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FINAL REGULATION ORDER

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

Note: The amendments 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 “ * * * * ”.

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

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

Vehicles and Engines.

(a) Purpose.

The purpose of this regulation is to reduce motor vehicle and motor vehicle engine 

emissions by establishing emission standards and other requirements for onboard 

diagnostic systems (OBD II systems) that are installed on 2004 and subsequent 

model-year passenger cars, light-duty trucks, and medium-duty vehicles and 

engines certified for sale in California. The OBD II systems, through the use of an 

onboard computer(s), shall monitor emission systems in-use for the actual life of the 

vehicle and shall be capable of detecting malfunctions of the monitored emission 

systems, illuminating a malfunction indicator light (MIL) to notify the vehicle operator 

of detected malfunctions, and storing fault codes identifying the detected 

malfunctions. The use and operation of OBD systems will ensure reductions in inuse motor vehicle and motor vehicle engine emissions through improvements of 

emission system durability and performance.

* * * * 

(c) Definitions.

* * * * 

“Alternate phase-in” is a phase-in schedule that achieves equivalent compliance 

volume by the end of the last year of a scheduled phase-in provided in this 

regulation. The compliance volume is the number calculated by multiplying the 

percent of vehicles (based on the manufacturer’s projected sales volume of all 

vehicles unless specifically stated otherwise in section (e) or (f)) meeting the new 

requirements per year by the number of years implemented prior to and including 

the last year of the scheduled phase-in and then summing these yearly results to 

determine a cumulative total (e.g., a three year, 30/60/100 percent scheduled phasein would be calculated as (30*3 years) + (60*2 years) + (100*1 year) = 310). On 

phase-ins scheduled to begin prior to the 2004 model year, manufacturers are 

allowed to include vehicles introduced before the first year of the scheduled phase-in 
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(e.g., in the previous example, 10 percent introduced one year before the scheduled 

phase-in begins would be calculated as (10*4 years) and added to the cumulative 

total). However, on phase-ins scheduled to begin in 2004 or subsequent model 

years, manufacturers are only allowed to include vehicles introduced up to one 

model year before the first year of the scheduled phase-in. The Executive Officer 

shall consider acceptable any alternate phase-in that results in an equal or larger 

cumulative total by the end of the last year of the scheduled phase-in and ensures 

that all vehicles subject to the phase-in will comply with the respective requirements 

no later than two model years following the last year of the scheduled phase-in. 

* * * * 

“Driving Cycle” consists of engine startup and engine shutoff and includes the 

period of engine off time up to the next engine startup. For vehicles that employ 

engine shutoff strategies (e.g., engine shutoff at idle), the manufacturer may request 

Executive Officer approval to use an alternate definition for driving cycle (e.g., key 

on and key off). Executive officer approval of the alternate definition shall be based

on equivalence to engine startup and engine shutoff signaling the beginning and 

ending of a single driving event for a conventional vehicle. For applications that are 

used in both medium-duty and heavy-duty classes, the manufacturer may use the 

driving cycle definition of the title 13, CCR, section 1971.1 in lieu of this definition. 

Engine restarts following an engine shut-off that has been neither commanded by 

the vehicle operator nor by the engine control strategy but caused by an event such 

as an engine stall may be considered a new driving cycle or a continuation of the 

existing driving cycle.

 

“Emission standard,” as it applies to OBD compliance and the remedies provided 

for in the Health and Safety Code for noncompliance, relates to the emission 

characteristics of a motor vehicle and engine and means:

(1) a numerical limit on the amount of a given pollutant that a motor vehicle or 

motor vehicle engine may emit into the atmosphere; or

(2) a requirement that a motor vehicle or motor vehicle engine be equipped with 

a certain type of pollution-control device or some other design feature related 

to the control of emissions.

“Engine misfire” means lack of combustion in the cylinder due to absence of 

spark, poor fuel metering, poor compression, or any other cause. This does not 

include lack of combustion events in non-active cylinders due to default fuel shut-off 

or cylinder deactivation strategies.

“Engine start” is defined as the point when the engine reaches a speed 150 rpm 

below the normal, warmed-up idle speed (as determined in the drive position for 

vehicles equipped with an automatic transmission). For hybrid vehicles or for 

engines employing alternate engine start hardware or strategies (e.g., integrated 

starter and generators, etc.), the manufacturer may request Executive Officer 
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approval to use an alternate definition for engine start (e.g., ignition key “on”). 

