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FINAL REGULATION ORDER

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

Note: The proposed amendments are shown in underline to indicate additions and 

strikeout to indicate deletions from the existing regulatory text. 

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

Model-Year Heavy-Duty 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 systems) that are installed on 2010 and subsequent 

model-year engines certified for sale in heavy-duty applications in California. The OBD 

systems, through the use of an onboard computer(s), shall monitor emission systems 

in-use for the actual life of the engine 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 in-use motor vehicle and motor vehicle engine emissions through improvements of

emission system durability and performance.

(b) Applicability.

Except as specified in section (d)(7) and elsewhere in this regulation (title 13, CCR 

section 1971.1), all 2010 and subsequent model-year heavy-duty engines shall be 

equipped with an OBD system that has been certified by the Executive Officer as 

meeting all applicable requirements of this regulation (title 13, CCR section 

1971.1).1 

(c) Definitions.

“Actual life” refers to the entire period that an engine is operated on public roads 

in California up to the time an engine is retired from use. 

“Alternate-fueled engine” refers to an engine using a fuel different from or in 

addition to gasoline fuel or diesel fuel (e.g., compressed natural gas (CNG), 

liquefied petroleum gas). For the purposes of this regulation, alternate-fueled 

engines include dedicated alternate-fueled engines (i.e., engines designed to 

operate exclusively on the alternate fuel) and engines that can use more than one 

type of fuel but cannot be reasonably operated in-use exclusively on gasoline or 

diesel fuel (e.g., engines with diesel pilot injection and CNG main injection where 

engine operation is limited to idle if CNG fuel is not available or engines which use 

gasoline-only operation during cold start and CNG-only operation for the rest of the 

driving cycle and engine operation defaults to a limp-home restricted speed and load

if CNG fuel is not available). For engines that can use more than one type of fuel 

but can be operated in-use exclusively on gasoline or diesel fuel, the engines are 

 1 Unless otherwise noted, all section references refer to section 1971.1 of title 13, CCR.
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considered alternate-fueled engines only for the portion of operation the engine 

uses a fuel other than exclusively gasoline or diesel (e.g., a gasoline and CNG 

engine that can operate exclusively on gasoline is considered an alternate-fueled 

engine only while operating on CNG and is not subject to the provisions or relief of 

this regulation for alternate-fueled engines while operating exclusively on gasoline). 

For alternate-fueled engines, the manufacturer shall meet the requirements of 

section (d)(7.5).

“Alternate phase-in”, as allowed in section (g)(5.8), 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 engines (based on the manufacturer’s 

projected sales volume of all engines unless specifically stated otherwise in section 

(e), (f), or (g)) 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, 

20/50/100 percent scheduled phase-in would be calculated as (20*3 years) + (50*2 

years) + (100*1 year) = 260; a two-year 20/50 percent scheduled phase-in would be 

calculated as (20*2 years) + (50*1 year) = 90). Manufacturers are allowed to 

include engines introduced before the first year of the scheduled phase-in (e.g., in 

the previous example, 10 percent introduced one year before the scheduled phasein begins would be calculated as (10*4 years) and added to the cumulative total). 

However, manufacturers are only allowed to include engines 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 engines 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.

For alternate phase-in schedules resulting in all engines complying one 

model year following the last year of the scheduled phase-in, the compliance 

volume shall be calculated as described directly above. For example, a 

20/50/100 percent scheduled phase-in during the 2016-2018 model years would 

have a cumulative total of 260. If the manufacturer’s planned alternate phase-in 

schedule is 40/50/80/100 percent during the 2016-2019 model years, the final 

compliance volume calculation would be (40*3 years) + (50*2 years) + (80*1 

year) = 300, which is greater than 260 and therefore would be acceptable as an 

alternate phase-in schedule.

For alternate phase-in schedules resulting in all engines complying two model 

years following the last year of the scheduled phase-in, the compliance volume 

calculation shall be calculated as described directly above and shall also include 

a negative calculation for engines not complying until one or two model years 

following the last year of the scheduled phase-in. The negative calculation shall 

be calculated by multiplying the percent of engines not meeting the new 

requirements in the final year of the phase-in by negative one and the percent of 

engines not meeting the new requirements in the one year after the final year of 

the phase-in by negative two. For example, if 10 percent of a manufacturer’s 

engines did not comply by the final year of the scheduled phase-in and 5 percent 

did not comply by the end of the first year after the final year of the scheduled 

phase-in, the negative calculation result would be (10*(-1 years)) + (5*(-2 years)) 
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= -20. The final compliance volume calculation is the sum of the original 

compliance volume calculation and the negative calculation. For example, a 

20/50/100 percent scheduled phase-in during the 2016-2018 model years would 

have a cumulative total of 260. If a manufacturer’s planned alternate phase-in 

schedule is 40/70/80/90/100 percent during the 2016-2020 model years, the final 

compliance volume calculation would be (40*3 years) + (70*2 years) + (80*1 

year) + (20*(-1 year)) + (10*(-2 years)) = 300, which is greater than 260 and 

therefore would be acceptable as an alternate phase-in schedule.

“Applicable standards” refers to the specific exhaust emission standards or 

family emission limits (FEL), including the Federal Test Procedure (FTP) and 

Supplemental Emission Test (SET) standards, to which the engine is certified.

“Auxiliary Emission Control Device (AECD)” refers to any approved AECD (as

defined by 40 Code of Federal Regulations (CFR) 86.082-2 and 86.094-2).

“Emission Increasing Auxiliary Emission Control Device (EI-AECD)” refers to 

any approved AECD that: reduces the effectiveness of the emission control 

system under conditions which may reasonably be expected to be encountered 

in normal vehicle operation and use; and the need for the AECD is justified in 

terms of protecting the vehicle against damage or accident. An AECD that is 

certified as an NTE deficiency shall not be considered an EI-AECD. An AECD 

that does not sense, measure, or calculate any parameter or command or trigger 

any action, algorithm, or alternate strategy shall not be considered an EI-AECD. 

An AECD that is activated solely due to any of the following conditions shall not 

be considered an EI-AECD: (1) operation of the vehicle above 8000 feet in 

elevation; (2) ambient temperature; (3) when the engine is warming up and is not 

reactivated once the engine has warmed up in the same driving cycle; (4) failure 

detection (storage of a fault code) by the OBD system; (5) execution of an OBD 

monitor; or (6) execution of an infrequent regeneration event. 

“Base fuel schedule” refers to the fuel calibration schedule programmed into the 

Powertrain Control Module or programmable read-only memory (PROM) when 

manufactured or when updated by some off-board source, prior to any learned 

on-board correction.

“Auxiliary Emission Control Device (AECD)” refers to any approved AECD (as 

defined by 40 Code of Federal Regulations (CFR) 86.082-2 and 86.094-2).

“Emission Increasing Auxiliary Emission Control Device (EI-AECD)” refers to 

any approved AECD that: reduces the effectiveness of the emission control 

system under conditions which may reasonably be expected to be encountered 

in normal vehicle operation and use; and the need for the AECD is justified in 

terms of protecting the vehicle against damage or accident. An AECD that is 

certified as an NTE deficiency shall not be considered an EI-AECD. An AECD 

that does not sense, measure, or calculate any parameter or command or trigger 

any action, algorithm, or alternate strategy shall not be considered an EI-AECD. 

An AECD that is activated solely due to any of the following conditions shall not 

be considered an EI-AECD: (1) operation of the vehicle above 8000 feet in 

elevation; (2) ambient temperature; (3) when the engine is warming up and is not 

reactivated once the engine has warmed up in the same driving cycle; (4) failure 

detection (storage of a fault code) by the OBD system; (5) execution of an OBD 

monitor; or (6) execution of an infrequent regeneration event. 
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“Calculated load value” refers to the percent of engine capacity being used and 

is defined in Society of Automotive Engineers (SAE) J1979 "E/E Diagnostic Test 

Modes," May 2007February 2012 (SAE J1979), incorporated by reference (section 

(h)(1.4)). For diesel applications, the calculated load value is determined by the 

ratio of current engine output torque to maximum engine output torque at current 

engine speed as defined by parameter definition 5.2.1.7 of SAE J1939-71 “Vehicle 

Application Layer (Through February 2008May 2010),” January 2009March 2011.

“Confirmed fault code,” for purposes of engines using International Standards 

Organization (ISO) 15765-4, is defined as the diagnostic trouble code stored when 

an OBD system has confirmed that a malfunction exists (e.g., typically on the 

second driving cycle that the malfunction is detected) in accordance with the 

requirements of sections (d)(2), (f), (g), and (h)(4.4).

“Continuously,” if used in the context of monitoring conditions for circuit 

continuity, lack of circuit continuity, circuit faults, and out-of-range values, means 

monitoring is always enabled, unless alternate enable conditions have been 

approved by the Executive Officer in accordance with section (d)(3.1.1), and 

sampling of the signal used for monitoring occurs at a rate no less than two samples 

per second. If a computer input component is sampled less frequently for control 

purposes, the signal of the component may instead be evaluated each time 

sampling occurs.

“Deactivate” means to turn-off, shutdown, desensitize, or otherwise make 

inoperable through software programming or other means during the actual life of 

the engine.

“Diagnostic or emission critical” electronic control unit refers to the engine control 

unit and any other on-board electronic powertrain control unit containing software

that: 

(1) has primary control over any of the monitors required by sections (e)(1) 

through (f)(9), (g)(1) through (g)(2), and (g)(4), but does not include circuit or 

out-of-range fault monitors required by sections (e)(9.2.1)(A)(ii), 

(e)(9.2.1)(B)(ii), (e)(9.2.2)(B), (e)(9.2.4)(B), (f)(8.2.1)(B), (f)(8.2.2)(B), 

(f)(8.2.2)(D), (f)(8.2.3)(A), (f)(8.2.3)(B), and (g)(1.1.2); or 

(2) excluding except for anti-lock brake system (ABS) control units or 

stability/traction control units,:

(a) has primary control over the any rationality fault diagnostics or functional 

check for more than two four of the input components or more than two 

output components required to be monitored by section (g)(3).; or

(b) for 2016 and subsequent model year engines, is field reprogrammable 

and has primary control over any rationality fault diagnostic or function check 

for any input or output component required to be monitored by section (g)(3).

For purposes of criteria (1) and (2) above, “primary control” over a monitor means 

the control unit does any of the following: (a) determines if any enable conditions are 

satisfied; (b) calculates all or part of the diagnostic decision statistic or metric by 

which pass or fail decisions are made (e.g., the comparison of a component’s 

measured or calculated level of performance to a fault threshold); or (c) makes or 

processes pass or fail decisions (e.g., debounces diagnostic decision statistics or 

commands MIL illumination or fault code storage). Further, fFor purposes of 

criteriaon (2)(a) above, all glow plugs in an engine shall be considered “one” output

component in lieu of each glow plug being considered a separate component. 
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Additionally, for purposes of criterion (2)(b) above, “field reprogrammable” means a 

control unit that is capable of supporting a manufacturer service procedure intended 

to be executed in a dealership or other vehicle service environment that results in

the downloading of new software and/or calibration data into the control unit.

“Diesel engine” refers to an engine using a compression ignition thermodynamic 

cycle.

“Driving cycle” is defined as a trip that meets any of the four conditions below:

(a1) Begins with engine start and ends with engine shutoff;

(b2) Begins with engine start and ends after four hours of continuous engine-on 

operation;

(c3) Begins at the end of the previous four hours of continuous engine-on 

operation and ends after four hours of continuous engine-on operation; or

(d4) Begins at the end of the previous four hours of continuous engine-on 

operation and ends with engine shutoff.

For monitors that run during engine-off conditions, the period of engine-off time 

following engine shutoff and up to the next engine start may be considered part of 

the driving cycle for conditions (a1) and (d4). For vehicles that employ engine 

shutoff strategies that do not require the vehicle operator to restart the engine to 

continue driving (e.g., hybrid bus with 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. 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. For engines that are not likely to be routinely operated for 

long continuous periods of time, a manufacturer may also request Executive Officer 

approval to use an alternate definition for driving cycle (e.g., solely based on engine 

start and engine shutoff without regard to four hours of continuous engine-on time). 

Executive Officer approval of the alternate definition shall be based on 

manufacturer-submitted data and/or information demonstrating the typical usage, 

operating habits, and/or driving patterns of these vehicles. 

“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 family” means a grouping of vehicles or engines in a manufacturer’s 

product line determined in accordance with 40 CFR 86.098-24.

“Engine rating” means a unique combination of displacement, rated power, 

calibration (fuel, emission, and engine control), AECDs, and other engine and 

emission control components within an engine family.

“OBD parent rating” means the specific engine rating selected according to 

section (d)(7.1.1) or (d)(7.2.2)(B) for compliance with section 1971.1.
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“OBD child rating” means an engine rating (other than the OBD parent rating) 

within the engine family containing the OBD parent rating selected according to 

section (d)(7.1.1) or an engine rating within the OBD group(s) defined according 

to section (d)(7.2.1) and subject to section (d)(7.2.3).

“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 the 

engine 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 an engine is certified.

“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), the manufacturer may request Executive Officer 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.

“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.

“Fault memory” means information pertaining to malfunctions stored in the 

onboard computer, including fault codes, stored engine conditions, and MIL status.

“Federal Test Procedure (FTP) test” refers to an exhaust emission test 

conducted according to the test procedures incorporated by reference in title 13, 

CCR section 1956.8(b) and (d) that is used to determine compliance with the FTP 

standard to which an engine is certified.

“FTP cycle”. For engines certified on an engine dynamometer, FTP cycle 

refers to the engine dynamometer schedule in 40 CFR appendix 1 of part 86, 

section (f)(1), entitled, “EPA Engine Dynamometer Schedule for Heavy-Duty 

Otto-Cycle Engines,” or section (f)(2), entitled, “EPA Engine Dynamometer 

Schedule for Heavy-Duty Diesel Engines.”

“FTP standard” refers to the certification exhaust emission standards and test 

procedures applicable to the FTP cycle incorporated by reference in title 13, 

CCR sections 1956.8(b) and (d) to which the engine is certified.

“Fuel trim” refers to feedback adjustments to the base fuel schedule. Short-term 

fuel trim refers to dynamic or instantaneous adjustments. Long-term fuel trim refers 

to much more gradual adjustments to the fuel calibration schedule than short-term 

trim adjustments.

“Fueled engine operation” is the state where any fuel is introduced into the 

engine for the purposes of combustion.

“Functional check” for an output component or system means verification of 

proper response of the component and system to a computer command.
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“Gasoline engine” refers to an Otto-cycle engine or an alternate-fueled engine.

“Heavy-duty engine” means an engine that is used to propel a heavy-duty 

vehicle.

“Heavy-duty vehicle” means any motor vehicle having a manufacturer’s gross 

vehicle weight rating (GVWR) greater than 14,000 pounds.

“Hybrid vehicle” refers to a vehicle that has both of the following on-vehicle 

sources of stored energy and can draw propulsion energy from the source 

mentioned in 2): 1) a consumable fuel and 2) an energy storage device such as a 

battery, capacitor, pressure reservoir, or flywheel.

“Ignition Cycle” means a driving cycle that begins with engine start, meets the 

engine start definition for at least two seconds plus or minus one second, and ends 

with engine shutoff. For hybrid vehicles, “ignition cycle” means a driving cycle that 

begins when the propulsion system active definition is met for at least two seconds 

plus or minus one second, and ends when the propulsion system active definition is 

no longer met.

“Keep-alive memory (KAM),” for the purposes of this regulation, is defined as a 

type of memory that retains its contents as long as power is provided to the onboard control unit. KAM is not erased upon shutting off the engine but may be 

erased if power to the on-board control unit is interrupted (e.g., vehicle battery 

disconnected, fuse to control unit removed). In some cases, portions of KAM may 

be erased with a scan tool command to reset KAM.

“Key on, engine off position” refers to a vehicle with the ignition key in the engine 

run position (not engine crank or accessory position) but with the engine not 

running.

“Malfunction” means any deterioration or failure of a component or system that 

causes the performance to be outside of the applicable limits in sections (e) through 

(g).

“Manufacturer” for the purpose of this regulation means the holder of the 

Executive Order for the engine family. 

“MIL-on fault code,” for purposes of engines using SAE J1939, refers to the 

diagnostic trouble code stored when an OBD system has confirmed that a 

malfunction exists (e.g., typically on the second driving cycle that the malfunction is 

detected) and has commanded the MIL on in accordance with the requirements of 

sections (d)(2), (e), (g), and (h)(4.4). 

“Non-volatile random access memory (NVRAM),” for the purposes of this 

regulation, is defined as a type of memory that retains its contents even when power 

to the on-board control unit is interrupted (e.g., vehicle battery disconnected, fuse to 

control unit removed). NVRAM is typically made non-volatile either by use of a 

back-up battery within the control unit or through the use of an electrically erasable 

and programmable read-only memory (EEPROM) chip.

“Not-To-Exceed (NTE) control area” refers to the bounded region of the engine’s 

torque and speed map, as defined in 40 CFR 86.1370-2007, where emissions must 

not exceed a specific emission cap for a given pollutant under the NTE requirement.

“Manufacturer-specific NOx NTE carve-out area” refers to regions within the 

NTE control area for NOx where the manufacturer has limited NTE testing as 

allowed by 40 CFR 86.1370-2007(b)(7).
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“Manufacturer-specific PM NTE carve-out area” refers to regions within the 

NTE control area for PM where the manufacturer has limited NTE testing as 

allowed by 40 CFR 86.1370-2007(b)(7).

“NTE deficiency” refers to regions or conditions within the NTE control area 

for NOx or PM where the manufacturer has received a deficiency as allowed by 

40 CFR 86.007-11(a)(4)(iv).

“OBD group” refers to a combination of engines, engine families, or engine 

ratings that use the same OBD strategies and similar calibrations. A manufacturer 

is required to submit a grouping plan for Executive Officer review and approval 

detailing the OBD groups and the engine families and engine ratings within each 

group for a model year.

“Pending fault code” is defined as the diagnostic trouble code stored upon the 

initial detection of a malfunction (e.g., typically on a single driving cycle) prior to 

illumination of the MIL in accordance with the requirements of sections (d)(2), (e) 

through (g), and (h)(4.4).

“Permanent fault code” is defined as a confirmed or MIL-on fault code that is 

currently commanding the MIL on and is stored in NVRAM as specified in sections 

(d)(2) and (h)(4.4).

“Percentage of misfire” as used in sections (e)(2) and (f)(2) means the 

percentage of misfires out of the total number of firing events for the specified 

interval.

“Power Take-Off (PTO) unit” refers to an engine driven output provision for the 

purposes of powering auxiliary equipment (e.g., a dump-truck bed, aerial bucket, or 

tow-truck winch).

“Previously MIL-on fault code,” for purposes of engines using SAE J1939, is 

defined as the diagnostic trouble code stored when an OBD system has confirmed 

that a malfunction no longer exists (e.g., after the third consecutive driving cycle in 

which the corresponding monitor runs and the malfunction is not detected), 

extinguishes the MIL, and erases the corresponding MIL-on fault code in 

accordance with the requirements of sections (d)(2), (e), (g), and (h)(4.4).

“Propulsion system active” is the state where the powertrain (e.g., engine, 

electric machine) is enabled by the driver (e.g., after ignition on for conventional 

vehicles, after power button pushed for some hybrid vehicles) such that the vehicle 

is ready to be used (e.g., vehicle is ready to be driven, ready to be shifted from 

“park” to “drive”). For purposes of this definition, “the state where the powertrain is 

enabled” does not include activations that are not driver-initiated (e.g., conditions 

where portions of the vehicle system wake up to perform OBD monitoring).

“Rationality fault diagnostic” for an input component means verification of the 

accuracy of the input signal while in the range of normal operation and when 

compared to all other available information.

“Redline engine speed” shall be defined by the manufacturer as either the 

recommended maximum engine speed as normally displayed on instrument panel 

tachometers or the engine speed at which fuel shutoff occurs.

“Response rate” for exhaust gas sensors refers to the delay from when the 

sensor is exposed to a different make-up of exhaust gas constituents until it outputs 

a signal reflecting the different make-up of exhaust gas constituents. For example, 

for oxygen sensors, response rate is the delay from when the oxygen sensor is 

exposed to a change in exhaust gas from richer/leaner than stoichiometric to 
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leaner/richer than stoichiometric to the time when the oxygen sensor indicates the 

lean/rich condition. Similarly, for wide-range air-fuel (A/F) sensors, response rate is 

the delay from when the sensor is exposed to a different A/F ratio to the time it 

indicates the different A/F ratio. For NOx and PM sensors, response rate is the 

delay from when the sensor is exposed to a different NOx or PM exhaust gas level 

until it indicates the different NOx or PM exhaust gas level.

“Secondary air” refers to air introduced into the exhaust system by means of a 

pump or aspirator valve or other means that is intended to aid in the oxidation of HC 

and CO contained in the exhaust gas stream.

“Similar conditions” as used in sections (e)(1), (e)(2), (f)(1), and (f)(2) means 

engine conditions having an engine speed within 375 rpm, load conditions within 20 

percent, and the same warm-up status (i.e., cold or hot) as the engine conditions 

stored pursuant to (e)(1.4.2)(E), (e)(2.4.2)(C), (f)(1.4.5), and (f)(2.4.4). The 

Executive Officer may approve other definitions of similar conditions based on 

comparable timeliness and reliability in detecting similar engine operation.

“Small volume manufacturer” is defined in title 13, CCR section 1900(b), with the 

exception that California sales of less than 1200 heavy-duty engines will be used in 

lieu of 4500 heavy-duty engines.

“Start of production” is the time when the manufacturer has produced two 

percent of the projected volume for the engine or vehicle, whichever is specified in 

sections (k) and (l).

“Supplemental Emission Test (SET) cycle” refers to the driving schedule defined 

as the “supplemental steady state emission test” in 40 CFR 86.1360-2007.

“SET standard” refers to the certification exhaust emission standards and test 

procedures applicable to the SET cycle incorporated by reference in title 13, CCR 

sections 1956.8(b) and (d) to which the engine is certified

“Warm-up cycle” means a driving cycle with sufficient vehicle operation such that 

the coolant temperature has risen by at least 40 degrees Fahrenheit from engine 

start and reaches a minimum temperature of at least 160 degrees Fahrenheit (140 

degrees Fahrenheit for applications with diesel engines). Alternatively, 

manufacturers may define warm-up cycle as a driving cycle with vehicle operation in 

which the following criteria are met: for vehicles using the ISO 15765-4 protocol, the

manufacturers may use the criteria specified in sections (d)(2.3.1)(C)(ii)b.3.i., ii., and 

iii. herein, and for vehicles using the SAE J1939 protocol, the manufacturer may use 

the criteria specified in sections (d)(2.3.2)(D)(ii)b.3.i., ii., and iii. herein.

“Weighted sales number” means a manufacturer’s projected sales number for 

engines to be used in California heavy-duty vehicles multiplied by a weight class 

factor. Sales numbers for diesel engines for heavy-duty vehicles less than 19,499 

pounds GVWR shall be multiplied by 1.0. Sales numbers for diesel engines for 

heavy-duty vehicles from 19,500 to 33,000 pounds shall be multiplied by 1.68. 

Sales numbers for diesel engines for heavy-duty vehicles greater than 33,000 

pounds and urban buses shall be multiplied by 3.95. Sales numbers for all gasoline 

engines for heavy-duty vehicles shall be multiplied by 1.0.

(d) General Requirements.

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

performance requirements for components and systems that shall be monitored are 

set forth in sections (e) through (g) below. The OBD system is required to detect all 
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malfunctions specified in sections (e) through (g). However, except as specified 

elsewhere, the OBD system is not required to use a unique monitor to detect each 

malfunction specified.

(1) The OBD System.

(1.1) If a malfunction is present as specified in sections (e) through (g), the OBD 

system shall detect the malfunction, store a pending, confirmed, MIL-on, or 

previously MIL-on fault code in the onboard computer’s memory, and 

illuminate the MIL as required. 

(1.2) The OBD system shall be equipped with a standardized data link connector 

to provide access to the stored fault codes as specified in section (h). 

(1.3) The OBD system shall be designed to operate, without any required 

scheduled maintenance, for the actual life of the engine in which it is installed 

and may not be programmed or otherwise designed to deactivate based on 

age and/or mileage of the vehicle during the actual life of the engine. This 

section is not intended to alter existing law and enforcement practice 

regarding a manufacturer’s liability for an engine beyond its useful life, except 

where an engine has been programmed or otherwise designed so that an 

OBD system deactivates based on age and/or mileage of the engine.

(1.4) Computer-coded engine operating parameters may not be changeable 

without the use of specialized tools and procedures (e.g. soldered or potted 

computer components or sealed (or soldered) computer enclosures). Subject 

to Executive Officer approval, manufacturers may exempt from this 

requirement those product lines that are unlikely to require protection. 

Criteria to be evaluated in making an exemption include current availability of 

performance chips, performance capability of the engine, and sales volume.

(2) MIL and Fault Code Requirements.

(2.1) MIL Specifications.

(2.1.1) The MIL shall be located on the driver's side instrument panel and be of 

sufficient illumination and location to be readily visible under all lighting 

conditions and shall be amber in color when illuminated. The MIL, when 

illuminated, shall display the International Standards Organization (ISO) 

engine symbol. There shall be only one MIL used to indicate all faults 

detected by the OBD system on a single vehicle. 

(2.1.2) The MIL shall illuminate in the key on, engine off position before engine 

cranking to indicate that the MIL is functional. The MIL shall continuously 

illuminate during this functional check for a minimum of 15-20 seconds. 

During this functional check of the MIL, the data stream value for MIL 

status shall indicate commanded off (see section (h)(4.2)) unless the MIL 

has also been commanded on for a detected malfunction. This functional 

check of the MIL is not required during vehicle operation in the key on, 

engine off position subsequent to the initial engine cranking of an ignition 

cycle (e.g., due to an engine stall or other non-commanded engine 

shutoff).

(2.1.3) At the manufacturer's option, the MIL may be used to indicate readiness 

status in a standardized format (see section (h)(4.1.36)) in the key on, 

engine off position.

(2.1.4) A manufacturer may request Executive Officer approval to also use the 

MIL to indicate which, if any, fault codes are currently stored (e.g., to 
11

“blink” the stored codes). The Executive Officer shall approve the request 

upon determining that the manufacturer has demonstrated that the 

method used to indicate the fault codes will not be unintentionally 

activated during a California inspection test or during routine driver 

operation.

(2.1.5) The MIL may not be used for any purpose other than specified in this 

regulation.

(2.2) MIL Illumination and Fault Code Storage Protocol.

(2.2.1) For vehicles using the ISO 15765-4 protocol for the standardized functions 

required in section (h):

(A) Upon detection of a malfunction, the OBD system shall store a pending 

fault code within 10 seconds indicating the likely area of the malfunction.

(B) After storage of a pending fault code, if the identified malfunction is again 

detected before the end of the next driving cycle in which monitoring 

occurs, the OBD system shall illuminate the MIL continuously, keep the 

pending fault code stored, and store a confirmed fault code within 10 

seconds. If a malfunction is not detected before the end of the next 

driving cycle in which monitoring occurs (i.e., there is no indication of the 

malfunction at any time during the driving cycle), the corresponding 

pending fault code set according to section (d)(2.2.1)(A) shall be erased at 

the end of the driving cycle.

(C) A manufacturer may request Executive Officer approval to employ 

alternate statistical MIL illumination and fault code storage protocols to 

those specified in these requirements. The Executive Officer shall grant 

approval upon determining that the manufacturer has provided data 

and/or engineering evaluation that demonstrate that the alternative 

protocols can evaluate system performance and detect malfunctions in a 

manner that is equally effective and timely. Strategies requiring on 

average more than six driving cycles for MIL illumination may not be 

accepted.

(D) Storage and erasure of freeze frame conditions.

(i) The OBD system shall store and erase “freeze frame” conditions (as 

defined in section (h)(4.3)) present at the time a malfunction is 

detected.

(ii) The storage and erasure of For 2010 through 2015 model year 

engines, the OBD system shall store and erase freeze frame 

conditions shall be done in conjunction with the storage and erasure of 

either pending or confirmed fault codes as required elsewhere in 

section (d)(2.2).

(iii) For 2016 and subsequent model year engines, except as provided for 

in section (d)(2.2.1)(D)(iv), the OBD system shall store freeze frame 

conditions in conjunction with the storage of a pending fault code. 

a. If the pending fault code is erased in the next driving cycle in which 

monitoring occurs and a malfunction is not detected (as described 

in section (d)(2.2.1)(B)), the OBD system may erase the 

corresponding freeze frame conditions. 

b. If the pending fault code matures to a confirmed fault code (as 

described in section (d)(2.2.1)(B)), the OBD system shall either 
12

retain the currently stored freeze frame conditions or replace the 

stored freeze frame conditions with freeze frame conditions 

regarding the confirmed fault code. The OBD system shall erase 

the freeze frame information in conjunction with the erasure of the 

confirmed fault code (as described under section (d)(2.3.1)(B)).

(iv) For alternate strategies that do not store pending fault codes (i.e., 

monitors using alternate statistical strategies described in section 

(d)(2.2.1)(C) such as monitors that store a confirmed fault code and 

illuminate the MIL upon the first detection of a malfunction), the OBD 

system shall store and erase freeze frame conditions in conjunction 

with the storage and erasure of the confirmed fault code.

(E) The OBD system shall illuminate the MIL and store a confirmed fault code 

within 10 seconds to inform the vehicle operator whenever the engine 

enters a default or “limp home” mode of operation that can affect 

emissions or the performance of the OBD system or in the event of a 

malfunction of an on-board computer(s) itself that can affect the 

performance of the OBD system. If the default or “limp home” mode of 

operation is recoverable (i.e., the diagnostic or control strategy that 

caused the default or “limp home” mode of operation can run on the next 

driving cycle and confirm the presence of the condition that caused the 

default or “limp home” operation), the OBD system may, in lieu of 

illuminating the MIL within 10 seconds on the first driving cycle where the 

default or “limp home” mode of operation is entered, delay illumination of

the MIL until the condition causing the default or “limp home” mode of 

operation is again detected before the end of the next driving cycle.

(F) Before the end of an ignition cycle, the OBD system shall store confirmed 

fault codes that are currently causing the MIL to be illuminated in NVRAM 

as permanent fault codes (as defined in section (h)(4.4.1)(F)).

(2.2.2) For vehicles using the SAE J1939 protocol for the standardized functions 

required in section (h):

(A) Upon detection of a malfunction, the OBD system shall store a pending 

fault code within 10 seconds indicating the likely area of the malfunction.

(B) After storage of a pending fault code, if the identified malfunction is again 

detected before the end of the next driving cycle in which monitoring 

occurs, the OBD system shall illuminate the MIL continuously, erase the 

pending fault code, and store a MIL-on fault code within 10 seconds. If a 

malfunction is not detected before the end of the next driving cycle in 

which monitoring occurs (i.e., there is no indication of the malfunction at 

any time during the driving cycle), the corresponding pending fault code 

set according to section (d)(2.2.2)(A) shall be erased at the end of the 

driving cycle.

(C) A manufacturer may request Executive Officer approval to employ 

alternate statistical MIL illumination and fault code storage protocols to 

those specified in these requirements. The Executive Officer shall grant 

approval upon determining that the manufacturer has provided data 

and/or engineering evaluation that demonstrate that the alternative 

protocols can evaluate system performance and detect malfunctions in a 

manner that is equally effective and timely. Strategies requiring on 
13

average more than six driving cycles for MIL illumination may not be 

accepted.

(D) Storage and erasure of freeze frame conditions.

(i) The OBD system shall store and erase “freeze frame” conditions (as 

defined in section (h)(4.3)) present at the time a malfunction is 

detected. 

(ii) The OBD system shall store freeze frame conditions in conjunction 

with the storage of a pending fault code.

(iii) If the pending fault code is erased in the next driving cycle in which 

monitoring occurs and a malfunction is not detected (as described 

under section (d)(2.2.2)(B)), the OBD system may erase the 

corresponding freeze frame conditions.

(iv) If the pending fault code matures to a MIL-on fault code (as described 

under section (d)(2.2.2)(B)), the OBD system shall either retain the 

currently stored freeze frame conditions or replace the stored freeze 

frame conditions with freeze frame conditions regarding the MIL-on

fault code. The OBD system shall erase the freeze frame information 

in conjunction with the erasure of the previously MIL-on fault code (as 

described under section (d)(2.3.2)(C)).

(v) For alternate strategies that do not store pending fault codes (i.e., 

monitors using alternate statistical strategies described in section 

(d)(2.2.1)(C) such as monitors that store a MIL-on fault code and 

illuminate the MIL upon the first detection of a malfunction), the OBD 

system shall store and erase freeze frame conditions in conjunction 

with the storage and erasure of the MIL-on fault code.

(E) The OBD system shall illuminate the MIL and store a MIL-on fault code 

within 10 seconds to inform the vehicle operator whenever the engine 

enters a default or “limp home” mode of operation that can affect 

emissions or the performance of the OBD system or in the event of a 

malfunction of an on-board computer(s) itself that can affect the 

performance of the OBD system. If the default or “limp home” mode of 

operation is recoverable (i.e., the diagnostic or control strategy that 

caused the default or “limp home” mode of operation can run on the next 

driving cycle and confirm the presence of the condition that caused the 

default or “limp home” operation), the OBD system may, in lieu of 

illuminating the MIL within 10 seconds on the first driving cycle where the 

default or “limp home” mode of operation is entered, delay illumination of 

the MIL until the condition causing the default or “limp home” mode of 

operation is again detected before the end of the next driving cycle.

(F) Before the end of an ignition cycle, the OBD system shall store MIL-on

fault codes that are currently causing the MIL to be illuminated in NVRAM 

as permanent fault codes (as defined in section (h)(4.4.2)(F)).

(2.3) MIL Extinguishing and Fault Code Erasure Protocol.

(2.3.1) For vehicles using the ISO 15765-4 protocol for the standardized functions 

required in section (h):

(A) Extinguishing the MIL. Except as otherwise provided in sections 

(e)(1.4.2)(F), (e)(2.4.2)(D), (e)(6.4.2), (f)(1.4.6), (f)(2.4.5), and (f)(7.4.2) 

(for diesel fuel system, diesel misfire, diesel empty reductant tank,
14

gasoline fuel system, gasoline misfire, and gasoline evaporative system 

malfunctions), once the MIL has been illuminated, it may shall be 

extinguished after at least three subsequent sequential driving cycles 

during which the monitoring system responsible for illuminating the MIL 

functions and the previously detected malfunction is no longer present 

provided no other malfunction has been detected that would 

independently illuminate the MIL according to the requirements outlined 

above. 

(B) Erasing a confirmed fault code. For 2010 through 2015 model year 

engines, Tthe OBD system may erase a confirmed fault code if the

identified malfunction has not been again detected in at least 40 engine

warm-up cycles and the MIL is presently not illuminated for that 

malfunction. For 2016 and subsequent model year engines, the OBD 

system shall erase a confirmed fault code if the identified malfunction has 

not been again detected in 40 warm-up cycles and the MIL is presently 

not illuminated for that malfunction.

(C) Erasing a permanent fault code. 

(i) If the OBD system is commanding the MIL on, the OBD system shall 

erase a permanent fault code only if the OBD system itself determines 

that the malfunction that caused the permanent fault code to be stored 

is no longer present and is not commanding the MIL on, pursuant to

the requirements of section (d)(2.3.1)(A) (which for the purposes of 

this section shall apply to all monitors). Erasure of the permanent fault 

code shall occur in conjunction with extinguishing the MIL or no later 

than the start of the first drive cycle that begins with the MIL 

commanded off.

