing the use of 
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manufacturer-specific or enhanced equipment provided the manufacturer 

meets one of the following conditions: 

(6.4.1) makes available to the aftermarket scan tool industry the information 

needed to manufacture scan tools to perform the same emission-related 

diagnosis and repair procedures (excluding any reprogramming) in a 

comparable manner as the manufacturer-specific diagnostic scan tool, or

(6.4.2) makes available for purchase, at a fair and reasonable price to the 

automotive repair industry, a manufacturer-specific or enhanced tool to 

perform the emission-related diagnosis and repair procedures (excluding 

any reprogramming).

(6.5) Manufacturers shall make available:

(6.5.1) Information to utilize the test results reported as required in section 

(h)(4.5). The information must include a description of the test and test 

result, typical passing and failing values, associated fault codes with the 

test result, and scaling, units, and conversion factors necessary to convert 

the results to engineering units.

(6.5.2) A generic description of each of the diagnostics used to meet the 

requirements of this regulation. The generic description must include a 

text description of how the diagnostic is performed, typical enable 

conditions, typical malfunction thresholds, typical monitoring time, fault 

codes associated with the diagnostic, and test results (section (h)(4.5)) 

associated with the diagnostic. Vehicles that have diagnostics not 

adequately represented by the typical values identified above shall be 

specifically identified along with the appropriate typical values.

(6.5.3) Information necessary to execute each of the diagnostics used to meet the 

requirements of sections (e)(1) through (f)(9). The information must 

include either a description of sample driving patterns designed to be 

operated in-use or a written description of the conditions the vehicle needs 

to operate in to execute each of the diagnostics necessary to change the 

readiness status from “not complete” to “complete” for all monitors. The 

information shall be able to be used to exercise all necessary monitors in 

a single driving cycle as well as be able to be used to exercise the 

monitors to individually change the readiness status for each specific 

monitor from “not complete” to “complete”.

* * * *

(i) Monitoring System Demonstration Requirements for Certification.

* * * *

(3) Required Testing:

Except as provided below, the manufacturer shall perform single-fault testing 

based on the applicable test with the following components/systems set at their 

malfunction criteria limits as determined by the manufacturer for meeting the 

requirements of sections (e), (f), and (g) or sections (d)(7.1.2) and (d)(7.2.3) for 

extrapolated OBD systems.

(3.1) Required testing for Diesel/Compression Ignition Engines: 

* * * *
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(3.1.2) Misfire Monitoring: For 2010 through 2012 model year engines, a For 

2013 model year engines subject to section (e)(2.2.5), the manufacturer 

shall perform a test at the malfunction limit specified in section (e)(2.2.5). 

A misfire demonstration test is not required for diesel engines not subject 

to section (e)(2.2.5). For 2013 and subsequent model year engines, the 

manufacturer shall perform a test at the malfunction criteria limit specified 

in section (e)(2.2.2).

* * * *

(j) Certification Documentation.

* * * *

(2) The following information shall be submitted as part of the certification 

application. Except as provided below for demonstration data, the Executive 

Officer will not issue an Executive Order certifying the covered engines without 

the information having been provided. The information must include:

* * * *

(2.19) A list of the test results required to be made available under section (gh)(4.5) 

and the corresponding diagnostic(s) noted by fault code for each test result.

* * * *
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Amend section 1968.2, title 13, California Code of Regulations, to read as follows:

Note: The amendments that were approved by the Board at the January 26-27, 2012 

board hearing are shown in single underline to indicate additions and single strikeout to 

indicate deletions from the existing regulatory text. These amendments were formally 

approved by the Office of Administrative Law on August 7, 2012, and became operative 

on August 7, 2012. The amendments proposed with the 45-day notice are shown in 

double underline to indicate additions and double strikeout to indicate deletions from the 

existing regulatory text. New amendments proposed with these staff suggested 

modifications are shown in bold italic double underline to indicate additions and bold 

italic double strikeout to indicate deletions from the existing regulatory text. Various 

portions of the regulations that are not modified by the proposed amendments are 

omitted from the text shown and indicated by “ * * * * ”.

§1968.2. Malfunction and Diagnostic System Requirements -- 2004 and 

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

Vehicles and Engines 

* * * * 

(e) Monitoring Requirements for Gasoline/Spark-Ignited Engines.