Executive Officer approval of the alternate definition shall be based on equivalence 

to an engine start for a conventional vehicle.

“Evaporative emission standards” are a subset of emission standards that refer 

to the specific motor vehicle fuel evaporative emission standards and test 

procedures incorporated by reference in title 13, CCR section 1976 to which a 

vehicle is certified.

“Exhaust emission standards” or “tailpipe emission standards” are a subset of 

emission standards that collectively refer to the specific FTP standards and SET 

standards to which a vehicle is certified.

“Family Emission Limit (FEL)” refers to the exhaust emission levels to which an 

engine family is certified under the averaging, banking, and trading program 

incorporated by reference in title 13, CCR section 1956.8.

* * * * 

(d) General Requirements.

Section (d) sets forth the general requirements of the OBD II system. Specific 

performance requirements for components and systems that shall be monitored are 

set forth in sections (e) and (f) below.

* * * * 

(3) Monitoring Conditions.

Section (d)(3) sets forth the general monitoring requirements while sections (e) 

and (f) set forth the specific monitoring requirements as well as identify which of 

the following general monitoring requirements in section (d)(3) are applicable for 

each monitored component or system identified in sections (e) and (f).

* * * * 

(3.2) As specifically provided for in sections (e) and (f), manufacturers shall define 

monitoring conditions in accordance with the criteria in sections (d)(3.2.1) 

through (3.2.3). The requirements of section (d)(3.2) shall be phased in as 

follows: 30 percent of all 2005 model year vehicles, 60 percent of all 2006 

model year vehicles, and 100 percent of all 2007 and subsequent model year 

vehicles. 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) with the exception that 

100 percent of 2007 and subsequent model year vehicles shall comply with 

the requirements. Small volume manufacturers shall meet the requirements 

on 100 percent of 2007 and subsequent model year vehicles but shall not be 

required to meet the specific phase-in requirements for the 2005 and 2006 

model years.
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(3.2.1) Manufacturers shall define monitoring conditions that, in addition to 

meeting the criteria in section (d)(3.1), ensure that the monitor yields an 

in-use performance ratio (as defined in section (d)(4)) that meets or 

exceeds the minimum acceptable in-use monitor performance ratio on inuse vehicles. For purposes of this regulation, except as provided below in 

section (d)(3.2.1)(D), the minimum acceptable in-use monitor performance 

ratio is:

(A) 0.260 for secondary air system monitors and other cold start related 

monitors utilizing a denominator incremented in accordance with section 

(d)(4.3.2)(E);

(B) For evaporative system monitors:

(i) 0.260 for monitors designed to detect malfunctions identified in section 

(e)(4.2.2)(C) (i.e., 0.020 inch leak detection); and

(ii) 0.520 for monitors designed to detect malfunctions identified in section 

(e)(4.2.2)(A) and (B) (i.e., purge flow and 0.040 inch leak detection); 

(C)0.336 for catalyst, oxygen sensor, EGR, VVT system, and all other 

monitors specifically required in sections (e) and (f) to meet the monitoring 

condition requirements of section (d)(3.2); 

(D)For introductory interim years:

(i) through the 2007 model year, for the first three years a vehicle is 

certified to the in-use performance ratio monitoring requirements of 

section (d)(3.2), 0.100 for all monitors specified in section (d)(3.2.1)(A) 

through (C) above. For example, the 0.100 ratio shall apply to the 

2004, 2005, and 2006 model years for vehicles first certified in the 

2004 model year and to the 2007, 2008, and 2009 model years for 

vehicles first certified in the 2007 model year;

(ii) through the 2014 model year, for fuel system air-fuel ratio cylinder 

imbalance monitors, 0.100;

(iii) through the 2011 model year, for secondary exhaust gas sensor 

monitors specified in (e)(7.2.2)(C), 0.100;

(iv)through the 2012 model year, for vehicles subject to the monitoring 

requirements of section (f), 0.100 for all monitors specified in section 

(d)(3.2.1)(C) above.;

(v) through the 2016 model year for plug-in hybrid electric vehicles, 0.100 

for all monitors specifically required in sections (e) and (f) to meet the 

monitoring condition requirements of section (d)(3.2) and that are for 

systems or components that require engine operation.;

(vi)for 2016 through 2018 model year medium-duty vehicles certified to an 

engine dynamometer tailpipe emission standard, 0.100 for diesel PM 

filter filtering performance monitors (section (f)(9.2.1)) and missing 

substrate monitors (section (f)(9.2.5)) not using the denominator 

criteria in section(d)(4.3.2)(G).