(ii) If all fault information in the on-board computer other than the 

permanent fault code has been cleared (i.e., through the use of a scan 

tool or battery disconnect) and the OBD system is not commanding the 

MIL on:

a. Except as provided for in section (d)(2.3.1)(C)(ii)c., if the monitor of 

the malfunction that caused the permanent fault code to be stored 

is subject to the minimum ratio requirements of section (d)(3.2) 

(e.g., catalyst monitor, comprehensive component input component 

rationality monitors), the OBD system shall erase the permanent 

fault code at the end of a driving cycle if the monitor has run and 

made one or more determinations during a driving cycle that the 

malfunction of the component or the system is not present and has 

not made any determinations within the same driving cycle that the 

malfunction is present.

b. If the monitor of the malfunction that caused the permanent fault 

code to be stored is not subject to the minimum ratio requirements 

of section (d)(3.2) (e.g., gasoline misfire monitor, gasoline fuel 

system monitor, comprehensive component circuit continuity 

monitors), the OBD system shall erase the permanent fault code at 

the end of a driving cycle if:

1. The monitor has run and made one or more determinations 

during a driving cycle that the malfunction of the component or 
15

the system is not present and has not made any determinations 

within the same driving cycle that the malfunction is present;

2. The monitor has not made any determinations that the 

malfunction is present subsequent to the most recent driving 

cycle in which the criteria of section (d)(2.3.1)(C)(ii)b.1. are met; 

and

3. The following criteria are satisfied on any single driving cycle 

(which may be a different driving cycle than that in which the 

criteria of section (d)( 2.3.1)(C)(ii)b.1. are satisfied):

i. Except as provided in section (d)(2.3.1)(C)(ii)b.3.v. below, 

Ccumulative time since engine start is greater than or equal 

to 600 seconds;

ii. Cumulative gasoline engine operation at or above 25 miles 

per hour or diesel engine operation at or above 1150 rpm, 

either of which occurs for greater than or equal to 300 

seconds;

iii. Continuous vehicle operation at idle (i.e., accelerator pedal 

released by driver and either vehicle speed less than or 

equal to one mile per hour or engine speed less than or 

equal to 200 rpm above normal warmed-up idle (as 

determined in the drive position for vehicles equipped with 

an automatic transmission)) for greater than or equal to 30 

seconds; and

iv. The monitor has not made any determinations that the 

malfunction is present. 

v. For hybrid vehicles, manufacturers shall use “cumulative 

propulsion system active time” in lieu of “cumulative time 

since engine start” for the criterion in section 

(d)(2.3.1)(C)(ii)b.3.i.

4. Monitors required to use “similar conditions” as defined in 

section (c) to store and erase pending and confirmed fault 

codes may not require that the similar conditions be met prior to 

erasure of the permanent fault code.

c. For monitors subject to section (d)(2.3.1)(C)(ii)a., the manufacturer 

may choose to erase the permanent fault code using the criteria 

under section (d)(2.3.1)(C)(ii)b. in lieu of the criteria under section 

(d)(2.3.1)(C)(ii)a.

d. For 2010 through 2012 model year engines, manufacturers may 

request Executive Officer approval to use alternate criteria to erase 

the permanent fault code. The Executive Officer shall approve 

alternate criteria that will not likely require driving conditions that 

are longer and more difficult to meet than those required under 

section (d)(2.3.1)(C)(ii)b.

(2.3.2) For vehicles using the SAE J1939 protocol for the standardized functions 

required in section (h):

(A) Extinguishing the MIL. Except as otherwise provided in sections 

(e)(1.4.2)(F), (e)(2.4.2)(D) and (e)(6.4.2) for fuel system malfunctions, 

misfire malfunctions, and empty reductant tanks, once the MIL has been 
16

illuminated, it may shall be extinguished after at least three subsequent 

sequential driving cycles during which the monitoring system responsible 

for illuminating the MIL functions and the previously detected malfunction 

is no longer present provided no other malfunction has been detected that 

would independently illuminate the MIL according to the requirements 

outlined above.

(B) Erasing a MIL-on fault code. The OBD system may erase a MIL-on fault 

code in conjunction with extinguishing the MIL as described under section 

(d)(2.3.2)(A). In addition to the erasure of the MIL-on fault code, the OBD 

system shall store a previously MIL-on fault code for that failure. 

(C) Erasing a previously MIL-on fault code. For 2010 through 2015 model 

year engines, Tthe OBD system may erase a previously MIL-on fault code 

if the identified malfunction has not been again detected in at least 40 

engine warm-up cycles and the MIL is presently not illuminated for that 

malfunction. For 2016 and subsequent model year engines, the OBD 

system shall erase a previously MIL-on fault code if the identified 

malfunction has not been again detected in 40 warm-up cycles and the 

MIL is presently not illuminated for that malfunction.

(D) Erasing a permanent fault code. The OBD system shall erase a 

permanent fault code under the following conditions:

(i) If the OBD system is commanding the MIL on, the OBD system shall 

erase a permanent fault code only if the OBD system itself determines 

that the malfunction that caused the permanent fault code to be stored 

is no longer present and is not commanding the MIL on, pursuant to

the requirements of section (d)(2.3.2)(A) (which for the purposes of 

this section shall apply to all monitors). Erasure of the permanent fault 

code shall occur in conjunction with extinguishing the MIL or no later 

than the start of the first drive cycle that begins with the MIL 

commanded off.

(ii) If all fault information in the on-board computer has been cleared (i.e., 

through the use of a scan tool or battery disconnect) and the OBD 

system is not commanding the MIL on:

a. Except as provided for in section (d)(2.3.2)(D)(ii)c., if the monitor of 

the malfunction that caused the permanent fault code to be stored 

is subject to the minimum ratio requirements of section (d)(3.2) 

(e.g., catalyst monitor, comprehensive component input component 

rationality monitors), the OBD system shall erase the permanent 

fault code at the end of a driving cycle if the monitor has run and 

made one or more determinations during a driving cycle that the 

malfunction of the component or the system is not present and has 

not made any determinations within the same driving cycle that the 

malfunction is present.

b. If the monitor of the malfunction that caused the permanent fault 

code to be stored is not subject to the minimum ratio requirements 

of section (d)(3.2) (e.g., continuous diesel fuel system monitors,

comprehensive component circuit continuity monitors), the OBD 

system shall erase the permanent fault code at the end of a driving 

cycle if:
17

1. The monitor has run and made one or more determinations 

during a driving cycle that the malfunction of the component or 

the system is not present and has not made any determinations 

within the same driving cycle that the malfunction is present;

2. The monitor has not made any determinations that the 

malfunction is present subsequent to the most recent driving 

cycle in which the criteria of section (d)(2.3.2)(D)(ii)b.1. are met; 

and

3. The following criteria are satisfied on any single driving cycle 

(which may be a different driving cycle than that in which the 

criteria of section (d)(2.3.2)(D)(ii)b.1. are satisfied):

i. Except as provided in section (d)(2.3.2)(D)(ii)b.3.v. below,

Ccumulative time since engine start is greater than or equal 

to 600 seconds;

ii. Cumulative gasoline engine operation at or above 25 miles 

per hour or diesel engine operation at or above 1150 rpm, 

either of which occurs for greater than or equal to 300 

seconds; 

iii. Continuous vehicle operation at idle (i.e., accelerator pedal 

released by driver and either vehicle speed less than or 

equal to one mile per hour or engine speed less than or 

equal to 200 rpm above normal warmed-up idle (as 

determined in the drive position for vehicles equipped with 

an automatic transmission)) for greater than or equal to 30 

seconds; and

iv. The monitor has not made any determinations that the 

malfunction is present.

v. For hybrid vehicles, manufacturers shall use “cumulative 

propulsion system active time” in lieu of “cumulative time 

since engine start” for the criterion in section 

(d)(2.3.2)(D)(ii)b.3.i.

4. Monitors required to use “similar conditions” as defined in 

section (c) to store and erase pending and confirmed/MIL-on

fault codes may not require that the similar conditions be met 

prior to erasure of the permanent fault code.

c. For monitors subject to section (d)(2.3.2)(D)(ii)a., the manufacturer 

may choose to erase the permanent fault code using the criteria 

under section (d)(2.3.2)(D)(ii)b. in lieu of the criteria under section 

(d)(2.3.2)(D)(ii)a.

d. For 2010 through 2012 model year engines, manufacturers may 

request Executive Officer approval to use alternate criteria to erase 

the permanent fault code. The Executive Officer shall approve 

alternate criteria that will not likely require driving conditions that 

are longer and more difficult to meet than those required under 

section (d)(2.3.2)(D)(ii)b.

(2.4) Exceptions to MIL and Fault Code Requirements.

(2.4.1) If the engine enters a default mode of operation, a manufacturer may 

request Executive Officer approval to be exempt from illuminating the MIL
18

if any of the following conditions listed below occurs. The Executive 

Officer shall approve the request upon determining that the manufacturer 

has submitted data and/or engineering evaluation that verify the 

conditions below either of the following:

(A) The default strategy (1) causes an overt indication (e.g., illumination of a 

red engine shut-down warning light) such that the driver is certain to 

respond and have the problem corrected, and (2) is not caused by or 

invoked to protect a component required to be monitored by the OBD 

system under sections (e) through (g), and (3) is not invoked to protect a 

component required to be monitored by the OBD system under sections 

(e) through (g); or

(B) The default strategy is an AECD that is properly activated due to the 

occurrence of conditions that have been approved by the Executive 

Officer.

(2.4.2) For gasoline engines, a manufacturer may elect to meet the MIL and fault 

code requirements in title 13, CCR section 1968.2(d)(2) in lieu of meeting 

the requirements of (d)(2).

(3) Monitoring Conditions.

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

through (g) sets forth the specific monitoring requirements as well as identifies 

which of the following general monitoring requirements in section (d)(3) are 

applicable for each monitored component or system identified in sections (e) 

through (g).

(3.1) For all engines:

(3.1.1) As specifically provided for in sections (e) through (g), manufacturers shall 

define monitoring conditions, subject to Executive Officer approval, for 

detecting malfunctions identified in sections (e) through (g). The 

Executive Officer shall approve manufacturer-defined monitoring 

conditions that are determined (based on manufacturer-submitted data 

and/or other engineering documentation) to be: technically necessary to 

ensure robust detection of malfunctions (e.g., avoid false passes and 

false indications of malfunctions); designed to ensure monitoring will occur 

under conditions that may reasonably be expected to be encountered in 

normal vehicle operation and use; and designed to ensure monitoring will 

occur during the FTP cycle.

(3.1.2) Monitoring shall occur at least once per driving cycle in which the 

monitoring conditions are met.

(3.1.3) Manufacturers may request Executive Officer approval to define 

monitoring conditions that are not encountered during the FTP cycle as 

required in section (d)(3.1.1). In evaluating the manufacturer's request, 

the Executive Officer shall consider the degree to which the requirement 

to run during the FTP cycle restricts in-use monitoring, the technical 

necessity for defining monitoring conditions that are not encountered 

during the FTP cycle, data and/or an engineering evaluation submitted by 

the manufacturer which demonstrate that the component/system does not 

normally function, or monitoring is otherwise not feasible, during the FTP 

cycle, and, where applicable in section (d)(3.2), the ability of the 

manufacturer to demonstrate the monitoring conditions will satisfy the 
19

minimum acceptable in-use monitor performance ratio requirement as 

defined in section (d)(3.2) (e.g., data which show in-use driving meets the 

minimum requirements).

(3.2) As specifically provided for in sections (e) through (g), manufacturers shall 

define monitoring conditions in accordance with the criteria in sections 

(d)(3.2.1) through (3.2.3).

(3.2.1) Manufacturers shall implement software algorithms in the OBD system to 

individually track and report in-use performance of the following monitors 

in the standardized format specified in section (d)(5):

(A) NMHC converting catalyst (section (e)(5.3.1))

(B) NOx converting catalyst (section (e)(6.3.1))

(C) Catalyst (section (f)(6.3));

(D) Exhaust gas sensor (sections (e)(9.3.1)(A) or (f)(8.3.1)(A));

(E) Evaporative system (section (f)(7.3.2));

(F) EGR system (sections (e)(3.3.2) and (3.3.3) or (f)(3.3.1)) and VVT system 

(sections (e)(10.3) or (f)(9.3)); 

(G) Secondary air system (section (f)(5.3.1));

(H) PM filter (section (e)(8.3));

(I) Boost pressure control system (sections (e)(4.3.2) and (e)(4.3.3)); 

(J) NOx adsorber (section (e)(7.3.1)); 

(K) Fuel system (section (e)(1.3.3)); and

(L) Secondary oxygen sensor (section (f)(8.3.2)(A)).

The OBD system is not required to track and report in-use performance 

for monitors other than those specifically identified above.

(3.2.2) For all 2013 and subsequent model year engines, manufacturers shall 

define monitoring conditions that, in addition to meeting the criteria in 

sections (d)(3.1) and (d)(3.2.1), 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 for in-use vehicles. 

For purposes of this regulation, the minimum acceptable in-use monitor 

performance ratio is 0.100 for all monitors specifically required in sections 

(e) through (g) to meet the monitoring condition requirements of section 

(d)(3.2).

(3.2.3) Manufacturers may not use the calculated ratio (or any element thereof) or 

any other indication of monitor frequency as a monitoring condition for a 

monitor (e.g., using a low ratio to enable more frequent monitoring 

through diagnostic executive priority or modification of other monitoring 

conditions, or using a high ratio to enable less frequent monitoring).

(3.2.4) Upon request of a manufacturer or upon the best engineering judgment of 

ARB, the Executive Officer may revise the minimum acceptable in-use 

monitoring performance ratio specified in section (d)(3.2.2) for a specific 

monitor if the most reliable monitoring method developed requires a lower 

ratio. 

(4) In-Use Monitor Performance Ratio Definition.

(4.1) For monitors required to meet the requirements in section (d)(3.2), the ratio 

shall be calculated in accordance with the following specifications for the 

numerator, denominator, and ratio. 

(4.2) Numerator Specifications
20

(4.2.1) Definition: The numerator is defined as a measure of the number of times 

a vehicle has been operated such that all monitoring conditions necessary 

for a specific monitor to detect a malfunction have been encountered.

(4.2.2) Specifications for incrementing:

(A) Except as provided for in section (d)(4.2.2)(E), the numerator, when 

incremented, shall be incremented by an integer of one. The numerator 

may not be incremented more than once per driving cycle.

(B) The numerator for a specific monitor shall be incremented within 10 

seconds if and only if the following criteria are satisfied on a single driving 

cycle:

(i) Every monitoring condition necessary for the monitor of the specific 

component to detect a malfunction and store a pending fault code has 

been satisfied, including enable criteria, presence or absence of 

related fault codes, sufficient length of monitoring time, and diagnostic 

executive priority assignments (e.g., diagnostic “A” must execute prior 

to diagnostic “B”). For the purpose of incrementing the numerator, 

satisfying all the monitoring conditions necessary for a monitor to 

determine the component is passing may not, by itself, be sufficient to 

meet this criteria.

(ii) For monitors that require multiple stages or events in a single driving 

cycle to detect a malfunction, every monitoring condition necessary for 

all events to have completed must be satisfied.

(iii) For monitors that require intrusive operation of components to detect a 

malfunction, a manufacturer shall request Executive Officer approval 

of the strategy used to determine that, had a malfunction been 

present, the monitor would have detected the malfunction. Executive 

Officer approval of the request shall be based on the equivalence of 

the strategy to actual intrusive operation and the ability of the strategy 

to accurately determine if every monitoring condition necessary for the 

intrusive event to occur was satisfied.

(iv) For the secondary air system monitor, the criteria in sections 

(d)(4.2.2)(B)(i) through (iii) above are satisfied during normal operation 

of the secondary air system. Monitoring during intrusive operation of 

the secondary air system later in the same driving cycle solely for the 

purpose of monitoring may not, by itself, be sufficient to meet this 

criteria.

(C) For monitors that can generate results in a “gray zone” or “non-detection 

zone” (i.e., results that indicate neither a passing system nor a 

malfunctioning system) or in a “non-decision zone” (e.g., monitors that 

increment and decrement counters until a pass or fail threshold is 

reached), the manufacturer shall submit a plan for appropriate 

incrementing of the numerator to the Executive Officer for review and 

approval. In general, the Executive Officer shall not approve plans that 

allow the numerator to be incremented when the monitor indicates a result 

in the “non-detection zone” or prior to the monitor reaching a decision. In 

reviewing the plan for approval, the Executive Officer shall consider data 

and/or engineering evaluation submitted by the manufacturer 

demonstrating the expected frequency of results in the “non-detection 
21

zone” and the ability of the monitor to accurately determine if a monitor 

would have detected a malfunction instead of a result in the “nondetection zone” had an actual malfunction been present.

(D) For monitors that run or complete during engine-off operation, the 

numerator shall be incremented within 10 seconds after the monitor has 

completed during engine-off operation or during the first 10 seconds of 

engine start on the subsequent driving cycle.

(E) Except as specified in section (d)(4.2.2)(F) for exponentially weighted 

moving averages, manufacturers utilizing alternate statistical MIL 

illumination protocols as allowed in sections (d)(2.2.1)(C) and (d)(2.2.2)(C) 

for any of the monitors requiring a numerator shall submit a plan for 

appropriate incrementing of the numerator to the Executive Officer for 

review and approval. Executive Officer approval of the plan shall be 

conditioned upon the manufacturer providing supporting data and/or 

engineering evaluation demonstrating the equivalence of the incrementing 

in the manufacturer's plan to the incrementing specified in section 

(d)(4.2.2) for monitors using the standard MIL illumination protocol and the 

overall equivalence of the manufacturer's plan in determining that the 

minimum acceptable in-use performance ratio in section (d)(3.2) is 

satisfied.

(F) Manufacturers using an exponentially weighted moving average (EWMA) 

as the alternate statistical MIL illumination protocol approved in 

accordance with sections (d)(2.2.1)(C) and (d)(2.2.2)(C) shall increment 

the numerator as follows:

(i) Following a reset or erasure of the EWMA result, the numerator may 

not be incremented until after the requisite number of decisions 

necessary for MIL illumination have been fully executed.

(ii) After the number of decisions required in section (d)(4.2.2)(F)(i) above, 

the numerator, when incremented, shall be incremented by an integer 

of one and may not be incremented more than once per driving cycle. 

Incrementing of the numerator shall also be in accordance with 

sections (d)(4.2.2)(B), (C), and (D).

(4.3) Denominator Specifications

(4.3.1) Definition: The denominator is defined as a measure of the number of 

times a vehicle has been operated as defined in (d)(4.3.2).

(4.3.2) Specifications for incrementing:

(A) The denominator, when incremented, shall be incremented by an integer 

of one. The denominator may not be incremented more than once per 

driving cycle.

(B) Except as provided for in sections (d)(4.3.2)(F), (I), and (J), Tthe 

denominator for each monitor shall be incremented within 10 seconds if 

and only if the following criteria are satisfied on a single driving cycle:

(i) Cumulative time since engine start of driving cycle is greater than or 

equal to 600 seconds while at an elevation of less than 8,000 feet 

above sea level and at an ambient temperature of greater than or 

equal to 20 degrees Fahrenheit;

(ii) Cumulative gasoline engine operation at or above 25 miles per hour or 

diesel engine operation at or above 1150 rpm, either of which occurs 
22

for greater than or equal to 300 seconds while at an elevation of less 

than 8,000 feet above sea level and at an ambient temperature of 

greater than or equal to 20 degrees Fahrenheit; and

(iii) Continuous vehicle operation at idle (i.e., accelerator pedal released 

by driver and either vehicle speed less than or equal to one mile per 

hour or engine speed less than or equal to 200 rpm above normal 

warmed-up idle (as determined in the drive position for vehicles 

equipped with an automatic transmission)) for greater than or equal to 

30 seconds while at an elevation of less than 8,000 feet above sea 

level and at an ambient temperature of greater than or equal to 20 

degrees Fahrenheit.

(iv) For 2010 through 2012 model year diesel engines, manufacturers may 

use diesel engine operation at or above 15% calculated load in lieu of 

1150 rpm for the criterion in section (d)(4.3.2)(B)(ii) above.

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

evaporative system monitor denominator(s), the comprehensive 

component input component temperature sensor rationality monitors 

(section (g)(3)) (e.g., intake air temperature sensor, ambient temperature 

sensor, fuel temperature sensor), and the engine cooling system input 

components (section (g)(1)), the denominator(s) shall be incremented if 

and only if:

(i) Cumulative time since engine start of driving cycle is greater than or 

equal to 600 seconds while at an ambient temperature of greater than 

or equal to 40 degrees Fahrenheit but less than or equal to 95 degrees 

Fahrenheit; and

(ii) Engine cold start occurs with engine coolant temperature at engine 

start greater than or equal to 40 degrees Fahrenheit but less than or 

equal to 95 degrees Fahrenheit and less than or equal to 12 degrees 

Fahrenheit higher than ambient temperature at engine start.

(D) 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 the component or strategy is commanded “on” for a cumulative time 

greater than or equal to 10 seconds:

(i) Secondary Air System (section (f)(5))

(ii) Cold Start Emission Reduction Strategy (sections (e)(11) or (f)(4)) 

(iii) Components or systems that operate only at engine start-up (e.g., 

glow plugs, intake air heaters) and are subject to monitoring under 

“other emission control systems” (section (g)(4)) or comprehensive 

component output components (section (g)(3))

For purposes of determining this commanded “on” time, the OBD system 

may not include time during intrusive operation of any of the components 

or strategies later in the same driving cycle solely for the purposes of 

monitoring.

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

denominator(s) for the following component 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)(D)) shall be 

incremented if and only if the component is commanded to function (e.g., 
23

commanded “on”, “open”, “closed”, “locked”) for a cumulative time greater 

than or equal to 10 seconds:

(i) Variable valve timing and/or control system (sections (e)(10) or (f)(9)) 

(ii) “Other emission control systems” (section (g)(4))

(iii) Comprehensive component output component (section (g)(3)) (e.g., 

turbocharger waste-gates, variable length manifold runners)

(iv) PM filter active/intrusive injection (section (e)(8.2.6))

(v) PM sensor heater (section (e)(9.2.4)(A))

As an alternative, in addition to the requirements of section (d)(4.3.2)(B), 

the manufacturers may use the criteria specified in title 13, CCR section 

1968.2(d)(4.3.2)(F) in lieu of the criteria specified in section (d)(4.3.2)(E) 

above.

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

2010 through 2015 model year engines, the manufacturer may use the 

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

(d)(4.3.2)(E) above.

For the PM sensor heater monitor, as an alternative for 2010 through 

2015 model year engines, the manufacturer may use the criteria specified 

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

(d)(4.3.2)(E) above.

(F) For monitors of the following components monitors, the manufacturer may 

request Executive Officer approval to use alternate or additional criteria to 

that set forth in section (d)(4.3.2)(B) above for incrementing the 

denominator. Executive Officer approval of the proposed criteria shall be 

based on the equivalence of the proposed criteria in measuring the 

frequency of monitor operation relative to the amount of vehicle operation 

in accordance with the criteria in section (d)(4.3.2)(B) above:

(i) Engine cooling system input components (section (g)(1))

(ii)(i) “Other emission control systems” (section (g)(4))

(iii)(ii) Comprehensive component input components that require extended 

monitoring evaluation (section (g)(3)) (e.g., stuck fuel level sensor 

rationality)

(iv)Comprehensive component input component temperature sensor 

rationality monitors (section (g)(3)) (e.g., intake air temperature sensor, 

ambient temperature sensor, fuel temperature sensor)

(v)(iii) PM filter frequent regeneration (section (e)(8.2.2))

(iv) PM sensor monitoring capability monitor (section (e)(9.2.2)(D))

(G) For monitors of the following monitors of components or other emission 

controls that experience infrequent regeneration events, the 

denominator(s) shall be incremented during a driving cycle in which the 

following two criteria are met: (1) the requirements of section (d)(4.3.2)(B) 

are met on the current driving cycle, and (2) the number of minutes of 

cumulative engine run time since the denominator was last incremented is 

greater than or equal to 800 minutes. The 800-minute engine run time 

counter shall be reset to zero and begin counting again after the 

denominator has been incremented and no later than the start of the next 

ignition cycle:

(i) Diesel NMHC converting catalyst (section (e)(5.2.2))
24

(ii) Diesel NMHC converting catalyst other aftertreatment assistance 

functions (sections (e)(5.2.3)(B) and (D)) 

(iii) Particulate matter Catalyzed PM filters NMHC conversion (sections

(e)(8.2.1), (e)(8.2.4), and (8.2.5))

(iv) 2010 through 2015 model year PM filter filtering performance and 

missing substrate (sections (e)(8.2.1) and (8.2.5))

As an alternative, for 2010 through 2012 model year engines, the 

manufacturer may request Executive Officer approval to use alternate or 

additional criteria to that set forth in section (d)(4.3.2)(G) above for 

incrementing the denominator. Executive Officer approval of the 

proposed criteria shall be based on the effectiveness of the proposed 

criteria in measuring the frequency of monitor operation relative to the 

amount of vehicle operation.

(H) For 2013 and subsequent model year engines, 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 10 seconds:

(i) Diesel NMHC converting catalyst other aftertreatment assistance 

functions (sections (e)(5.2.3)(A) and (C))

(ii) PM filter incomplete regeneration (section (e)(8.2.3))

(iii) PM filter active/intrusive injection (section (e)(8.2.6))

(I) For hybrid vehicles, vehicles that employ alternate engine start hardware 

or strategies (e.g., integrated starter and generators a vehicle with a startstop system that does not meet the definition of a hybrid vehicle as 

defined in section (c)), or alternate-fueled vehicles engines (e.g., 

dedicated, bi-fuel, or dual-fuel applications), the manufacturer may 

request Executive Officer approval to use alternate criteria to that set forth 

in section (d)(4.3.2)(B) above for incrementing the denominator. In 

general, the Executive Officer shall not approve alternate criteria for 

vehicles that only employ engine shut off at or near idle/vehicle stop 

conditions. Executive Officer approval of the alternate criteria shall be 

based on the equivalence of the alternate criteria to determine the amount 

of vehicle operation relative to the measure of conventional vehicle 

operation in accordance with the criteria in section (d)(4.3.2)(B) above.

(J) For hybrid vehicles, in lieu of the criteria in section (d)(4.3.2)(B) above, the 

denominator for each monitor shall be incremented within ten seconds if 

and only if the following criteria are satisfied on a single driving cycle:

(i) Cumulative propulsion system active time is greater than or equal to 

600 seconds while at an elevation of less than 8,000 feet above sea 

level and at an ambient temperature of greater than or equal to 20 

degrees Fahrenheit;

(ii) Cumulative gasoline engine operation at or above 25 miles per hour or 

diesel engine operation at or above 1150 rpm, either of which occurs 

for greater than or equal to 300 seconds while at an elevation of less

than 8,000 feet above sea level and at an ambient temperature of 

greater than or equal to 20 degrees Fahrenheit; 

(iii) Continuous vehicle operation at idle (i.e., accelerator pedal released 

by driver and either vehicle speed less than or equal to one mile per 
25

hour or engine speed less than or equal to 200 rpm above normal 

warmed-up idle (as determined in the drive position for vehicles 

equipped with an automatic transmission)) for greater than or equal to 

30 seconds while at an elevation of less than 8,000 feet above sea 

level and at an ambient temperature of greater than or equal to 20 

degrees Fahrenheit; and

(iv) Cumulative fueled engine operation for greater than or equal to 10 

seconds while at an elevation of less than 8,000 feet above sea level 

and at an ambient temperature of greater than or equal to 20 degrees 

Fahrenheit.

As an alternative, for 2010 through 2015 model year hybrid vehicles, the 

manufacturer may use the criteria specified in section (d)(4.3.2)(I) in lieu 

of the criteria specified in section (d)(4.3.2)(J) above.

(4.4) Ratio Specifications

(4.4.1) Definition: The ratio is defined as the numerator divided by the 

denominator.

(4.5) Disablement of Numerators and Denominators

(4.5.1) Within 10 seconds of a malfunction being detected (i.e., a pending, 

confirmed, or MIL-on fault code being stored) that disables a monitor 

required to meet the monitoring conditions in section (d)(3.2), the OBD 

system shall disable further incrementing of the corresponding numerator 

and denominator for each monitor that is disabled. When the malfunction 

is no longer detected (e.g., the pending code is erased through selfclearing or through a scan tool command), incrementing of all 

corresponding numerators and denominators shall resume within 10 

seconds.

(4.5.2) Within 10 seconds of the start of a PTO (see section (c)) operation that 

disables a monitor required to meet the monitoring conditions in section 

(d)(3.2), the OBD system shall disable further incrementing of the 

corresponding numerator and denominator for each monitor that is 

disabled. When the PTO operation ends, incrementing of all 

corresponding numerators and denominators shall resume within 10 

seconds.

(4.5.3) The OBD system shall disable further incrementing of all numerators and 

denominators within 10 seconds if a malfunction of any component used 

to determine if the criteria in of sections (d)(4.3.2)(B) through (C) are 

satisfied (i.e., vehicle speed/calculated load, ambient temperature, 

elevation, idle operation, engine cold start, or time of operation) has been 

detected (i.e., a pending, confirmed, or MIL-on fault code has been 

stored). Incrementing of all numerators and denominators shall resume 

within 10 seconds from when the malfunction is no longer present (e.g., 

pending code erased through self-clearing or by a scan tool command).

(5) Standardized tracking and reporting of monitor performance.

(5.1) For monitors required to track and report in-use monitor performance in 

section (d)(3.2), the performance data shall be tracked and reported in 

accordance with the specifications in sections (d)(4), (d)(5), and (h)(5.1). The 

OBD system shall separately report an in-use monitor performance 

numerator and denominator for each of the following components:
26

(5.1.1) For diesel engines, fuel system, NMHC catalyst bank 1, NMHC catalyst 

bank 2, NOx catalyst bank 1, NOx catalyst bank 2, exhaust gas sensor 

bank 1, exhaust gas sensor bank 2, EGR/VVT system, PM filter, boost 

pressure control system, and NOx adsorber. The OBD system shall also 

report a general denominator and an ignition cycle counter in the 

standardized format specified in sections (d)(5.5), (d)(5.6), and (h)(5.1).

(5.1.2) For gasoline engines, catalyst bank 1, catalyst bank 2, primary oxygen 

sensor bank 1, primary oxygen sensor bank 2, secondary oxygen sensor,

evaporative leak detection system, EGR/VVT system, and secondary air 

system. The OBD system shall also report a general denominator and an 

ignition cycle counter in the standardized format specified in sections 

(d)(5.5), (d)(5.6), and (h)(5.1).

(5.2) Numerator

(5.2.1) The OBD system shall report a separate numerator for each of the 

components listed in section (d)(5.1).

(5.2.2) For specific components or systems that have multiple monitors that are 

required to be reported under section (e) (e.g., exhaust gas sensor bank 1 

may have multiple monitors for sensor response or other sensor 

characteristics), the OBD system shall separately track numerators and 

denominators for each of the specific monitors and report only the 

corresponding numerator and denominator for the specific monitor that 

has the lowest numerical ratio. If two or more specific monitors have 

identical ratios, the corresponding numerator and denominator for the 

specific monitor that has the highest denominator shall be reported for the 

specific component.

(5.2.3) The numerator(s) shall be reported in accordance with the specifications 

in section (h)(5.1.2)(A).

(5.3) Denominator

(5.3.1) The OBD system shall report a separate denominator for each of the 

components listed in section (d)(5.1).

(5.3.2) The denominator(s) shall be reported in accordance with the 

specifications in section (h)(5.1.2)(A).

(5.4) Ratio

(5.4.1) For purposes of determining which corresponding numerator and 

denominator to report as required in section (d)(5.2.2), the ratio shall be 

calculated in accordance with the specifications in section (h)(5.1.2)(B).

(5.5) Ignition cycle counter

(5.5.1) Definition:

(A) The ignition cycle counter is defined as a counter that indicates the 

number of ignition cycles a vehicle has experienced as defined in section 

(d)(5.5.2)(B).

(B) The ignition cycle counter shall be reported in accordance with the 

specifications in section (h)(5.1.2)(A).

(5.5.2) Specifications for incrementing:

(A) The ignition cycle counter, when incremented, shall be incremented by an 

integer of one. The ignition cycle counter may not be incremented more 

than once per ignition cycle. 

(B) The ignition cycle counter shall be incremented within 10 seconds if and 
27

only if the following criteria are met: 

(i) Except as required in section (d)(5.5.2)(B)(ii) below, the engine 

exceeds an engine speed of 50 to 150 rpm below the normal, warmedup idle speed (as determined in the drive position for vehicles 

equipped with an automatic transmission) for at least two seconds plus 

or minus one second.

(ii) For hybrid vehicles, the vehicle meets the propulsion system active 

definition (see section (c)) for at least two seconds plus or minus one 

second.

(C) The OBD system shall disable further incrementing of the ignition cycle 

counter within 10 seconds if a malfunction of any component used to 

determine if the criteria in section (d)(5.5.2)(B) are satisfied (i.e., engine 

speed or time of operation) has been detected and the corresponding 

pending fault code has been stored. The ignition cycle counter may not 

be disabled from incrementing for any other condition. Incrementing of 

the ignition cycle counter shall resume within 10 seconds when the 

malfunction is no longer present (e.g., pending code erased through selfclearing or by a scan tool command).

(5.6) General Denominator

(5.6.1) Definition:

(A) The general denominator is defined as a measure of the number of times 

a vehicle has been operated as defined in section (d)(5.6.2)(B).

(B) The general denominator shall be reported in accordance with the 

specifications in section (h)(5.1.2)(A).

(5.6.2) Specifications for incrementing:

(A) The general denominator, when incremented, shall be incremented by an 

integer of one. The general denominator may not be incremented more 

than once per driving cycle.

(B) The general denominator shall be incremented within 10 seconds if and 

only if the criteria identified in section (d)(4.3.2)(B) are satisfied on a single 

driving cycle.

(C) The OBD system shall disable further incrementing of the general 

denominator within 10 seconds if a malfunction of any component used to 

determine if the criteria in section (d)(4.3.2)(B) are satisfied (i.e., vehicle 

speed/load, ambient temperature, elevation, idle operation, or time of 

operation) has been detected and the corresponding pending fault code 

has been stored. The general denominator may not be disabled from 

incrementing for any other condition (e.g., the disablement criteria in 

sections (d)(4.5.1) and (d)(4.5.2) may not disable the general 

denominator). Incrementing of the general denominator shall resume 

within 10 seconds when the malfunction is no longer present (e.g., 

pending code erased through self-clearing or by a scan tool command).

(6) Malfunction Criteria Determination.

(6.1) In determining the malfunction criteria for diesel engine monitors in sections 

(e) and (g) that are required to indicate a malfunction before emissions 

exceed an emission threshold based on any applicable standard (e.g., 2.0

times any of the applicable standards), the manufacturer shall:
28

(6.1.1) Use the emission test cycle and standard (i.e., FTP or SET) determined 

by the manufacturer, through use of data and/or engineering analysis, to 

be more stringent (i.e., to result in higher emissions with the same level of 

monitored component malfunction) as the “applicable standard”. The 

manufacturer shall use data and/or engineering analysis to determine the 

test cycle and standard that is more stringent.

(6.1.2) Identify in the certification documentation required under section (j), the 

test cycle and standard determined by the manufacturer to be more

stringent for each applicable monitor.

(6.1.3) If the Executive Officer reasonably believes that a manufacturer has 

incorrectly determined the test cycle and standard that is more stringent, 

the Executive Officer shall require the manufacturer to provide emission 

data and/or engineering analysis showing that the other test cycle and 

standard are less stringent.