* * * *

(15) Comprehensive Component Monitoring

* * * * 

(15.4) MIL Illumination and Fault Code Storage:

* * * * 

(15.4.3)For purposes of determining the emission increase in section 

(e)(15.4.2)(A), the manufacturer shall request Executive Officer approval 

of the test cycle/vehicle operating conditions for which the emission 

increase will be determined. Executive Officer approval shall be granted 

upon determining that the manufacturer has submitted data and/or 

engineering evaluation that demonstrate that the testing conditions 

represent in-use driving conditions where emissions are likely to be most 

affected by the malfunctioning component. For purposes of determining 

whether the specified percentages in section (e)(15.4.2)(A) are exceeded, 

if the approved testing conditions are comprised of an emission test cycle 

with an exhaust emission standard, the measured increase shall be 

compared to a percentage of the exhaust emission standard (e.g., if the 

increase is equal to or more than 15 percent of the exhaust emission 

standard for that test cycle). If the approved testing conditions are 

comprised of a test cycle or vehicle operating condition that does not have 

an exhaust emission standard, the measured increase shall be calculated 

as a percentage of the baseline test (e.g., if the increase from a back-toback test sequence between normal and malfunctioning condition is equal 
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to or more than 15 percent of the baseline test results from the normal 

condition).

* * * * 

(f) Monitoring Requirements for Diesel/Compression-Ignition Engines. 

(1) Non-Methane Hydrocarbon (NMHC) Converting Catalyst Monitoring

* * * *

(1.2) Malfunction Criteria:

* * * *

(1.2.2) Conversion Efficiency:

(A) The OBD II system shall detect an NMHC catalyst malfunction when the 

catalyst conversion capability decreases to the point that emissions 

exceed:

* * * *

(ii) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

a. 2.5 times the applicable NMHC standards for 2007 through 2012 

model year vehicles; and

b. 2.0 times the applicable NMHC standards or the applicable NOx 

standard by more than 0.2 g/bhp-hr (e.g., cause emissions to 

exceed 0.4 g/bhp-hr if the exhaust emission standard is 0.2 g/bhphr) for 2013 and subsequent model year vehicles.

* * * *

(1.2.3) Other Aftertreatment Assistance Functions. Additionally, for 2010 and 

subsequent model year vehicles, the catalyst(s) shall be monitored for 

other aftertreatment assistance functions:

* * * *

(B) For 20105 and subsequent model year passenger cars, light-duty trucks, 

and MDPVs certified to a chassis dynamometer tailpipe emission standard 

and 20135 and subsequent model year medium-duty vehicles (including 

MDPVs) certified to an engine dynamometer tailpipe emission standard, 

for catalysts used to generate a feedgas constituency to assist SCR 

systems (e.g., to increase NO2 concentration upstream of an SCR 

system), the OBD II system shall detect a malfunction when the catalyst is 

unable to generate the necessary feedgas constituents for proper SCR 

system operation. Catalysts are exempt from feedgas generation this

monitoring if both of the following criteria are satisfied: (1) no

malfunction of the catalyst’s feedgas generation ability can cause 

emissions to (1) increase by 15 percent or more of the applicable full 

useful life standard as measured from an applicable emission test cycle; 

or and (2) no malfunction of the catalyst’s feedgas generation ability 

can cause emissions to exceed the applicable full useful life standard as 

measured from an applicable emission test cycle.

* * * *
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(2) Oxides of Nitrogen (NOx) Converting Catalyst Monitoring

* * * *

(2.2) Malfunction Criteria:

* * * *

(2.2.2) Conversion Efficiency:

(A) The OBD II system shall detect a NOx catalyst malfunction when the 

catalyst conversion capability decreases to the point that NOx or NMHC 

emissions exceed:

* * * *

(ii) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

a. the applicable NOx standard by more than 0.5 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.7 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test or 3.5 times the applicable NMHC standard for 2007 

through 2009 model year vehicles;

b. the applicable NOx standard by more than 0.4 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.6 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test or 2.5 times the applicable NMHC standard for 2010 

through 2012 model year vehicles; and

c. the applicable NOx standard by more than 0.3 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.5 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test or 2.0 times the applicable NMHC standard for 2013 

through 2015 model year vehicles; and

cd. the applicable NOx standard by more than 0.2 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.4 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test or 2.0 times the applicable NMHC standard for 2013

2016 and subsequent model year vehicles.

* * * *

(2.3) Monitoring Conditions:

(2.3.1) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (f)(2.2.2), (f)(2.2.3)(A), and (f)(2.2.3)(C) (i.e., catalyst 

efficiency, reductant delivery performance, and improper reductant) in 

accordance with sections (d)(3.1) and (d)(3.2) (i.e., minimum ratio 

requirements). For purposes of tracking and reporting as required in 

section (d)(3.2.2), all monitors used to detect malfunctions identified in 

section (f)(2.2.2) shall be tracked separately but reported as a single set of 

values as specified in section (d)(5.2.2).