* * * * 
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(4) In-Use Monitor Performance Ratio Definition.

* * * * 

(4.3) Denominator Specifications

* * * *

(4.3.2) Specifications for incrementing:

* * * * 

(F) In addition to the requirements of section (d)(4.3.2)(B) above, the 

denominator(s) for the following monitors of output components (except 

those operated only at engine start-up and subject to the requirements of 

the previous section (d)(4.3.2)(E)) shall be incremented if and only if the 

component is commanded to function (e.g., commanded “on”, “open”, 

“closed”, “locked”, etc.) on two or more occasions for greater than two 

seconds during the driving cycle or for a cumulative time greater than or 

equal to ten seconds, whichever occurs first:

(i) Air conditioning system (section (e)(12))

(ii) Variable valve timing and/or control system (sections (e)(13) and 

(f)(13)) 

(iii) “Other emission control or source device” (sections (e)(16) and (f)(16)) 

(iv)Comprehensive component output component (sections (e)(15) and 

(f)(15)) (e.g., turbocharger waste-gates, variable length manifold 

runners, torque converter clutch lock-up solenoids, etc.)

(v) PM sensor heater (section (f)(5.2.4)(A))

(vi)PM filter active/intrusive injection (section (f)(9.2.6))

For the PM sensor heater monitor, as an alternative for 2013 through 2015 

model year vehicles, the manufacturer may use the criteria in section 

(d)(4.3.2)(B) in lieu of the criteria specified in section (d)(4.3.2)(F) above.

For the PM filter active/intrusive injection monitor, as an alternative for 

2013 through 2015 model year vehicles, the manufacturer may use the 

criteria in section (d)(4.3.2)(I) in lieu of the criteria specified in section 

(d)(4.3.2)(F) above.

(G)For the following monitors, the denominator(s) shall be incremented by 

one during a driving cycle in which the following two criteria are met: (1) 

the requirements of section (d)(4.3.2)(B) have been met on at least one 

driving cycle since the denominator was last incremented, and (2) the 

number of cumulative miles of vehicle operation since the denominator 

was last incremented is greater than or equal to 500 miles:

(i) Diesel NMHC converting catalyst (section (f)(1.2.2)) 

(ii) Diesel NMHC converting catalyst other aftertreatment assistance 

functions (sections (f)(1.2.3)(B) and (f)(1.2.3)(D))

(iii) Diesel PM filter NMHC conversion (sections (f)(9.2.1), (f)(9.2.4), and 

(f)(9.2.5))

(iv)Diesel PM filter filtering performance and missing substrate (sections 

(f)(9.2.1) and (f)(9.2.5)) for passenger cars, light-duty trucks, and 

MDPVs certified to a chassis dynamometer tailpipe emission standard

(v) Diesel PM filter filtering performance and missing substrate (sections 
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(f)(9.2.1) and (f)(9.2.5)) for 2004 through 2015 model year mediumduty vehicles certified to an engine dynamometer tailpipe emission 

standard

* * * * 

(I) For 2013 and subsequent model year vehicles, in addition to the 

requirements of section (d)(4.3.2)(B) above, the denominator(s) for the 

following monitors shall be incremented if and only if a regeneration event 

is commanded for a time greater than or equal to ten seconds:

(i) Diesel NMHC converting catalyst other aftertreatment assistance 

functions (sections (f)(1.2.3)(A) and (f)(1.2.3)(C))

(ii) PM filter incomplete regeneration (section (f)(9.2.3))

(iii) PM filter active/intrusive injection (section (f)(9.2.6))

* * * * 

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

* * * * 

(6) Fuel System Monitoring

(6.1) Requirement:

(6.1.1) The OBD II system shall monitor the fuel delivery system to determine its 

ability to provide compliance with emission applicable standards.

* * * *

(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 

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

condition).