(6.2) On engines equipped with emission controls that experience infrequent 

regeneration events, a manufacturer shall adjust the emission test results that

are used to determine the malfunction criterion for monitors that are required 

to indicate a malfunction before emissions exceed a certain emission 

threshold (e.g., 2.0 times any of the applicable standards). Except as 

provided in section (d)(6.2.3), for each monitor, the manufacturer shall adjust 

the emission result using the procedure described in CFR title 40, part 

86.004-28(i) with the component for which the malfunction criteria is being 

established deteriorated to the malfunction threshold. The adjusted emission 

value shall be used for purposes of determining whether or not the specified 

emission threshold is exceeded (e.g., a malfunction must be detected before 

the adjusted emission value exceeds 2.0 times any applicable standard).

(6.2.1) For purposes of section (d)(6.2), “regeneration” means an event during 

which emissions levels change while the emission control performance is 

being restored by design.

(6.2.2) For purposes of section (d)(6.2), “infrequent” means having an expected 

frequency of less than once per FTP cycle.

(6.2.3) In lieu of using the procedure described in CFR title 40, part 86.004-28(i), 

the manufacturer may submit an alternate plan to calculate the 

adjustment factors for determining the adjusted emission values to the 

Executive Officer for review and approval. Executive Officer approval of 

the plan shall be conditioned upon the manufacturer providing data and/or 

engineering evaluation demonstrating the procedure is consistent with

good engineering judgment in determining appropriate modifications to 

the tailpipe certification adjustment factors.

(6.3) In lieu of meeting the malfunction criteria for gasoline engine monitors in 

sections (f) and (g), the manufacturer may request Executive Officer approval 

to utilize OBD systems certified to the requirements of title 13, CCR section 

1968.2 on medium-duty engines or vehicles. The Executive Officer shall 

approve the request upon finding that the manufacturer has used good 

engineering judgment in determining equivalent malfunction detection criteria 

on the heavy-duty engine.

(7) Implementation Schedule

(7.1) Except as specified in sections (d)(7.4) and (d)(7.5) for small volume 
29

manufacturers and alternate-fueled engines, for the 2010 through 2012 

model year engines:

(7.1.1) Full OBD. Except as specified in section (d)(7.1.3) below, a manufacturer 

shall implement an OBD system meeting the requirements of section 

1971.1 on one engine rating (i.e., the OBD parent rating) within one of the 

manufacturer’s engine families. The OBD parent rating shall be from the 

manufacturer’s heavy-duty engine family with the highest weighted sales 

number for the 2010 model year and shall be the engine rating with the 

highest weighted sales number within that engine family.

(7.1.2) Extrapolated OBD. For all other engine ratings within the engine family 

selected according to section (d)(7.1.1) (i.e., the OBD child ratings), 

except as specified in section (d)(7.1.3) below), a manufacturer shall 

implement an OBD system meeting the requirements of section 1971.1 

with the exception that the OBD system is not required to detect a 

malfunction prior to exceeding the emission thresholds specified in the 

malfunction criteria in sections (e) through (g). In lieu of detecting a 

malfunction prior to exceeding the emission thresholds, a manufacturer 

shall submit a plan for Executive Officer review and approval detailing the 

engineering evaluation the manufacturer will use to establish the 

malfunction criteria for the OBD child ratings. The Executive Officer shall 

approve the plan upon determining that the manufacturer is using good 

engineering judgment to establish the malfunction criteria for robust 

detection of malfunctions, including consideration of differences of base 

engine, calibration, emission control components, and emission control 

strategies.

(7.1.3) For all engine ratings (i.e., OBD parent and OBD child ratings) within the 

engine family selected according to (d)(7.1.1):

(A) The OBD system is exempt from having to comply with the 

standardization requirements set forth in the incorporated documents to 

this regulation (e.g., SAE J1939 defined format) within the following 

sections:

(i) (d)(1.2) and (h)(2) (standardized connector)

(ii) (d)(2.1.1) and (2.1.5) (dedicated standardized MIL)

(iii) (h)(3) (communication protocol)

(iv) (h)(4) (standardized communication functions with respect to the 

requirements to make the data available in a standardized format or in 

accordance with SAE J1979/1939 specifications)

(v) (h)(5.1.1) and (h)(5.2.1) with respect to the requirements to make the 

data available in a standardized format or in accordance with SAE 

J1979/1939 specifications.

(B) The OBD system shall meet the requirements of either sections (d)(2.2.1) 

and (2.3.1) or (d)(2.2.2) and (2.3.2) regardless of the communication 

protocol (e.g., standardized, proprietary) used by the OBD system.

(7.1.4) Engine Manufacturer Diagnostic (EMD) Systems. For all engine ratings in 

the manufacturer’s engine families not selected according to section 

(d)(7.1.1), a manufacturer shall: 

(A) Implement an EMD system meeting the requirements of title 13, CCR 

section 1971 in lieu of meeting the requirements of section 1971.1; and 
30

(B) Monitor the NOx aftertreatment (i.e., catalyst, adsorber) on engines soequipped. A malfunction shall be detected if:

(i) The NOx aftertreatment system has no detectable amount of NOx 

aftertreatment capability (i.e., NOx catalyst conversion or NOx 

adsorption); 

(ii) The NOx aftertreatment substrate is completely destroyed, removed, 

or missing; or 

(iii) The NOx aftertreatment assembly is replaced with a straight pipe.

(7.2) Except as specified in section (d)(7.5) for alternate-fueled engines, for the 

2013 through 2015 model year engines:

(7.2.1) A manufacturer shall be required to define one or more OBD groups to 

cover all engine ratings in all engine families.

(7.2.2) Full OBD. A manufacturer shall implement an OBD system meeting the 

requirements of section 1971.1:

(A) On all engine ratings (i.e., OBD parent and OBD child ratings) within the 

engine family selected according to section (d)(7.1.1); and 

(B) On one engine rating (i.e., OBD parent rating) within each of the 

manufacturer’s OBD groups. The OBD parent rating shall be the engine 

rating with the highest weighted sales number for the 2013 model year 

within each OBD group.

(7.2.3) Extrapolated OBD. For all engine ratings not subject to section (d)(7.2.2) 

(i.e., OBD child ratings), a manufacturer shall implement an OBD system 

meeting the requirements of section 1971.1 with the exception that the 

OBD system is not required to detect a malfunction prior to exceeding the 

emission thresholds specified in the malfunction criteria in sections (e) 

through (g). In lieu of detecting a malfunction prior to exceeding the 

emission thresholds, a manufacturer shall submit a plan for Executive 

Officer review and approval detailing the engineering evaluation the 

manufacturer will use to establish the malfunction criteria for the OBD 

child ratings. The Executive Officer shall approve the plan upon 

determining that the manufacturer is using good engineering judgment to 

establish the malfunction criteria for robust detection of malfunctions, 

including consideration of differences of base engine, calibration, 

emission control components, and emission control strategies.

(7.3) Except as specified in section (d)(7.5) for alternate-fueled engines, for the 

2016 and subsequent model year engines:

(7.3.1) A manufacturer shall implement an OBD system meeting the 

requirements of section 1971.1 on all engine ratings in all engine families.

(7.4) Small volume manufacturers shall be exempt from the requirements of 

section 1971.1 for 2010 through 2012 model year engines. For purposes of 

this requirement, a small volume manufacturer is defined as a manufacturer 

with projected engine sales for California heavy-duty vehicles of less than 

1200 engines per year for the 2010 model year. 

(7.5) For alternate-fueled engines:

(7.5.1) For 2010 through 2012 model year engines, a manufacturer shall be 

exempt from the requirements of section 1971.1.

(7.5.2) For 2013 through 20192017 model year engines, the manufacturer shall:

(A) Implement an EMD system meeting the requirements of title 13, CCR 
31

section 1971 in lieu of meeting the requirements of section 1971.1; and 

(B) Monitor the NOx aftertreatment (i.e., catalyst, adsorber) on engines soequipped. A malfunction shall be detected if:

(i) The NOx aftertreatment system has no detectable amount of NOx 

aftertreatment capability (i.e., NOx catalyst conversion or NOx 

adsorption); 

(ii) The NOx aftertreatment substrate is completely destroyed, removed, 

or missing; or 

(iii) The NOx aftertreatment assembly is replaced with a straight pipe.

(7.5.3) For 2020 2018 and subsequent model year engines, a manufacturer shall 

implement an OBD system meeting the requirements of section 1971.1. 

The manufacturer shall submit a plan to the Executive Officer for approval 

of the monitoring requirements in sections (e) through (g) determined by 

the manufacturer to be applicable to the engine. Executive Officer 

approval shall be based on the appropriateness of the monitoring plan 

with respect to the components and systems on the engine (e.g., a sparkignited dedicated CNG engine with a particulate matter (PM) filter and a 

selective catalytic reduction (SCR) system would be monitored in 

accordance with the misfire monitoring requirements in section (f) for 

spark-ignited engines and with the PM filter and SCR system monitoring 

requirements in section (e) for diesel engines typically equipped with the 

same components).

(7.6) For 2013 model year hybrid vehicles: In lieu of meeting all other requirements 

of section 1971.1, a manufacturer may meet the alternative requirements set 

forth in sections (d)(7.6.1) through (d)(7.6.5) below for 2013 model year 

hybrid vehicles:

(7.6.1) A California-certified 2013 model year engine shall be used as the base 

engine in the hybrid vehicle design.

(7.6.2) Any modifications made to the base engine’s certified OBD system shall 

be solely for the purpose of preventing false malfunction determinations 

that could otherwise occur as a result of the integration of the hybrid 

system hardware and software, and such modifications shall only be 

made to the extent necessary to achieve this purpose. All modifications 

are subject to Executive Officer approval. The Executive Officer shall 

grant approval upon determining that the modifications are necessary and 

reasonable for the purposes of preventing false malfunction 

determinations on in-use hybrid vehicles.

(7.6.3) Notwithstanding section (d)(7.6.2) above, no modifications shall be made 

that would render the certified base engine noncompliant with the EMD 

plus NOx aftertreatment monitoring requirements set forth in section 

(d)(7.1.4).

(7.6.4) For all hybrid components, manufacturers shall be exempt from the 

monitoring requirements of section (g)(3).

(7.6.5) Manufacturers shall apply for certification to the requirements of this 

section. The application for certification shall identify and describe the 

certified base engine, the hybrid system mated to it, all changes made to 

the certified engine along with the rationale describing the need for each 

change, and the vehicle applications into which the hybrid system will be 
32

installed.

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

(1) Fuel System Monitoring

(1.1) Requirement:

The OBD 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 

(g)(3).

(1.2) Malfunction Criteria:

(1.2.1) Fuel system pressure control: The OBD system shall detect a malfunction 

of the fuel system pressure control system (e.g., fuel, hydraulic fluid) when 

the fuel system pressure control system is unable to maintain an engine’s 

NMHC, NOx, or CO emissions at or below 2.0 times the applicable 

standards or the engine’s PM emissions at or below the applicable 

standard plus 0.02 grams per brake horsepower-hour (g/bhp-hr). For 

engines in which no failure or deterioration of the fuel system pressure 

control could result in an engine’s emissions exceeding these emission 

levels, the OBD system shall detect a malfunction when the system has 

reached its control limits such that the commanded fuel system pressure 

cannot be delivered.

(1.2.2) Injection quantity: The OBD system shall detect a malfunction of the fuel 

injection system when the system is unable to deliver the commanded 

quantity of fuel necessary to maintain an engine’s NMHC, CO, and NOx 

emissions at or below 2.0 times the applicable standards or the engine’s 

PM emissions at or below the applicable standard plus 0.02 g/bhp-hr. For 

engines in which no failure or deterioration of the fuel injection quantity 

could result in an engine’s emissions exceeding these emission levels, the 

OBD system shall detect a malfunction when the system has reached its 

control limits such that the commanded fuel quantity cannot be delivered.

(1.2.3) Injection Timing: The OBD system shall detect a malfunction of the fuel 

injection system when the system is unable to deliver fuel at the proper 

crank angle/timing (e.g., injection timing too advanced or too retarded) 

necessary to maintain an engine’s NMHC, CO, and NOx emissions at or 

below 2.0 times the applicable standards or the engine’s PM emissions at 

or below the applicable standard plus 0.02 g/bhp-hr. For engines in which 

no failure or deterioration of the fuel injection timing could result in an 

engine’s emissions exceeding these emission levels, the OBD system 

shall detect a malfunction when the system has reached its control limits 

such that the commanded fuel injection timing cannot be achieved.

(1.2.4) Feedback control: Except as provided for in section (e)(1.2.5), if the 

engine is equipped with feedback or feed-forward control of the fuel 

system (e.g., feedback control of pressure or pilot injection quantity), the 

OBD system shall detect a malfunction:

(A) If the system fails to begin control within a manufacturer specified time 

interval;
33

(B) If a failure or deterioration causes open loop or default operation; or

(C) If the control system has used up all of the adjustment allowed by the 

manufacturer or reached its maximum authority and cannot achieve the 

target.

(1.2.5) A manufacturer may request Executive Officer approval to temporarily 

disable monitoring for the malfunction criteria specified in section 

(e)(1.2.4)(C) during conditions that a manufacturer cannot robustly 

distinguish between a malfunctioning system and a properly operating 

system. The Executive Officer shall approve the disablement upon the 

manufacturer submitting data and/or analysis demonstrating that the 

control system, when operating as designed on an engine with all 

emission controls working properly, routinely operates during these 

conditions with all of the adjustment allowed by the manufacturer used up. 

(1.2.6) In lieu of detecting the malfunctions specified in sections (e)(1.2.4)(A) and 

(B) with a fuel system-specific monitor, the OBD system may monitor the 

individual parameters or components that are used as inputs for fuel 

system feedback control provided that the monitors detect all malfunctions 

that meet the criteria in sections (e)(1.2.4)(A) and (B).

(1.2.7) For purposes of determining the fuel system malfunction criteria in 

sections (e)(1.2.1) through (1.2.3):

(A) For 2010 through 2012 model year engines, the malfunction criteria shall 

be established by using a fault that affects either a single injector or all 

injectors equally. 

(B) For 2013 and subsequent model year engines, for section (e)(1.2.1), the 

malfunction criteria shall be established by using a fault that affects all 

injectors equally. Additionally, for systems that have single component 

failures which could affect a single injector (e.g., systems that build 

injection pressure within the injector that could have a single component 

pressure fault caused by the injector itself), the malfunction criteria shall 

also be established by using a fault that affects a single injector.

(C) For 2013 and subsequent model year engines, for sections (e)(1.2.2) 

through (1.2.3), the malfunction criteria shall be established by both (1) a 

fault that affects all the injectors equally and (2) a fault that affects only 

one injector. 

(1.3) Monitoring Conditions:

(1.3.1) Except as provided in sections (e)(1.3.2) and (e)(1.3.4), the OBD system 

shall monitor continuously for malfunctions identified in sections (e)(1.2.1) 

and (e)(1.2.4) (i.e., fuel pressure control and feedback operation).

(1.3.2) For fuel systems that achieve injection fuel pressure within the injector or 

increase pressure within the injector (e.g. in the injector of an amplified 

common rail system), manufacturers may request Executive Officer 

approval to define the monitoring conditions for malfunctions identified in 

sections (e)(1.2.1) in accordance with sections (d)(3.1) and (d)(3.2) (i.e., 

minimum ratio requirements). The Executive Officer shall approve the 

monitoring conditions upon the manufacturer submitting data and/or 

analysis identifying all possible failure modes and the effect each has 

(e.g., failure modes and effects analysis) on fuel pressure across the 

entire range of engine operating conditions, and upon the Executive 
34

Officer determining based on the data and/or analysis that the monitoring 

conditions allow for robust detection of all causes of fuel pressure 

malfunctions.

(1.3.3) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (e)(1.2.2) and (e)(1.2.3) (i.e., injection quantity and 

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

ratio requirements). For all 2013 and subsequent model year engines, for 

purposes of tracking and reporting as required in section (d)(3.2.1), all 

monitors used to detect malfunctions identified in sections (e)(1.2.2) and 

(e)(1.2.3) shall be tracked separately but reported as a single set of 

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

(1.3.4) 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.

(1.4) MIL Illumination and Fault Code Storage: 

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

forth in section (d)(2).

(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:

(A) A pending fault code shall be stored immediately upon the fuel system 

exceeding the malfunction criteria established pursuant to section 

(e)(1.2.1).

(B) Except as provided below, if a pending fault code is stored, the OBD

system shall immediately illuminate the MIL and store a confirmed/MIL-on

fault code if a malfunction is again detected during either of the following 

two events: (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 those that occurred when the pending fault code was 

stored are encountered.

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

in which similar conditions have been encountered without an exceedance 

of the specified fuel system malfunction criteria. The pending code may 

also be erased if similar conditions are not encountered during the 80 

driving cycles immediately after the initial detection of a malfunction for 

which the pending code was set.

(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 
35

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.

(E) Storage of fuel system conditions for determining similar conditions of 

operation. 

(i) Upon detection of a fuel system malfunction under section (e)(1.4.2), 

the OBD system shall store the engine speed, load, and warm-up 

status of the first fuel system malfunction that resulted in the storage of 

the pending fault code.

(ii) The manufacturer may request Executive Officer approval to use an 

alternate definition of similar conditions in lieu of the definition 

specified in section (c). The Executive Officer shall approve the 

alternate definition upon the manufacturer providing data or analysis 

demonstrating that the alternate definition provides for equivalent 

robustness in detection of fuel system faults that vary in severity 

depending on engine speed, load, and/or warm-up status.

(F) Extinguishing the MIL. The MIL may be extinguished after three 

sequential driving cycles in which similar conditions have been 

encountered without a malfunction of the fuel system.

(2) Misfire Monitoring

(2.1) Requirement:

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

emissions. The OBD 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 system shall also identify the 

specific misfiring cylinder.

(2.1.2) If more than one cylinder is continuously misfiring, a separate fault code 

shall be stored indicating that multiple cylinders are misfiring. When 

identifying multiple cylinder misfire, the manufacturer OBD system is not 

required to also identify each of the continuously misfiring cylinders 

individually through separate fault codes.

(2.2) Malfunction Criteria:

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

cylinders are continuously misfiring.

(2.2.2) Additionally, for 2013 and subsequentthrough 2015 model year engines 

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 diesel engines, 50 

percent of 2017 model year diesel engines, and 100 percent of 2018 

model year diesel engines (percentage based on the manufacturer’s 

projected California sales volume of all diesel engines subject to this 

regulation), the OBD system shall detect a misfire malfunction when the 
36

percentage of misfire is equal to or exceeds five percent causing the

engine’s NMHC, CO, or NOx emissions to exceed 2.0 times the applicable 

standards or the engine’s PM emissions to exceed the applicable 

standard plus 0.02 g/bhp-hr.

(A) Manufacturers shall determine evaluate the percentage of misfire 

evaluated in 1000 revolution increments that would cause NMHC, CO, or 

NOx emissions from an emission durability demonstration engine to 

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

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

(B) 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.

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

specified in section (e)(2.2.2)(A) is exceeded regardless of the pattern of 

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

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

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

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

by a single component failure. 

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

manufacturer has submitted data and/or engineering evaluation that

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

misfire malfunction criteria in section (e)(2.2.2) upward to exclude 

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

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

PM emissions to exceed the applicable standard plus 0.02 g/bhp-hr. 

(2.3) Monitoring Conditions: 

(2.3.1) Except as provided in section (e)(2.3.2), Tthe OBD system shall monitor 

for misfires identified in section (e)(2.2.1) during engine idle conditions at 

least once per driving cycle in which the monitoring conditions for misfire 

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); 
37

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

conditions.

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

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

specified in section (e)(2.3.1). 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. 

(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 engine speed and load conditions.

(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 conditions 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 100 percent of the 

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

torque above the positive torque line.

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

engine speed and load conditions as required in section (e)(2.3.3)(A), 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.
38

(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. 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.

(2.4) MIL Illumination and Fault Code Storage:

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

forth in section (d)(2).

(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:

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

(e)(2.2.2)(A), 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 (e)(2.2.2) 

during a single driving cycle.

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

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

percentage of misfire specified in section (e)(2.2.2) 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.
39

(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.

(C) Storage of misfire conditions for similar conditions determination. Upon 

detection of misfire under section (e)(2.4.2), the OBD system shall store 

the following engine conditions: engine speed, load, and warm-up status 

of the first misfire event that resulted in the storage of the pending fault 

code.

(D) Extinguishing the MIL. The MIL may be extinguished after three 

sequential driving cycles in which similar conditions have been 

encountered without an exceedance of the specified percentage of 

misfire.

(3) Exhaust Gas Recirculation (EGR) System Monitoring

(3.1) Requirement: 

(3.1.1) The OBD system shall monitor the EGR system on engines so-equipped 

for low flow rate, high flow rate, and slow response malfunctions. For 

engines equipped with EGR coolers (e.g., heat exchangers), the OBD 

system shall monitor the cooler system for insufficient cooling 

malfunctions. The individual electronic components (e.g., actuators, 

valves, sensors) that are used in the EGR system shall be monitored in 

accordance with the comprehensive component requirements in section 

(g)(3).

(3.1.2) For engines with other charge control strategies that affect EGR flow (e.g., 

systems that modify EGR flow to achieve a desired fresh air flow rate

instead of a desired EGR flow rate), the manufacturer shall submit a 

monitoring plan to the Executive Officer for approval. The Executive 

Officer shall approve the request upon determining that the manufacturer 

has submitted data and an engineering evaluation that demonstrate that 

the monitoring plan is as reliable and effective as the monitoring plan 

required for EGR systems under section (e)(3).

(3.2) Malfunction Criteria:

(3.2.1) Low Flow: The OBD system shall detect a malfunction of the EGR system 

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

would cause an engine’s NMHC, CO, or NOx emissions to exceed 2.0 

times any of the applicable standards or the engine’s PM emissions to 

exceed the applicable standard plus 0.02 g/bhp-hr. For engines in which 

no failure or deterioration of the EGR system that causes a decrease in 
40

flow could result in an engine’s emissions exceeding these levels, the 

OBD system shall detect a malfunction when either the EGR system has 

reached its control limits such that it cannot increase EGR flow to achieve 

the commanded flow rate or, for non-feedback controlled EGR systems, 

the EGR system has no detectable amount of EGR flow when EGR flow is 

expected.

(3.2.2) High Flow: The OBD system shall detect a malfunction of the EGR 

system, including a leaking EGR valve (i.e., exhaust gas flowing through 

the valve when the valve is commanded closed), prior to an increase from 

the manufacturer's specified EGR flow rate that would cause an engine’s 

NMHC, CO, or NOx emissions to exceed 2.0 times any of the applicable 

standards or the engine’s PM emissions to exceed the applicable 

standard plus 0.02 g/bhp-hr. For engines in which no failure or 

deterioration of the EGR system that causes an increase in flow could 

result in an engine’s emissions exceeding these levels, the OBD system 

shall detect a malfunction when either the EGR system has reached its 

control limits such that it cannot reduce EGR flow to achieve the 

commanded flow rate or, for non-feedback controlled EGR systems, the 

EGR system has maximum detectable EGR flow when little or no EGR 

flow is expected.

(3.2.3) Slow Response: The OBD system shall detect a malfunction of the EGR 

system prior to any failure or deterioration in the EGR system response 

(e.g., capability to achieve the specified flow rate within a manufacturerspecified time) that would cause an engine’s NMHC, CO, or NOx 

emissions to exceed 2.0 times any of the applicable standards or the 

engine’s PM emissions to exceed the applicable standard plus 0.02 

g/bhp-hr. The OBD system shall monitor the EGR system response 

under both increasing and decreasing EGR flow rates. For engines in 

which no failure or deterioration of the EGR system response could result 

in an engine’s emissions exceeding these levels, the OBD system shall 

detect a malfunction of the EGR system when no detectable response to 

a change in commanded or expected flow rate occurs.

(3.2.4) Feedback control: Except as provided for in section (e)(3.2.7), if the 

engine is equipped with feedback or feed-forward control of the EGR 

system (e.g., feedback control of flow, valve position, pressure differential 

across the valve via intake throttle or exhaust backpressure), the OBD 

system shall detect a malfunction:

(A) If the system fails to begin control within a manufacturer specified time 

interval;

(B) If a failure or deterioration causes open loop or default operation; or

(C) If the control system has used up all of the adjustment allowed by the 

manufacturer or reached its maximum authority and cannot achieve the 

target.

(3.2.5) EGR Cooler Performance: The OBD system shall detect a malfunction of 

the EGR cooler system prior to a reduction from the manufacturer's 

specified cooling performance that would cause an engine’s NMHC, CO, 

or NOx emissions to exceed 2.0 times any of the applicable standards or 

the engine’s PM emissions to exceed the applicable standard plus 0.02 
41

g/bhp-hr. For engines in which no failure or deterioration of the EGR 

cooler system could result in an engine’s emissions exceeding these 

levels, the OBD system shall detect a malfunction when the system has 

no detectable amount of EGR cooling.

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

2013 and subsequent model year engines 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) Except as provided for in section (e)(3.2.6)(B) below, the OBD system 

shall detect a malfunction when the catalyst has no detectable amount of 

constituent (e.g., hydrocarbons, soluble organic fractions) oxidation.

(B) 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.

(3.2.7) A manufacturer may request Executive Officer approval to temporarily 

disable monitoring for the malfunction criteria specified in section 

(e)(3.2.4)(C) during conditions that a manufacturer cannot robustly 

distinguish between a malfunctioning system and a properly operating 

system. The Executive Officer shall approve the disablement upon the 

manufacturer submitting data and/or analysis demonstrating that the 

control system, when operating as designed on an engine with all 

emission controls working properly, routinely operates during these 

conditions with all of the adjustment allowed by the manufacturer used up.

(3.2.8) In lieu of detecting the malfunctions specified in sections (e)(3.2.4)(A) and 

(B) with an EGR system-specific monitor, the OBD system may monitor 

the individual parameters or components that are used as inputs for EGR 

system feedback control provided that the monitors detect all malfunctions 

that meet the criteria in sections (e)(3.2.4)(A) and (B).

(3.2.9) For purposes of determining the EGR cooler performance malfunction 

criteria in section (e)(3.2.5) for EGR cooler systems that consist of more 

than one cooler (e.g., a pre-cooler and a main cooler, two or more coolers 

in series), the manufacturer shall submit an EGR cooler system aging and 

monitoring plan to the Executive Officer for review and approval. The plan 

shall include the description and location of each component, the 

monitoring strategy for each component and combination of components, 

and the method for determining the malfunction criteria of section 

(e)(3.2.5) including the deterioration/aging process. Executive Officer 

approval of the plan shall be based on the representativeness of the aging 

to real world EGR cooler system component deterioration under normal 

and malfunctioning engine operating conditions and the effectiveness of 

the method used to determine the malfunction criteria of section 

(e)(3.2.5).

(3.3) Monitoring Conditions:

(3.3.1) Except as provided in section (e)(3.3.4), the OBD system shall monitor 

continuously for malfunctions identified in sections (e)(3.2.1), (3.2.2), and 

(e)(3.2.4) (i.e., EGR low and high flow, feedback control).
42

(3.3.2) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (e)(3.2.3) (i.e., slow response) 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). For purposes of tracking and reporting as 

required in section (d)(3.2.1), all monitors used to detect malfunctions 

identified in section (e)(3.2.3) shall be tracked separately but reported as 

a single set of values as specified in section (d)(5.2.2).

(3.3.3) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (e)(3.2.5) and (e)(3.2.6) (i.e., cooler performance and 

EGR catalyst performance) 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)(3.2.1), all monitors used to detect 

malfunctions identified in section (e)(3.2.5) shall be tracked separately but 

reported as a single set of values as specified in section (d)(5.2.2).

(3.3.4) Manufacturers may request Executive Officer approval to temporarily 

disable continuous monitoring under specific conditions technically 

necessary to ensure robust detection of malfunctions and to avoid false 

passes and false indications of malfunctions (e.g., disable EGR low flow 

monitoring when no or very little flow is commanded, disable EGR high 

and low flow monitoring when freezing may affect performance of the 

system). 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 EGR 

system cannot be distinguished from a malfunctioning EGR system and 

that the disablement interval is limited only to that which is technically 

necessary.

(3.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(4) Boost Pressure Control System Monitoring

(4.1) Requirement: 

(4.1.1) The OBD system shall monitor the boost pressure control system (e.g., 

turbocharger) on engines so-equipped for under and over boost 

malfunctions and slow response malfunctions. For engines equipped with 

charge air cooler systems, the OBD system shall monitor the charge air 

cooler system for cooling system performance malfunctions. The 

individual electronic components (e.g., actuators, valves, sensors) that are 

used in the boost pressure control system shall be monitored in 

accordance with the comprehensive component requirements in section 

(g)(3).

(4.1.2) For engines with other charge control strategies that affect boost pressure 

(e.g., systems that modify boost pressure to achieve a desired air-fuel 

ratio instead of a desired boost pressure), the manufacturer shall submit a 

monitoring plan to the Executive Officer for approval. The Executive 

Officer shall approve the request upon determining that the manufacturer 

has submitted data and an engineering evaluation that demonstrate that 
43

the monitoring plan is as reliable and effective as the monitoring plan 

required for boost pressure control systems under section (e)(4).

(4.2) Malfunction Criteria:

(4.2.1) Underboost: The OBD system shall detect a malfunction of the boost 

pressure control system prior to a decrease from the manufacturer's 

commanded or expected boost pressure that would cause an engine’s 

NMHC, CO, or NOx emissions to exceed 2.0 times any of the applicable 

standards or the engine’s PM emissions to exceed the applicable 

standard plus 0.02 g/bhp-hr. For engines in which no failure or 

deterioration of the boost pressure control system that causes a decrease 

in boost could result in an engine’s emissions exceeding these levels, the 

OBD system shall detect a malfunction when either the boost system has 

reached its control limits such that it cannot increase boost to achieve the 

commanded boost pressure or, for non-feedback controlled boost 

systems, the boost system has no detectable amount of boost when boost 

is expected.

(4.2.2) Overboost: The OBD system shall detect a malfunction of the boost 

pressure control system prior to an increase from the manufacturer's 

commanded or expected boost pressure that would cause an engine's 

NMHC, CO, or NOx emissions to exceed 2.0 times any of the applicable 

standards or the engine’s PM emissions to exceed the applicable 

standard plus 0.02 g/bhp-hr. For engines in which no failure or 

deterioration of the boost pressure control system that causes an increase 

in boost could result in an engine’s emissions exceeding these levels, the 

OBD system shall detect a malfunction when either the boost system has 

reached its control limits such that it cannot decrease boost to achieve the 

commanded boost pressure or, for non-feedback controlled boost 

systems, the boost system has maximum detectable boost when little or 

no boost is expected.

(4.2.3) Slow response: 

(A) For 2010 through 2012 model year engines equipped with variable 

geometry turbochargers (VGT), the OBD system shall detect a 

malfunction prior to any failure or deterioration in the capability of the VGT 

system to achieve the commanded turbocharger geometry within a 

manufacturer-specified time that would cause an engine's NMHC, CO, or 

NOx emissions to exceed 2.0 times any of the applicable standards or the 

engine’s PM emissions to exceed the applicable standard plus 0.02 

g/bhp-hr. For engines in which no failure or deterioration of the VGT 

system response could result in an engine’s emissions exceeding these 

levels, the OBD system shall detect a malfunction of the VGT system 

when no detectable response to a change in commanded turbocharger 

geometry occurs.

(B) For 2013 and subsequent model year engines, the OBD system shall 

detect a malfunction prior to any failure or deterioration in the boost 

pressure control system response (e.g., capability to achieve the 

commanded or expected boost pressure within a manufacturer-specified 

time) that would cause an engine's NMHC, CO, or NOx emissions to 

exceed 2.0 times any of the applicable standards or the engine’s PM 
44

emissions to exceed the applicable standard plus 0.02 g/bhp-hr. For 

engines in which no failure or deterioration of the boost system response 

could result in an engine’s emissions exceeding these levels, the OBD 

system shall detect a malfunction of the boost system when no detectable 

response to a commanded or expected change in boost pressure occurs.

(4.2.4) Charge Air Undercooling: The OBD system shall detect a malfunction of 

the charge air cooling system prior to a decrease from the manufacturer's 

specified cooling rate that would cause an engine’s NMHC, CO, or NOx 

emissions to exceed 2.0 times any of the applicable standards or the 

engine’s PM emissions to exceed the applicable standard plus 0.02 

g/bhp-hr. For engines in which no failure or deterioration of the charge air 

cooling system that causes a decrease in cooling performance could 

result in an engine’s emissions exceeding these levels, the OBD system 

shall detect a malfunction when the system has no detectable amount of 

charge air cooling.

(4.2.5) Feedback control: Except as provided for in section (e)(4.2.6), if the 

engine is equipped with feedback or feed-forward control of the boost 

pressure system (e.g., control of variable geometry turbocharger position, 

turbine speed, manifold pressure) the OBD system shall detect a 

malfunction:

(A) If the system fails to begin control within a manufacturer specified time 

interval;

(B) If a failure or deterioration causes open loop or default operation; or

(C) If the control system has used up all of the adjustment allowed by the 

manufacturer or reached its maximum authority and cannot achieve the 

target.

(4.2.6) A manufacturer may request Executive Officer approval to temporarily 

disable monitoring for the malfunction criteria specified in section 

(e)(4.2.5)(C) during conditions that a manufacturer cannot robustly 

distinguish between a malfunctioning system and a properly operating 

system. The Executive Officer shall approve the disablement upon the 

manufacturer submitting data and/or analysis demonstrating that the 

control system, when operating as designed on an engine with all 

emission controls working properly, routinely operates during these 

conditions with all of the adjustment allowed by the manufacturer used up.

(4.2.7) In lieu of detecting the malfunctions specified in sections (e)(4.2.5)(A) and 

(B) with a boost pressure system-specific monitor, the OBD system may 

monitor the individual parameters or components that are used as inputs 

for boost pressure system feedback control provided that the monitors 

detect all malfunctions that meet the criteria in sections (e)(4.2.5)(A) and 

(B).

(4.2.8) For purposes of determining the charge air cooling performance 

malfunction criteria in section (e)(4.2.4) for charge air cooling systems that 

consist of more than one cooler (e.g., a pre-cooler and a main cooler, two 

or more coolers in series), the manufacturer shall submit a charge air 

cooling system aging and monitoring plan to the Executive Officer for 

review and approval. The plan shall include the description and location 

of each component, the monitoring strategy for each component and 
45

combination of components, and the method for determining the 

malfunction criteria of section (e)(4.2.4) including the deterioration/aging 

process. Executive Officer approval of the plan shall be based on the 

representativeness of the aging to real world charge air cooling system 

component deterioration under normal and malfunctioning engine 

operating conditions and the effectiveness of the method used to 

determine the malfunction criteria of section (e)(4.2.4).

(4.3) Monitoring Conditions:

(4.3.1) Except as provided in section (e)(4.3.4), the OBD system shall monitor 

continuously for malfunctions identified in sections (e)(4.2.1), (4.2.2), and 

(4.2.5) (i.e., over and under boost, feedback control).

(4.3.2) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (e)(4.2.3) (i.e., slow response) 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). For purposes of tracking and reporting as 

required in section (d)(3.2.1), all monitors used to detect malfunctions 

identified in section (e)(4.2.3) shall be tracked separately but reported as 

a single set of values as specified in section (d)(5.2.2).

(4.3.3) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (e)(4.2.4) (i.e., charge air cooler performance) 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)(3.2.1), all monitors used to detect malfunctions identified in 

section (e)(4.2.4) shall be tracked separately but reported as a single set 

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

(4.3.4) 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 (e.g., disable monitoring of underboost 

when commanded or expected boost pressure is very low). 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.