(2.3.2) Except as provided for in section (f)(2.3.3), the OBD II system shall 

monitor continuously for malfunctions identified in sections (f)(2.2.3)(A),

(B), and (D) (e.g.i.e., SCR performance, insufficient reductant, feedback 

control).
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* * * *

(3) Misfire Monitoring

* * * *

(3.2) Malfunction Criteria:

(3.2.1) The OBD II system shall detect a misfire malfunction when one or more 

cylinders are continuously misfiring.

(3.2.2) Additionally, for all combustion sensor or combustion quality sensorequipped (e.g., for use in homogeneous charge compression ignition 

control systems) 2010 and subsequent model year vehicles passenger 

cars, light-duty trucks, and MDPVs certified to a chassis dynamometer 

tailpipe emission standard, for all combustion sensor or combustion 

quality sensor-equipped and 2010 through 2015 model year mediumduty vehicles equipped with sensors that can detect combustion or 

combustion quality (e.g., for use in homogeneous charge 

compression ignition (HCCI) control systems), and for 20 percent of 

2016 model year, 50 percent of 2017 model year, and 100 percent of 2018 

model year medium-duty vehicles (percentage based on the 

manufacturer’s projected California sales volume for all medium-duty 

diesel vehicles):

* * * *

(3.3) Monitoring Conditions: 

* * * *

(3.3.3) Additionally, fFor misfires identified in section (f)(3.2.2) 2010 and 

subsequent model year vehicles subject to (f)(3.2.2), the OBD II system 

shall monitor for misfire as follows:

(A) For passenger cars, light-duty trucks, and MDPVs certified to a chassis 

dynamometer tailpipe emission standard, Tthe OBD II system shall 

continuously monitor for misfire under all positive torque engine speeds 

and load conditions.

(B) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard, the OBD II system shall 

continuously monitor for misfire under the following conditions:

(i) For 2010 through 2018 model year vehicles and 2019 and subsequent 

model year vehicles that are not included in the phase-in specified in

section (f)(3.3.3)(B)(ii), under positive torque conditions up to75 

percent of peak torque with engine speed up to 75 percent of the 

maximum-rated engine speed and engine load up to 75 percent 

maximum-rated load except within the following range: the engine 

operating region bound by the positive torque line (i.e., engine load 

with transmission in neutral) and the two following engine-operating 

points: engine speed of 50 percent of maximum-rated engine speed 

with the engine load torque at the positive torque line, and 75 percent 

of the maximum-rated engine speed with the engine load torque 5 

percent above the positive torque line.
15

(ii) For 20 percent of 2019 model year, 50 percent of 2020 model year, 

and 100 percent of 2021 model year medium-duty vehicles 

(percentage based on the manufacturer’s projected California sales 

volume for all medium-duty diesel vehicles), under all positive torque 

engine speed and load conditions except within the following range: 

the engine operating region bound by the positive torque line (i.e., 

engine load with transmission in neutral) and the two following 

engine-operating points: engine speed of 50 percent of maximumrated engine speed with the engine torque at the positive torque 

line, and 100 percent of the maximum-rated engine speed with the 

engine torque 10 percent above the positive torque line.

* * * *

(D)A manufacturer may request Executive Officer approval to disable 

misfire monitoring or employ an alternate malfunction criterion when 

misfire cannot be distinguished from other effects.

(i) Upon determining that the manufacturer has presented 

documentation that demonstrates the disablement interval or 

period of use of an alternate malfunction criterion is limited only 

to that necessary for avoiding false detection, the Executive 

Officer shall approve the disablement or use of the alternate 

malfunction criterion for conditions involving:

a. rough road,

b. fuel cut,

c. gear changes for manual transmission vehicles,

d. traction control or other vehicle stability control activation 

such as anti-lock braking or other engine torque modifications 

to enhance vehicle stability,

e. off-board control or intrusive activation of vehicle components 

or diagnostics during service or assembly plant testing,

f. intrusive diagnostics during portions that can significantly 

affect engine stability, or

g. infrequent regeneration events during portions that can 

significantly affect engine stability.