* * * * 
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(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 2015 and subsequent model year passenger cars, light-duty trucks, 

and MDPVs certified to a chassis dynamometer tailpipe emission standard 

and 2015 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 this monitoring if both of the 

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

(2.3.3) Manufacturers may request Executive Officer approval to temporarily 

disable continuous monitoring under conditions technically necessary to 

ensure robust detection of malfunctions and to avoid false passes and 

false indications of malfunctions. The Executive Officer shall approve the 

request upon determining that the manufacturer has submitted data and/or 

an engineering evaluation which demonstrate that a properly operating 

system cannot be distinguished from a malfunctioning system and that the 

disablement interval is limited only to that which is technically necessary.

* * * *

(3) Misfire Monitoring

(3.1) Requirement:

(3.1.1) The OBD II system shall monitor the engine for misfire causing excess 

emissions. The OBD II system shall be capable of detecting misfire 

occurring in one or more cylinders. To the extent possible without adding 

hardware for this specific purpose, the OBD II system shall also identify 

the specific misfiring cylinder.

* * * *

(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 2010 through 2015 model year medium-duty 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):

(A) The OBD II system shall detect a misfire malfunction that would cause a 

vehicle’s NMHC, CO, NOx, or PM emissions to exceed as follows:

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

dynamometer tailpipe emission standard, the OBD II system shall 

detect a misfire malfunction that would cause a vehicle’s NMHC, CO, 

NOx, or PM emissions to exceed 1.5 times any of the applicable FTP 

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

dynamometer tailpipe emission standard, the OBD II system shall 

detect a misfire malfunction when the percentage of misfire is equal to 

or exceeds five percent 2.0 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.

(B) The manufacturers shall evaluate the percentage of misfire as follows:

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

dynamometer tailpipe emission standard, Mmanufacturers shall 

determine the percentage of misfire evaluated in 1000 revolution 

increments that would cause NMHC, CO, NOx, or PM emissions from 

an emission durability demonstration vehicle to exceed the levels 

specified in section (f)(3.2.2)(A) if the percentage of misfire were 

present from the beginning of the test. To establish this percentage of 

misfire, the manufacturer shall utilize misfire events occurring at 

equally spaced, complete engine cycle intervals, across randomly 

selected cylinders throughout each 1000-revolution increment. If this 

percentage of misfire is determined to be lower than one percent, the 

manufacturer may set the malfunction criteria at one percent. 

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

dynamometer tailpipe emission standard, the manufacturer shall 

evaluate the percentage of misfire in 1000 revolution increments. 

(C)Subject to Executive Officer approval, a manufacturer may employ other 

revolution increments. The Executive Officer shall grant approval upon 

determining that the manufacturer has demonstrated that the strategy 

would be equally effective and timely in detecting misfire.

(3.2.3) A malfunction shall be detected if the percentage of misfire established in 

section (f)(3.2.2)(B) is exceeded regardless of the pattern of misfire events 

(e.g., random, equally spaced, continuous).

(3.2.4) For multiple cylinder misfire situations that result in a misfire rate greater 

than or equal to 50 percent of all engine firings, the OBD II system shall 

only be required to detect a misfire malfunction for situations that are 

caused by a single component failure.

(3.2.5) Upon request by the manufacturer and upon determining that the 

manufacturer has submitted data and/or engineering evaluation which 

support the request, the Executive Officer shall revise the percentage of 

misfire malfunction criteria in section (f)(3.2.2)(A)(ii) upward to exclude 

detection of misfire that cannot cause the vehicle’s NMHC, CO, and NOx 

emissions to exceed 2.0 times the applicable standards and the vehicle’s 

PM emissions to exceed 0.03 g/bhp-hr as measured from an applicable 

cycle emission test. 

(3.3) Monitoring Conditions: 

(3.3.1) Except as provided in section (f)(3.3.2), Tthe OBD II system shall monitor 

for misfires identified in section (f)(3.2.1) during engine idle conditions at 

least once per driving cycle in which the monitoring conditions for misfire 
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are met. A manufacturer shall submit monitoring conditions to the 

Executive Officer for approval. The Executive Officer shall approve 

manufacturer-defined monitoring conditions that are determined (based on 

manufacturer-submitted data and/or other engineering documentation) to: 

(i) be technically necessary to ensure robust detection of malfunctions 

(e.g., avoid false passes and false detection of malfunctions), (ii) require 

no more than 1000 cumulative engine revolutions, and (iii) do not require 

any single continuous idle operation of more than 15 seconds to make a 

determination that a malfunction is present (e.g., a decision can be made 

with data gathered during several idle operations of 15 seconds or less); 

or satisfy the requirements of (d)(3.1) with alternative engine operating 

conditions.