(4.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

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

(5.1) Requirement: The OBD system shall monitor the NMHC converting 

catalyst(s) for proper NMHC conversion capability. For engines equipped 

with catalyzed PM filters that convert NMHC emissions, the catalyst function 

of the PM filter shall be monitored in accordance with the PM filter 

requirements in section (e)(8).

(5.2) Malfunction Criteria:
46

(5.2.1) For purposes of section (e)(5), each catalyst in a series configuration that 

converts NMHC shall be monitored either individually or in combination 

with others. 

(5.2.2) Conversion Efficiency:

(A) For 2010 through 2012 model year engines, the OBD system shall detect 

an NMHC catalyst malfunction when the catalyst conversion capability 

decreases to the point that NMHC emissions exceed 2.0 times any of the 

applicable standards.

(B) For 2013 and subsequent model year engines, the OBD system shall 

detect an NMHC catalyst malfunction when the catalyst conversion 

capability decreases to the point that NMHC emissions exceed 2.0 times 

any of the applicable standards or NOx emissions exceed any of the 

applicable standards 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/bhp-hr). 

(C) If no failure or deterioration of the catalyst conversion capability could 

result in an engine’s NMHC or NOx emissions exceeding the applicable 

malfunction criteria of section (e)(5.2.2), the OBD system shall detect a 

malfunction when the catalyst has no detectable amount of NMHC or NOx 

conversion capability.

(5.2.3) Other Aftertreatment Assistance Functions:

(A) For catalysts used to generate an exotherm to assist PM filter 

regeneration, the OBD system shall detect a malfunction when the 

catalyst is unable to generate a sufficient exotherm to achieve 

regeneration of the PM filter.

(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 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 

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 standard as measured from an 

applicable emission test cycle.

(C) For catalysts located downstream of a PM filter and used to convert 

NMHC emissions during PM filter regeneration, the OBD system shall 

detect a malfunction when the catalyst has no detectable amount of 

NMHC conversion capability.

(D) For catalysts located downstream of an SCR system (e.g., to prevent 

ammonia slip), the OBD system shall detect a malfunction when the 

catalyst has no detectable amount of NMHC, CO, NOx, or PM conversion 

capability. 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 where in which the 

catalyst is most likely to affect criteria pollutants (e.g., during conditions 
47

most likely to result in ammonia generation or excessive reductant 

delivery).

(5.2.4) Catalyst System Aging and Monitoring

(A) For purposes of determining the catalyst malfunction criteria in sections 

(e)(5.2.2) and (5.2.3) for individually monitored catalysts, the manufacturer 

shall use a catalyst deteriorated to the malfunction criteria using methods 

established by the manufacturer to represent real world catalyst 

deterioration under normal and malfunctioning engine operating 

conditions. If the catalyst system contains catalysts in parallel (e.g., a two 

bank exhaust system where each bank has its own catalyst), the 

malfunction criteria shall be determined with the “parallel” catalysts equally 

deteriorated.

(B) For purposes of determining the catalyst malfunction criteria in sections 

(e)(5.2.2) and (5.2.3) for catalysts monitored in combination with others, 

the manufacturer shall submit a catalyst system aging and monitoring plan 

to the Executive Officer for review and approval. The plan shall include 

the description, emission control purpose, and location of each 

component, the monitoring strategy for each component and/or 

combination of components, and the method for determining the

malfunction criteria of sections (e)(5.2.2) and (5.2.3) including the 

deterioration/aging process. If the catalyst system contains catalysts in 

parallel (e.g., a two bank exhaust system where each bank has its own 

catalyst), the malfunction criteria shall be determined with the “parallel” 

catalysts equally deteriorated. Executive Officer approval of the plan shall 

be based on the representativeness of the aging to real world catalyst 

system component deterioration under normal and malfunctioning engine 

operating conditions, the effectiveness of the method used to determine 

the malfunction criteria of section (e)(5.2), the ability of the component 

monitor(s) to pinpoint the likely area of malfunction and ensure the correct 

components are repaired/replaced in-use, and the ability of the 

component monitor(s) to accurately verify that each catalyst component is 

functioning as designed and as required in sections (e)(5.2.2) and (5.2.3). 

(5.3) Monitoring Conditions: 

(5.3.1) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (e)(5.2.2) and (5.2.3) 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)(3.2.1), all monitors used 

to detect malfunctions identified in sections (e)(5.2.2) and (5.2.3) shall be 

tracked separately but reported as a single set of values as specified in 

section (d)(5.2.2).

(5.4) MIL Illumination and Fault Code Storage:

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

forth in section (d)(2).

(5.4.2) The monitoring method for the catalyst(s) shall be capable of detecting all 

instances, except diagnostic self-clearing, when a catalyst fault code has 

been cleared but the catalyst has not been replaced (e.g., catalyst 

overtemperature histogram approaches are not acceptable).
48

(6) Oxides of Nitrogen (NOx) Converting Catalyst Monitoring

(6.1) Requirement: The OBD system shall monitor the NOx converting catalyst(s) 

for proper conversion capability. For engines equipped with selective 

catalytic reduction (SCR) systems or other catalyst systems that utilize an 

active/intrusive reductant injection (e.g., active lean NOx catalysts utilizing 

diesel fuel injection), the OBD system shall monitor the SCR or 

active/intrusive reductant injection system for proper performance. The 

individual electronic components (e.g., actuators, valves, sensors, heaters, 

pumps) in the SCR or active/intrusive reductant injection system shall be 

monitored in accordance with the comprehensive component requirements in 

section (g)(3).

(6.2) Malfunction Criteria: For purposes of section (e)(6), each catalyst in a series 

configuration that converts NOx shall be monitored either individually or in 

combination with others.

(6.2.1) Conversion Efficiency:

(A) For 2010 through 2012 model year engines:

(i) The OBD system shall detect a catalyst malfunction when the catalyst 

conversion capability decreases to the point that would cause an 

engine's NOx emissions to exceed any of the applicable standards by 

more than 0.4 g/bhp-hr (e.g., cause 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 (i.e., FTP or SET).

(ii) If no failure or deterioration of the catalyst NOx conversion capability 

could result in an engine’s NOx emissions exceeding any of the 

applicable standards by more than 0.4 g/bhp-hr, the OBD system shall 

detect a malfunction when the catalyst has no detectable amount of 

NOx conversion capability.

(B) For all 2013 model year engines and 2014 and 2015 model year engines

that are not included in the phase-in specified in section (e)(6.2.1)(C): 

(i) The OBD system shall detect a catalyst malfunction when the catalyst 

conversion capability decreases to the point that would cause an 

engine's emissions to exceed the applicable NOx standard by more 

than 0.4 g/bhp-hr (e.g., cause 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 2.0 times the applicable NMHC 

standard.

(ii) If no failure or deterioration of the catalyst system NOx conversion 

capability could result in an engine’s NOx or NMHC emissions 

exceeding the applicable malfunction criteria of section (e)(6.2.1)(B)(i), 

the OBD system shall detect a malfunction when the catalyst has no 

detectable amount of NOx or NMHC conversion capability.

(C) For at least 20 percent of 2014 model year diesel engines and at least 50 

percent of 2015 model year diesel engines (percentage based on the 

manufacturer’s projected California sales volume of all diesel engines

subject to this regulation):

(i) The OBD system shall detect a catalyst malfunction when the catalyst 

conversion capability decreases to the point that would cause an 

engine's emissions to exceed the applicable NOx standard by more 
49

than 0.3 g/bhp-hr (e.g., cause 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.

(ii) If no failure or deterioration of the catalyst system NOx conversion 

capability could result in an engine’s NOx or NMHC emissions 

exceeding the applicable malfunction criteria of section (e)(6.2.1)(C)(i), 

the OBD system shall detect a malfunction when the catalyst has no 

detectable amount of NOx or NMHC conversion capability.

(B)(D) Except as provided for below in section (e)(6.2.1)(E), Ffor 20132016

and subsequent model year engines:

(i) The OBD system shall detect a catalyst malfunction when the catalyst 

conversion capability decreases to the point that would cause an 

engine's emissions to exceed 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/bhp-hr) as measured from an 

applicable cycle emission test or 2.0 times the applicable NMHC 

standard.

(ii) If no failure or deterioration of the catalyst system NOx conversion 

capability could result in an engine’s NOx or NMHC emissions 

exceeding the applicable malfunction criteria of section 

(e)(6.2.1)(BD)(i), the OBD system shall detect a malfunction when the 

catalyst has no detectable amount of NOx or NMHC conversion 

capability.

(E) In lieu of using the malfunction criteria in section (e)(6.2.1)(D), a 

manufacturer may continue to use the malfunction criteria in section 

(e)(6.2.1)(C) for any 2016 model year engine that was previously certified 

in the 2014 or 2015 model year to the malfunction criteria in section 

(e)(6.2.1)(C) and carried over to the 2016 model year. 

(6.2.2) Selective Catalytic Reduction (SCR) or Other Active/Intrusive Reductant 

Injection System Performance:

(A) Reductant Delivery Performance:

(i) For 2010 through 2012 model year engines, the OBD system shall 

detect a malfunction prior to any failure or deterioration of the system 

to properly regulate reductant delivery (e.g., urea injection, separate 

injector fuel injection, post injection of fuel, air assisted 

injection/mixing) that would cause an engine's NOx emissions to 

exceed any of the applicable standards by more than 0.4 g/bhp-hr 

(e.g., cause 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 (i.e., FTP or SET). If no failure or deterioration of the 

SCR system could result in an engine’s NOx emissions exceeding any 

of the applicable standards by more than 0.4 g/bhp-hr, the OBD 

system shall detect a malfunction when the system has reached its 

control limits such that it is no longer able to deliver the desired 

quantity of reductant.
50

(ii) For all 2013 model year engines and 2014 and 2015 model year 

engines that are not included in the phase-in specified in section 

(e)(6.2.2)(A)(iii):

a. The OBD system shall detect a malfunction prior to any failure or 

deterioration of the system to properly regulate reductant delivery 

(e.g., urea injection, separate injector fuel injection, post injection of 

fuel, air assisted injection/mixing) that would cause an engine's 

emissions to exceed the applicable NOx standard by more than 0.4 

g/bhp-hr (e.g., cause 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 2.0 times the applicable NMHC 

standard.

b. If no failure or deterioration of the SCR system could result in an 

engine’s NOx or NMHC emissions exceeding the applicable 

malfunction criteria of section (e)(6.2.2)(A)(ii)a., the OBD system 

shall detect a malfunction when the system has reached its control 

limits such that it is no longer able to deliver the desired quantity of 

reductant.

(iii) For at least 20 percent of all 2014 model year diesel engines and at 

least 50 percent of all 2015 model year diesel engines (percentage 

based on the manufacturer’s projected California sales volume of all 

diesel engines subject to this regulation):

a. The OBD system shall detect a malfunction prior to any failure or 

deterioration of the system to properly regulate reductant delivery 

(e.g., urea injection, separate injector fuel injection, post injection of 

fuel, air assisted injection/mixing) that would cause an engine's 

emissions to exceed the applicable NOx standard by more than 0.3 

g/bhp-hr (e.g., cause 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.

b. If no failure or deterioration of the SCR system could result in an 

engine’s NOx or NMHC emissions exceeding the applicable 

malfunction criteria of section (e)(6.2.2)(A)(iii)a., the OBD system 

shall detect a malfunction when the system has reached its control 

limits such that it is no longer able to deliver the desired quantity of 

reductant.

(ii)(iv) Except as provided for below in section (e)(6.2.2)(A)(v), Ffor 2013

2016 and subsequent model year engines, the OBD system shall 

detect a system malfunction prior to any failure or deterioration of the 

system to properly regulate reductant delivery (e.g., urea injection, 

separate injector fuel injection, post injection of fuel, air assisted 

injection/mixing) that would cause an engine’s emissions to exceed 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/bhp-hr) as measured from an applicable cycle emission test or 

2.0 times the applicable NMHC standard. If no failure or deterioration 

of the SCR system could result in an engine’s NOx or NMHC 
51

emissions exceeding the applicable malfunction criteria above, the 

OBD system shall detect a malfunction when the system has reached 

its control limits such that it is no longer able to deliver the desired 

quantity of reductant.

(v) In lieu of using the malfunction criteria in section (e)(6.2.2)(A)(iv), a 

manufacturer may continue to use the malfunction criteria in section 

(e)(6.2.2)(A)(iii) for any 2016 model year engine that was previously 

certified in the 2014 or 2015 model year to the malfunction criteria in 

section (e)(6.2.2)(A)(iii) and carried over to the 2016 model year. 

(B) If the catalyst system uses a reductant other than the fuel used for the 

engine or uses a reservoir/tank for the reductant that is separate from the 

fuel tank used for the engine, the OBD system shall detect a malfunction 

when there is no longer sufficient reductant available to properly operate 

the reductant system (e.g., the reductant tank is empty).

(C) If the catalyst system uses a reservoir/tank for the reductant that is 

separate from the fuel tank used for the engine, the OBD system shall 

detect a malfunction when an improper reductant is used in the reductant 

reservoir/tank (e.g., the reductant tank is filled with something other than 

the reductant).

(D) Feedback control: Except as provided for in section (e)(6.2.2)(E), if the 

engine is equipped with feedback or feed-forward control of the reductant 

injection (e.g., pressure control), the OBD system shall detect a 

malfunction:

(i) If the system fails to begin control within a manufacturer specified time 

interval;

(ii) If a failure or deterioration causes open loop or default operation; or

(iii) If the control system has used up all of the adjustment allowed by the 

manufacturer or reached its maximum authority and cannot achieve 

the target.

(E) A manufacturer may request Executive Officer approval to temporarily 

disable monitoring for the malfunction criteria specified in section 

(e)(6.2.2)(D)(iii) during conditions that a manufacturer cannot robustly 

distinguish between a malfunctioning system and a properly operating 

system. The Executive Officer shall approve the disablement upon the 

manufacturer submitting data and/or analysis demonstrating that the 

control system, when operating as designed on an engine with all 

emission controls working properly, routinely operates during these 

conditions with all of the adjustment allowed by the manufacturer used up.

(F) In lieu of detecting the malfunctions specified in sections (e)(6.2.2)(D)(i) 

and (ii) with a reductant injection system-specific monitor, the OBD system

may monitor the individual parameters or components that are used as 

inputs for reductant injection feedback control provided that the monitors 

detect all malfunctions that meet the criteria in sections (e)(6.2.2)(D)(i) 

and (ii). 

(6.2.3) Catalyst System Aging and Monitoring

(A) For purposes of determining the catalyst malfunction criteria in section 

(e)(6.2.1) for individually monitored catalysts, the manufacturer shall use a 

catalyst deteriorated to the malfunction criteria using methods established 
52

by the manufacturer to represent real world catalyst deterioration under 

normal and malfunctioning engine operating conditions. If the catalyst 

system contains catalysts in parallel (e.g., a two bank exhaust system 

where each bank has its own catalyst), the malfunction criteria shall be 

determined with the “parallel” catalysts equally deteriorated.

(B) For purposes of determining the catalyst malfunction criteria in section 

(e)(6.2.1) for catalysts monitored in combination with others, the 

manufacturer shall submit a catalyst system aging and monitoring plan to 

the Executive Officer for review and approval. The plan shall include the 

description, emission control purpose, and location of each component, 

the monitoring strategy for each component and/or combination of 

components, and the method for determining the malfunction criteria of 

section (e)(6.2.1) including the deterioration/aging process. If the catalyst 

system contains catalysts in parallel (e.g., a two bank exhaust system 

where each bank has its own catalyst), the malfunction criteria shall be 

determined with the “parallel” catalysts equally deteriorated. Executive 

Officer approval of the plan shall be based on the representativeness of 

the aging to real world catalyst system component deterioration under 

normal and malfunctioning engine operating conditions, the effectiveness 

of the method used to determine the malfunction criteria of section 

(e)(6.2.1), the ability of the component monitor(s) to pinpoint the likely 

area of malfunction and ensure the correct components are 

repaired/replaced in-use, and the ability of the component monitor(s) to 

accurately verify that each catalyst component is functioning as designed 

and as required in section (e)(6.2.1). 

(6.3) Monitoring Conditions: 

(6.3.1) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (e)(6.2.1), (e)(6.2.2)(A), and (e)(6.2.2)(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)(3.2.1), all monitors used to detect malfunctions identified in 

section (e)(6.2.1) shall be tracked separately but reported as a single set 

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

(6.3.2) Except as provided in section (e)(6.3.3), the OBD system shall monitor 

continuously for malfunctions identified in sections (e)(6.2.2)(A), (B), and 

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

(6.3.3) 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.
53

(6.4) MIL Illumination and Fault Code Storage:

(6.4.1) Except as provided below for reductant faults, general requirements for

MIL illumination and fault code storage are set forth in section (d)(2).

(6.4.2) If the OBD system is capable of discerning that a system fault is being 

caused by a empty reductant tank:

(A) The manufacturer may request Executive Officer approval to delay 

illumination of the MIL if the vehicle is equipped with an alternative 

indicator for notifying the vehicle operator of the malfunction. The 

Executive Officer shall approve the request upon determining the 

alternative indicator is of sufficient illumination and location to be readily 

visible under all lighting conditions and provides equivalent assurance that 

a vehicle operator will be promptly notified and that corrective action will 

be undertaken. 

(B) If the vehicle is not equipped with an alternative indicator and the MIL 

illuminates, the MIL may be immediately extinguished and the 

corresponding fault codes erased once the OBD system has verified that 

the reductant tank has been properly refilled and the MIL has not been 

illuminated for any other type of malfunction.

(C) The Executive Officer may approve other strategies that provide 

equivalent assurance that a vehicle operator will be promptly notified and 

that corrective action will be undertaken.

(6.4.3) The monitoring method for the catalyst(s) shall be capable of detecting all

instances, except diagnostic self-clearing, when a catalyst fault code has 

been cleared but the catalyst has not been replaced (e.g., catalyst 

overtemperature histogram approaches are not acceptable).

(7) NOx Adsorber Monitoring

(7.1) Requirement: The OBD system shall monitor the NOx adsorber(s) on engines 

so-equipped for proper performance. For engines equipped with 

active/intrusive injection (e.g., in-exhaust fuel and/or air injection) to achieve 

desorption of the NOx adsorber(s), the OBD system shall monitor the 

active/intrusive injection system for proper performance. The individual 

electronic components (e.g., injectors, valves, sensors) that are used in the 

active/intrusive injection system shall be monitored in accordance with the 

comprehensive component requirements in section (g)(3).

(7.2) Malfunction Criteria:

(7.2.1) NOx adsorber capability:

(A) For 2010 through 2012 model year engines, the OBD system shall detect 

a NOx adsorber system malfunction when the NOx adsorber system 

capability decreases to the point that would cause an engine's NOx 

emissions to exceed any of the applicable standards by more than 0.3 

g/bhp-hr (e.g., cause 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 (i.e., FTP or SET). If no failure or deterioration of the NOx 

adsorber system capability could result in an engine’s NOx emissions 

exceeding any of the applicable standards by more than 0.3 g/bhp-hr, the 

OBD system shall detect a malfunction when the system has no 

detectable amount of NOx adsorber capability.
54

(B) For 2013 and subsequent model year engines, the OBD system shall 

detect a NOx adsorber system malfunction when the NOx adsorber 

capability decreases to the point that would cause an engine's emissions 

to exceed the applicable NOx standards 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/bhp-hr) as measured from an applicable cycle emission test (i.e., 

FTP or SET) or 2.0 times the applicable NMHC standard. If no failure or 

deterioration of the NOx adsorber capability could result in an engine’s 

NOx or NMHC emissions exceeding the applicable malfunction criteria 

above, the OBD system shall detect a malfunction when the system has 

no detectable amount of NOx adsorber capability.

(7.2.2) For systems that utilize active/intrusive injection (e.g., in-cylinder post fuel 

injection, in-exhaust air-assisted fuel injection) to achieve desorption of 

the NOx adsorber, the OBD system shall detect a malfunction if any 

failure or deterioration of the injection system’s ability to properly regulate 

injection causes the system to be unable to achieve desorption of the NOx 

adsorber. 

(7.2.3) Feedback control: Except as provided for in section (e)(7.2.4), if the 

engine is equipped with feedback or feed-forward control of the NOx 

adsorber or active/intrusive injection system (e.g., feedback control of 

injection quantity, time), the OBD system shall detect a malfunction:

(A) If the system fails to begin control within a manufacturer specified time 

interval;

(B) If a failure or deterioration causes open loop or default operation; or

(C) If the control system has used up all of the adjustment allowed by the 

manufacturer or reached its maximum authority and cannot achieve the 

target.

(7.2.4) A manufacturer may request Executive Officer approval to temporarily 

disable monitoring for the malfunction criteria specified in section 

(e)(7.2.3)(C) during conditions that a manufacturer cannot robustly 

distinguish between a malfunctioning system and a properly operating

system. The Executive Officer shall approve the disablement upon the 

manufacturer submitting data and/or analysis demonstrating that the 

control system, when operating as designed on an engine with all 

emission controls working properly, routinely operates during these 

conditions with all of the adjustment allowed by the manufacturer used up.

(7.2.5) In lieu of detecting the malfunctions specified in sections (e)(7.2.3)(A) and 

(B) with a NOx adsorber-specific monitor, the OBD system may monitor 

the individual parameters or components that are used as inputs for NOx 

adsorber or active/intrusive injection system feedback control provided 

that the monitors detect all malfunctions that meet the criteria in sections 

(e)(7.2.3)(A) and (B).

(7.2.6) For purposes of determining the NOx adsorber system malfunction criteria 

in section (e)(7.2.1) for NOx adsorber systems that consist of more than 

one NOx adsorber (e.g., two or more adsorbers in series), the 

manufacturer shall submit a system aging and monitoring plan to the 

Executive Officer for review and approval. The plan shall include the 

description and location of each component, the monitoring strategy for 
55

each component and/or combination of components, and the method for 

determining the malfunction criteria of section (e)(7.2.1) including the 

deterioration/aging process. Executive Officer approval of the plan shall 

be based on the representativeness of the aging to real world NOx 

adsorber system component deterioration under normal and 

malfunctioning engine operating conditions, the effectiveness of the 

method used to determine the malfunction criteria of section (e)(7.2.1), 

the ability of the component monitor(s) to pinpoint the likely area of 

malfunction and ensure the correct components are repaired/replaced inuse, and the ability of the component monitor(s) to accurately verify that 

each NOx adsorber system component is functioning as designed and as 

required in section (e)(7.2.1).

(7.3) Monitoring Conditions:

(7.3.1) Manufacturers shall define the monitoring conditions for malfunctions

identified in sections (e)(7.2.1) (i.e., adsorber capability) 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)(3.2.1), all 

monitors used to detect malfunctions identified in sections (e)(7.2.1) shall 

be tracked separately but reported as a single set of values as specified in 

section (d)(5.2.2).

(7.3.2) Except as provided in section (e)(7.3.3), the OBD system shall monitor 

continuously for malfunctions identified in sections (e)(7.2.2) and (7.2.3) 

(e.g., injection function, feedback control).

(7.3.3) 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.

(7.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(8) Particulate Matter (PM) Filter Monitoring

(8.1) Requirement: The OBD system shall monitor the PM filter on engines soequipped for proper performance. For engines equipped with active 

regeneration systems that utilize an active/intrusive injection (e.g., in-exhaust 

fuel injection, in-exhaust fuel/air burner), the OBD system shall monitor the 

active/intrusive injection system for proper performance. The individual 

electronic components (e.g., injectors, valves, sensors) that are used in the 

active/intrusive injection system shall be monitored in accordance with the 

comprehensive component requirements in section (g)(3).

(8.2) Malfunction Criteria:

(8.2.1) Filtering Performance:

(A) For 2010 through 2012 model year engines, the OBD system shall detect 

a malfunction prior to a decrease in the filtering capability of the PM filter 
56

(e.g., cracking) that would cause an engine's PM emissions to exceed 

either of the following thresholds, whichever is higher: 0.07 g/bhp-hr as 

measured from an applicable emission test cycle (i.e., FTP or SET); or the 

applicable standard plus 0.06 g/bhp-hr (e.g., 0.07 g/bhp-hr if the exhaust

emission standard is 0.01 g/bhp-hr). If no failure or deterioration of the 

PM filtering performance could result in an engine’s PM emissions 

exceeding these levels, the OBD system shall detect a malfunction when 

no detectable amount of PM filtering occurs.

(B) Except as specified in section (e)(8.2.1.)(C) below, fFor all 2013 model 

year engines and 2014 and through 2015 model year engines that are not 

included in the phase-in specified in section (e)(8.2.1)(C), the OBD 

system shall detect a malfunction prior to a decrease in the filtering 

capability of the PM filter (e.g., cracking) that would cause an engine's PM 

emissions to exceed either of the following thresholds, whichever is 

higher: 0.05 g/bhp-hr as measured from an applicable emission test cycle 

(i.e., FTP or SET); or the applicable standard plus 0.04 g/bhp-hr (e.g., 

0.05 g/bhp-hr if the exhaust emission standard is 0.01 g/bhp-hr). If no 

failure or deterioration of the PM filtering performance could result in an 

engine’s PM emissions exceeding these levels, the OBD system shall 

detect a malfunction when no detectable amount of PM filtering occurs.

(C)For 2014 through 2015 model year engines, the manufacturer shall meet 

one of the following two options below:

(i) For at least 20 percent of 2014 model year diesel engines and at least 

20 percent of 2015 model year diesel engines (percentage based on 

the manufacturer’s projected California sales volume of all diesel 

engines subject to this regulation), the OBD system shall use the 

malfunction criteria of section (e)(8.2.1)(B) without using the provisions

of section (g)(5.1) to exclude specific failure modes.

(ii) For at least 50 percent of 2015 model year diesel engines (percentage 

based on the manufacturer’s projected California sales volume of all 

diesel engines subject to this regulation), the OBD system shall detect 

a malfunction prior to a decrease in the filtering capability of the PM 

filter that would cause an engine's PM emissions to exceed either of 

the following thresholds, whichever is higher, without using the 

provisions of section (g)(5.1) to exclude specific failure modes: 0.03 

g/bhp-hr as measured from an applicable emission test cycle (i.e., FTP 

or SET); or the applicable standard plus 0.02 g/bhp-hr (e.g., 0.03 

g/bhp-hr if the exhaust emission standard is 0.01 g/bhp-hr). If no 

failure or deterioration of the PM filtering performance could result in 

an engine’s PM emissions exceeding these levels, the OBD system 

shall detect a malfunction when no detectable amount of PM filtering 

occurs.

(C)(D) For 2013 through 2015 model year engines subject to (d)(7.2.2)(A) 

andExcept as provided in section (e)(8.2.1)(E), for all 2016 and 

subsequent model year engines, the OBD system shall detect a 

malfunction prior to a decrease in the filtering capability of the PM filter 

that would cause an engine's PM emissions to exceed either of the 

following thresholds, whichever is higher: 0.03 g/bhp-hr as measured from 
57

an applicable emission test cycle (i.e., FTP or SET); or the applicable 

standard plus 0.02 g/bhp-hr (e.g., 0.03 g/bhp-hr if the exhaust emission 

standard is 0.01 g/bhp-hr). If no failure or deterioration of the PM filtering 

performance could result in an engine’s PM emissions exceeding these 

levels, the OBD system shall detect a malfunction when no detectable 

amount of PM filtering occurs.

(E) In lieu of the malfunction criteria in section (e)(8.2.1)(D), a manufacturer 

may continue to use the malfunction criteria in section (e)(8.2.1)(C)(i) for 

any 2016 model year engine that was previously certified in the 2014 or 

2015 model year to the malfunction criteria in section (e)(8.2.1)(C)(i) and 

carried over to the 2016 model year.

(F) For the phase-in schedules described in section (e)(8.2.1)(C) above, the 

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

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

(8.2.2) Frequent Regeneration: The OBD system shall detect a malfunction when 

the PM filter regeneration occurs more frequently than (i.e., occurs more 

often than) the manufacturer’s specified regeneration frequency to a level 

such that it would cause an engine's emissions to exceed the following:

(A) For 2010 through 2012 model year engines, 2.0 times the applicable 

NMHC standards.

(B) For 2013 and subsequent model year engines, 2.0 times the applicable 

NMHC standards or the applicable NOx standard by more than 0.2 g/bhphr (e.g., cause NOx emissions to exceed 0.4 g/bhp-hr if the exhaust

emission standard is 0.2 g/bhp-hr). 

(C) If no failure or deterioration causes an increase in the PM filter 

regeneration frequency that could result in an engine’s emissions 

exceeding the emission levels specified above, the OBD system shall 

detect a malfunction when the PM filter regeneration frequency exceeds 

the manufacturer’s specified design limits for allowable regeneration 

frequency.

(8.2.3) Incomplete regeneration: The OBD system shall detect a regeneration 

malfunction when the PM filter does not properly regenerate under 

manufacturer-defined conditions where regeneration is designed to occur.

(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 this 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 increase 

by 15 percent or more of the applicable standard as measured from an 
58

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

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

the applicable 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 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 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 standard as measured from an applicable emission 

test cycle.

(8.2.5) Missing substrate: The OBD system shall detect a malfunction if either the 

PM filter substrate is completely destroyed, removed, or missing, or if the 

PM filter assembly is replaced with a muffler or straight pipe.

(8.2.6) Active/Intrusive Injection: For systems that utilize active/intrusive injection 

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

to achieve regeneration of the PM filter, the OBD system shall detect a 

malfunction if any failure or deterioration of the injection system’s ability to 

properly regulate injection causes the system to be unable to achieve 

regeneration of the PM filter.

(8.2.7) Feedback Control: Except as provided for in section (e)(8.2.8), if the 

engine is equipped with feedback or feed-forward control of the PM filter 

regeneration (e.g., feedback control of oxidation catalyst inlet 

temperature, PM filter inlet or outlet temperature, in-cylinder or in-exhaust 

fuel injection), the OBD system shall detect a malfunction:

(A) If the system fails to begin control within a manufacturer specified time 

interval;

(B) If a failure or deterioration causes open loop or default operation; or

(C) If the control system has used up all of the adjustment allowed by the 

manufacturer or reached its maximum authority and cannot achieve the 

target.

(8.2.8) A manufacturer may request Executive Officer approval to temporarily 

disable monitoring for the malfunction criteria specified in section 

(e)(8.2.7)(C) during conditions that a manufacturer cannot robustly 

distinguish between a malfunctioning system and a properly operating 

system. The Executive Officer shall approve the disablement upon the 

manufacturer submitting data and/or analysis demonstrating that the 

control system, when operating as designed on an engine with all 

emission controls working properly, routinely operates during these 

conditions with all of the adjustment allowed by the manufacturer used up.

(8.2.9) In lieu of detecting the malfunctions specified in sections (e)(8.2.7)(A) and 

(B) with a PM filter-specific monitor, the OBD system may monitor the 
59

individual parameters or components that are used as inputs for PM filter 

regeneration feedback control provided that the monitors detect all 

malfunctions that meet the criteria in sections (e)(8.2.7)(A) and (B).

(8.3) Monitoring Conditions: 

(8.3.1) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (e)(8.2.1) through (8.2.6) 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). For purposes of tracking and reporting as required in 

section (d)(3.2.1), all monitors used to detect malfunctions identified in 

sections (e)(8.2.1) shall be tracked separately but reported as a single set 

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

(8.3.2) Except as provided in section (e)(8.3.3), the OBD II system shall monitor 

continuously for malfunctions identified in section (e)(8.2.7) (i.e., PM filter 

feedback control).

(8.3.3) 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.

(8.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(9) Exhaust Gas Sensor Monitoring

(9.1) Requirement:

(9.1.1) The OBD system shall monitor all exhaust gas sensors (e.g., oxygen, airfuel ratio, NOx) used for emission control system feedback (e.g., EGR 

control/feedback, SCR control/feedback, NOx adsorber control/feedback)

or as a monitoring device for proper output signal, activity, response rate, 

and any other parameter that can affect emissions.

(9.1.2) For engines equipped with heated exhaust gas sensors, the OBD system 

shall monitor the heater for proper performance.

(9.2) Malfunction Criteria:

(9.2.1) Air-Fuel Ratio Sensors: 

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

(i) Sensor performance faults: The OBD 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 an engine's NMHC, CO, or NOx 

emissions to exceed 2.0 times any of the applicable standards or the 

engine’s PM emissions to exceed any of the applicable standards plus 

0.02 g/bhp-hr.
60

(ii) Circuit faults: The OBD system shall detect malfunctions of the sensor 

caused by either a lack of circuit continuity or out-of-range values.

(iii) Feedback faults: The OBD system shall detect a malfunction of the

sensor when a sensor failure or deterioration causes an emission 

control system (e.g., EGR, SCR, or NOx adsorber) to stop using that 

sensor as a feedback or feed-forward input (e.g., causes default or 

open-loop operation).

(iv) Monitoring capability: To the extent feasible, the OBD system shall 

detect a malfunction of the sensor when the sensor output voltage, 

resistance, impedance, current, amplitude, activity, offset, or other 

characteristics are no longer sufficient for use as an OBD system 

monitoring device (e.g., for catalyst, EGR, SCR, or NOx adsorber 

monitoring).

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

(i) Sensor performance faults:

a. For 2010 through 2012 model year engines, the OBD 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 an 

engine's NMHC emissions to exceed 2.5 times any of the 

applicable standards, cause an engine's NOx emissions to exceed 

any of the applicable standards by more than 0.3 g/bhp-hr (e.g., 

cause 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 (i.e., FTP or SET), or cause an engine’s PM 

emissions to exceed (whichever is higher): 0.05 g/bhp-hr as 

measured from an applicable cycle emission test (i.e., FTP or 

SET); or any of the applicable standards by more than 0.04 g/bhphr (e.g., cause emissions to exceed 0.05 g/bhp-hr if the exhaust

emission standard is 0.01 g/bhp-hr).

b. For 2013 and subsequent model year engines, the OBD 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 an 

engine's NMHC emissions to exceed 2.0 times any of the 

applicable standards, cause an engine's NOx emissions to exceed 

any of the applicable standards 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/bhp-hr) as measured from an applicable cycle 

emission test (i.e., FTP or SET), or cause an engine's PM 

emissions to exceed (whichever is higher): 0.03 g/bhp-hr as 

measured from an applicable cycle emission test (i.e., FTP or 

SET); or any of the applicable standards by more than 0.02 g/bhphr (e.g., cause emissions to exceed 0.03 g/bhp-hr if the exhaust

emission standard is 0.01 g/bhp-hr).

(ii) Circuit faults: The OBD system shall detect malfunctions of the sensor 

caused by either a lack of circuit continuity or out-of-range values.
61

(iii) Feedback faults: The OBD system shall detect a malfunction of the 

sensor when a sensor failure or deterioration causes an emission 

control system (e.g., EGR, SCR, or NOx adsorber) to stop using that 

sensor as a feedback or feed-forward input (e.g., causes default or 

open-loop operation).

(iv) Monitoring capability: To the extent feasible, the OBD system shall 

detect a malfunction of the sensor when the sensor output voltage, 

resistance, impedance, current, amplitude, activity, offset, or other 

characteristics are no longer sufficient for use as an OBD system 

monitoring device (e.g., for catalyst, EGR, SCR, or NOx adsorber 

monitoring).

(9.2.2) NOx and PM sensors:

(A) Sensor performance faults:

(i) For 2010 through 2012 model year engines, the OBD 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 an engine's NOx 

emissions to exceed any of the applicable standards by more than 0.4

g/bhp-hr (e.g., cause 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 (i.e., FTP or SET), or cause an engine's PM 

emissions to exceed (whichever is higher): 0.05 g/bhp-hr as measured 

from an applicable cycle emission test (i.e., FTP or SET); or any of the 

applicable standards by more than 0.04 g/bhp-hr (e.g., cause 

emissions to exceed 0.05 g/bhp-hr if the exhaust emission standard is 

0.01 g/bhp-hr).