* * * *

(4) Fuel System Monitoring

* * * *

(4.2) Malfunction Criteria:

(4.2.1) Fuel system pressure control:

(A) The OBD II system shall detect a malfunction of the fuel system pressure 

control system (e.g., fuel, hydraulic fluid) prior to any failure or 

deterioration that would cause a vehicle’s NMHC, CO, NOx, or PM 

emissions to exceed:

* * * *

(ii) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:
16

a. 1.5 times any of the applicable NMHC, CO, and NOx standards or 

0.03 g/bhp-hr PM as measured from an applicable cycle emission 

test for 2007 and subsequent model year vehicles certified to an 

engine dynamometer tailpipe NOx emission standard of greater 

than 0.50 g/bhp-hr NOx;

b. 2.5 times any of the applicable NMHC or CO standards, the 

applicable NOx standard by more than 0.3 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.5 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test, or 0.03 g/bhp-hr PM as measured from an applicable 

cycle emission test for 2007 through 2012 model year vehicles 

certified to an engine dynamometer tailpipe NOx emission standard 

of less than or equal to 0.50 g/bhp-hr NOx; and

c. 2.0 times any of the applicable NMHC or CO standards, the 

applicable NOx standard by more than 0.2 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.4 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test, or 0.03 g/bhp-hr PM as measured from an applicable 

cycle emission test for 2013 and subsequent model year vehicles 

certified to an engine dynamometer tailpipe NOx emission standard 

of less than or equal to 0.50 g/bhp-hr NOx;

* * * *

(5) Exhaust Gas Sensor Monitoring

* * * *

(5.2) Malfunction Criteria:

(5.2.1) Air-Fuel Ratio Sensors: 

(A) For sensors located upstream of the exhaust aftertreatment:

(i) Sensor performance faults: The OBD II system shall detect a 

malfunction prior to any failure or deterioration of the sensor voltage, 

resistance, impedance, current, response rate, amplitude, offset, or 

other characteristic(s) that would cause a vehicle’s NMHC, CO, NOx, 

or PM emissions to exceed:

* * * *

b. For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

1. 1.5 times the applicable NMHC, CO, and NOx standards or 0.03 

g/bhp-hr PM as measured from an applicable cycle emission 

test for 2007 and subsequent model year vehicles certified to an 

engine dynamometer tailpipe NOx emission standard of greater 

than 0.50 g/bhp-hr NOx;

2. 2.5 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.3 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.5 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test, or 0.03 g/bhp-hr PM as measured from an 
17

applicable cycle emission test for 2007 through 2012 model 

year vehicles certified to an engine dynamometer tailpipe NOx 

emission standard of less than or equal to 0.50 g/bhp-hr NOx; 

and

3. 2.0 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.2 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.4 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test, or 0.03 g/bhp-hr PM as measured from an 

applicable cycle emission test for 2013 and subsequent model 

year vehicles certified to an engine dynamometer tailpipe NOx 

emission standard of less than or equal to 0.50 g/bhp-hr NOx.

* * * *

(B) For sensors located downstream of the exhaust aftertreatment:

(i) Sensor performance faults: The OBD II system shall detect a 

malfunction prior to any failure or deterioration of the sensor voltage, 

resistance, impedance, current, response rate, amplitude, offset, or 

other characteristic(s) that would cause a vehicle’s NMHC, CO, NOx, 

or PM emissions to exceed:

* * * *

b. For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

1. 2.5 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.5 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.7 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test, or 0.05 g/bhp-hr PM as measured from an 

applicable cycle emission test for 2007 through 2009 model 

year vehicles certified to an engine dynamometer tailpipe NOx 

emission standard of greater than 0.50 g/bhp-hr NOx;

2. 2.5 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.3 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.5 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test, or 0.05 g/bhp-hr PM as measured from an 

applicable cycle emission test for 2007 through 2012 model 

year vehicles certified to an engine dynamometer tailpipe NOx 

emission standard of less than or equal to 0.50 g/bhp-hr NOx; 

and

3. 2.0 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.2 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.4 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test, or 0.03 g/bhp-hr PM as measured from an 

applicable cycle emission test for 2013 and subsequent model 
18

year vehicles certified to an engine dynamometer tailpipe NOx 

emission standard of less than or equal to 0.50 g/bhp-hr NOx.

* * * *

(5.2.2) NOx and PM sensors:

(A) Sensor performance faults: The OBD II system shall detect a malfunction 

prior to any failure or deterioration of the sensor voltage, resistance, 

impedance, current, response rate, amplitude, offset, or other 

characteristic(s) that would cause a vehicle’s emissions to exceed:

* * * *

(ii) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

a. 2.5 times the applicable NMHC standards, the applicable NOx 

standard by more than 0.5 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.7 g/bhp-hr if the exhaust emission standard is 0.2 g/bhphr) as measured from an applicable cycle emission test or 0.05 

g/bhp-hr PM as measured from an applicable cycle emission test 

for 2007 through 2009 model year vehicles;

b. 2.5 times the applicable NMHC standards, the applicable NOx 

standard by more than 0.4 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.6 g/bhp-hr if the exhaust emission standard is 0.2 g/bhphr) as measured from an applicable cycle emission test or 0.05 

g/bhp-hr PM as measured from an applicable cycle emission test 

for 2010 through 2012 model year vehicles; and

c. 2.0 times the applicable NMHC standard, the applicable NOx 

standard by more than 0.3 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.5 g/bhp-hr if the exhaust emission standard is 0.2 g/bhphr) as measured from an applicable cycle emission test, or 0.03 

g/bhp-hr PM as measured from an applicable cycle emission test 

for 2013 through 2015 model year vehicles; and

cd. 2.0 times the applicable NMHC standards, the applicable NOx 

standard by more than 0.2 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.4 g/bhp-hr if the exhaust emission standard is 0.2 g/bhphr) as measured from an applicable cycle emission test or 0.03 

g/bhp-hr PM as measured from an applicable cycle emission test 

for 2013 2016 and subsequent model year vehicles.

* * * *

(5.3) Monitoring Conditions:

(5.3.1) Exhaust Gas Sensors

(A) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (f)(5.2.1)(A)(i), (5.2.1)(B)(i), and (5.2.2)(A), and 

(5.2.2)(D) (e.g., sensor performance faults) in accordance with sections 

(d)(3.1) and (d)(3.2) (i.e., minimum ratio requirements). For all 2010 and 

subsequent model year vehicles, for purposes of tracking and reporting as 

required in section (d)(3.2.2), all monitors used to detect malfunctions 
19

identified in sections (f)(5.2.1)(A)(i), (5.2.1)(B)(i), and (5.2.2)(A), and for 

2016 and subsequent model year medium-duty vehicles certified to an 

engine dynamometer tailpipe emission standard, section (f)(5.2.2)(D)

shall be tracked separately but reported as a single set of values as 

specified in section (d)(5.2.2).

* * * *

(6) Exhaust Gas Recirculation (EGR) System Monitoring

* * * *

(6.2) Malfunction Criteria:

(6.2.1) Low Flow:

(A) The OBD II system shall detect a malfunction of the EGR system at or 

prior to a decrease from the manufacturer's specified EGR flow rate that 

would cause a vehicle’s NMHC, CO, NOx, or PM emissions to exceed:

* * * *

(ii) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

a. 1.5 times the applicable FTP standards for 2004 through 2006 

model year vehicles;

b. 1.5 times the applicable NMHC, CO, and NOx standards or 0.03 

g/bhp-hr PM as measured from an applicable cycle emission test 

for 2007 and subsequent model year vehicles certified to an engine 

dynamometer tailpipe NOx emission standard of greater than 0.50 

g/bhp-hr NOx;

c. 2.5 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.3 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.5 g/bhp-hr if the exhaust emission standard 

is 0.2 g/bhp-hr) as measured from an applicable cycle emission 

test, or 0.03 g/bhp-hr PM as measured from an applicable cycle 

emission test for 2007 through 2012 model year vehicles certified to 

an engine dynamometer tailpipe NOx emission standard of less 

than or equal to 0.50 g/bhp-hr NOx; and

d. 2.0 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.2 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.4 g/bhp-hr if the exhaust emission standard 

is 0.2 g/bhp-hr) as measured from an applicable cycle emission 

test, or 0.03 g/bhp-hr PM as measured from an applicable cycle 

emission test for 2013 and subsequent model year vehicles 

certified to an engine dynamometer tailpipe NOx emission standard 

of less than or equal to 0.50 g/bhp-hr NOx.

* * * *

(6.2.6) EGR Catalyst Performance: For catalysts located in the EGR system on 

2013 and subsequent model year vehicles and used to convert 

constituents to reduce emissions or protect or extend the durability of 

other emission-related components (e.g., to reduce fouling of an EGR 

cooler or valve),:
20

(A)For 2004 through 2012 model year vehicles, the catalyst shall be 

monitored in accordance with the other emission control or source 

system monitoring requirements under section (f)(16).

(B)For 2013 and subsequent model year vehicles, except as provided 

for in section (f)(6.2.6)(C) below, the OBD II system shall detect a 

malfunction when the catalyst has no detectable amount of constituent 

(e.g., hydrocarbons, soluble organic fractions) oxidation. For 2004 

through 2012 model year vehicles, the catalyst shall be monitored in 

accordance with the other emission control or source system 

monitoring requirements under section (f)(16).

(C)Monitoring of the catalyst is not required if there is no measurable 

emission impact on the criteria pollutants (i.e., NMHC, CO, NOx, and

PM) during any reasonable driving condition in which the catalyst is 

most likely to affect criteria pollutants.