(3.3.2) Manufacturers may request Executive Officer approval to use alternate 

monitoring conditions (e.g., off-idle) in lieu of the monitoring conditions 

specified in section (f)(3.3.1). The Executive Officer shall approve 

alternate monitoring conditions that are determined (based on 

manufacturer-submitted data and/or other engineering documentation) to 

ensure equivalent robust detection of malfunctions and equivalent 

timeliness in detection of malfunctions. 

(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 engine speed except within the following range: the engine 

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

with transmission in neutral) and the two following points: engine 

speed of 50 percent of maximum engine speed with the engine torque 

at the positive torque line, and 75 percent of the maximum engine 

speed with the engine torque at 5 percent of peak torque above the 

positive torque line.

(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 conditions except within the following range: the engine 
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operating region bound by the positive torque line (i.e., engine load 

with transmission in neutral) and the two following points: engine 

speed of 50 percent of maximum engine speed with the engine torque 

at the positive torque line, and 100 percent of the maximum engine 

speed with the engine torque at 10 percent of peak torque above the 

positive torque line.

(B)(C) If a monitoring system cannot detect all misfire patterns under all 

required engine speed and load conditions as required in sections

(f)(3.3.3)(A) and (B), the manufacturer may request Executive Officer 

approval to accept the monitoring system. In evaluating the 

manufacturer’s request, the Executive Officer shall consider the following 

factors: the magnitude of the region(s) in which misfire detection is limited, 

the degree to which misfire detection is limited in the region(s) (i.e., the 

probability of detection of misfire events), the frequency with which said 

region(s) are expected to be encountered in-use, the type of misfire 

patterns for which misfire detection is troublesome, and demonstration 

that the monitoring technology employed is not inherently incapable of 

detecting misfire under required conditions (i.e., compliance can be 

achieved on other engines), and the extent to which the most reliable 

monitoring method developed is unable to ensure robust detection of 

misfire in the region(s). The evaluation shall be based on the following 

misfire patterns: equally spaced misfire occurring on randomly selected 

cylinders, single cylinder continuous misfire, and paired cylinder (cylinders 

firing at the same crank angle) continuous misfire.

(D)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. 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. Such disablements may include but are not limited to events 

involving:

(i) rough road,

(ii) fuel cut,

(iii) gear changes for manual transmission vehicles,

(iv)traction control or other vehicle stability control activation such as antilock braking or other engine torque modifications to enhance vehicle 

stability,

(v) off-board control or intrusive activation of vehicle components or 

diagnostics during service or assembly plant testing,

(vi)intrusive diagnostics during portions that can significantly affect engine

stability, or

(vii)infrequent regeneration events during portions that can significantly 

affect engine stability.
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(3.4) MIL Illumination and Fault Code Storage:

(3.4.1) General requirements for MIL illumination and fault code storage are set 

forth in section (d)(2).

(3.4.2) Additionally, for 2010 and subsequent model year vehicles subject to 

(f)(3.2.2):

(A) Upon detection of the percentage of misfire specified in section 

(f)(3.2.2)(B), the following criteria shall apply for MIL illumination and fault 

code storage:

(i) A pending fault code shall be stored no later than after the fourth 

exceedance of the percentage of misfire specified in section 

(f)(3.2.2)(B) during a single driving cycle.

(ii) If a pending fault code is stored, the OBD II system shall illuminate the 

MIL and store a confirmed fault code within 10 seconds if the 

percentage of misfire specified in section (f)(3.2.2)(B) is again 

exceeded four times during: (a) the driving cycle immediately following 

the storage of the pending fault code, regardless of the conditions 

encountered during the driving cycle; or (b) on the next driving cycle in 

which similar conditions (see section (c)) to the engine conditions that 

occurred when the pending fault code was stored are encountered.