(ii) For all 2013 model year engines and 2014 and 2015 model year 

engines that are not included in the phase-in specified in section 

(e)(9.2.2)(A)(iii), the OBD 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 an engine's NOx emissions to 

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

cause 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 cause an engine's PM emissions to exceed 

(whichever is higher): 0.03 g/bhp-hr as measured from an applicable 

cycle emission test (i.e., FTP or SET); or any of the applicable 

standards by more than 0.02 g/bhp-hr (e.g., cause emissions to 

exceed 0.03 g/bhp-hr if the exhaust emission standard is 0.01 g/bhphr).

(iii) For at least 20 percent of 2014 model year diesel engines and at least 

50 percent of 2015 model year diesel engines (percentage based on 

the manufacturer’s projected California sales volume of all diesel 

engines subject to this regulation), the OBD 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 an engine's NOx emissions to 
62

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

cause 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 cause an engine's PM emissions to exceed 

(whichever is higher): 0.03 g/bhp-hr as measured from an applicable 

cycle emission test (i.e., FTP or SET); or any of the applicable 

standards by more than 0.02 g/bhp-hr (e.g., cause emissions to 

exceed 0.03 g/bhp-hr if the exhaust emission standard is 0.01 g/bhphr).

(ii)(iv) Except as provided for below in section (e)(9.2.2)(A)(v), Ffor 2013

2016 and subsequent model year engines, the OBD 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 an engine's NOx 

emissions to exceed any of the applicable NOx standards 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/bhp-hr) as measured from an 

applicable cycle emission test (i.e., FTP or SET), cause an engine’s 

NMHC emissions to exceed 2.0 times the applicable NMHC standard, 

or cause an engine's PM emissions to exceed (whichever is higher): 

0.03 g/bhp-hr as measured from an applicable cycle emission test (i.e., 

FTP or SET); or any of the applicable standards by more than 0.02 

g/bhp-hr (e.g., cause emissions to exceed 0.03 g/bhp-hr if the exhaust

emission standard is 0.01 g/bhp-hr).

(v) In lieu of using the malfunction criteria in section (e)(9.2.2)(A)(iv), a 

manufacturer may continue to use the malfunction criteria in section 

(e)(9.2.2)(A)(iii) for any 2016 model year engine that was previously 

certified in the 2014 or 2015 model year to the malfunction criteria in 

section (e)(9.2.2)(A)(iii) and carried over to the 2016 model year. 

(B) Circuit faults: The OBD system shall detect malfunctions of the sensor 

caused by either a lack of circuit continuity or out-of-range values.

(C) Feedback faults: The OBD system shall detect a malfunction of the 

sensor when a sensor failure or deterioration causes an emission control 

system (e.g., EGR, SCR, or NOx adsorber) to stop using that sensor as a 

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

operation).

(D) Monitoring capability: To the extent feasible, the OBD system shall detect 

a malfunction of the sensor when the sensor output voltage, resistance, 

impedance, current, amplitude, activity, offset, or other characteristics are 

no longer sufficient for use as an OBD system monitoring device (e.g., for 

catalyst, EGR, PM filter, SCR, or NOx adsorber monitoring).

(9.2.3) Other exhaust gas sensors:

(A) For other exhaust gas sensors, the manufacturer shall submit a 

monitoring plan to the Executive Officer for approval. The Executive 

Officer shall approve the request upon determining that the manufacturer 

has submitted data and an engineering evaluation that demonstrate that 

the monitoring plan is as reliable and effective as the monitoring plan 
63

required for air-fuel ratio sensors, NOx sensors, and PM sensors under 

sections (e)(9.2.1) and (e)(9.2.2).

(9.2.4) Sensor Heaters:

(A) The OBD system shall detect a malfunction of the heater performance 

when the current or voltage drop in the heater circuit is no longer within 

the manufacturer's specified limits for normal operation (i.e., within the 

criteria required to be met by the component vendor for heater circuit 

performance at high mileage). Subject to Executive Officer approval, 

other malfunction criteria for heater performance malfunctions may be 

used upon the Executive Officer determining that the manufacturer has 

submitted data and/or an engineering evaluation that demonstrate the 

monitoring reliability and timeliness to be equivalent to the stated criteria 

in section (e)(9.2.4)(A).

(B) The OBD system shall detect malfunctions of the heater circuit including 

open or short circuits that conflict with the commanded state of the heater 

(e.g., shorted to 12 Volts when commanded to 0 Volts (ground)).

(9.3) Monitoring Conditions:

(9.3.1) Exhaust Gas Sensors

(A) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (e)(9.2.1)(A)(i), (9.2.1)(B)(i), and (9.2.2)(A), and

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

(d)(3.1) and (d)(3.2) (i.e., minimum ratio requirements). For purposes of 

tracking and reporting as required in section (d)(3.2.1), all monitors used 

to detect malfunctions identified in sections (e)(9.2.1)(A)(i), (9.2.1)(B)(i), 

and (9.2.2)(A), and for 2016 and subsequent model year engines, section 

(e)(9.2.2)(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 (e)(9.2.1)(A)(iv), and (9.2.1)(B)(iv), and (9.2.2)(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).

(C) Except as provided in section (e)(9.3.1)(D), monitoring for malfunctions 

identified in sections (e)(9.2.1)(A)(ii), (9.2.1)(A)(iii), (9.2.1)(B)(ii), 

(9.2.1)(B)(iii), (9.2.2)(B), and (9.2.2)(C) (i.e., circuit continuity and openloop malfunctions) shall be conducted continuously.

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

continuous exhaust gas sensor monitoring when an exhaust gas sensor 

malfunction cannot be distinguished from other effects (e.g., disable outof-range low monitoring during fuel cut conditions). The Executive Officer 

shall approve the disablement upon determining that the manufacturer 

has submitted test data and/or documentation that demonstrate a properly 

functioning sensor cannot be distinguished from a malfunctioning sensor 

and that the disablement interval is limited only to that necessary for 

avoiding false detection.

(9.3.2) Sensor Heaters
64

(A) Manufacturers shall define monitoring conditions for malfunctions 

identified in section (e)(9.2.4)(A) (i.e., sensor heater performance) in 

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

requirements).

(B) Monitoring for malfunctions identified in section (e)(9.2.4)(B) (i.e., circuit 

malfunctions) shall be conducted continuously.

(9.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2). To the 

extent feasible, the OBD system shall separately detect lack of circuit 

continuity and out-of-range faults as required under sections (e)(9.2.1)(A)(ii), 

(e)(9.2.1)(B)(ii), and (e)(9.2.2)(B) and store different fault codes for each 

distinct malfunction (e.g., out-of-range low, out-of-range high, open circuit). 

Manufacturers are not required to store separate fault codes for lack of circuit 

continuity faults that cannot be distinguished from other out-of-range circuit 

faults. 

(10) Variable Valve Timing and/or Control (VVT) System Monitoring

(10.1) Requirement: The OBD system shall monitor the VVT system on engines 

so-equipped for target error and slow response malfunctions. The individual 

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

VVT system shall be monitored in accordance with the comprehensive 

components requirements in section (g)(3).

(10.2) Malfunction Criteria:

(10.2.1) Target Error: The OBD 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 and/or lift 

tolerance that would cause an engine's NHMC, NOx, or CO emissions to 

exceed 2.0 times any of the applicable standards or an engine’s PM 

emissions to exceed a threshold of the applicable standard plus 0.02 

g/bhp-hr.

(10.2.2) Slow Response: The OBD 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 manufacturer-specified 

time that would cause an engine's NHMC, NOx, or CO emissions to 

exceed 2.0 times any of the applicable standards or an engine’s PM 

emissions to exceed a threshold of the applicable standard plus 0.02 

g/bhp-hr.

(10.2.3) For engines in which no failure or deterioration of the VVT system could 

result in an engine’s emissions exceeding the thresholds of sections 

(e)(10.2.1) or (10.2.2), the OBD system shall detect a malfunction of the 

VVT system when proper functional response of the system to computer 

commands does not occur.

(10.3) Monitoring Conditions: Manufacturers shall define the monitoring conditions 

for VVT system malfunctions identified in section (e)(10.2) 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). For purposes of tracking and reporting as required in 
65

section (d)(3.2.1), all monitors used to detect malfunctions identified in 

section (e)(10.2) shall be tracked separately but reported as a single set of 

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

(10.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(11) Cold Start Emission Reduction Strategy Monitoring

(11.1) Requirement:

(11.1.1) For all 2013 and subsequent model year engines that, if an engine

incorporates a specific engine control strategy to reduce cold start 

emissions, the OBD system shall monitor the system strategy to verify the 

strategythat it achieves the desired effect (e.g., to achieve accelerated 

catalyst light-off temperature) and monitor the commanded 

elements/components for proper function (e.g., injection timing, increased 

engine idle speed, increased engine load via intake or exhaust throttle 

activation) while the control strategy is active to ensure proper operation 

of the control strategy.

(11.1.2) For an element/component associated with the cold start emission 

reduction control strategy under section (e)(11) that is also required to be 

monitored elsewhere in section (e) or (g) (e.g., fuel injection timing), the 

manufacturer shall use different diagnostics to distinguish faults detected 

under section (e)(11) (i.e., faults associated with the cold start strategy) 

from faults detected under sections other than section (e)(11) (i.e., faults 

not associated with the cold start strategy).

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

malfunction if either of the following occurs:

(11.2.1) Any single commanded element/component does not properly respond 

to the commanded action while the cold start strategy is active. For 

purposes of this section, “properly respond” is defined as when the 

element responds:

(A) by a robustly detectable amount by the monitor; and 

(B) in the direction of the desired command; and

(C) above and beyond what the element/component would achieve on startup without the cold start strategy active (e.g., if the cold start strategy 

commands a higher idle engine speed, a fault must be detected if there is 

no detectable amount of engine speed increase above what the system 

would achieve without the cold start strategy active);

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

strategy that would cause an engine’s NMHC, NOx, or CO emissions to 

exceed 2.0 times the applicable standards or the engine’s PM emissions 

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

(11.2.3) For section (e)(11.2.2), to the extent feasible (without adding hardware 

for this purpose), the OBD system shall monitor the ability of the system to 

achieve the desired effect (e.g., strategies used to accelerate catalyst 

light-off by increasing catalyst inlet temperature shall verify the catalyst 

inlet temperature actually achieves the desired temperatures within an 

Executive Officer approved time interval after starting the engine) for 

failures that cause emissions to exceed the applicable emission levels 
66

specified in section (e)(11.2.2). For strategies where it is not feasible to 

be monitored as a system, the OBD system shall monitor the individual

elements/components (e.g., increased engine speed, increased engine 

load from restricting an exhaust throttle) for failures that cause emissions 

to exceed the applicable emission levels specified in section (e)(11.2.2).

(11.3) Monitoring Conditions: Manufacturers shall define the monitoring conditions 

for malfunctions identified in section (e)(11.2) in accordance with sections 

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

(11.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2). 

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

(1) Fuel System Monitoring

(1.1) Requirement: The OBD system shall monitor the fuel delivery system to 

determine its ability to provide compliance with emission applicable 

standards.

(1.2) Malfunction Criteria:

(1.2.1) The OBD system shall detect a malfunction of the fuel delivery system 

when:

(A) The fuel delivery system is unable to maintain an engine's emissions at or 

below 1.5 times the applicable standards; or

(B) If equipped, the feedback control based on a secondary oxygen or 

exhaust gas sensor is unable to maintain an vehicleengine’s emissions 

(except as a result of a malfunction specified in section (f)(1.2.1)(C)) at or 

below 1.5 times any of the applicable standards; or

(C) For 2014 and subsequent model year vehicles engines, an air-fuel ratio 

cylinder imbalance (e.g., the air-fuel ratio in one or more cylinders is 

different than the other cylinders due to a cylinder specific malfunction 

such as an intake manifold leak at a particular cylinder, fuel injector 

problem, an individual cylinder EGR runner flow delivery problem, an 

individual variable cam lift malfunction such that an individual cylinder is 

operating on the wrong cam lift profile, or other similar problems) occurs in 

one or more cylinders such that the fuel delivery system is unable to 

maintain an vehicleengine’s emissions at or below: 3.0 times the 

applicable standards for the 2014 through 2016 model years; and 1.5 

times the applicable FTP standards for all 2017 and subsequent model 

year vehicles engines. 

(1.2.2) Except as provided for in section (f)(1.2.3) below, if the engine is equipped 

with adaptive feedback control, the OBD system shall detect a malfunction 

when the adaptive feedback control has used up all of the adjustment 

allowed by the manufacturer.

(1.2.3) If the engine is equipped with feedback control that is based on a 

secondary oxygen (or equivalent) sensor, the OBD system is not required 

to detect a malfunction of the fuel system solely when the feedback 

control based on a secondary oxygen sensor has used up all of the 

adjustment allowed by the manufacturer. However, if a failure or 

deterioration results in engine emissions that exceed the malfunction 
67

criteria in section (f)(1.2.1)(B), the OBD system is required to detect a 

malfunction.

(1.2.4) The OBD system shall detect a malfunction whenever the fuel control 

system fails to enter closed-loop operation within an Executive Officerapproved time interval after engine start. Executive Officer approval of 

the time interval shall be granted upon determining that the data and/or 

engineering evaluation submitted by the manufacturer supports the 

specified times.

(1.2.5) For engines that employ engine shutoff strategies that do not require the 

vehicle operator to restart the engine to continue driving (e.g., hybrid bus 

with engine shutoff at idle), the OBD system shall detect whenever the 

fuel control system fails to enter closed-loop operation within an Executive 

Officer-approved time interval after an engine restart. Executive Officer 

approval of the time interval shall be granted upon determining that the 

data and/or engineering evaluation submitted by the manufacturer 

supports the specified times.

(1.3) Monitoring Conditions: 

(1.3.1) Except as provided in section (f)(1.3.5), the OBD system shall monitor 

continuously for malfunctions identified in sections (f)(1.2.1)(A),

(f)(1.2.1)(B), and (f)(1.2.2) (i.e., fuel delivery system, secondary feedback 

control, adaptive feedback control).

(1.3.2) Manufacturers shall define monitoring conditions for malfunctions 

identified in section (f)(1.2.1)(C) (i.e., air-fuel ratio cylinder imbalance 

malfunctions) in accordance with sections (d)(3.1) and (d)(3.2) (i.e., 

minimum ratio requirements).

(1.3.3) Manufacturers shall define monitoring conditions for malfunctions 

identified in section (f)(1.2.4) in accordance with sections (d)(3.1).

(1.3.4) Manufacturers shall define monitoring conditions for malfunctions 

identified in section (f)(1.2.5) in accordance with sections (d)(3.1) 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).

(1.3.5) 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 (e.g., for temporary introduction of large 

amounts of purge vapor). 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.

(1.4) MIL Illumination and Fault Code Storage: For malfunctions described under 

section (f)(1.2.1)(C) (i.e., air-fuel ratio cylinder imbalance malfunctions), 

general requirements for MIL illumination and fault code storage are set forth 

in section (d)(2). For all other fuel system malfunctions, the MIL illumination 

and fault code storage requirements are set forth in sections (f)(1.4.1) 

through (1.4.6) below.
68

(1.4.1) A pending fault code shall be stored immediately upon the fuel system 

exceeding the malfunction criteria established pursuant to section (f)(1.2).

(1.4.2) Except as provided below, if a pending fault code is stored, the OBD 

system shall immediately illuminate the MIL and store a confirmed fault 

code if a malfunction is again detected during either of the following two 

events: (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 those that occurred when the pending fault code was 

stored are encountered.

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

in which similar conditions have been encountered without an exceedance 

of the specified fuel system malfunction criteria. The pending code may 

also be erased if similar conditions are not encountered during the 80 

driving cycles immediately after the initial detection of a malfunction for 

which the pending code was set.

(1.4.4) Storage of freeze frame conditions.

(A) The 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 and erasing a confirmed fault code.

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

(see section (f)(2)) or fuel system malfunction when a fault code is stored 

as specified in section (f)(1.4.1) or (f)(1.4.2) above, the stored freeze 

frame information shall be replaced with freeze frame information 

regarding the fuel system malfunction.

(1.4.5) Storage of fuel system conditions for determining similar conditions of 

operation. 

(A) Upon detection of a fuel system malfunction under section (f)(1.2), the 

OBD system shall store the engine speed, load, and warm-up status of 

the first fuel system malfunction that resulted in the storage of the pending 

fault code.

(B) For fuel system faults detected using feedback control that is based on a 

secondary oxygen (or equivalent) sensor, the manufacturer may request 

Executive Officer approval to use an alternate definition of similar 

conditions in lieu of the definition specified in section (c). The Executive 

Officer shall approve the alternate definition upon the manufacturer 

providing data or analysis demonstrating that the alternate definition 

provides for equivalent robustness in detection of fuel system faults that 

vary in severity depending on engine speed, load, and/or warm-up status.

(1.4.6) Extinguishing the MIL. The MIL may be extinguished after three 

sequential driving cycles in which similar conditions have been 

encountered without a malfunction of the fuel system.

(2) Misfire Monitoring

(2.1) Requirement:

(2.1.1) The OBD system shall monitor the engine for misfire causing catalyst 

damage and misfire causing excess emissions.
69

(2.1.2) The OBD system shall identify the specific cylinder that is experiencing 

misfire. Manufacturers may request Executive Officer approval to store a 

general misfire fault code instead of a cylinder specific fault code under 

certain operating conditions. The Executive Officer shall approve the 

request upon determining that the manufacturer has submitted data 

and/or an engineering evaluation that demonstrate that the misfiring 

cylinder cannot be reliably identified when the conditions occur.

(2.1.3) If more than one cylinder is misfiring, a separate fault code shall be stored 

indicating that multiple cylinders are misfiring except as allowed below. 

When identifying multiple cylinder misfire, the OBD system is not required 

to also identify each of the misfiring cylinders individually through separate 

fault codes. If more than 90 percent of the detected misfires occur in a

single cylinder, the OBD system may elect to store the appropriate fault 

code indicating the specific misfiring cylinder in lieu of the multiple cylinder 

misfire fault code. If, however, two or more cylinders individually have 

more than 10 percent of the total number of detected misfires, a multiple 

cylinder fault code must be stored.

(2.2) Malfunction Criteria: The OBD system shall detect a misfire malfunction 

pursuant to the following:

(2.2.1) Misfire causing catalyst damage:

(A) Manufacturers shall determine the percentage of misfire evaluated in 200 

revolution increments for each engine speed and load condition that 

would result in a temperature that causes catalyst damage. The 

manufacturer shall submit documentation to support this percentage of 

misfire as required in section (j)(2.5). For every engine speed and load 

condition that this percentage of misfire is determined to be lower than 

five percent, the manufacturer may set the malfunction criteria at five 

percent.

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

longer interval than 200 revolutions but only for determining, on a given 

driving cycle, the first misfire exceedance as provided in section 

(f)(2.4.1)(A) below. Executive Officer approval shall be granted upon 

determining that the manufacturer has submitted data and/or an 

engineering evaluation that demonstrate that catalyst damage would not 

occur due to unacceptably high catalyst temperatures before the interval 

has elapsed.

(C) A misfire malfunction shall be detected if the percentage of misfire 

established in section (f)(2.2.1)(A) is exceeded. For multiple cylinder 

misfire situations that result in a misfire rate greater than or equal to 50 

percent, the OBD system shall only be required to detect a misfire 

malfunction for situations that are caused by a single component failure.

(D) For purposes of establishing the temperature at which catalyst damage 

occurs as required in section (f)(2.2.1)(A), manufacturers may not define 

catalyst damage at a temperature more severe than what the catalyst 

system could be operated at for 10 consecutive hours and still meet the 

applicable standards.

(2.2.2) Misfire causing emissions to exceed 1.5 times the applicable standards:
70

(A) Manufacturers shall determine the percentage of misfire evaluated in 

1000 revolution increments that would cause emissions from an emission 

durability demonstration engine to exceed 1.5 times any of the applicable 

standards 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.

(B) 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.

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

section (f)(2.2.2)(A) is exceeded regardless of the pattern of misfire 

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

(2.3) Monitoring Conditions:

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

conditions:

(A) Except as provided for in section (f)(2.3.6) below, fFrom no later than the 

end of the second crankshaft revolution after engine start,

(B) While under positive torque conditions during the rise time and settling 

time for engine speed to reach the desired idle engine speed at engine 

start-up (i.e., “flare-up” and “flare-down”), and 

(C) Under all positive torque engine speeds and load conditions except within 

the following range: the engine operating region bound by the positive 

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

following engine operating points: an engine speed of 3000 rpm with the 

engine load at the positive torque line, and the redline engine speed 

(defined in section (c)) with the engine's manifold vacuum at four inches of 

mercury lower than that at the positive torque line.

(2.3.2) If a monitoring system cannot detect all misfire patterns under all required 

engine speed and load conditions as required in section (f)(2.3.1) above, 

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). 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.
71

(2.3.3) A manufacturer may request Executive Officer approval of a monitoring 

system that has reduced misfire detection capability during the portion of 

the first 1000 revolutions after engine start that a cold start emission 

reduction strategy that reduces engine torque (e.g., spark retard 

strategies) is active. The Executive Officer shall approve the request 

upon determining that the manufacturer has demonstrated that the 

probability of detection is greater than or equal to 75 percent during the 

worst case condition (i.e., lowest generated torque) for a vehicle operated 

continuously at idle (park/neutral idle) on a cold start between 50 and 86 

degrees Fahrenheit and that the technology cannot reliably detect a 

higher percentage of the misfire events during the conditions.

(2.3.4) 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.

(A) 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:

(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) portions of intrusive evaporative system or EGR diagnostics that can 

significantly affect engine stability (i.e., while the purge valve is open 

during the vacuum pull-down of a evaporative system leak check but 

not while the purge valve is closed and the evaporative system is 

sealed or while an EGR diagnostic causes the EGR valve to be 

intrusively cycled on and off during positive torque conditions), or

(vii) engine speed, load, or torque transients due to throttle movements 

more rapid than occurs over the FTP cycle for the worst case engine 

within each engine family.

(B) Additionally, the Executive Officer will approve a manufacturer's request 

in accordance with sections (g)(5.3), (g)(5.4), and (g)(5.6) to disable 

misfire monitoring when the fuel level is 15 percent or less of the nominal 

capacity of the fuel tank, when PTO units are active, or while engine 

coolant temperature is below 20 degrees Fahrenheit. The Executive 

Officer will approve a request to continue disablement on engine starts 

when engine coolant temperature is below 20 degrees Fahrenheit at 

engine start until engine coolant temperature exceeds 70 degrees 

Fahrenheit.

(C) In general, the Executive Officer shall not approve disablement for 

conditions involving normal air conditioning compressor cycling from onto-off or off-to-on, automatic transmission gear shifts (except for shifts 
72

occurring during wide open throttle operation), transitions from idle to offidle, normal engine speed or load changes that occur during the engine 

speed rise time and settling time (i.e., “flare-up” and “flare-down”) 

immediately after engine starting without any vehicle operator-induced 

actions (e.g., throttle stabs), or excess acceleration (except for 

acceleration rates that exceed the maximum acceleration rate obtainable 

at wide open throttle while the vehicle is in gear due to abnormal 

conditions such as slipping of a clutch).

(D) The Executive Officer may approve misfire monitoring disablement or use 

of an alternate malfunction criterion for any other condition on a case by 

case basis upon determining that the manufacturer has demonstrated that 

the request is based on an unusual or unforeseen circumstance and that 

it is applying the best available computer and monitoring technology.

(2.3.5) For engines with more than eight cylinders that cannot meet the 

requirements of section (f)(2.3.1), a manufacturer may request Executive 

Officer approval to use alternative misfire monitoring conditions. The 

Executive Officer shall approve the request upon determining that the 

manufacturer has submitted data and/or an engineering evaluation that 

demonstrate that misfire detection throughout the required operating 

region cannot be achieved when employing proven monitoring technology 

(i.e., a technology that provides for compliance with these requirements 

on other engines) and provided misfire is detected to the fullest extent 

permitted by the technology. However, the Executive Officer may not 

grant the request if the misfire detection system is unable to monitor 

during all positive torque operating conditions encountered during an FTP 

cycle.

(2.3.6) For engines that employ engine shutoff strategies that do not require the 

vehicle operator to restart the engine to continue driving (e.g., hybrid bus 

with engine shutoff at idle), the OBD system shall monitor for misfire from 

no later than the end of the second crankshaft revolution after each 

engine restart engine fueling begins for the initial start and after each time 

fueling resumes. 

(2.4) MIL Illumination and Fault Code Storage:

(2.4.1) Misfire causing catalyst damage. Upon detection of the percentage of misfire 

specified in section (f)(2.2.1) above, the following criteria shall apply for MIL 

illumination and fault code storage:

(A) Pending fault codes

(i) A pending fault code shall be stored immediately if, during a single 

driving cycle, the specified percentage of misfire is exceeded three 

times when operating in the positive torque region encountered during 

an FTP cycle or is exceeded on a single occasion when operating at 

any other engine speed and load condition in the positive torque 

region defined in section (f)(2.3.1).

(ii) Immediately after a pending fault code is stored as specified in section 

(f)(2.4.1)(A)(i) above, the MIL shall blink once per second at all times 

while misfire is occurring during the driving cycle.

a. The MIL may be extinguished during those times when misfire is not 

occurring during the driving cycle.
73

b. If, at the time a misfire malfunction occurs, the MIL is already 

illuminated for a malfunction other than misfire, the MIL shall blink 

as previously specified in section (f)(2.4.1)(A)(ii) while misfire is 

occurring. If misfiring ceases, the MIL shall stop blinking but 

remain illuminated as required by the other malfunction.

(B) Confirmed fault codes

(i) If a pending fault code for exceeding the percentage of misfire set forth 

in section (f)(2.2.1) is stored, the OBD system shall immediately store 

a confirmed fault code if the percentage of misfire specified in section 

(f)(2.2.1) is again exceeded one or more times during either: (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.

(ii) If a pending fault code for exceeding the percentage of misfire set forth 

in section (f)(2.2.2) is stored from a previous driving cycle, the OBD 

system shall immediately store a confirmed fault code if the 

percentage of misfire specified in section (f)(2.2.1) is exceeded one or 

more times regardless of the conditions encountered.

(iii) Upon storage of a confirmed fault code, the MIL shall blink as 

specified in subparagraph (f)(2.4.1)(A)(ii) above as long as misfire is 

occurring and the MIL shall remain continuously illuminated if the 

misfiring ceases.

(C) Erasure of pending fault codes

Pending fault codes shall 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 any 

exceedance of the specified percentage of misfire. The pending code 

may also be erased if similar driving conditions are not encountered 

during the next 80 driving cycles subsequent to the initial detection of a 

malfunction.

(D) Exemptions for engines with fuel shutoff and default fuel control. 

Notwithstanding sections (f)(2.4.1)(A) and (B) above, in engines that 

provide for fuel shutoff and default fuel control to prevent over fueling 

during catalyst damage misfire conditions, the MIL is not required to blink. 

Instead, the MIL may illuminate continuously in accordance with the 

requirements for continuous MIL illumination in sections (f)(2.4.1)(B)(iii) 

above upon detection of misfire, provided that the fuel shutoff and default 

control are activated as soon as misfire is detected. Fuel shutoff and 

default fuel control may be deactivated only to permit fueling outside of 

the misfire range. Manufacturers may also periodically, but not more than 

once every 30 seconds, deactivate fuel shutoff and default fuel control to 

determine if the specified catalyst damage percentage of misfire is still 

being exceeded. Normal fueling and fuel control may be resumed if the 

specified catalyst damage percentage of misfire is no longer being 

exceeded.
74

(E) Manufacturers may request Executive Officer approval of strategies that 

continuously illuminate the MIL in lieu of blinking the MIL during extreme 

catalyst damage misfire conditions (i.e., catalyst damage misfire occurring 

at all engine speeds and loads). Executive Officer approval shall be 

granted upon determining that the manufacturer employs the strategy only 

when catalyst damage misfire levels cannot be avoided during reasonable 

driving conditions and the manufacturer has demonstrated that the 

strategy will encourage operation of the vehicle in conditions that will 

minimize catalyst damage (e.g., at low engine speeds and loads).

(2.4.2) Misfire causing emissions to exceed 1.5 times the FTP standards. Upon 

detection of the percentage of misfire specified in section (f)(2.2.2), the 

following criteria shall apply for MIL illumination and fault code storage:

(A) Misfire within the first 1000 revolutions after engine start.

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

exceedance of the specified percentage of misfire during a single 

driving cycle if the exceedance occurs within the first 1000 revolutions 

after engine start (defined in section (c)) during which misfire detection 

is active.

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

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

exceedance of the specified percentage of misfire is again detected in 

the first 1000 revolutions during any subsequent driving cycle, 

regardless of the conditions encountered during the driving cycle.

(iii) The pending fault code shall 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 

the initial detection of the malfunction.

(B) Exceedances after the first 1000 revolutions after engine start.

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

exceedance of the percentage of misfire specified in section (f)(2.2.2) 

during a single driving cycle.

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

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

percentage of misfire specified in section (f)(2.2.2) 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 
75

encountered during the next 80 driving cycles immediately following 

initial detection of the malfunction.

(2.4.3) Storage of freeze frame conditions.

(A) The 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 and erasing a confirmed fault code. 

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

or fuel system malfunction (see section (f)(1)) when a fault code is stored 

as specified in section (f)(2.4) above, the stored freeze frame information 

shall be replaced with freeze frame information regarding the misfire 

malfunction.

(2.4.4) Storage of misfire conditions for similar conditions determination. Upon 

detection of misfire under sections (f)(2.4.1) or (2.4.2), the OBD system 

shall store the following engine conditions: engine speed, load, and 

warm-up status of the first misfire event that resulted in the storage of the 

pending fault code.

(2.4.5) Extinguishing the MIL. The MIL may be extinguished after three 

sequential driving cycles in which similar conditions have been 

encountered without an exceedance of the specified percentage of 

misfire.

(3) Exhaust Gas Recirculation (EGR) System Monitoring

(3.1) Requirement: The OBD system shall monitor the EGR system on engines 

so-equipped for low and high flow rate malfunctions. The individual electronic 

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

system shall be monitored in accordance with the comprehensive component 

requirements in section (g)(3).

(3.2) Malfunction Criteria:

(3.2.1) The OBD system shall detect a malfunction of the EGR system prior to a 

decrease from the manufacturer's specified EGR flow rate that would 

cause an engine's emissions to exceed 1.5 times any of the applicable 

standards. For engines in which no failure or deterioration of the EGR 

system that causes a decrease in flow could result in an engine’s 

emissions exceeding 1.5 times any of the applicable standards, the OBD 

system shall detect a malfunction when the system has no detectable 

amount of EGR flow.

(3.2.2) The OBD system shall detect a malfunction of the EGR system prior to an 

increase from the manufacturer's specified EGR flow rate that would 

cause an engine's emissions to exceed 1.5 times any of the applicable 

standards. For engines in which no failure or deterioration of the EGR 

system that causes an increase in flow could result in an engine’s 

emissions exceeding 1.5 times any of the applicable standards, the OBD 

system shall detect a malfunction when the system has reached its control 

limits such that it cannot reduce EGR flow.

(3.3) Monitoring Conditions:

(3.3.1) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (f)(3.2) (i.e., flow rate) in accordance with sections 

(d)(3.1) and (d)(3.2) (i.e., minimum ratio requirements). For purposes of 
76

tracking and reporting as required in section (d)(3.2.1), all monitors used 

to detect malfunctions identified in section (f)(3.2) shall be tracked 

separately but reported as a single set of values as specified in section 

(d)(5.2.2).

(3.3.2) Manufacturers may request Executive Officer approval to temporarily 

disable the EGR system check under conditions when monitoring may not 

be reliable (e.g., when freezing may affect performance of the system). 

The Executive Officer shall approve the request upon determining that the 

manufacturer has submitted data and/or an engineering evaluation which 

demonstrate that a reliable check cannot be made when these conditions 

exist.

(3.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(4) Cold Start Emission Reduction Strategy Monitoring

(4.1) Requirement: 

(4.1.1) If an engine incorporates a specific engine control strategy to reduce cold 

start emissions, the OBD system shall monitor the commanded 

elements/components for proper function (e.g., increased engine idle 

speed, mass air flow, commanded ignition timing retard), other than 

secondary air, while the control strategy is active to ensure proper 

operation of the control strategy. Secondary air systems shall be 

monitored under the provisions of section (f)(5).

(4.1.2) For an element/component associated with the cold start emission 

reduction control strategy under section (f)(4) that is also required to be 

monitored elsewhere in section (f) or (g) (e.g., fuel injection timing), the 

manufacturer shall use different diagnostics to distinguish faults detected 

under section (f)(4) (i.e., faults associated with the cold start strategy) 

from faults detected under sections other than section (f)(4) (i.e., faults not 

associated with the cold start strategy).

(4.2) Malfunction Criteria:

(4.2.1) For 2010 through 2012 model year engines: 

(A) The OBD system shall detect a malfunction prior to any failure or 

deterioration of the individual elements/components associated with the 

cold start emission reduction control strategy that would cause an 

engine’s emissions to exceed 1.5 times the applicable standards. 

Manufacturers shall:

(i) Establish the malfunction criteria based on data from one or more 

representative engine(s).

(ii) Provide an engineering evaluation for establishing the malfunction 

criteria for the remainder of the manufacturer’s product line. The 

Executive Officer shall waive the evaluation requirement each year if, 

in the judgment of the Executive Officer, technological changes do not 

affect the previously determined malfunction criteria.

(B) For components where no failure or deterioration of the 

element/component used for the cold start emission reduction strategy 

could result in an engine’s emissions exceeding 1.5 times the applicable 

standards, the individual element/component shall be monitored for 
77

proper functional response in accordance with the malfunction criteria in 

section (g)(3.2) while the control strategy is active.

(4.2.2) For 2013 and subsequent model year engines, the OBD system shall, to 

the extent feasible, detect a malfunction if either of the following occurs:

(A) Any single commanded element/component does not properly respond to 

the commanded action while the cold start strategy is active. For 

elements/components involving spark timing (e.g., retarded spark timing), 

the monitor may verify final commanded spark timing in lieu of verifying 

actual delivered spark timing. For purposes of this section, “properly 

respond” is defined as when the element responds:

(i) by a robustly detectable amount; and 

(ii) in the direction of the desired command; and

(iii) above and beyond what the element/component would achieve on 

start-up without the cold start strategy active (e.g., if the cold start 

strategy commands a higher idle engine speed, a fault must be 

detected if there is no detectable amount of engine speed increase 

above what the system would achieve without the cold start strategy 

active);

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

strategy that would cause an engine’s emissions to be equal to or above 

1.5 times the applicable standards. For this requirement, the OBD

system shall either monitor the combined effect of the 

elements/components of the system as a whole (e.g., measuring air flow 

and modeling overall heat into the exhaust) or the individual 

elements/components (e.g., increased engine speed, commanded final 

spark timing) for failures that cause engine emissions to exceed 1.5 times 

the applicable standards.

(4.3) Monitoring Conditions: Manufacturers shall define the monitoring conditions 

for malfunctions identified in section (f)(4.2) in accordance with sections 

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

(4.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2). 

(5) Secondary Air System Monitoring

(5.1) Requirement: 

(5.1.1) The OBD system on engines equipped with any form of secondary air 

delivery system shall monitor the proper functioning of the secondary air 

delivery system including all air switching valve(s). The individual 

electronic components (e.g., actuators, valves, sensors) in the secondary 

air system shall be monitored in accordance with the comprehensive 

component requirements in section (g)(3).