* * * *

(7) Boost Pressure Control System Monitoring

* * * *

(7.2) Malfunction Criteria:

(7.2.1) Underboost:

(A) The OBD II system shall detect a malfunction of the boost pressure control 

system at or prior to a decrease from the manufacturer's commanded or 

expected boost pressure that would cause a vehicle’s NMHC, CO, NOx, 

or PM emissions to exceed:

* * * *

(ii) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

a. 2.5 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.3 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.5 g/bhp-hr if the exhaust emission standard 

is 0.2 g/bhp-hr) as measured from an applicable cycle emission 

test, or 0.03 g/bhp-hr PM as measured from an applicable cycle 

emission test for 2010 through 2012 model year vehicles; and

b. 2.0 times the applicable NMHC or CO standards, the applicable 

NOx standard by more than 0.2 g/bhp-hr (e.g., cause NOx 

emissions to exceed 0.4 g/bhp-hr if the exhaust emission standard 

is 0.2 g/bhp-hr) as measured from an applicable cycle emission 

test, or 0.03 g/bhp-hr PM as measured from an applicable cycle 

emission test for 2013 and subsequent model year vehicles.

* * * *

(8) NOx Adsorber Monitoring

* * * *

(8.2) Malfunction Criteria:

(8.2.1) NOx adsorber capability:
21

(A) The OBD II system shall detect a NOx adsorber system malfunction when 

the NOx adsorber system capability decreases to the point that would 

cause a vehicle's NOx or NMHC emissions to exceed:

* * * *

(ii) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

a. the applicable NOx standard by more than 0.5 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.7 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test or 3.5 times the applicable NMHC standard for 2007 

through 2009 model year vehicles;

b. the applicable NOx standard by more than 0.3 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.5 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test or 2.5 times the applicable NMHC standard for 2010 

through 2012 model year vehicles; and

c. the applicable NOx standard by more than 0.2 g/bhp-hr (e.g., cause 

NOx emissions to exceed 0.4 g/bhp-hr if the exhaust emission 

standard is 0.2 g/bhp-hr) as measured from an applicable cycle 

emission test or 2.0 times the applicable NMHC standard for 2013 

and subsequent model year vehicles.

* * * *

(9) Particulate Matter (PM) Filter Monitoring

* * * *

(9.2) Malfunction Criteria:

* * * *

(9.2.2) Frequent Regeneration:

(A) For 2010 and subsequent model year vehicles, the OBD II system shall 

detect a malfunction when PM filter regeneration occurs more frequently 

than (i.e., occurs more often than) the manufacturer’s specified 

regeneration frequency such that it would cause a vehicle's emissions to 

exceed:

* * * *

(ii) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

a. 2.5 times the applicable NMHC standards or the applicable NOx 

standard by more than 0.3 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.5 g/bhp-hr if the exhaust emission standard is 0.2 g/bhphr) as measured from an applicable cycle emission test for 2010 

through 2012 model year vehicles; and

b. 2.0 times the applicable NMHC standards or the applicable NOx 

standard by more than 0.2 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.4 g/bhp-hr if the exhaust emission standard is 0.2 g/bhphr) as measured from an applicable cycle emission test for 2013 

and subsequent model year vehicles.
22

* * * *

(9.2.4) Catalyzed PM Filter:

(A)NMHC conversion: For 20105 and subsequent model year passenger 

cars, light-duty trucks, and MDPVs certified to a chassis dynamometer

tailpipe emission standard and 20135 and subsequent model year 

medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard with catalyzed PM filters that 

convert NMHC emissions, the OBD II system shall monitor the catalyst 

function of the PM filter and detect a malfunction when the NMHC 

conversion capability decreases to the point that NMHC emissions exceed 

the applicable emission levels specified in section (f)(9.2.2)(A). If no 

failure or deterioration of the NMHC conversion capability could result in a 

vehicle’s NMHC emissions exceeding these emission levels, the OBD II 

system shall detect a malfunction when the system has no detectable 

amount of NMHC conversion capability. PM filters are exempt from 

NMHC conversion capability this monitoring if both of the following 

criteria are satisfied: (1) no malfunction of the PM filter’s NMHC 

conversion capability can cause emissions to (1) increase by 15 percent 

or more of the applicable full useful life standard as measured from an 

applicable emission test cycle; or and (2) no malfunction of the PM 

filter’s NMHC conversion capability can cause emissions to exceed 

the applicable full useful life standard as measured from an applicable 

emission test cycle.

(B)Feedgas generation: For 2016 and subsequent model year mediumduty vehicles with catalyzed PM filters used to generate a feedgas 

constituency to assist SCR systems (e.g., to increase NO2

concentration upstream of an SCR system), the OBD II system shall 

detect a malfunction when the system is unable to generate the 

necessary feedgas constituents for proper SCR system operation. 