(iii) The pending fault code may be erased at the end of the next driving 

cycle in which similar conditions to the engine conditions that occurred 

when the pending fault code was stored have been encountered 

without an exceedance of the specified percentage of misfire. The 

pending code may also be erased if similar conditions are not 

encountered during the next 80 driving cycles immediately following 

initial detection of the malfunction.

* * * *

(4) Fuel System Monitoring

(4.1) Requirement:

The OBD II system shall monitor the fuel delivery system to determine its 

ability to comply with emission applicable standards. The individual electronic 

components (e.g., actuators, valves, sensors, pumps) that are used in the fuel 

system and not specifically addressed in this section shall be monitored in 

accordance with the comprehensive component requirements in section 

(f)(15).

(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:

* * * *
14

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

dynamometer tailpipe emission standard:

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;
15

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 

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 
16

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.

* * * *

(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 
17

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 

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, 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).

(B) Manufacturers shall define the monitoring conditions for malfunctions 

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

(e.g., monitoring capability) in accordance with sections (d)(3.1) and 

(d)(3.2) (i.e., minimum ratio requirements) with the exception that 

monitoring shall occur every time the monitoring conditions are met during 

the driving cycle in lieu of once per driving cycle as required in section 

(d)(3.1.2).

* * * *

(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;
18

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),:

(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:
19

(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:

(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 
20

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:

(9.2.1) Filtering Performance:

(A) The OBD II system shall detect a malfunction prior to a decrease in the 

filtering capability of the PM filter that would cause a vehicle's PM 

emissions to exceed:

* * * *

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

dynamometer tailpipe emission standard:

a. 0.09 g/bhp-hr PM as measured from an applicable cycle emission 

test for 2004 through 2009 model year vehicles;

b. 0.07 g/bhp-hr PM as measured from an applicable cycle emission 

test for 2010 through 2012 model year vehicles; and

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

test for 2013 and subsequent model year vehicles.

(iii) For 2014 through 2015 model year medium-duty vehicles (including 

MDPVs) certified to an engine dynamometer tailpipe emission 

standard, the manufacturer shall use the malfunction criteria in section 

(f)(9.2.1)(A)(ii)c. above without using the provisions of section (f)(17.1) 

to exclude specific failure modes on vehicles under one of the following 

two options below:

a. At least 20 percent of 2014 model year vehicles and at least 20 

percent of 2015 model year vehicles (percentage based on the 

manufacturer’s projected California sales volume for all mediumduty diesel vehicles), or

b. At least 50 percent of 2015 model year vehicles (percentage based 

on the manufacturer’s projected California sales volume for all 

medium-duty diesel vehicles).

(iv)For the phase-in schedules described in section (f)(9.2.1)(A)(iii) above, 

the manufacturer may not use an alternate phase-in schedule as 

defined in section (c) in lieu of the required phase-in schedules. 
21

* * * *

(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.

* * * *

(9.2.4) Catalyzed PM Filter:

(A) NMHC conversion: For 2015 and subsequent model year passenger cars, 

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

emission standard and 2015 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 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 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 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.
22

(B) Feedgas generation: For 2016 and subsequent model year medium-duty 

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:

* * * *

(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:
23

(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 

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 2015 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 
24

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. 

(i) The system shall detect a fault if the compensation being used by the 

control system does not match the compensation designated for the 

installed component (e.g., the flow characteristic coding designated on 

a specific injector does not match the compensation being used by the 

fuel control system for that injector). If a manufacturer demonstrates 

that a single component (e.g., injector) using the wrong compensation 

cannot cause a measurable increase in emissions during any 

reasonable driving condition, the manufacturer shall detect a 

malfunction for the minimum number of components using the wrong 

compensation needed to cause an emission increase. Further, the 

stored fault code shall identify the specific component that does not 

match the compensation.

(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 increase by 15 

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

from an applicable emission test cycle; 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 

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

updating of the compensation value).
25

* * * *

(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 

2013 model year light-duty vehicles and 2007 through 20132015 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. 

* * * *
26

(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 

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).