(5.1.2) For purposes of section (f)(5), “air flow” is defined as the air flow delivered 

by the secondary air system to the exhaust system. For engines using 

secondary air systems with multiple air flow paths/distribution points, the 

air flow to each bank (i.e., a group of cylinders that share a common 

exhaust manifold, catalyst, and control sensor) shall be monitored in 

accordance with the malfunction criteria in section (f)(5.2) unless complete 
78

blocking of air delivery to one bank does not cause a measurable increase 

in emissions.

(5.1.3) For purposes of section (f)(5), “normal operation” is defined as the 

condition when the secondary air system is activated during catalyst 

and/or engine warm-up following engine start. “Normal operation” does 

not include the condition when the secondary air system is intrusively 

turned on solely for the purpose of monitoring.

(5.2) Malfunction Criteria:

(5.2.1) Except as provided in section (f)(5.2.3), the OBD system shall detect a 

secondary air system malfunction prior to a decrease from the 

manufacturer's specified air flow during normal operation that would 

cause an engine's emissions to exceed 1.5 times any of the applicable 

standards.

(5.2.2) Except as provided in section (f)(5.2.34), the OBD system shall detect a 

secondary air system malfunction prior to an increase from the 

manufacturer's specified air flow during normal operation that would 

cause an engine's emissions to exceed 1.5 times any of the applicable 

standards.

(5.2.3) For engines in which no deterioration or failure of the secondary air 

system that causes a decrease in air flow would result in an engine’s 

emissions exceeding 1.5 times any of the applicable standards, the OBD 

system shall detect a malfunction when no detectable amount of air flow 

is delivered during normal operation of the secondary air system.

(5.2.4) For 2016 and subsequent model year engines in which no deterioration or 

failure of the secondary air system that causes an increase in air flow 

would result in an engine’s emissions exceeding 1.5 times any of the 

applicable standards, the OBD system shall detect a malfunction when 

the secondary air system has reached its control limits such that it cannot 

reduce air flow during normal operation.

(5.3) Monitoring Conditions:

(5.3.1) Manufacturers shall define the monitoring conditions 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)(3.2.1), all 

monitors used to detect malfunctions identified in section (f)(5.2) during 

normal operation of the secondary air system shall be tracked separately 

but reported as a single set of values as specified in section (d)(5.2.2).

(5.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(6) Catalyst Monitoring

(6.1) Requirement: The OBD system shall monitor the catalyst system for proper 

conversion capability.

(6.2) Malfunction Criteria:

(6.2.1) The OBD system shall detect a catalyst system malfunction when the 

catalyst system’s conversion capability decreases to the point that any of 

the following occurs:

(A) Non-Methane Hydrocarbon (NMHC) emissions exceed 1.75 times the 

applicable standards to which the engine has been certified.
79

(B) The average FTP test NMHC conversion efficiency of the monitored 

portion of the catalyst system falls below 50 percent (i.e., the cumulative 

NMHC emissions measured at the outlet of the monitored catalyst(s) are 

more than 50 percent of the cumulative engine-out emissions measured 

at the inlet of the catalyst(s)). With Executive Officer approval, 

manufacturers may use a conversion efficiency malfunction criteria of less 

than 50 percent if the catalyst system is designed such that the monitored 

portion of the catalyst system must be replaced along with an adjacent 

portion of the catalyst system sufficient to ensure that the total portion 

replaced will meet the 50 percent conversion efficiency criteria. Executive 

Officer approval shall be based on data and/or engineering evaluation 

demonstrating the conversion efficiency of the monitored portion and the 

total portion designed to be replaced, and the likelihood of the catalyst 

system design to ensure replacement of the monitored and adjacent 

portions of the catalyst system.

(C) Oxides of nitrogen (NOx) emissions exceed 1.75 times the applicable 

NOx standard to which the engine has been certified.

(6.2.2) For purposes of determining the catalyst system malfunction criteria in 

section (f)(6.2.1):

(A) The manufacturer shall use a catalyst system deteriorated to the 

malfunction criteria using methods established by the manufacturer to 

represent real world catalyst deterioration under normal and 

malfunctioning operating conditions.

(B) Except as provided below in section (f)(6.2.2)(C), the malfunction criteria 

shall be established by using a catalyst system with all monitored and 

unmonitored (downstream of the sensor utilized for catalyst monitoring) 

catalysts simultaneously deteriorated to the malfunction criteria.

(C) For engines using fuel shutoff to prevent over-fueling during misfire 

conditions (see section (f)(2.4.1)(D)), the malfunction criteria shall be 

established by using a catalyst system with all monitored catalysts 

simultaneously deteriorated to the malfunction criteria while unmonitored 

catalysts shall be deteriorated to the end of the engine's useful life.

(6.3) Monitoring Conditions: Manufacturers shall define the monitoring conditions 

for malfunctions identified in section (f)(6.2) 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)(3.2.1), all monitors used to 

detect malfunctions identified in section (f)(6.2) shall be tracked separately 

but reported as a single set of values as specified in section (d)(5.2.2).

(6.4) MIL Illumination and Fault Code Storage:

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

forth in section (d)(2).

(6.4.2) The monitoring method for the catalyst(s) shall be capable of detecting 

when a catalyst fault code has been cleared (except OBD system 

self-clearing), but the catalyst has not been replaced (e.g., catalyst 

overtemperature histogram approaches are not acceptable).
80

(7) Evaporative System Monitoring

(7.1) Requirement: The OBD system shall verify purge flow from the evaporative 

system and shall monitor the complete evaporative system, excluding the 

tubing and connections between the purge valve and the intake manifold, for 

vapor leaks to the atmosphere. Individual components of the evaporative 

system (e.g. valves, sensors) shall be monitored in accordance with the 

comprehensive components requirements in section (g)(3) (e.g., for circuit 

continuity, out of range values, rationality, proper functional response). 

Vehicles not required to be equipped with subject to evaporative emission 

standards systems shall be exempt from monitoring of the evaporative 

system. For alternate-fueled engines subject to evaporative emission 

standards, manufacturers shall submit a monitoring plan to the Executive 

Officer for approval. The Executive Officer shall approve the request upon 

determining that the manufacturer has submitted data and an engineering 

evaluation that demonstrate that the monitoring plan is as reliable and 

effective as the monitoring plan required for gasoline engines under section 

(f)(7). 

(7.2) Malfunction Criteria:

(7.2.1) For purposes of section (f)(7), an “orifice” is defined as an O’Keefe 

Controls Co. precision metal “Type B” orifice with NPT connections with a 

diameter of the specified dimension (e.g., part number B-31-SS for a 

stainless steel 0.031 inch diameter orifice).

(7.2.2) The OBD system shall detect an evaporative system malfunction when 

any of the following conditions exist:

(A) No purge flow from the evaporative system to the engine can be detected 

by the OBD system; or

(B) The complete evaporative system contains a leak or leaks that 

cumulatively are greater than or equal to a leak caused by a 0.150 inch 

diameter orifice.

(7.2.3) A manufacturer may request the Executive Officer to revise the orifice size 

in section (f)(7.2.2)(B) if the most reliable monitoring method available 

cannot reliably detect a system leak of the magnitudes specified. 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.

(7.2.4) 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 orifice size in 

section (f)(7.2.2)(B) upward to exclude detection of leaks that cannot 

cause evaporative or running loss emissions to exceed 1.5 times the 

applicable evaporative emission standards.

(7.2.5) For vehicles engines that utilize more than one purge flow path (e.g., a 

turbo-charged engine with a low pressure purge line and a high pressure 

purge line), the OBD system shall verify the criteria of (f)(7.2.2)(A) (i.e., 

purge flow to the engine) for both all purge flow paths. If a manufacturer 

demonstrates that blockage, leakage, or disconnection of one of the 

purge flow paths cannot cause a measurable emission increase during 
81

any reasonable in-use driving conditions, monitoring of that flow path is 

not required.

(7.3) Monitoring Conditions:

(7.3.1) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (f)(7.2.2)(A) (i.e., purge flow) in accordance with 

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

(7.3.2) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (f)(7.2.2)(B) (i.e., 0.150 inch leak detection) 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)(3.2.1), all monitors used to detect malfunctions identified in 

section (f)(7.2.2)(B) shall be tracked separately but reported as a single 

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

(7.3.3) Manufacturers may disable or abort an evaporative system monitor when 

the fuel tank level is over 85 percent of nominal tank capacity or during a 

refueling event.

(7.3.4) Manufacturers may request Executive Officer approval to execute the 

evaporative system monitor only on driving cycles determined by the 

manufacturer to be cold starts if the condition is needed to ensure reliable 

monitoring. The Executive Officer shall approve the request upon 

determining that data and/or an engineering evaluation submitted by the 

manufacturer demonstrate that a reliable check can only be made on 

driving cycles when the cold start criteria are satisfied. However, in 

making a decision, the Executive Officer will not approve conditions that 

exclude engine starts from being considered as cold starts solely on the 

basis that ambient temperature exceeds (i.e., indicates a higher 

temperature than) engine coolant temperature at engine start. 

(7.3.5) Manufacturers may temporarily disable the evaporative purge system to 

perform an evaporative system leak check.

(7.4) MIL Illumination and Fault Code Storage:

(7.4.1) Except as provided below for fuel cap leaks, general requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(7.4.2) If the OBD system is capable of discerning that a system leak is being 

caused by a missing or improperly secured fuel cap:

(A) The manufacturer is not required to illuminate the MIL or store a fault 

code if the vehicle is equipped with an alternative indicator for notifying 

the vehicle operator of the malfunction. The alternative indicator shall be 

of sufficient illumination and location to be readily visible under all lighting 

conditions. 

(B) If the vehicle is not equipped with an alternative indicator and the MIL 

illuminates, the MIL may be extinguished and the corresponding fault 

codes erased once the OBD system has verified that the fuel cap has 

been securely fastened and the MIL has not been illuminated for any 

other type of malfunction.

(C) The Executive Officer may approve other strategies that provide 

equivalent assurance that a vehicle operator will be promptly notified of a 

missing or improperly secured fuel cap and that corrective action will be 

undertaken.
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(8) Exhaust Gas Sensor Monitoring

(8.1) Requirement:

(8.1.1) The OBD system shall monitor the output signal, response rate, and any 

other parameter which can affect emissions of all primary (fuel control) 

oxygen sensors (conventional switching sensors and wide range or 

universal sensors) for malfunction. 

(8.1.2) The OBD system shall also monitor all secondary oxygen sensors (those 

used for fuel trim control or as a monitoring device) for proper output 

signal, activity, and response rate.

(8.1.3) For engines equipped with heated oxygen sensors, the OBD system shall 

monitor the heater for proper performance.

(8.1.4) For other types of sensors (e.g., hydrocarbon sensors, NOx sensors), the 

manufacturer shall submit a monitoring plan to the Executive Officer for 

approval. The Executive Officer shall approve the request upon 

determining that the manufacturer has submitted data and an engineering 

evaluation that demonstrate that the monitoring plan is as reliable and 

effective as the monitoring plan required for conventional sensors under 

section (f)(8).

(8.2) Malfunction Criteria:

(8.2.1) Primary Sensors:

(A) The OBD system shall detect a malfunction prior to any failure or 

deterioration of the oxygen sensor output voltage, resistance, impedance, 

current, response rate, amplitude, offset, or other characteristic(s) 

(including drift or bias corrected for by secondary sensors) that would 

cause an engine's emissions to exceed 1.5 times any of the applicable 

standards. For response rate (see section (c)), the OBD system shall 

detect asymmetric malfunctions (i.e., malfunctions that primarily affect 

only the lean-to-rich response rate or only the rich-to-lean response rate) 

and symmetric malfunctions (i.e., malfunctions that affect both the lean-torich and rich-to-lean response rates). As defined in section (c), response 

rate includes delays in the sensor to initially react to a change in exhaust 

gas composition as well as delays during the transition from a rich-to-lean 

(or lean-to-rich) sensor output. For 2013 and subsequent model year 

engines, the manufacturer shall submit data and/or engineering analysis 

to demonstrate that the calibration method used ensures proper detection 

of all symmetric and asymmetric response rate malfunctions as part of the 

certification application.

(B) The OBD system shall detect malfunctions of the oxygen sensor caused 

by either a lack of circuit continuity or out-of-range values.

(C) The OBD system shall detect a malfunction of the oxygen sensor when a 

sensor failure or deterioration causes the fuel system to stop using that 

sensor as a feedback input (e.g., causes default or open-loop operation)

or causes the fuel system to fail to enter closed-loop operation within a 

manufacturer-specified time interval.

(D) The OBD system shall detect a malfunction of the oxygen sensor when 

the sensor output voltage, resistance, impedance, current, amplitude, 
83

activity, or other characteristics are no longer sufficient for use as an OBD 

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

(8.2.2) Secondary Sensors:

(A) The OBD system shall detect a malfunction prior to any failure or 

deterioration of the oxygen sensor voltage, resistance, impedance, 

current, response rate, amplitude, offset, or other characteristic(s) that 

would cause an engine's emissions to exceed 1.5 times any of the 

applicable standards.

(B) The OBD system shall detect malfunctions of the oxygen sensor caused 

by a lack of circuit continuity.

(C) Sufficient sensor performance for other monitors.

(i) The OBD system shall detect a malfunction of the oxygen sensor when 

the sensor output voltage, resistance, impedance, current, amplitude, 

activity, offset, or other characteristics are no longer sufficient for use 

as an OBD system monitoring device (e.g., for catalyst monitoring). 

For this requirement, “sufficient” is defined as the capability of the 

worst performing acceptable sensor to detect the best performing 

unacceptable other monitored system or component (e.g., catalyst).

(ii) For systems where it is not technically feasible to satisfy the criteria of 

section (f)(8.2.2)(C)(i) completely, the OBD system shall, at a 

minimum, detect a slow rich-to-lean response malfunction during a fuel 

shut-off event (e.g., deceleration fuel cut event) on all 2013 and 

subsequent model year engines. The rich-to-lean response check 

shall monitor both the sensor response time from a rich condition (e.g., 

0.7 Volts) prior to the start of fuel shut-off to a lean condition (e.g., 0.1 

Volts) expected during fuel shut-off conditions and the sensor 

transition time in the intermediate sensor range (e.g., from 0.55 Volts 

to 0.3 Volts).

(iii) Additionally, for systems where it is not technically feasible to satisfy 

the criteria in section (f)(8.2.2)(C)(i), prior to certification of 2013 model 

year engines, the manufacturer must submit a comprehensive plan to 

the Executive Officer demonstrating the manufacturer’s efforts to 

minimize any gap remaining between the worst performing acceptable 

sensor and a sufficient sensor. The plan should include quantification 

of the gap and supporting documentation for efforts to close the gap 

including sensor monitoring improvements, other system component 

monitor improvements (e.g., changes to make the catalyst monitor less 

sensitive to oxygen sensor response), and sensor specification 

changes, if any. The Executive Officer shall approve the plan upon 

determining the submitted information supports the necessity of the 

gap and the plan demonstrates that the manufacturer is taking 

reasonable efforts to minimize or eliminate the gap in a timely manner.

(D) The OBD system shall detect malfunctions of the oxygen sensor caused 

by out-of-range values.

(E) The OBD system shall detect a malfunction of the oxygen sensor when a 

sensor failure or deterioration causes the fuel system (e.g., fuel control) to 

stop using that sensor as a feedback input (e.g., causes default or openloop operation).
84

(8.2.3) Sensor Heaters:

(A) The OBD system shall detect a malfunction of the heater performance 

when the current or voltage drop in the heater circuit is no longer within 

the manufacturer's specified limits for normal operation (i.e., within the 

criteria required to be met by the component vendor for heater circuit 

performance at high mileage). Subject to Executive Officer approval, 

other malfunction criteria for heater performance malfunctions may be 

used upon the Executive Officer determining that the manufacturer has 

submitted data and/or an engineering evaluation that demonstrate the 

monitoring reliability and timeliness to be equivalent to the stated criteria 

in section (f)(8.2.3)(A).

(B) The OBD system shall detect malfunctions of the heater circuit including 

open or short circuits that conflict with the commanded state of the heater 

(e.g., shorted to 12 Volts when commanded to 0 Volts (ground)).

(8.3) Monitoring Conditions:

(8.3.1) Primary Sensors

(A) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (f)(8.2.1)(A) and (D) (e.g., proper response rate) 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)(3.2.1), all monitors used to detect malfunctions identified in 

sections (f)(8.2.1)(A) and (D) shall be tracked separately but reported as a 

single set of values as specified in section (d)(5.2.2).

(B) Except as provided in section (f)(8.3.1)(C), monitoring for malfunctions 

identified in sections (f)(8.2.1)(B) and (C) (i.e., circuit continuity, out-ofrange, and open-loop malfunctions) shall be conducted continuously.

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

continuous exhaust gas sensor monitoring when an exhaust gas sensor 

malfunction cannot be distinguished from other effects (e.g., disable outof-range low monitoring during fuel cut conditions). The Executive Officer 

shall approve the disablement upon determining that the manufacturer 

has submitted test data and/or documentation that demonstrate a properly 

functioning sensor cannot be distinguished from a malfunctioning sensor 

and that the disablement interval is limited only to that necessary for 

avoiding false detection.

(8.3.2) Secondary Sensors

(A) Manufacturers shall define monitoring conditions for malfunctions 

identified in sections (f)(8.2.2)(A) and (C) (e.g., proper sensor activity) in 

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

requirements). For all 2013 and subsequent model year engines meeting 

the monitoring requirements of section (f)(8.2.2)(C)(i) or (ii), for purposes 

of tracking and reporting as required in section (d)(3.2.1), all monitors 

used to detect malfunctions identified in sections (f)(8.2.2)(A) and (C) shall

be tracked separately but reported as a single set of values as specified in 

section (d)(5.2.2).

(B) Except as provided in section (f)(8.3.2)(C), monitoring for malfunctions 

identified in sections (f)(8.2.2)(B), (D), and (E) (i.e., open circuit, out-of-
85

range malfunctions, open-loop malfunctions) shall be conducted 

continuously.

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

continuous exhaust gas sensor monitoring when an oxygen sensor 

malfunction cannot be distinguished from other effects (e.g., disable outof-range low monitoring during fuel cut conditions). The Executive Officer 

shall approve the disablement upon determining that the manufacturer 

has submitted test data and/or documentation that demonstrate a properly 

functioning sensor cannot be distinguished from a malfunctioning sensor 

and that the disablement interval is limited only to that necessary for 

avoiding false detection.

(8.3.3) Sensor Heaters

(A) Manufacturers shall define monitoring conditions for malfunctions 

identified in section (f)(8.2.3)(A) (i.e., sensor heater performance) in 

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

requirements).

(B) Monitoring for malfunctions identified in section (f)(8.2.3)(B) (i.e., circuit 

malfunctions) shall be conducted continuously.

(8.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2). To the 

extent feasible, the OBD system shall separately detect lack of circuit 

continuity and out-of-range faults as required under sections (f)(8.2.1)(B), 

(f)(8.2.2)(B), and (f)(8.2.2)(D) and store different fault codes for each distinct 

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

Manufacturers are not required to store separate fault codes for lack of circuit 

continuity faults that cannot be distinguished from other out-of-range circuit 

faults.

(9) Variable Valve Timing and/or Control (VVT) System Monitoring

(9.1) Requirement: The OBD system shall monitor the VVT system on engines 

so-equipped for target error and slow response malfunctions. The individual 

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

VVT system shall be monitored in accordance with the comprehensive 

components requirements in section (g)(3).

(9.2) Malfunction Criteria:

(9.2.1) Target Error: The OBD 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 and/or lift 

tolerance that would cause an engine’s emissions to exceed 1.5 times any 

of the applicable standards.

(9.2.2) Slow Response: The OBD 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 manufacturer-specified 

time that would cause an engine’s emissions to exceed 1.5 times any of 

the applicable standards for gasoline engines.

(9.2.3) For engines in which no failure or deterioration of the VVT system could 

result in an engine’s emissions exceeding 1.5 times any of the applicable 

standards, the OBD system shall detect a malfunction of the VVT system 
86

when proper functional response of the system to computer commands 

does not occur.

(9.3) Monitoring Conditions: Manufacturers shall define the monitoring conditions 

for VVT system malfunctions identified in section (f)(9.2) 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). For purposes of tracking and reporting as required in 

section (d)(3.2.1), all monitors used to detect malfunctions identified in 

section (f)(9.2) shall be tracked separately but reported as a single set of 

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

(9.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(g) Monitoring Requirements For All Engines.

(1) Engine Cooling System Monitoring

(1.1) Requirement:

(1.1.1) The OBD system shall monitor the thermostat on engines so-equipped for

proper operation.

(1.1.2) The OBD system shall monitor the engine coolant temperature (ECT) 

sensor for circuit continuity, out-of-range values, and rationality faults.

(1.1.3) For engines that use a system other than the cooling system and ECT 

sensor (e.g., oil temperature, cylinder head temperature) for an indication 

of engine operating temperature for emission control purposes (e.g., to 

modify spark or fuel injection timing or quantity), the manufacturer shall 

submit a monitoring plan to the Executive Officer for approval. The 

Executive Officer shall approve the request upon determining that the 

manufacturer has submitted data and an engineering evaluation that 

demonstrate that the monitoring plan is as reliable and effective as the 

monitoring required for the engine cooling system under section (g)(1).

(1.2) Malfunction Criteria:

(1.2.1) Thermostat

(A) The OBD system shall detect a thermostat malfunction if, within an 

Executive Officer-approved time interval after engine start, any of the 

following conditions occur: 

(i) The coolant temperature does not reach the highest temperature 

required by the OBD system to enable other diagnostics;

(ii) The coolant temperature does not reach a warmed-up temperature 

within 20 degrees Fahrenheit of the manufacturer’s nominal thermostat

regulating temperature. Subject to Executive Officer approval, a 

manufacturer may utilize lower temperatures for this criterion upon the 

Executive Officer determining that the manufacturer has demonstrated 

that the fuel, spark timing, and/or other coolant temperature-based 

modifications to the engine control strategies would not cause an 

emission increase of 50 or more percent of any of the applicable 

standards (e.g., 50 degree Fahrenheit emission test).

(B) For 2016 and subsequent model year engines, the OBD system shall 

detect a thermostat fault if, after the coolant temperature has reached the 
87

temperatures indicated in sections (g)(1.2.1)(A)(i) and (ii), the coolant 

temperature drops below the temperature indicated in section 

(g)(1.2.1)(A)(i).

(C) Executive Officer approval of the time interval after engine start under 

section (g)(1.2.1)(A) above shall be granted upon determining that the 

data and/or engineering evaluation submitted by the manufacturer 

supports the specified times.

(D) For monitoring of malfunctions under section (g)(1.2.1)(A), with Executive 

Officer approval, a manufacturer may use alternate malfunction criteria 

and/or monitoring conditions (see section (g)(1.3)) that are a function of 

temperature at engine start on engines that do not reach the temperatures 

specified in the malfunction criteria when the thermostat is functioning 

properly. Executive Officer approval shall be granted upon determining 

that the manufacturer has submitted data that demonstrate that a properly 

operating system does not reach the specified temperatures, that the 

monitor is capable of meeting the specified malfunction criteria at engine 

start temperatures greater than 50 degrees Fahrenheit, and that the 

possibility for cooling system malfunctions to go undetected and disable 

other OBD monitors is minimized to the extent technically feasible.

(E) A manufacturer may request Executive Officer approval to be exempted 

from the requirements of thermostat monitoring. Executive Officer 

approval shall be granted upon determining that the manufacturer has 

demonstrated that a malfunctioning thermostat cannot cause a 

measurable increase in emissions during any reasonable driving condition 

nor cause any disablement of other monitors.

(1.2.2) ECT Sensor

(A) Circuit Continuity. The OBD system shall detect a malfunction when a 

lack of circuit continuity or out-of-range values occur.

(B) Time to Reach Closed-Loop/Feedback Enable Temperature.

(i) The OBD system shall detect a malfunction if the ECT sensor does not 

achieve the highest stabilized minimum temperature which is needed 

for closed-loop/feedback control of all emission control systems (e.g., 

fuel system, EGR system) within an Executive Officer-approved time 

interval after engine start.

(ii) The time interval shall be a function of starting ECT and/or a function 

of intake air temperature. Executive Officer approval of the time 

interval shall be granted upon determining that the data and/or 

engineering evaluation submitted by the manufacturer supports the 

specified times.

(iii) Manufacturers are exempted from the requirements of section 

(g)(1.2.2)(B) if the manufacturer does not utilize ECT to enable closedloop/feedback control of any emission control system.

(C) Stuck in Range Below the Highest Minimum Enable Temperature. To the 

extent feasible when using all available information, the OBD system shall 

detect a malfunction if the ECT sensor inappropriately indicates a 

temperature below the highest minimum enable temperature required by 

the OBD system to enable other diagnostics (e.g., an OBD system that 

requires ECT to be greater than 140 degrees Fahrenheit to enable a 
88

diagnostic must detect malfunctions that cause the ECT sensor to 

inappropriately indicate a temperature below 140 degrees Fahrenheit). 

Manufacturers are exempted from this requirement for temperature 

regions in which the monitors required under sections (g)(1.2.1) or 

(g)(1.2.2)(B) will detect ECT sensor malfunctions as defined in section 

(g)(1.2.2)(C).

(D) Stuck in Range Above the Lowest Maximum Enable Temperature.

(i) To the extent feasible when using all available information, the OBD 

system shall detect a malfunction if the ECT sensor inappropriately 

indicates a temperature above the lowest maximum enable 

temperature required by the OBD system to enable other diagnostics 

(e.g., an OBD system that requires ECT to be less than 90 degrees 

Fahrenheit at engine start to enable a diagnostic must detect 

malfunctions that cause the ECT sensor to inappropriately indicate a 

temperature above 90 degrees Fahrenheit).

(ii) Manufacturers are exempted from this requirement for temperature 

regions in which the monitors required under sections (g)(1.2.1), 

(g)(1.2.2)(B), or (g)(1.2.2)(C) (i.e., ECT sensor or thermostat 

malfunctions) will detect ECT sensor malfunctions as defined in 

section (g)(1.2.2)(D) or in which the MIL will be illuminated under the 

requirements of sections (d)(2.2.1)(E) or (d)(2.2.2)(E) for default mode 

operation (e.g., overtemperature protection strategies).

(iii) Manufacturers are exempted from the requirements of section 

(g)(1.2.2)(D) for temperature regions where the temperature gauge 

indicates a temperature in the red zone (engine overheating zone) for 

vehicles that have a temperature gauge (not a warning light) on the 

instrument panel and utilize the same ECT sensor for input to the OBD 

system and the temperature gauge.

(1.3) Monitoring Conditions:

(1.3.1) Thermostat

(A) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (g)(1.2.1)(A) in accordance with section (d)(3.1)

except as provided for in section (g)(1.3.1)(E). Additionally, except as 

provided for in sections (g)(1.3.1)(B) and through (CE), monitoring for 

malfunctions identified in section (g)(1.2.1)(A) shall be conducted once 

per driving cycle on every driving cycle in which the ECT sensor indicates, 

at engine start, a temperature lower than the temperature established as 

the malfunction criteria in section (g)(1.2.1)(A).

(B) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (g)(1.2.1)(B) in accordance with section (d)(3.1) 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.

(C) Manufacturers may disable thermostat monitoring at ambient engine 

temperatures below 20 degrees Fahrenheit.

(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 
89

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 above

125 degrees Fahrenheit).

(E) Notwithstanding section (g)(1.3.1)(D), manufacturers may request 

Executive Officer approval to enable thermostat monitoring during a 

portion of the driving cycles where the ECT at engine start is warmer than 

35 degrees Fahrenheit below 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 

manufacturer may request approval to have the monitor enabled for a 

portion of the ECT at engine start region between 125 and 160 degrees 

Fahrenheit). The Executive Officer shall approve the request upon 

determining that the manufacturer has submitted test data and/or 

engineering evaluation that demonstrate that the monitor is able to 

robustly detect thermostat malfunctions (e.g., cannot result in false passes

or false indications of malfunctions) on driving cycles where it is enabled. 

(E)(F) With respect to defining enable conditions that are encountered during 

the FTP cycle as required in (d)(3.1.1) for malfunctions identified in 

section (g)(1.2.1)(A), the FTP cycle shall refer to on-road driving following 

the FTP cycle in lieu of testing on an engine dynamometer.

(1.3.2) ECT Sensor

(A) Except as provided below in section (g)(1.3.2)(E), monitoring for 

malfunctions identified in section (g)(1.2.2)(A) (i.e., circuit continuity and 

out-of-range) shall be conducted continuously.

(B) Manufacturers shall define the monitoring conditions for malfunctions 

identified in section (g)(1.2.2)(B) in accordance with section (d)(3.1). 

Additionally, except as provided for in section (g)(1.3.2)(D), monitoring for 

malfunctions identified in section (g)(1.2.2)(B) shall be conducted once 

per driving cycle on every driving cycle in which the ECT sensor indicates 

a temperature lower than the closed-loop enable temperature at engine 

start (i.e., all engine start temperatures greater than the ECT sensor outof-range low temperature and less than the closed-loop enable 

temperature). 

(C) Manufacturers shall define the monitoring conditions for malfunctions 

identified in sections (g)(1.2.2)(C) and (D) in accordance with sections 

(d)(3.1) and (d)(3.2) (i.e., minimum ratio requirements). 
90

(D) Manufacturers may suspend or delay the time to reach closed-loop 

enable temperature diagnostic if the vehicle is subjected to conditions 

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

than 50 to 75 percent of the warm-up time).

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

continuous ECT sensor monitoring when an ECT sensor malfunction 

cannot be distinguished from other effects. The Executive Officer shall 

approve the disablement upon determining that the manufacturer has 

submitted test data and/or engineering evaluation that demonstrate a 

properly functioning sensor cannot be distinguished from a malfunctioning 

sensor and that the disablement interval is limited only to that necessary 

for avoiding false detection.

(1.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2).

(2) Crankcase Ventilation (CV) System Monitoring

(2.1) Requirement: The OBD system shall monitor the CV system on engines 

so-equipped for system integrity. Engines not subject to crankcase emission 

control requirements shall be exempt from monitoring of the CV system.

(2.2) Malfunction Criteria:

(2.2.1) For the purposes of section (g)(2), “CV system” is defined as any form of 

crankcase ventilation system, regardless of whether it utilizes positive 

pressure or whether it vents to the atmosphere, the intake, or the exhaust. 

“CV valve” is defined as any form of valve orifice, and/or filter/separator

used to restrict, control, or alter the composition (e.g., remove oil vapor or 

particulate matter) of the crankcase vapor flow. Further, any additional 

external CV system tubing or hoses used to equalize crankcase pressure 

or to provide a ventilation path between various areas of the engine (e.g., 

crankcase and valve cover) are considered part of the CV system 

“between the crankcase and the CV valve” and subject to the malfunction 

criteria in section (g)(2.2.2) below.

(2.2.2) Except as provided below, the OBD system shall detect a malfunction of 

the CV system when a disconnection of the system occurs between either 

the crankcase and the CV valve, or between the CV valve and the intake 

ducting.

(2.2.3) If disconnection in the system results in a rapid loss of oil or other overt 

indication of a CV system malfunction such that the vehicle operator is 

certain to respond and have the vehicle repaired, the Executive Officer 

shall exempt the manufacturer from detection of that disconnection.

(2.2.4) The Executive Officer shall exempt a manufacturer from detecting a 

disconnection between the crankcase and the CV valve upon determining 

that the disconnection cannot be made without first disconnecting a 

monitored portion of the system (e.g., the CV system is designed such 

that the CV valve is fastened directly to the crankcase in a manner which 

makes it significantly more difficult to remove the valve from the 

crankcase rather than disconnect the line between the valve and the 

intake manifold/ducting (taking aging effects into consideration)) and the 

line between the valve and the intake ducting is monitored for 
91

disconnection. The manufacturer shall file a request and submit data 

and/or engineering evaluation in support of the exemption.

(2.2.5) Subject to Executive Officer approval, system designs that utilize tubing 

between the valve and the crankcase shall be exempted from the 

monitoring requirement for detection of disconnection between the CV 

valve and the crankcase. The manufacturer shall file a request and 

submit data and/or engineering evaluation in support of the request. The 

Executive Officer shall approve the request upon determining that the 

connections between the valve and the crankcase are: (1) resistant to 

deterioration or accidental disconnection, (2) significantly more difficult to 

disconnect than the line between the valve and the intake 

manifold/ducting, and (3) not subject to disconnection per manufacturer’s 

maintenance, service, and/or repair procedures for non-CV system repair 

work. 

(2.2.6) The Executive Officer shall exempt a manufacturer from detecting a 

disconnection between the CV valve and the intake manifold upon 

determining that the disconnection (1) causes the vehicle to stall 

immediately during idle operation; or (2) is unlikely to occur due to a CV 

system design that is integral to the induction system (e.g., machined 

passages rather than tubing or hoses). The manufacturer shall file a 

request and submit data and/or engineering evaluation in support of the 

exemption.

(2.2.7) For engines certified on an engine dynamometer having an open CV 

system (i.e., a system that releases crankcase emissions to the 

atmosphere without routing them to the intake ducting or to the exhaust 

upstream of the aftertreatment), the manufacturer shall submit a plan for 

Executive Officer approval of the monitoring strategy, malfunction criteria, 

and monitoring conditions prior to OBD certification. Executive Officer 

approval shall be based on the effectiveness of the monitoring strategy to 

(i) monitor the performance of the CV system to the extent feasible with 

respect to the malfunction criteria in section (g)(2.2.1) through (g)(2.2.4) 

and the monitoring conditions required by the diagnostic, and (ii) monitor 

the ability of the CV system to control crankcase vapor emitted to the 

atmosphere relative to the manufacturer’s design and performance 

specifications for a properly functioning system (e.g., if the system is 

equipped with a filter and/or separator to reduce crankcase emissions to 

the atmosphere, the OBD system shall monitor the integrity of the filter

and/or function of the separator).

(2.3) Monitoring Conditions: Manufacturers shall define the monitoring conditions 

for malfunctions identified in section (g)(2.2) in accordance with sections 

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

(2.4) MIL Illumination and Fault Code Storage: General requirements for MIL 

illumination and fault code storage are set forth in section (d)(2). The stored 

fault code need not specifically identify the CV system (e.g., a fault code for 

idle speed control or fuel system monitoring can be stored) if the 

manufacturer demonstrates that additional monitoring hardware would be 

necessary to make this identification, and provided the manufacturer’s 
92

diagnostic and repair procedures for the detected malfunction include 

directions to check the integrity of the CV system.

(3) Comprehensive Component Monitoring

(3.1) Requirement:

(3.1.1) Except as provided in sections (g)(3.1.4), (g)(3.1.5), (g)(3.1.6), and (g)(4), 

the OBD system shall monitor for malfunction any electronic engine

powertrain component/system not otherwise described in sections (e)(1) 

through (g)(2) that either provides input to (directly or indirectly) or 

receives commands from the on-board computer(s), and: (1) can affect 

emissions during any reasonable in-use driving condition, or (2) is used as 

part of the diagnostic strategy for any other monitored system or 

component.

(A) Input Components: Input components required to be monitored may 

include the crank angle sensor, knock sensor, throttle position sensor, 

cam position sensor, intake air temperature sensor, boost pressure 

sensor, manifold pressure sensor, mass air flow sensor, exhaust 

temperature sensor, exhaust pressure sensor, fuel pressure sensor, fuel 

composition sensor (e.g. flexible fuel vehicles), and electronic 

components used to comply with any applicable engine idling 

requirements of title 13, CCR section 1956.8.

(B) Output Components/Systems: Output components/systems required to be 

monitored may include the idle speed control system, fuel injectors, glow 

plug system, variable length intake manifold runner systems, 

supercharger or turbocharger electronic components, heated fuel 

preparation systems, and the wait-to-start lamp on diesel applications.