Catalyzed PM filters are exempt from this monitoring if both of the 

following criteria are satisfied: (1) no malfunction of the catalyzed PM 

filter’s feedgas generation ability can cause emissions to increase by 

15 percent or more of the applicable full useful life standard as 

measured from an applicable emission test cycle; and (2) no

malfunction of the catalyzed PM filter’s feedgas generation ability 

can cause emissions to exceed the applicable full useful life 

standard as measured from an applicable emission test cycle.

* * * *

(12) Cold Start Emission Reduction Strategy Monitoring

* * * *

(12.2) Malfunction Criteria: The OBD II system shall, to the extent feasible, detect a 

malfunction if either of the following occurs:

* * * *
23

(12.2.2) Any failure or deterioration of the cold start emission reduction control 

strategy that would cause a vehicle’s NMHC, CO, NOx, or PM emissions 

to exceed:

* * * *

(B) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

(i) 2.0 times the applicable NMHC or CO standards, the applicable NOx 

standard by more than 0.2 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.4 g/bhp-hr if the exhaust emission standard is 0.2 g/bhp-hr) 

as measured from an applicable cycle emission test, or 0.03 g/bhp-hr 

PM as measured from an applicable cycle emission test for 2013 and 

subsequent model year vehicles.

* * * *

(13) Variable Valve Timing And/Or Control (VVT) System Monitoring

* * * *

(13.2) Malfunction Criteria:

(13.2.1) Target Error: The OBD II system shall detect a malfunction prior to any 

failure or deterioration in the capability of the VVT system to achieve the 

commanded valve timing and/or control within a crank angle or lift 

tolerance that would cause a vehicle's NMHC, CO, NOx, or PM emissions 

to exceed:

* * * *

(B) For medium-duty vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard:

(i) 1.5 times the applicable NMHC, CO, and NOx standards or 0.03 

g/bhp-hr PM as measured from an applicable cycle emission test for 

2006 and subsequent model year vehicles certified to an engine 

dynamometer tailpipe NOx emission standard of greater than 0.50 

g/bhp-hr NOx;

(ii) 2.5 times the applicable NMHC or CO standards, the applicable NOx 

standard by more than 0.3 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.5 g/bhp-hr if the exhaust emission standard is 0.2 g/bhp-hr) 

as measured from an applicable cycle emission test, or 0.03 g/bhp-hr 

PM as measured from an applicable cycle emission test for 2006 

through 2012 model year vehicles certified to an engine dynamometer 

tailpipe NOx emission standard of less than or equal to 0.50 g/bhp-hr 

NOx; and

(iii) 2.0 times the applicable NMHC or CO standards, the applicable NOx 

standard by more than 0.2 g/bhp-hr (e.g., cause NOx emissions to 

exceed 0.4 g/bhp-hr if the exhaust emission standard is 0.2 g/bhp-hr) 

as measured from an applicable cycle emission test, or 0.03 g/bhp-hr 

PM as measured from an applicable cycle emission test for 2013 and 

subsequent model year vehicles certified to an engine dynamometer 
24

tailpipe NOx emission standard of less than or equal to 0.50 g/bhp-hr 

NOx.

* * * *

(15) Comprehensive Component Monitoring

* * * *

(15.2) Malfunction Criteria:

* * * *

(15.2.2) Output Components/Systems:

* * * *

(F) For 20132015 and subsequent model year vehicles that utilize fuel control 

system components (e.g., injectors, fuel pump) that have tolerance 

compensation features implemented in hardware or software during 

production or repair procedures (e.g., individually coded injectors for flow 

characteristics that are programmed into an electronic control unit to 

compensate for injector to injector tolerances, fuel pumps that use in-line 

resistors to correct for differences in fuel pump volume output), the 

components shall be monitored to ensure the proper compensation is 

being used. 

* * * *

(ii) Monitoring of the fuel control system components under section 

(f)(15.2.2)(F)(i) is not required if the manufacturer demonstrates that 

both of the following criteria are satisfied: (1) no fault of the 

components’ tolerance compensation features (e.g., wrong 

compensation being used) could cause emissions to (1) increase by 15 

percent or more of the applicable full useful life standard as measured 

from an applicable emission test cycle; or and (2) no fault of the 

components’ tolerance compensation features could cause 

emissions to exceed the applicable full useful life standard as 

measured from an applicable emission test cycle. For purposes of 

determining if the emission criteria above are met, the manufacturers 

shall request Executive Officer approval of the test plan for which the 

emission impact will be determined. The test plan shall include the 

combination of failed components and the degree of mismatch (e.g., 

wrong compensation) used as well as the test procedure and emission 

test cycles used to demonstrate the emission impact, including the 

necessary preconditioning cycles used by the system to correct or 

adapt for any mismatch and mitigate the emission impact. Executive 

Officer approval shall be granted upon determining that the 

manufacturer has submitted data and/or engineering analysis that 

demonstrate that the conditions necessary for the system to correct or 

adapt will readily occur in a timely manner during in-use operation and 

that the test conditions represent worst case emissions from typical inuse service actions when considering the distribution and variance of 

the compensation values and parts (e.g., replacement of one or more 
25

plus-one-sigma injectors with minus-one-sigma injectors without 

updating of the compensation value).