* * * *

(17.1.5) For 2004 through 2015 model year medium-duty diesel vehicles (except 

MDPVs) certified to a chassis dynamometer tailpipe emission standard, 

the monitoring requirements and malfunction criteria in section (f) 

applicable to medium-duty diesel vehicles certified to an engine 

dynamometer tailpipe emission standard shall apply. However, the 

manufacturer shall request Executive Officer approval of manufacturerproposed medium-duty chassis dynamometer-based malfunction criteria 

in lieu of the engine dynamometer-based malfunction criteria required for 

each monitor in section (f). The Executive Officer shall approve the 

request upon finding that:

(A) the manufacturer has used good engineering judgment in determining the 

malfunction criteria,

(B) the malfunction criteria will provide for similar timeliness in detection of 

malfunctioning components with respect to detection of malfunctions on 

medium-duty diesel vehicles certified to an engine dynamometer tailpipe 

emission standard,

(C) the malfunction criteria are set as stringently as technologically feasible 

with respect to indicating a malfunction at the lowest possible tailpipe 

emission levels (but not lower than 1.5 times the chassis dynamometer 

tailpipe emission standard the vehicle is certified to), considering the best 

available monitoring technology to the extent that it is known or should 

have been known to the manufacturer,

(D) the malfunction criteria will prevent detection of a malfunction when the 

monitored component is within the performance specifications for 

components aged to the end of the full useful life, and

(E) the manufacturer has provided emission data showing the emission levels 

at which the malfunctions are detected.

(17.1.6) For 2016 and subsequent model year medium-duty diesel vehicles 

(except MDPVs) certified to a chassis dynamometer tailpipe emission 
27

standard, the following monitoring requirements and malfunction criteria 

shall apply:

(A) Except as provided for in sections (f)(17.1.6)(B) and (C) below, the 

monitoring requirements and malfunction criteria in section (f) applicable 

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

dynamometer tailpipe emission standard shall apply. 

(B) For NMHC catalyst conversion efficiency monitoring (section (f)(1.2.2)), 

the manufacturer shall detect an NMHC catalyst malfunction when the 

catalyst conversion capability decreases to the point that emissions

exceed 1.75 times the applicable FTP NMHC or NOx standards.

(C)For misfire monitoring (section (f)(3)), the manufacturer shall use the 

monitoring requirements and malfunction criteria applicable to mediumduty vehicles certified to an engine dynamometer tailpipe emission 

standard.

(17.2) Whenever the requirements in section (f) of this regulation require a 

manufacturer to meet a specific phase-in schedule: 

(17.2.1) The phase-in percentages shall be based on the manufacturer’s 

projected sales volume for all vehicles subject to the requirements of title 

13, CCR section 1968.2 unless specifically stated otherwise in section (f).

(17.2.2) 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 of for in-use monitor performance ratio 

monitoring conditions in section (d)(3.2) and the PM filter monitor in 

section (f)(9.2.1)(A).

(17.2.3) Small volume manufacturers may use an alternate phase-in schedule in 

accordance with section (f)(17.2.2) in lieu of the required phase-in 

schedule or may use a different schedule as follows:

(A)For the diesel PM filter monitor phase-in schedule in section 

(f)(9.2.1)(A)(iii), the manufacturer may use the malfunction criteria in 

section (f)(9.2.1)(A)(ii)c. for all 2014 and 2015 model year medium-duty 

vehicles in lieu of the malfunction criteria and required phase-in schedule 

in section (f)(9.2.1)(A)(iii).

(B) For phase-in schedules not listed in section (f)(17.2.3)(A) above, the 

manufacturer may meet the requirement on all vehicles by the final year of 

the phase-in in lieu of meeting the specific phase-in requirements for each 

model year.

* * * *

(h) Monitoring System Demonstration Requirements For Certification

* * * *
28

(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).

* * * *

(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).

* * * *

(i) Certification Documentation

(1) When submitting an application for certification of a test group, the manufacturer 

shall submit the following documentation. If any of the items listed below are 

standardized for all of a manufacturer’s test groups, the manufacturer may, for 

each model year, submit one set of documents covering the standardized items 

for all of its test groups.

(1.1) For the required documentation not standardized across all test groups, the 

manufacturer may propose to the Executive Officer that documentation 

covering a specified combination of test groups be used. These combinations 

shall be known as “OBD II groups”. Executive Officer approval shall be 

granted for those groupings that include test groups using the same OBD II 

strategies and similar calibrations. If approved by the Executive Officer, the 

manufacturer may submit one set of documentation from one or more 

representative test group(s) that are a part of the OBD II group. The 

Executive Officer shall determine whether a selected test group(s) is 

representative of the OBD II group as a whole. To be approved as 

representative, the test group(s) must possess the most stringent exhaust

emission standards and OBD II monitoring requirements and cover all of the 

emission control devices within the OBD II group.