(3.1.2) For purposes of criteria (1) in section (g)(3.1.1) above, the manufacturer 

shall determine whether an engine input or output component/system can 

affect emissions. If the Executive Officer reasonably believes that a 

manufacturer has incorrectly determined that a component/system cannot 

affect emissions, the Executive Officer shall require the manufacturer to 

provide emission data showing that the component/system, when 

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

emission effect. The Executive Officer may request emission data for any 

reasonable driving condition.

(3.1.3) Manufacturers shall monitor for malfunction electronic powertrain input or 

output components/systems associated with an electronic transfer case, 

electronic power steering system, transmission (except as provided below 

in section (g)(3.1.6)), or other components that are driven by the engine 

and not related to the control of fueling, air handling, or emissions only if 

the component or system is used as part of the diagnostic strategy for any 

other monitored system or component.

(3.1.4) Except as specified for hybrids vehicles in section (g)(3.1.5), 

manufacturers shall monitor for malfunction electronic powertrain input or 

output components/systems associated with components that only affect 

emissions by causing additional electrical load to the engine and are not 

related to the control of fueling, air handling, or emissions only if the 
93

component or system is used as part of the diagnostic strategy for any 

other monitored system or component.

(3.1.5) Except as provided in section (d)(7.6), Ffor hybrids vehicles, 

manufacturers shall submit a plan to the Executive Officer for approval of 

the hybrid components determined by the manufacturer to be subject to 

monitoring in section (g)(3.1.1). In general, the Executive Officer shall 

approve the plan if it includes monitoring of all components/systems used 

as part of the diagnostic strategy for any other monitored system or 

component, monitoring of all energy input devices to the electrical 

propulsion system, monitoring of battery and charging system 

performance, monitoring of electric motor performance, and monitoring of 

regenerative braking performance.

(3.1.6) For OBD systems that receive vehicle speed information from a 

transmission control unit and use vehicle speed as part of the diagnostic 

strategy for any other OBD monitored system or component:

(A) The OBD system shall monitor the vehicle speed information to the extent 

feasible in accordance with the requirements of section (g)(3);

(B) The OBD system shall detect a fault and illuminate the MIL when the 

OBD system is unable to properly receive the vehicle speed information; 

and

(C) If the transmission control unit monitors the vehicle speed information and 

indicates an error of the information to the OBD system (e.g., valid vehicle 

speed data is no longer available), the OBD system shall handle the error 

indication as a default mode of operation subject to the MIL illumination 

requirements under section (d)(2.2).

(3.2) Malfunction Criteria:

(3.2.1) Input Components:

(A) The OBD system shall detect malfunctions of input components caused 

by a lack of circuit continuity, out-of-range values, and, where feasible, 

rationality faults. To the extent feasible, the rationality fault diagnostics 

shall verify that a sensor output is neither inappropriately high nor 

inappropriately low (i.e., shall be “two-sided” diagnostics). 

(B) To the extent feasible, the OBD system shall separately detect and store 

different fault codes that distinguish rationality faults from lack of circuit 

continuity and out-of-range faults. For input component lack of circuit 

continuity and out-of-range faults, the OBD system shall, to the extent 

feasible, separately detect and store different fault codes for each distinct 

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

OBD system is not required to store separate fault codes for lack of circuit 

continuity faults that cannot be distinguished from other out-of-range 

circuit faults.

(C) For input components that are used to activate alternate strategies that 

can affect emissions (e.g., AECDs, engine shutdown systems or 

strategies to meet NOx idling standards required by title 13, CCR section 

1956.8), the OBD system shall detect rationality malfunctions that cause 

the system to erroneously activate or deactivate the alternate strategy. To 

the extent feasible when using all available information, the rationality fault 

diagnostics shall detect a malfunction if the input component 
94

inappropriately indicates a value that activates or deactivates the alternate 

strategy. For example, if an alternate strategy requires the intake air 

temperature to be greater than 120 degrees Fahrenheit to activate, the 

OBD system shall detect malfunctions that cause the intake air 

temperature sensor to inappropriately indicate a temperature above 120 

degrees Fahrenheit.

(D) For input components that are directly or indirectly used for any emission 

control strategies that are not covered under sections (e), (f), and (g)(1) 

(e.g., exhaust temperature sensors used for a control strategy that 

regulates SCR catalyst inlet temperature within a target window), the OBD 

system shall detect rationality malfunctions that prevent the component 

from correctly sensing any condition necessary for the strategy to operate 

in its intended manner. These malfunctions include faults that 

inappropriately prevent or delay the activation of the emission control 

strategy, cause the system to erroneously exit the emission control 

strategy, or where the control strategy has used up all of the adjustments 

or authority allowed by the manufacturer and is still unable to achieve the 

desired condition. The Executive Officer may waive detection of specific 

malfunctions upon determining that the manufacturer has submitted data 

and/or an engineering evaluation that demonstrate that reliable detection 

of the malfunction is technically infeasible or would require additional 

hardware.

(E) For engines that require precise alignment between the camshaft and the 

crankshaft, the OBD system shall monitor the crankshaft position 

sensor(s) and camshaft position sensor(s) to verify proper alignment 

between the camshaft and crankshaft in addition to monitoring the 

sensors for circuit continuity and rationality malfunctions. Proper 

alignment monitoring between a camshaft and a crankshaft shall only be 

required in cases where both are equipped with position sensors. For 

engines equipped with VVT systems and a timing belt or chain, the OBD 

system shall detect a malfunction if the alignment between the camshaft 

and crankshaft is off by one or more cam/crank sprocket cogs (e.g., the 

timing belt/chain has slipped by one or more teeth/cogs). If a 

manufacturer demonstrates that a single tooth/cog misalignment cannot 

cause a measurable increase in emissions during any reasonable driving 

condition, the OBD system shall detect a malfunction when the minimum 

number of teeth/cogs misalignment needed to cause a measurable 

emission increase has occurred.

(3.2.2) Output Components/Systems:

(A) The OBD system shall detect a malfunction of an output 

component/system when proper functional response of the component 

and system to computer commands does not occur. If a functional check 

is not feasible, the OBD system shall detect malfunctions of output 

components/systems caused by a lack of circuit continuity or circuit fault 

(e.g., short to ground or high voltage). For output component lack of 

circuit continuity faults and circuit faults, the OBD system is not required to 

store different fault codes for each distinct malfunction (e.g., open circuit, 

shorted low). Manufacturers are not required to activate an output 
95

component/system when it would not normally be active for the purposes 

of performing functional monitoring of output components/systems as 

required in section (g)(3).

(B) The idle control system shall be monitored for proper functional response 

to computer commands.

(i) For gasoline engines using monitoring strategies based on deviation 

from target idle speed, a malfunction shall be detected when either of 

the following conditions occur:

a. The idle speed control system cannot achieve the target idle speed 

within 200 revolutions per minute (rpm) above the target speed or 

100 rpm below the target speed. The Executive Officer shall allow 

larger engine speed tolerances upon determining that a 

manufacturer has submitted data and/or an engineering evaluation 

which demonstrate that the tolerances can be exceeded without a 

malfunction being present.

b. The idle speed control system cannot achieve the target idle speed 

within the smallest engine speed tolerance range required by the 

OBD system to enable any other monitors.

(ii) For diesel engines, a malfunction shall be detected when any of the 

following conditions occur:

a. The idle control system cannot achieve or maintain the idle speed 

within +/-50 percent of the manufacturer-specified target or desired 

engine speed. 

b. The idle control system cannot achieve the target or desired idle 

speed within the smallest engine speed tolerance range required 

by the OBD system to enable any other monitors.

c. For 2013 and subsequent model year engines, the idle control 

system cannot achieve the fueling quantity within the smallest 

fueling quantity tolerance range required by the OBD system to 

enable any other monitors.

d. For 2013 and subsequent model year engines, the idle control 

system cannot achieve the target idle speed with a fuel injection 

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

achieve the target idle speed for a properly functioning engine and 

the given known operating conditions.

(C) Glow plugs/intake air heater systems shall be monitored for proper 

functional response to computer commands and for circuit continuity 

faults. The glow plug/intake air heater circuit(s) shall be monitored for 

proper current and voltage drop. The Executive Officer shall approve 

other monitoring strategies based on manufacturer’s data and/or 

engineering analysis demonstrating equally reliable and timely detection 

of malfunctions. Except as provided below, the OBD system shall detect 

a malfunction when a single glow plug no longer operates within the 

manufacturer’s specified limits for normal operation. If a manufacturer 

demonstrates that a single glow plug failure cannot cause a measurable 

increase in emissions during any reasonable driving condition, the OBD 

system shall detect a malfunction for the minimum number of glow plugs 

needed to cause an emission increase. Further, to the extent feasible on 
96

existing engine designs (without adding additional hardware for this 

purpose) and on all 2013 and subsequent model year engines, the stored 

fault code shall identify the specific malfunctioning glow plug(s).

(D) The wait-to-start lamp circuit shall be monitored for malfunctions that 

cause the lamp to fail to illuminate when commanded on (e.g., burned out 

bulb).

(E) For output components/systems that are directly or indirectly used for any 

emission control strategies that are not covered under sections (e), (f), 

and (g)(1) (e.g., an intake throttle used for a control strategy that adjusts 

intake throttle position to regulate SCR catalyst inlet temperature within a 

target window), the OBD system shall detect functional malfunctions that 

prevent the component/system from achieving the desired functional 

response necessary for the strategy to operate in its intended manner. 

These malfunctions include faults that inappropriately prevent or delay the 

activation of the emission control strategy, cause the system to 

erroneously exit the emission control strategy, or where the control 

strategy has used up all of the adjustments or authority allowed by the 

manufacturer and is still unable to achieve the desired condition. The 

Executive Officer may waive detection of specific malfunctions upon 

determining that the manufacturer has submitted data and/or an 

engineering evaluation that demonstrate that reliable detection of the 

malfunction is technically infeasible or would require additional hardware.

(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. 

(i) Except as provided in section (g)(3.2.2)(F)(ii) below, Tthe 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 

(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 

components’ tolerance compensation features (e.g., wrong 
97

compensation being used) could cause emissions to increase by 15 

percent or more of the applicable standard as measured from an

applicable emission test cycle; and (2) no fault of the components’ 

tolerance compensation features can cause emissions to exceed the 

applicable 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 in-use 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 minusone-sigma injectors without updating of the compensation value). 

(3.3) Monitoring Conditions:

(3.3.1) Input Components:

(A) Except as provided in section (g)(3.3.1)(C), input components shall be 

monitored continuously for proper range of values and circuit continuity.

(B) For rationality monitoring (where applicable) manufacturers shall define 

the monitoring conditions for detecting malfunctions in accordance with 

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

exception that rationality 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).

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

continuous input component proper range of values or circuit continuity 

monitoring when a malfunction cannot be distinguished from other effects. 

The Executive Officer shall approve the disablement upon determining 

that the manufacturer has submitted test data and/or documentation that 

demonstrate a properly functioning input component cannot be 

distinguished from a malfunctioning input component and that the 

disablement interval is limited only to that necessary for avoiding false 

detection.

(3.3.2) Output Components/Systems:

(A) Except as provided in section (g)(3.3.2)(D), monitoring for circuit 

continuity and circuit faults shall be conducted continuously.

(B) Except as provided in section (g)(3.3.2)(C), for functional monitoring, 

manufacturers shall define the monitoring conditions for detecting 

malfunctions in accordance with sections (d)(3.1) and (d)(3.2) (i.e., 

minimum ratio requirements).
98

(C) For the idle control system, manufacturers shall define the monitoring 

conditions for functional monitoring in accordance with sections (d)(3.1) 

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

functional 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).

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

continuous output component circuit continuity or circuit fault monitoring 

when a malfunction cannot be distinguished from other effects. The 

Executive Officer shall approve the disablement upon determining that the 

manufacturer has submitted test data and/or documentation that 

demonstrate a properly functioning output component cannot be 

distinguished from a malfunctioning output component and that the 

disablement interval is limited only to that necessary for avoiding false 

detection.

(3.4) MIL Illumination and Fault Code Storage:

(3.4.1) Except as provided in sections (g)(3.4.2) and (3.4.4) below, general 

requirements for MIL illumination and fault code storage are set forth in 

section (d)(2).

(3.4.2) Exceptions to general requirements for MIL illumination. MIL illumination 

is not required in conjunction with storing a confirmed or MIL-on fault code 

for any comprehensive component if:

(A) the component or system, when malfunctioning, could not cause engine 

emissions to increase by 15 percent or more of the FTP standard during 

any reasonable driving condition; and 

(B) the component or system is not used as part of the diagnostic strategy for 

any other monitored system or component.

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

(g)(3.4.2)(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 (g)(3.4.2)(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).
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(3.4.4) For malfunctions required to be detected by section (g)(3.2.2)(B)(ii)d. (idle 

control fuel injection quantity faults), the stored fault code is not required 

to specifically identify the idle control system (e.g., a fault code for cylinder 

fuel injection quantity imbalance or combustion quality monitoring can be 

stored).

(4) Other Emission Control System Monitoring

(4.1) Requirement: For other emission control systems that are: (1) not identified or 

addressed in sections (e)(1) through (g)(3) (e.g., hydrocarbon traps, 

homogeneous charge compression ignition (HCCI) control systems), or (2) 

identified or addressed in section (g)(3) but not corrected or compensated for 

by an adaptive control system (e.g., swirl control valves), manufacturers shall 

submit a plan for Executive Officer approval of the monitoring strategy, 

malfunction criteria, and monitoring conditions prior to introduction on a 

production engine. Executive Officer approval shall be based on the 

effectiveness of the monitoring strategy, the malfunction criteria utilized, the 

monitoring conditions required by the diagnostic, and, if applicable, the 

determination that the requirements of section (g)(4.2) and (g)(4.3) below are 

satisfied.

(4.2) For engines that utilize emission control systems that alter intake air flow or 

cylinder charge characteristics by actuating valve(s), flap(s), etc. in the intake 

air delivery system (e.g., swirl control valve systems), the manufacturers, in 

addition to meeting the requirements of section (g)(4.1) above, may elect to 

have the OBD system monitor the shaft to which all valves in one intake bank 

are physically attached in lieu of monitoring the intake air flow, cylinder 

charge, or individual valve(s)/flap(s) for proper functional response. For nonmetal shafts or segmented shafts, the monitor shall verify all shaft segments 

for proper functional response (e.g., by verifying the segment or portion of the 

shaft furthest from the actuator properly functions). For systems that have 

more than one shaft to operate valves in multiple intake banks, 

manufacturers are not required to add more than one set of detection 

hardware (e.g., sensor, switch) per intake bank to meet this requirement.

(4.3) For emission control strategies that are not covered under sections (e), (f), 

and (g)(1) (e.g., a control strategy that regulates SCR catalyst inlet 

temperatures within a target window), Executive Officer approval shall be 

based on the effectiveness of the plan in detecting malfunctions that prevent 

the strategy from operating in its intended manner. These malfunctions 

include faults that inappropriately prevent or delay the activation of the 

emission control strategy, faults that cause the system to erroneously exit the 

emission control strategy, and faults where the control strategy has used up 

all of the adjustments or authority allowed by the manufacturer and is still 

unable to achieve the desired condition. The Executive Officer may waive 

detection of specific malfunctions upon determining that the manufacturer 

has submitted data and/or an engineering evaluation that demonstrate that 

reliable detection of the malfunction is technically infeasible or would require 

additional hardware.

(5) Exceptions to Monitoring Requirements
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(5.1) Upon request of a manufacturer or upon the best engineering judgment of 

ARB, the Executive Officer may revise the emission threshold for any monitor 

in sections (e) through (g) or if the most reliable monitoring method 

developed requires a higher threshold to prevent false indications of a 

malfunction. Additionally, except as specified in section (e)(8.2.1)(C), for 

2010 through 2015 model year engines, the Executive Officer may revise the 

PM filter malfunction criteria of section (e)(8.2.1) to exclude detection of 

specific failure modes (e.g., partially melted substrates) if the most reliable 

monitoring method developed requires a higher threshold (or, in the case of 

section (e)(8.2.1), the exclusion of specific failure modes) to prevent 

significant errors of commission in detecting false indications of a 

malfunction. 

(5.2) For 2010 through 2012 model year diesel engines, in determining the 

malfunction criteria for diesel engine monitors in sections (e)(1), (3), (4), (5), 

(8.2.2), (9.2.1)(A), and (e)(10), the manufacturer shall use a threshold of 2.5 

times any of the applicable NMHC, CO, or NOx standards in lieu of 2.0 times 

any of the applicable standards.

(5.3) Manufacturers may request Executive Officer approval to disable an OBD 

system monitor at ambient temperatures below 20 degrees Fahrenheit (low 

ambient temperature conditions may be determined based on intake air or 

engine coolant temperature at engine start) or at elevations above 8000 feet 

above sea level. The Executive Officer shall approve the request upon 

determining that the manufacturer has provided data and/or an engineering 

evaluation that demonstrate that monitoring during the conditions would be 

unreliable. A manufacturer may further request, and the Executive Officer 

shall approve, that an OBD system monitor be disabled at other ambient 

temperatures upon determining that the manufacturer has demonstrated with 

data and/or an engineering evaluation that misdiagnosis would occur at the 

ambient temperatures because of its effect on the component itself (e.g., 

component freezing).

(5.4) Manufacturers may request Executive Officer approval to disable monitoring 

systems that can be affected by low fuel level or running out of fuel (e.g., 

misfire detection) when the fuel level is 15 percent or less of the nominal 

capacity of the fuel tank. The Executive Officer shall approve the request 

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

engineering evaluation that demonstrate that monitoring at the fuel levels 

would be unreliable and the OBD system is able to detect a malfunction if the 

component(s) used to determine fuel level erroneously indicates a fuel level 

that causes the disablement.

(5.5) Manufacturers may disable monitoring systems that can be affected by 

vehicle battery or system voltage levels.

(5.5.1) For monitoring systems affected by low vehicle battery or system voltages, 

manufacturers may disable monitoring systems when the battery or 

system voltage is below 11.0 Volts. Manufacturers may request Executive 

Officer approval to utilize a voltage threshold higher than 11.0 Volts to 

disable system monitoring. The Executive Officer shall approve the 

request upon determining that the manufacturer has submitted data 

and/or an engineering evaluation that demonstrate that monitoring at the 
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voltages would be unreliable and that either operation of a vehicle below 

the disablement criteria for extended periods of time is unlikely or the 

OBD system monitors the battery or system voltage and will detect a 

malfunction at the voltage used to disable other monitors.

(5.5.2) For monitoring systems affected by high vehicle battery or system 

voltages, manufacturers may request Executive Officer approval to 

disable monitoring systems when the battery or system voltage exceeds a 

manufacturer-defined voltage. The Executive Officer shall approve the 

request upon determining that the manufacturer has submitted data 

and/or an engineering evaluation that demonstrate that monitoring above 

the manufacturer-defined voltage would be unreliable and that either the 

electrical charging system/alternator warning light is illuminated (or voltage 

gauge is in the “red zone”) or the OBD system monitors the battery or 

system voltage and will detect a malfunction at the voltage used to disable 

other monitors.

(5.6) A manufacturer may request Executive Officer approval to disable monitors 

that can be affected by PTO activation on engines or vehicles designed to 

accommodate the installation of PTO units (as defined in section (c)).

(5.6.1) Except as allowed in section (g)(5.6.2) below, a manufacturer may request 

Executive Officer approval to disable an affected monitor provided 

disablement occurs only while the PTO unit is active and the OBD 

readiness status (specified under section (h)(4.1)) and PTO activation 

time are appropriately tracked and erased as described in this section. 

The Executive Officer shall approve the request for disablement based on 

the manufacturer’s demonstration that the affected monitor cannot 

robustly detect malfunctions (e.g., cannot avoid false passes or false 

indications of malfunctions) while the PTO unit is active. The OBD system 

shall track the cumulative engine runtime with PTO active and clear OBD 

readiness status (i.e., set all monitors to indicate “not complete”) no later 

than the start of the next ignition cycle if 750 minutes of cumulative engine 

runtime with PTO active has occurred since the last time the affected 

monitor has determined the component or system monitored by the 

affected monitor is or is not malfunctioning (i.e., has completed). The 

PTO timer shall pause whenever PTO changes from active to not active 

and resume counting when PTO is re-activated. The timer shall be reset 

to zero after the affected monitor has completed and no later than the 

start of the next ignition cycle. Once the PTO timer has reached 750 

minutes and the OBD readiness status has been cleared, the PTO timer 

may not cause the OBD system to clear the readiness status again until 

after the PTO timer has reset to zero (after the monitor has completed) 

and again reached 750 minutes.

(5.6.2) For 2010 through 2012 model year engines, in lieu of requesting 

Executive Officer approval for disabling an affected monitor according to 

section (g)(5.6.1) above, a manufacturer may disable affected monitors, 

provided disablement occurs only while the PTO unit is active, and the 

OBD readiness status is cleared by the on-board computer (i.e., all 

monitors set to indicate “not complete”) while the PTO unit is activated. If 
102

the disablement occurs, the readiness status may be restored to its state 

prior to PTO activation when the disablement ends.

(5.7) 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, (2) a malfunction of the component does not affect the diagnostic 

strategy for any other monitored component or system, and (3) the ambient 

temperature 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. 

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

a manufacturer to meet a specific phase-in schedule: 

(5.8.1) Except as provided for in section (g)(5.8.3) below for the diesel NOx 

converting catalyst and NOx and PM sensor phase-ins and in section 

(e)(8.2.1) for the PM filter monitor phase-in, manufacturers may use an 

alternate phase-in schedule in lieu of the phase-in schedule set forth in 

sections (e), (f), or (g) if the alternate phase-in schedule provides for 

equivalent compliance volume as defined in section (c).

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

accordance with section (g)(5.8.1) in lieu of the required phase-in 

schedule or may use a different schedule as follows: 

(A) For the diesel misfire monitor phase-in schedule in section (e)(2.2.2), the 

manufacturer may meet the requirement on all engines by the 2018 model 

year in lieu of meeting the specific phase-in requirements for the 2016 

and 2017 model years.

(B) For the diesel misfire monitor phase-in schedule in section (e)(2.3.3), the 

manufacturer may meet the monitoring conditions requirements of section 

(e)(2.3.3)(A)(i) on all engines subject to (e)(2.2.2) through the 2020 model 

year and the monitoring conditions requirements of section (e)(2.3.3)(A)(ii) 

on all 2021 and subsequent model year engines in lieu of the specific 

phase-in requirements in section (e)(2.3.3)(A) for the 2019 and 2020 

model years.

(C)For the diesel NOx converting catalyst monitor phase-in schedules in 

section (e)(6), the manufacturer may use the malfunction criteria in 

sections (e)(6.2.1)(B) and (e)(6.2.2)(A)(ii) for all 2014 and 2015 model 

year engines in lieu of the malfunction criteria and required phase-in 

schedule in sections (e)(6.2.1)(C) and (e)(6.2.2)(A)(iii).

(D)For the diesel PM filter monitor phase-in schedule in section (e)(8), the 

manufacturer may use the malfunction criteria in section (e)(8.2.1)(B) for 
103

all 2014 and 2015 model year engines in lieu of the malfunction criteria 

and required phase-in schedule in section (e)(8.2.1)(C).

(E) For the diesel NOx sensor phase-in schedules in section (e)(9), the 

manufacturer may use the malfunction criteria in section (e)(9.2.2)(A)(ii) 

for all 2014 and 2015 model year engines in lieu of the malfunction criteria 

and required phase-in schedule in section (e)(9.2.2)(A)(iii).

(5.8.3) In lieu of meeting the diesel NOx converting catalyst and NOx and PM 

sensor phase-ins set forth in sections (e)(6.2.1), (e)(6.2.2), and (e)(9.2.2), 

a manufacturer may request Executive Officer approval to use a 

manufacturer-defined phase-in for each requirement. The Executive 

Officer shall approve the manufacturer-defined phase-in if it meets the 

following criteria:

(A) For the requirements in sections (e)(6.2.1)(C), (e)(6.2.2)(A)(iii), and 

(e)(9.2.2)(A)(iii) (i.e., requiring a NOx threshold of +0.3 g/bhp-hr):

(i) The phase-in shall provide for a compliance volume of engines certified 

to the +0.3 g/bhp-hr NOx threshold that is equivalent to the volume of 

the required phase-in set forth in each of the above-referenced 

sections (i.e., the phase-in of 20 percent of 2014 model year diesel 

engines and 50 percent of 2015 model year diesel engines). The 

compliance volume shall be calculated in accordance with the 

calculation methodology in the definition of “alternate phase-in” in 

section (c) (i.e., (20*2 years) + (50*1 year) = 90 for the required phasein). The compliance volume shall be considered equivalent if the 

calculated total is equal to or greater than 90.

(ii) The calculated compliance volume for the manufacturer-defined 

phase-in may not include engines meeting the +0.3 g/bhp-hr NOx 

threshold requirement earlier than the 2013 model year. 

(iii) For the 2013 through 2017 model years, engines meeting the 

requirements in sections (e)(6.2.1)(D), (e)(6.2.2)(A)(iv), and 

(e)(9.2.2)(A)(iv) (i.e., requiring a NOx threshold of +0.2 g/bhp-hr) shall 

also be considered as meeting the +0.3 g/bhp-hr NOx threshold 

requirement and included in the calculated compliance volume and 

shall not be subtracted from the calculated compliance volume.

(iv) For the 2016 model year, if the proposed phase-in results in a 

combined percentage of engines meeting the +0.3 g/bhp-hr and the 

+0.2 g/bhp-hr thresholds being less than 50 percent of all diesel 

engines, the manufacturer shall subtract those engines that do not 

meet the above thresholds in both the 2015 and 2016 model years 

from the required percentage of 50 percent when calculating the 

compliance volume according to the calculation methodology in the 

definition of “alternate phase-in” section (c). 

(v) All engines shall meet either the +0.3 g/bhp-hr NOx threshold or the 

+0.2 g/bhp-hr NOx threshold no later than the 2017 model year. 

(B) For the requirements in sections (e)(6.2.1)(D), (e)(6.2.2)(A)(iv), and 

(e)(9.2.2)(A)(iv) (i.e., requiring a NOx threshold of +0.2 g/bhp-hr): 

(i) The phase-in shall provide for a compliance volume of engines certified 

to the +0.2 g/bhp-hr NOx threshold that is equivalent to the volume of 

the required phase-in set forth in each of the above-referenced 
104

sections (i.e., 100 percent of 2016 model year diesel engines). The 

compliance volume shall be calculated in accordance with the 

calculation methodology in the definition of “alternate phase-in” in 

section (c) (i.e., (100*1 year) = 100 for the required phase-in). The 

compliance volume shall be considered equivalent if the calculated 

total is equal to or greater than 100.

(ii) The calculated compliance volume for the manufacturer-defined 

phase-in shall not include engines meeting the +0.2 g/bhp-hr NOx 

threshold requirement earlier than the 2015 model year.

(iii) For the 2016 model year only, engines meeting the NOx threshold of 

+0.3 g/bhp-hr and carried over from the 2014 or 2015 model year per 

sections (e)(6.2.1)(E), (e)(6.2.2)(A)(v), and (e)(9.2.2)(A)(v) shall also 

be considered as meeting the +0.2 g/bhp-hr NOx threshold 

requirement and included in the calculated compliance volume and 

shall not be subtracted from the calculated compliance volume.

(iv) If the phase-in includes engines that do not meet the +0.2 g/bhp-hr 

NOx threshold in the 2017 model year, the manufacturer shall subtract 

those engines that do not meet the threshold in the 2016 and 2017 

model years (except as allowed for the 2016 model year in section 

(g)(5.8.3)(B)(iii) above) from the required percentage of 100 percent 

when calculating the compliance volume according to the calculation 

methodology in the definition of “alternate phase-in” section (c). 

(v) All engines shall meet the +0.2 g/bhp-hr NOx threshold no later than 

the 2018 model year. 

(5.7)(5.9) Whenever the requirements in sections (e) through (g) of this regulation 

require monitoring “to the extent feasible”, the manufacturer shall submit its 

proposed monitor(s) for Executive Officer approval. The Executive Officer 

shall approve the proposal upon determining that the proposed monitor(s) 

meets the criteria of “to the extent feasible” by considering the best available 

monitoring technology to the extent that it is known or should have been 

known to the manufacturer and given the limitations of the manufacturer’s 

existing hardware, the extent and degree to which the monitoring 

requirements are met in full, the limitations of monitoring necessary to 

prevent significant errors of commission and omission, and the extent to 

which the manufacturer has considered and pursued alternative monitoring 

concepts to meet the requirements in full. The manufacturer’s consideration 

and pursuit of alternative monitoring concepts shall include evaluation of 

other modifications to the proposed monitor(s), the monitored components 

themselves, and other monitors that use the monitored components (e.g., 

altering other monitors to lessen the sensitivity and reliance on the 

component or characteristic of the component subject to the proposed 

monitor(s)).

(h) Standardization Requirements.

(1) Reference Documents:

The following Society of Automotive Engineers (SAE) and International 

Organization of Standards (ISO) documents are incorporated by reference into 

this regulation:
105

(1.1) SAE J1930 "Electrical/Electronic Systems Diagnostic Terms, Definitions, 

Abbreviations, and Acronyms – Equivalent to ISO/TR 15031-2", October 

2008 (SAE J1930).

(1.1.1) SAE J1930-DA “Electrical/Electronic Systems Diagnostic Terms, 

Definitions, Abbreviations, and Acronyms Web Tool Spreadsheet”, March 

2012.

(1.2) SAE J1962 "Diagnostic Connector – Equivalent to ISO/DIS 15031-3: 

December 14, 2001", April 2002 (SAE J1962).

(1.3) SAE J1978 "OBD II Scan Tool – Equivalent to ISO/DIS 15031-4: December 

14, 2001", April 2002 (SAE J1978).

(1.4) SAE J1979 "E/E Diagnostic Test Modes", May 2007 February 2012 (SAE 

J1979).

(1.4.1) SAE J1979-DA “Digital Annex of E/E Diagnostic Test Modes”, October 

2011.

(1.5) SAE J2012 "Diagnostic Trouble Code Definitions", December 2007 (SAE 

J2012).

(1.5.1) SAE J2012-DA “Digital Annex of Diagnostic Trouble Code Definitions and 

Failure Type Byte Definitions”, July 2010.

(1.6) ISO 15765-4:2005 "Road Vehicles-Diagnostics Communication on over 

Controller Area Network (CAN) - Part 4: Requirements for emission-related 

systems", January 2005 February 2011 (ISO 15765-4).

(1.7) SAE J1939 consisting of:

(1.7.1) J1939 Recommended Practice for a Serial Control and Communications 

Vehicle Network, March 2009April 2011;

(1.7.2) J1939/1 Recommended Practice for On-Highway Equipment Control and 

Communications Network for On-Highway Equipment, September

2000May 2011;

(1.7.3) J1939/11 Physical Layer, 250K bits/s, Twisted Shielded Pair, September

2006;

(1.7.4) J1939/13 Off-Board Diagnostic Connector, March 2004October 2011;

(1.7.5) J1939/15 Reduced Physical Layer, 250K bits/sec, UN-Shielded Twisted 

Pair (UTP), August 2008;

(1.7.6) J1939/21 Data Link Layer, December 20062010;

(1.7.7) J1939/31 Network Layer, April 2004May 2010;

(1.7.8) J1939/71 Vehicle Application Layer (Through February 2008May 2010), 

January 2009March 2011;

(1.7.9) J1939/73 Application Layer—Diagnostics, September 2006February 

2010;

(1.7.10) J1939/81 Network Management, May 2003June 2011; and

(1.7.11) J1939/84 OBD Communications Compliance Test Cases For Heavy Duty 

Components and Vehicles, December 20082010.

(1.8) SAE J2403 “Medium/Heavy-Duty E/E Systems Diagnosis Nomenclature,” 

August 2007 February 2011 (SAE J2403).

(1.9) SAE J1699-3 – “Vehicle OBD II Compliance Test Cases”, May 2006

December 2009 (SAE J1699-3).

(1.10) SAE J2534-1 – “Recommended Practice for Pass-Thru Vehicle 

Programming”, December 2004 (SAE J2534-1).
106

(2) Diagnostic Connector:

A standard data link connector conforming to SAE J1962 or SAE J1939-13 

specifications (except as specified in section (h)(2.3)) shall be incorporated in 

each vehicle.

(2.1) For the 2010 through 2012 model year engines:

(2.1.1) The connector shall be located in the driver’s side foot-well region of the 

vehicle interior in the area bound by the driver’s side of the vehicle and 

the driver's side edge of the center console (or the vehicle centerline if the 

vehicle does not have a center console) and at a location no higher than 

the bottom of the steering wheel when in the lowest adjustable position. 

The connector may not be located on or in the center console (i.e., neither 

on the horizontal faces near the floor-mounted gear selector, parking 

brake lever, or cup-holders nor on the vertical faces near the car stereo, 

climate system, or navigation system controls). 

(2.1.2) If the connector is covered, the cover must be removable by hand without 

the use of any tools and be labeled “OBD” to aid technicians in identifying 

the location of the connector. Access to the diagnostic connector may not 

require opening or the removal of any storage accessory (e.g., ashtray, 

coinbox). The label shall be submitted to the Executive Officer for review 

and approval, at or before the time the manufacturer submits its 

certification application. The Executive Officer shall approve the label 

upon determining that it clearly identifies that the connector is located 

behind the cover and is consistent with language and/or symbols 

commonly used in the automotive industry.

(2.2) For 2013 and subsequent model year engines:

(2.2.1) The connector shall be located in the driver’s side foot-well region of the 

vehicle interior in the area bound by the driver’s side of the vehicle and 

the foot pedal closest to the driver’s side of the vehicle (left most pedal in 

a left hand drive vehicle) excluding a foot-activated emergency brake if 

equipped (e.g., typically the brake pedal for an automatic transmission 

equipped vehicle or the clutch pedal for a manual transmission equipped 

vehicle) and at a location no higher than the bottom of the steering wheel 

when in the lowest adjustable position.

(2.2.2) The connector shall be mounted in an uncovered location and may not be 

covered with or located behind any form of panel, access door, or storage 

device (e.g., fuse panel cover, hinged door, ashtray, coinbox) that requires 

opening or removal to access the connector. The connector may be 

equipped with a dust cap in the shape and size of the diagnostic 

connector for environmental protection purposes but the dust cap must be 

removable by hand without the use of any tools and be labeled “OBD” to 

aid technicians in identifying the connector.

(2.2.3) The connector shall be mounted in a manner that allows vehicle operation 

and driving (e.g., does not interfere with use of driver controls such as the 

clutch, brake, and accelerator pedal) while a scan tool is connected to the 

vehicle. 

(2.3) The location of the connector shall be capable of being easily identified and 

accessed (e.g., to connect an off-board tool). For vehicles equipped with a 

driver’s side door, the connector shall be capable of being easily identified 
107

and accessed by a technician standing (or “crouched”) on the ground outside 

the driver’s side of the vehicle with the driver’s side door open.

(2.4) If the ISO 15765-4 protocol (see section (h)(3)) is used for the required OBD 

standardized functions, the connector shall meet the “Type A” specifications 

of SAE J1962. Any pins in the connector that provide electrical power shall 

be properly fused to protect the integrity and usefulness of the connector for 

diagnostic purposes and may not exceed 20.0 Volts DC regardless of the 

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

(2.5) If the SAE J1939 protocol (see section (h)(3)) is used for the required OBD 

standardized functions, the connector shall meet the “Type 1” or “Type 2” 

specifications of SAE J1939-13 if the 250 kbps baud rate of J1939 is used 

and the “Type 2” specifications of J1939-13 if the 500 kbps baud rate of 

J1939 is used. Any pins in the connector that provide electrical power shall 

be properly fused to protect the integrity and usefulness of the connector for 

diagnostic purposes.