* * * *

(15.4) MIL Illumination and Fault Code Storage:

* * * *

(15.4.3) For purposes of determining the emission increase in section 

(f)(15.4.2)(A), the manufacturer shall request Executive Officer approval of 

the test cycle/vehicle operating conditions for which the emission increase 

will be determined. Executive Officer approval shall be granted upon 

determining that the manufacturer has submitted data and/or engineering 

evaluation that demonstrate that the testing conditions represent in-use 

driving conditions where emissions are likely to be most affected by the 

malfunctioning component. For purposes of determining whether the 

specified percentages in section (f)(15.4.2)(A) are exceeded, if the 

approved testing conditions are comprised of an emission test cycle with 

an exhaust emission standard, the measured increase shall be compared 

to a percentage of the exhaust emission standard (e.g., if the increase is 

equal to or more than 15 percent of the exhaust emission standard for 

that test cycle). If the approved testing conditions are comprised of a test 

cycle or vehicle operating condition that does not have an exhaust

emission standard, the measured increase shall be calculated as a 

percentage of the baseline test (e.g., if the increase from a back-to-back 

test sequence between normal and malfunctioning condition is equal to or 

more than 15 percent of the baseline test results from the normal 

condition).

* * * *

(17) Exceptions to Monitoring Requirements

(17.1) Except as provided in sections (f)(17.1.1) through (17.1.4) below, upon 

request of a manufacturer or upon the best engineering judgment of ARB, the 

Executive Officer may revise the emission threshold for a malfunction on any 

diagnostic required in section (f) for medium-duty vehicles if the most reliable 

monitoring method developed requires a higher threshold to prevent 

significant errors of commission in detecting false indications of a malfunction. 

Additionally, except as specified in section (f)(9.2.1)(A)(iii), for 2007 through 

20092013 model year light-duty vehicles and 2007 through 2012 2013 2015

model year medium-duty vehicles, the Executive Officer may revise the PM 

filter malfunction criteria of section (f)(9.2.1) to exclude detection of specific 

failure modes (e.g., combined failure of partially melted and partially cracked 

substrates) if the most reliable monitoring method developed requires the 

exclusion of specific failure modes to prevent significant errors of commission 

in detecting false indications of a malfunction. 

* * * *

(17.1.3) For medium-duty diesel vehicles (including MDPVs) certified to an engine 

dynamometer tailpipe emission standard, the Executive Officer shall 

approve a malfunction criteria of “the applicable PM standard plus 0.02 
26

g/bhp-hr PM (e.g., unable to maintain PM emissions at or below 0.03 

g/bhp-hr if the exhaust emission standard is 0.01 g/bhp-hr) as measured 

from an applicable cycle emission test” in lieu of “0.03 g/bhp-hr PM as 

measured from an applicable cycle emission test” wherever required in 

section (f). The Executive Officer shall also approve a malfunction criteria 

of “the applicable PM standard plus 0.04 g/bhp-hr PM (e.g., unable to 

maintain PM emissions at or below 0.05 g/bhp-hr if the exhaust emission 

standard is 0.01 g/bhp-hr) as measured from an applicable cycle emission 

test” in lieu of “0.05 g/bhp-hr PM as measured from an applicable cycle 

emission test” wherever required in section (f).

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(h) Monitoring System Demonstration Requirements For Certification

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(4) Required Testing for Diesel/Compression-ignition vehicles:

Except as provided below, the manufacturer shall perform single-fault testing 

based on the applicable test with the following components/systems set at their 

malfunction criteria limits as determined by the manufacturer for meeting the 

requirements of section (f).

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(4.3) Misfire Monitoring: For 2010 and subsequent model year vehicles subject to 

section (f)(3.2.2)(A)(i) or (f)(3.2.5), the manufacturer shall perform a test at 

the malfunction criteria limit specified in section (f)(3.2.2)(A)(i) or (f)(3.2.5). A 

misfire monitor demonstration test is not required for vehicles not subject to 

section (f)(3.2.2)(A)(i) and not subject to section (f)(3.2.5).

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