* * * *

(2) The following information shall be submitted as “Part 1” of the certification 

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

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

the information having been provided. The information must include:

* * * *

(2.5) Data supporting the misfire monitor: 
29

(2.52.5.1) For gasoline vehicles, data supporting the misfire monitor, shall

includinge:

(2.5.1 A)The established percentage of misfire that can be tolerated without 

damaging the catalyst over the full range of engine speed and load 

conditions.

(2.5.2B)Data demonstrating the probability of detection of misfire events of 

the misfire monitoring system over the full engine speed and load 

operating range for the following misfire patterns: random cylinders 

misfiring at the malfunction criteria established in section (e)(3.2.2), one 

cylinder continuously misfiring, and paired cylinders continuously misfiring.

(2.5.3C) Data identifying all disablement of misfire monitoring that occurs 

during the FTP and US06 cycles. For every disablement that occurs 

during the cycles, the data should identify: when the disablement occurred 

relative to the driver’s trace, the number of engine revolutions that each 

disablement was present for, and which disable condition documented in 

the certification application caused the disablement. The data shall be 

submitted in the standardized format detailed in Attachment A: Misfire 

Disablement and Detection Chart of ARB Mail-Out #06-23, December 21, 

2006, incorporated by reference.

(2.5.4D) Manufacturers are not required to use the durability demonstration 

vehicle to collect the misfire data for sections (i)(2.5.1)(A) though (2.5.3C).

(2.5.2)For diesel medium-duty vehicles subject to the monitoring requirements of 

section (f)(3.2.2), data supporting the misfire monitor shall include:

(A) Data demonstrating the probability of detection of misfire events of the 

misfire monitoring system over the required engine speed and load 

operating range for the following misfire patterns: random cylinders 

misfiring at the malfunction criteria established in section (f)(3.2.2), one 

cylinder continuously misfiring, and paired cylinders continuously misfiring.

(B) Data identifying all disablement of misfire monitoring that occurs during 

the chassis dynamometer FTP and Unified cycles. For every disablement 

that occurs during the cycles, the data shall identify: when the disablement 

occurred relative to the driver’s trace, the number of engine revolutions 

that each disablement was present for, and which disable condition 

documented in the certification application caused the disablement. The 

number of 1000-revolution intervals completed and the number of 1000-

revoluation intervals in which the misfire threshold was exceeded shall 

also be identified. The data shall be submitted in the standardized format 

detailed in Attachment A: Misfire Disablement and Detection Chart of ARB 

Mail-Out #06-23. 

* * * *

(j) Production Vehicle Evaluation Testing.

* * * *
30

(2) Verification of Monitoring Requirements.

* * * *

(2.3) Evaluation requirements:

* * * *

(2.3.4)Malfunctions may be mechanically implanted or electronically simulated 

but internal on-board computer hardware or software changes may not be 

used to simulate malfunctions. Emission testing to confirm that the 

malfunction is detected before the appropriate emission standards are

malfunction threshold (e.g., 1.5 times the applicable standards) is 

exceeded is not required.

* * * *

NOTE: Authority cited: Sections 39010, 39600, 39601, 43000.5, 43013, 43016, 43018, 43100, 43101,

43104, 43105, 43105.5 and 43106, Health and Safety Code. Reference: Sections 39002, 39003, 39010, 

39018, 39021.5, 39024, 39024.5, 39027, 39027.3, 39028, 39029, 39031, 39032, 39032.5, 39033, 39035, 

39037.05, 39037.5, 39038, 39039, 39040, 39042, 39042.5, 39046, 39047, 39053, 39054, 39058, 39059, 

39060, 39515, 39600, -39601, 43000, 43000.5, 43004, 43006, 43013, 43016, 43018, 43100, 43101, 

43102, 43104, 43105, 43105.5, 43106, 43150, 43151, 43152, 43153, 43154, 43155, 43156, 43204, 

43211 and 43212, Health and Safety Code.