(2.6) Manufacturers may equip vehicles with additional diagnostic connectors for 

manufacturer-specific purposes (i.e., purposes other than the required OBD 

functions). However, if the additional connector conforms to the “Type A” 

specifications of SAE J1962 or the specifications of SAE J1939-13:

(2.6.1) and For 2010 through 2015 model year engines, if the additional 

connector is located in the vehicle interior near the required connector of 

section (h)(2), the connector(s) must be clearly labeled to identify which 

connector is used to access the standardized OBD information required in 

section (h).

(2.6.2) For 2016 and subsequent model year engines, the additional connector 

may not be in the location specified in section (h)(2.2.1).

(3) Communications to a Scan Tool:

All OBD control modules (e.g., engine, auxiliary emission control module) on a 

single vehicle shall use the same protocol for communication of required 

emission-related messages from on-board to off-board network communications 

to a scan tool meeting SAE J1978 specifications or designed to communicate 

with an SAE J1939 network. Engine manufacturers shall not alter normal 

operation of the engine emission control system due to the presence of off-board 

test equipment accessing information required by section (h). The OBD system 

shall use one of the following standardized protocols:

(3.1) ISO 15765-4. All required emission-related messages using this protocol 

shall use a 500 kbps baud rate. 

(3.2) SAE J1939. This protocol may only be used on vehicles with diesel engines

(including diesel engines converted to alternate-fueled engines). For 2010 

through 2015 model year engines, all required emission-related messages 

using this protocol on an individual vehicle shall use either the 250 kbps or 

the 500 kbps baud rate. The 250 kbps baud rate may not be used on 2016 

or subsequent model year engines.

(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 
108

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 

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);

(B) Gasoline misfire (section (f)(2)); and

(C) Diesel and gasoline comprehensive component (section (g)(3)).

(4.1.2) For the evaporative system monitor, the readiness status shall be set in 

accordance with section (h)(4.1) when both the functional check of the 

purge valve and, if applicable, the leak detection monitor of the orifice size 

specified in section (f)(7.2.2)(B) (e.g., 0.150 inch) indicate that they are 

complete. For 2010 through 2015 model year engines, for components 

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

shall immediately indicate “complete” upon the respective monitor(s) 

(except those monitors specified under section (h)(4.1.7) 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. 
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(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)

(C) Diesel EGR/VVT: sections (e)(3.2.1), (e)(3.2.2), (e)(3.2.3), (e)(3.2.5), 

(e)(3.2.6), and (e)(10.2)

(D) Diesel Boost Pressure Control System: sections (e)(4.2.1), (e)(4.2.2), 

(e)(4.2.3), and (e)(4.2.4)

(E) Diesel NMHC Converting Catalyst: sections (e)(5.2.2) and (e)(5.2.3)(A)

(F) Diesel NOx Converting Catalyst: section (e)(6.2.1)

(G) Diesel NOx Aftertreatment: sections (e)(7.2.1) and (e)(7.2.2)

(H) Diesel PM Filter: sections (e)(8.2.1), (e)(8.2.2), (e)(8.2.5), and (e)(8.2.6) 

(I) Diesel Exhaust Gas Sensor: sections (e)(9.2.1)(A)(i), (e)(9.2.1)(A)(iv), 

(e)(9.2.1)(B)(i), (e)(9.2.1)(B)(iv), (e)(9.2.2)(A), (e)(9.2.2)(D), and 

(e)(9.2.3)(A)

(J) Gasoline Fuel System: section (f)(1.2.1)(C)

(K) Gasoline EGR/VVT: sections (f)(3.2.1), (f)(3.2.2), (f)(9.2.1), (f)(9.2.2), and 

(f)(9.2.3)

(L) Gasoline Secondary Air System: sections (f)(5.2.1), (f)(5.2.2), (f)(5.2.3), 

and (f)(5.2.4)

(M) Gasoline Catalyst: section (f)(6.2.1)

(N) Gasoline Evaporative System: sections (f)(7.2.2)(A) and (f)(7.2.2)(B)

(O) Gasoline Oxygen Sensor: sections (f)(8.2.1)(A), (f)(8.2.1)(D), (f)(8.2.2)(A), 

and (f)(8.2.2)(C)

(4.1.4) For 2016 and subsequent model year engines, for monitors that detect 

faults of more than one major emission-related component (e.g., a single 

monitor that is used to detect both oxygen sensor faults that are tied to 

the oxygen sensor readiness bit and air-fuel ratio cylinder imbalance faults 

that are tied to the fuel system readiness bit), the manufacturer shall 

include the monitor only in the readiness status for the 

component/system that the monitor is primarily calibrated, intended, or 

expected in-use to detect faults of.

(4.1.5) Except for the readiness bits listed under section (h)(4.1.1) above, 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 
110

vehicle shut down (i.e., key off, engine off) may not cause the readiness 

status to indicate “not complete”.

(4.1.3)(4.1.6) If the manufacturer elects to additionally indicate readiness status 

through the MIL in the key on, engine off position as provided for in 

section (d)(2.1.3), the readiness status shall be indicated in the following 

manner: If the readiness status for all monitored components or systems 

is “complete”, the MIL shall remain continuously illuminated in the key on, 

engine off position for at least 15-20 seconds as required by section 

(d)(2.1.2). If the readiness status for one or more of the monitored 

components or systems is “not complete”, after 15-20 seconds of 

operation in the key on, engine off position with the MIL illuminated 

continuously as required by section (d)(2.1.2), the MIL shall blink once per 

second for 5-10 seconds. The data stream value for MIL status (section 

(h)(4.2)) shall indicate “commanded off” during this sequence unless the 

MIL has also been “commanded on” for a detected fault.

(4.1.4)(4.1.7) Manufacturers are not required to use the following monitors in 

determining the readiness status for the specific component or system:

(A) Circuit and out-of-range monitors that are required to be continuous;

(B) Gasoline and diesel exhaust gas sensor feedback monitors specified in 

sections (e)(9.2.1)(A)(iii), (e)(9.2.1)(B)(iii), (e)(9.2.2)(C), (f)(8.2.1)(C), and 

(f)(8.2.2)(E);

(C) Diesel feedback control monitors specified in sections (e)(1.2.4), 

(e)(3.2.4), (e)(4.2.5), (e)(6.2.2)(D), (e)(7.2.3), and (e)(8.2.7);

(D) Gasoline fuel system monitors specified in sections (f)(1.2.1)(A), 

(f)(1.2.1)(B), (f)(1.2.2), (f)(1.2.4), and (f)(1.2.5).

(4.2) Data Stream: The following signals shall be made available on demand 

through the standardized data link connector in accordance with SAE 

J1979/J1939 specifications. The actual signal value shall always be used 

instead of a default or limp home value. 

(4.2.1) For all gasoline engines:

(A) Calculated load value, engine coolant temperature, engine speed, vehicle 

speed, time elapsed since engine start; and

(B) Absolute load, fuel level (if used to enable or disable any other 

diagnostics), barometric pressure (directly measured or estimated), 

engine control module system voltage, commanded equivalence ratio; 

and

(C) Number of stored confirmed fault codes, catalyst temperature (if directly 

measured or estimated for purposes of enabling the catalyst monitor(s)), 

monitor status (i.e., disabled for the rest of this driving cycle, complete this 

driving cycle, or not complete this driving cycle) since last engine shut-off 

for each monitor used for readiness status, distance traveled (or engine 

run time for engines not utilizing vehicle speed information) while MIL 

activated, distance traveled (or engine run time for engines not utilizing 

vehicle speed information) since fault memory last cleared, and number of 

warm-up cycles since fault memory last cleared, OBD requirements to 

which the engine is certified (e.g., California OBD, EPA OBD, European 

OBD, non-OBD) and MIL status (i.e., commanded-on or commanded-off).

(4.2.2) For all diesel engines:
111

(A) Calculated load (engine torque as a percentage of maximum torque 

available at the current engine speed), driver’s demand engine torque (as 

a percentage of maximum engine torque), actual engine torque (as a 

percentage of maximum engine torque), reference engine maximum 

torque, reference maximum engine torque as a function of engine speed 

(suspect parameter numbers (SPN) 539 through 543 defined by SAE 

J1939 within parameter group number (PGN) 65251 for engine 

configuration), engine coolant temperature, engine oil temperature (if used

for emission control or any OBD diagnostics), engine speed, time elapsed 

since engine start;

(B) Fuel level (if used to enable or disable any other diagnostics), vehicle 

speed (if used for emission control or any OBD diagnostics), barometric 

pressure (directly measured or estimated), engine control module system 

voltage;

(C) Number of stored confirmed/MIL-on fault codes, monitor status (i.e., 

disabled for the rest of this driving cycle, complete this driving cycle, or not 

complete this driving cycle) since last engine shut-off for each monitor 

used for readiness status, distance traveled (or engine run time for 

engines not utilizing vehicle speed information) while MIL activated, 

distance traveled (or engine run time for engines not utilizing vehicle 

speed information) since fault memory last cleared, number of warm-up 

cycles since fault memory last cleared, OBD requirements to which the 

engine is certified (e.g., California OBD, California OBD-child rating (i.e., 

for engines subject to (d)(7.1.2) or (d)(7.2.3)) EPA OBD, European OBD, 

non-OBD), MIL status (i.e., commanded-on or commanded-off);

(D) NOx NTE control area status (i.e., inside control area, outside control 

area, inside manufacturer-specific NOx NTE carve-out area, or deficiency 

active area), PM NTE control area status (i.e., inside control area, outside 

control area, inside manufacturer-specific PM NTE carve-out area, or 

deficiency active area);

(E) For 2013 and subsequent model year engines, normalized trigger for PM 

filter regeneration (SPN 5466 defined by SAE J1939 for 2016 and 

subsequent model year engines), PM filter regeneration status (SPN 3700

defined by SAE J1939 for 2016 and subsequent model year engines); and

(F) For 2013 and subsequent model year engines, average distance (or 

engine run time for engines not utilizing vehicle speed information) 

between PM filter regenerations.

(G)For 2016 and subsequent model year engines, fuel rate (mg/stroke),

engine torque (including fan or accessory torque), and modeled exhaust 

flow (mass/time).

(GH) For purposes of the calculated load and torque parameters in section 

(h)(4.2.2)(A) and the torque, fuel rate, and modeled exhaust flow

parameters in section (h)(4.2.2)(G), manufacturers shall report the most 

accurate values that are calculated within the applicable electronic control 

unit (e.g., the engine control module). “Most accurate values”, in this

context, shall be of sufficient accuracy, resolution, and filtering to be used

for the purposes of in-use emission testing with the engine still in a vehicle 

(e.g., using portable emission measurement equipment).
112

(4.2.3) For all engines so equipped:

(A) Absolute throttle position, relative throttle position, fuel control system 

status (e.g., open loop, closed loop), fuel trim, fuel pressure, ignition 

timing advance, fuel injection timing, intake air/manifold temperature, 

engine intercooler temperature, manifold absolute pressure, air flow rate 

from mass air flow sensor, secondary air status (upstream, downstream, 

or atmosphere), ambient air temperature, commanded purge valve duty 

cycle/position, commanded EGR valve duty cycle/position, actual EGR 

valve duty cycle/position, EGR error between actual and commanded, 

PTO status (active or not active), redundant absolute throttle position (for 

electronic throttle or other systems that utilize two or more sensors), 

absolute pedal position, redundant absolute pedal position, commanded 

throttle motor position, fuel rate, boost pressure, commanded/target boost 

pressure, turbo inlet air temperature, fuel rail pressure, commanded fuel 

rail pressure, PM filter inlet pressure, PM filter inlet temperature, PM filter 

outlet pressure, PM filter outlet temperature, PM filter delta pressure, 

exhaust pressure sensor output, exhaust gas temperature sensor output, 

injection control pressure, commanded injection control pressure, 

turbocharger/turbine speed, variable geometry turbo position, commanded 

variable geometry turbo position, turbocharger compressor inlet 

temperature, turbocharger compressor inlet pressure, turbocharger 

turbine inlet temperature, turbocharger turbine outlet temperature, 

wastegate valve position, glow plug lamp status; 

(B) For 2013 and subsequent model year engines, EGR temperature, 

variable geometry turbo control status (e.g., open loop, closed loop), 

reductant level (e.g., urea tank fill level), alcohol fuel percentage, type of 

fuel currently being used, NOx adsorber regeneration status, NOx 

adsorber deSOx status, hybrid battery pack remaining charge; 

(C) Oxygen sensor output, air/fuel ratio sensor output, NOx sensor output, 

evaporative system vapor pressure; and

(D) For 2013 and subsequent model year engines, PM sensor output and

distance traveled while low/empty SCR reductant driver 

warning/inducement active.

(E) For 2016 and subsequent model year engines, reductant quality sensor 

output and corrected NOx sensor output (e.g., raw sensor signal corrected 

for estimated ammonia concentrations or auto-zero calculations and used 

by the applicable electronic control unit).

(4.3) Freeze Frame:

(4.3.1) “Freeze frame” information required to be stored pursuant to sections 

(d)(2.2.1)(D), (d)(2.2.2)(D), (e)(1.4.2)(D), (e)(2.4.2)(B), (f)(1.4.4), and 

(f)(2.4.3) shall be made available on demand through the standardized 

data link connector in accordance with SAE J1979/J1939-73 

specifications.

(4.3.2) “Freeze frame” conditions must include the fault code which caused the 

data to be stored and all of the signals required in sections (h)(4.2.1)(A) 

and (4.2.2)(A). Freeze frame conditions shall also include all of the 

signals required on the engine in sections (h)(4.2.1)(B), (4.2.2)(B),

(4.2.2)(E), (4.2.3)(A), and (4.2.3)(B) that are used for diagnostic or control 
113

purposes in the specific diagnostic or emission-critical powertrain control 

unit that stored the fault code. 

(4.3.3) Only one frame of data is required to be recorded. Manufacturers may 

choose to store additional frames provided that at least the required frame 

can be read by a scan tool meeting SAE J1978 specifications or designed 

to communicate with an SAE J1939 network.

(4.4) Fault Codes:

(4.4.1) For vehicles using the ISO 15765-4 protocol for the standardized functions 

required in section (h):

(A) For all monitored components and systems, stored pending, confirmed, 

and permanent fault codes shall be made available through the diagnostic 

connector in a standardized format in accordance with SAE J1979 

specifications. Standardized fault codes conforming to SAE J2012 shall 

be employed.

(B) The stored fault code shall, to the fullest extent possible, pinpoint the 

likely cause of the malfunction. To the extent feasible, manufacturers 

shall use separate fault codes for every diagnostic where the diagnostic 

and repair procedure or likely cause of the failure is different. In general, 

rationality and functional diagnostics shall use different fault codes than 

the respective circuit continuity diagnostics. Additionally, input component 

circuit continuity diagnostics shall use different fault codes for distinct 

malfunctions (e.g., out-of-range low, out-of-range high, open circuit).

(C) Manufacturers shall use appropriate SAE-defined fault codes of SAE 

J2012 (e.g., P0xxx, P2xxx) whenever possible. With Executive Officer 

approval, manufacturers may use manufacturer-defined fault codes in 

accordance with SAE J2012 specifications (e.g., P1xxx). Factors to be 

considered by the Executive Officer for approval shall include the lack of 

available SAE-defined fault codes, uniqueness of the diagnostic or 

monitored component, expected future usage of the diagnostic or 

component, and estimated usefulness in providing additional diagnostic 

and repair information to service technicians. Manufacturer-defined fault 

codes shall be used consistently (i.e., the same fault code may not be 

used to represent two different failure modes) across a manufacturer’s 

entire product line.

(D) A pending or confirmed fault code (as required in sections (d) and (e) 

through (g)) shall be stored and available to an SAE J1978 scan tool 

within 10 seconds after a diagnostic has determined that a malfunction 

has occurred. A permanent fault code shall be stored and available to an 

SAE J1978 scan tool no later than the end of an ignition cycle (including 

electronic control unit shutdown) in which the corresponding confirmed 

fault code causing the MIL to be illuminated has been stored.

(E) Pending fault codes:

(i) Pending fault codes for all components and systems (including 

continuously and non-continuously monitored components) shall be 

made available through the diagnostic connector in accordance with 

SAE J1979 specifications (e.g., Mode/Service $07).

(ii) A pending fault code(s) shall be stored and available through the 

diagnostic connector for all currently malfunctioning monitored 
114

component(s) or system(s), regardless of the MIL illumination status or 

confirmed fault code status (e.g., even after a pending fault has 

matured to a confirmed fault code and the MIL is illuminated, a 

pending fault code shall be stored and available if the most recent 

monitoring event indicates the component is malfunctioning).

(iii) Manufacturers using alternate statistical protocols for MIL illumination 

as allowed in section (d)(2.2.1)(C) shall submit to the Executive Officer 

a protocol for setting pending fault codes. The Executive Officer shall 

approve the proposed protocol upon determining that, overall, it is 

equivalent to the requirements in sections (h)(4.4.1)(E)(i) and (ii) and 

that it effectively provides service technicians with a quick and 

accurate indication of a pending failure.

(F) Permanent fault codes:

(i) Permanent fault codes for all components and systems shall be made 

available through the diagnostic connector in a standardized format 

that distinguishes permanent fault codes from both pending fault 

codes and confirmed fault codes.

(ii) A confirmed fault code shall be stored as a permanent fault code no 

later than the end of the ignition cycle and subsequently at all times 

that the confirmed fault code is commanding the MIL on (e.g., for 

currently failing systems but not during the 40 warm-up cycle selfhealing process described in section (d)(2.3.1)(B)).

(iii) Permanent fault codes shall be stored in NVRAM and may not be 

erasable by any scan tool command (generic or enhanced) or by 

disconnecting power to the on-board computer.

(iv) Permanent fault codes may not be erased when the control module

containing the permanent fault code is reprogrammed unless the 

readiness status bits (refer to section (h)(4.1)) for all monitored 

components and systems in all modules that reported supported 

readiness for a readiness bit other than the comprehensive 

components readiness bit are set to “not complete” in conjunction with 

the reprogramming event.

(v) The OBD system shall have the ability to store a minimum of four 

current confirmed fault codes as permanent fault codes in NVRAM. If 

the number of confirmed fault codes currently commanding the MIL on 

exceeds the maximum number of permanent fault codes that can be 

stored, the OBD system shall store the earliest detected confirmed 

fault codes as permanent fault codes. If additional confirmed fault 

codes are stored when the maximum number of permanent fault 

codes is already stored in NVRAM, the OBD system may not replace 

any existing permanent fault code with the additional confirmed fault 

codes.

(4.4.2) For vehicles using the SAE J1939 protocol for the standardized functions 

required in section (h):
115

(A) For all monitored components and systems, stored pending, MIL-on, and 

previously MIL-on fault codes shall be made available through the 

diagnostic connector in a standardized format in accordance with SAE 

J1939 specifications (i.e., Diagnostic Message (DM) 6, DM12, and DM23). 

Standardized fault codes conforming to SAE J1939 shall be employed.

(B) The stored fault code shall, to the fullest extent possible, pinpoint the 

likely cause of the malfunction. To the extent feasible, manufacturers 

shall use separate fault codes for every diagnostic where the diagnostic 

and repair procedure or likely cause of the failure is different. In general, 

rationality and functional diagnostics shall use different fault codes than 

the respective circuit continuity diagnostics. Additionally, input component 

circuit continuity diagnostics shall use different fault codes for distinct 

malfunctions (e.g., out-of-range low, out-of-range high, open circuit).

(C) Manufacturers shall use appropriate SAE-defined fault codes of SAE 

J939 whenever possible. With Executive Officer approval, manufacturers 

may use manufacturer-defined fault codes in accordance with SAE J1939 

specifications. Factors to be considered by the Executive Officer for 

approval shall include the lack of available SAE-defined fault codes, 

uniqueness of the diagnostic or monitored component, expected future 

usage of the diagnostic or component, and estimated usefulness in 

providing additional diagnostic and repair information to service 

technicians. Manufacturer-defined fault codes shall be used consistently 

(i.e., the same fault code may not be used to represent two different 

failure modes) across a manufacturer’s entire product line.

(D) A pending or MIL-on fault code (as required in sections (d), (e), and (g)) 

shall be stored and available to an SAE J1939 scan tool within 10 

seconds after a diagnostic has determined that a malfunction has 

occurred. A permanent fault code shall be stored and available to an SAE 

J1939 scan tool no later than the end of an ignition cycle (including 

electronic control unit shutdown) in which the corresponding MIL-on fault 

code causing the MIL to be illuminated has been stored.

(E) Pending fault codes:

(i) Pending fault codes for all components and systems (including 

continuously and non-continuously monitored components) shall be 

made available through the diagnostic connector in accordance with 

SAE J1939 specifications (i.e., DM6).

(ii) Manufacturers using alternate statistical protocols for MIL illumination 

as allowed in section (d)(2.2.2)(C) shall submit to the Executive Officer 

a protocol for setting pending fault codes. The Executive Officer shall 

approve the proposed protocol upon determining that, overall, it is 

equivalent to the requirements in sections (h)(4.4.2)(E)(i) and that it 

effectively provides service technicians with a quick and accurate 

indication of a pending failure.

(F) Permanent fault codes:

(i) Permanent fault codes for all components and systems shall be made 

available through the diagnostic connector in a standardized format 

that distinguishes permanent fault codes from pending fault codes, 

MIL-on fault codes, and previously MIL-on fault codes.
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(ii) A MIL-on fault code shall be stored as a permanent fault code no later 

than the end of the ignition cycle and subsequently at all times that the 

MIL-on fault code is commanding the MIL on (e.g., for currently failing 

systems).

(iii) Permanent fault codes shall be stored in NVRAM and may not be 

erasable by any scan tool command (generic or enhanced) or by 

disconnecting power to the on-board computer.

(iv) Permanent fault codes may not be erased when the control module

containing the permanent fault codes is reprogrammed unless the 

readiness status bits (refer to section (h)(4.1)) for all monitored 

components and systems in all modules that reported supported 

readiness for a readiness bit other than the comprehensive 

components readiness bit are set to “not complete” in conjunction with 

the reprogramming event.

(v) The OBD system shall have the ability to store a minimum of four 

current MIL-on fault codes as permanent fault codes in NVRAM. If the 

number of MIL-on fault codes currently commanding the MIL on 

exceeds the maximum number of permanent fault codes that can be 

stored, the OBD system shall store the earliest detected MIL-on fault 

codes as permanent fault codes. If additional MIL-on fault codes are 

stored when the maximum number of permanent fault codes is already 

stored in NVRAM, the OBD system may not replace any existing 

permanent fault code with the additional MIL-on fault codes.

(4.5) Test Results:

(4.5.1) Except as provided in section (h)(4.5.7), for all monitored components and 

systems identified in sections (e)(1) through (f)(9), results of the most 

recent monitoring of the components and systems and the test limits 

established for monitoring the respective components and systems shall 

be stored and available through the data link in accordance with the 

standardized format specified in SAE J1979 for the ISO 15765-4 protocol 

or SAE J1939.

(4.5.2) The test results shall be reported such that properly functioning 

components and systems (e.g., “passing” systems) do not store test 

values outside of the established test limits. Test limits shall include both 

minimum and maximum acceptable values and shall be defined so that a 

test result equal to either test limit is a “passing” value, not a “failing” 

value.

(4.5.3) The test results shall be standardized such that the name of the monitored 

component (e.g., catalyst bank 1) can be identified by a generic scan tool 

and the test results and limits can be scaled and reported with the 

appropriate engineering units by a generic scan tool.

(4.5.4) The test results shall be stored until updated by a more recent valid test 

result or the fault memory of the OBD system computer is cleared.

(4.5.5) If the OBD system fault memory is cleared,:

(A) For vehicles using the ISO 15765-4 protocol for the standardized 

functions required in section (h), all test results shall report values of zero 

for the test result and test limits. The test results shall be updated once
117

the applicable monitor has run and has valid test results and limits to 

report.

(B) For vehicles using the SAE J1939 protocol for the standardized functions 

required in section (h):

(i) For 2010 through 2015 model year engines, all test results shall either 

(a) report values of zero for the test results and test limits, or (b) report 

values corresponding to ‘test not complete’ in accordance with SAE 

J1939-73 specifications. The test results shall be updated once the 

applicable monitor has run and has valid test results and limits to 

report.

(ii) For 2016 and subsequent model year engines, all test results shall 

report values corresponding to ‘test not complete’ in accordance with 

SAE J1939-73 specifications. The test results shall be updated once 

the applicable monitor has run and has valid test results and limits to 

report.

(4.5.6) All test results and test limits shall always be reported. The OBD system 

shall store and report unique test results for each separate diagnostic.

(4.5.7) The requirements of section (h)(4.5) do not apply to gasoline fuel system 

monitors specified under sections (f)(1.2.1)(A), (f)(1.2.1)(B), (f)(1.2.2), 

(f)(1.2.4), and (f)(1.2.5), exhaust gas sensor monitors specified under 

sections (e)(9.2.1)(A)(iii), (e)(9.2.1)(B)(iii), (e)(9.2.2)(C), (f)(8.2.1)(C), and 

(f)(8.2.2)(E), cold start emission reduction strategy monitors, circuit and

out-of-range monitors that are required to be continuous, and diesel 

feedback control monitors specified under sections (e)(1.2.4), (e)(3.2.4), 

(e)(4.2.5), (e)(6.2.2)(D), (e)(7.2.3), and (e)(8.2.7).

(4.6) Software Calibration Identification:

(4.6.1) Except as provided for in section (h)(4.6.3), on all vehicles, a single 

software calibration identification number (CAL ID) for each diagnostic or 

emission critical control unit(s) shall be made available through the 

standardized data link connector in accordance with the SAE 

J1979/J1939 specifications. 

(4.6.2) A unique CAL ID shall be used for every emission-related calibration 

and/or software set having at least one bit of different data from any other 

emission-related calibration and/or software set. Control units coded with 

multiple emission or diagnostic calibrations and/or software sets shall 

indicate a unique CAL ID for each variant in a manner that enables an offboard device to determine which variant is being used by the vehicle. 

Control units that utilize a strategy that will result in MIL illumination if the 

incorrect variant is used (e.g., control units that contain variants for 

manual and automatic transmissions but will illuminate the MIL if the 

variant selected does not match the type of transmission on the vehicle) 

are not required to use unique CAL IDs.

(4.6.3) Manufacturers may request Executive Officer approval to respond with 

more than one CAL ID per diagnostic or emission critical powertrain 

control unit. Executive Officer approval of the request shall be based on 

the method used by the manufacturer to ensure each control unit will 

respond to a generic scan tool with the CAL IDs in order of highest to 
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lowest priority with regards to areas of the software most critical to 

emission and OBD system performance.

(4.7) Software Calibration Verification Number:

(4.7.1) All vehicles shall use an algorithm to calculate a single calibration 

verification number (CVN) that verifies the on-board computer software 

integrity for each diagnostic or emission critical electronic control unit. 

The CVN shall be made available through the standardized data link 

connector in accordance with the SAE J1979/J1939 specifications. The 

CVN shall be capable of being used to determine if the emission-related 

software and/or calibration data are valid and applicable for that vehicle 

and CAL ID.

(4.7.2) One CVN shall be made available for each CAL ID made available. For 

diagnostic or emission critical powertrain control units with more than one 

CAL ID, each CVN shall be output to a generic scan tool in the same 

order as the CAL IDs are output to the generic scan tool to allow the scan 

tool to match each CVN to the corresponding CAL ID.

(4.7.3) Manufacturers shall submit information for Executive Officer approval of 

the algorithm used to calculate the CVN. Executive Officer approval of 

the algorithm shall be based on the complexity of the algorithm and the 

determination that the same CVN is difficult to achieve with modified 

calibration values.

(4.7.4) The CVN shall be calculated at least once per ignition cycle and stored 

until the CVN is subsequently updated. Except for immediately after a 

reprogramming event or a non-volatile memory clear or for the first 30 

seconds of engine operation after a volatile memory clear or battery 

disconnect, the stored value shall be made available through the data link 

connector to a generic scan tool in accordance with SAE J1979/J1939 

specifications. The stored CVN value may not be erased when fault

memory is erased by a generic scan tool in accordance with SAE 

J1979/J1939 specifications or during normal vehicle shut down (i.e., key 

off, engine off).

(4.7.5) When a CVN request message is received by the on-board computer, the 

stored CVN value shall be made available through the data link connector 

to a generic scan tool. Except as provided for below, the on-board 

computer may not use delayed timing in sending the CVN and may not 

respond with a message indicating that the CVN value is not currently 

available. If the CVN request message is received immediately following 

erasure of the stored CVN value (i.e., within the first 120 seconds of 

engine operation after a reprogramming event or a non-volatile memory 

clear or within the first 120 seconds of engine operation after a volatile 

memory clear or battery disconnect), the on-board computer may respond 

with one or more messages directing the scan tool to wait or resend the 

request message after the delay. Such messages and delays shall 

conform to the specifications for transmitting CVN data contained in SAE 

J1979 or J1939, whichever applies.

(4.7.5)(4.7.6) For purposes of Inspection and Maintenance (I/M) testing, 

manufacturers shall make the CVN and CAL ID combination information 

available for all vehicles in a standardized electronic format that allows for 
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off-board verification that the CVN is valid and appropriate for a specific 

vehicle and CAL ID. The standardized electronic format is detailed in 

Attachment F of ARB Mail-Out #MSC 09-22, July 7, 2009, incorporated by 

reference. Manufacturers shall submit the CVN and CAL ID information 

to the Executive Officer not more than 25 days after the close of a 

calendar quarter.

(4.8) Vehicle and Engine Identification Numbers:

(4.8.1) All vehicles shall have the vehicle identification number (VIN) available in 

a standardized format through the standardized data link connector in 

accordance with SAE J1979/J1939 specifications. Only one electronic 

control unit per vehicle shall report the VIN to an SAE J1978/J1939 scan 

tool.

(4.8.2) All 2013 and subsequent model year engines shall have the engine serial 

number (ESN) available in a standardized format through the 

standardized data link connector. Only one electronic control unit per 

vehicle shall report the ESN to an SAE J1978/J1939 scan tool.

(4.8.3) If the VIN or ESN is reprogrammable, in conjunction with reprogramming 

of the VIN or the ESN, the OBD system shall erase all emission-related 

diagnostic information identified in section (h)(4.10.1) in all control 

modules that reported supported readiness for a readiness bit other than 

the comprehensive components readiness bit shall be erased in 

conjunction with reprogramming of the VIN or the ESN.

(4.9) ECU Name: For 2013 and subsequent model year engines, the name of each 

electronic control unit that responds to an SAE J1978/J1939 scan tool with a 

unique address or identifier shall be communicated in a standardized format 

in accordance with SAE J1979/J1939 (e.g., ECUNAME in Service/Mode $09, 

InfoType $0A in SAE J1979).

(4.10) Erasure of Emission-Related Diagnostic Information: 

(4.10.1) For purposes of section (h)(4.10), “emission-related diagnostic 

information” includes all the following:

(A) Readiness status (section (h)(4.1))

(B) Data stream information (section (h)(4.2)) including number of stored 

confirmed/MIL-on fault codes, distance traveled while MIL activated, 

number of warm-up cycles since fault memory last cleared, and distance 

traveled since fault memory last cleared.

(C) Freeze frame information (section (h)(4.3))

(D) Pending, confirmed, MIL-on, and previously MIL-on fault codes (section 

(h)(4.4.))

(E) Test results (section (h)(4.5))

(4.10.2) For all vehicles, the emission-related diagnostic information shall be 

erased if commanded by a scan tool (generic or enhanced) and may be 

erased if the power to the on-board computer is disconnected. Except as 

provided for in sections (h)(4.4.1)(F)(iv), (h)(4.4.2)(F)(iv), and (h)(4.8.3), Iif 

any of the emission-related diagnostic information is commanded to be 

erased by a scan tool (generic or enhanced), all emission-related 

diagnostic information from all diagnostic or emission critical control units 

shall be erased. The OBD system may not allow a scan tool to erase a 

subset of the emission-related diagnostic information (e.g., the OBD 
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system may not allow a scan tool to erase only one of three stored fault 

codes or only information from one control unit without erasing information 

from the other control unit(s)).

(5) Tracking Requirements:

(5.1) In-use Performance Ratio Tracking Requirements:

(5.1.1) For each monitor required in sections (e) through (g) to separately report 

an in-use performance ratio, manufacturers shall implement software 

algorithms to report a numerator and denominator in the standardized 

format specified below and in accordance with the SAE J1979/J1939 

specifications.

(5.1.2) Numerical Value Specifications:

(A) For the numerator, denominator, general denominator, and ignition cycle 

counter:

(i) Each number shall have a minimum value of zero and a maximum 

value of 65,535 with a resolution of one.

(ii) Each number shall be reset to zero only when a non-volatile random 

access memory (NVRAM) reset occurs (e.g., reprogramming event) or, 

if the numbers are stored in keep-alive memory (KAM), when KAM is 

lost due to an interruption in electrical power to the control module 

(e.g., battery disconnect). Numbers may not be reset to zero under 

any other circumstances including when a scan tool command to clear 

fault codes or reset KAM is received.

(iii) If either the numerator or denominator for a specific component 

reaches the maximum value of 65,535 ±2, both numbers shall be 

divided by two before either is incremented again to avoid overflow 

problems.

(iv) If the ignition cycle counter reaches the maximum value of 65,535 ±2, 

the ignition cycle counter shall rollover and increment to zero on the 

next ignition cycle to avoid overflow problems.

(v) If the general denominator reaches the maximum value of 65,535 ±2, 

the general denominator shall rollover and increment to zero on the 

next driving cycle that meets the general denominator definition to 

avoid overflow problems.

(vi) If a vehicle is not equipped with a component (e.g., oxygen sensor 

bank 2, secondary air system), the corresponding numerator and 

denominator for that specific component shall always be reported as 

zero.

(B) For the ratio:

(i) The ratio shall have a minimum value of zero and a maximum value of 

7.99527 with a resolution of 0.000122.

(ii) A ratio for a specific component shall be considered to be zero 

whenever the corresponding numerator is equal to zero and the 

corresponding denominator is not zero.

(iii) A ratio for a specific component shall be considered to be the 

maximum value of 7.99527 if the corresponding denominator is zero or 

if the actual value of the numerator divided by the denominator 

exceeds the maximum value of 7.99527.
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(5.2) Engine Run Time Tracking Requirements:

(5.2.1) For all gasoline and diesel engines, manufacturers shall implement 

software algorithms to individually track and report in a standardized 

format the engine run time while being operated in the following 

conditions: 

(A) Total engine run time;

(B) Total idle run time (with “idle” defined as accelerator pedal released by 

driver, engine speed greater than or equal to 50 to 150 rpm below the 

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

vehicles equipped with an automatic transmission), PTO not active, and 

either vehicle speed less than or equal to one mile per hour or engine 

speed less than or equal to 200 rpm above normal warmed-up idle), and;

(C) Total run time with PTO active;

(D) For 2013 and subsequent model year diesel engines only:

(i) total run time with EI-AECD #1active;

(ii) total run time with EI-AECD #2 active; and so on up to

(iii) total run time with EI-AECD #n active.

(5.2.2) Numerical Value Specifications: For each counter specified in section 

(h)(5.2.1):

(A) Each number shall conform to the standardized format specified in SAE 

J1979/J1939.

(B) Each number shall be reset to zero only when a non-volatile memory 

reset occurs (e.g., reprogramming event). Numbers may not be reset to 

zero under any other circumstances including when a scan tool (generic 

or enhanced) command to clear fault codes or reset KAM is received.

(C) If any of the individual counters reach the maximum value, all counters 

shall be divided by two before any are incremented again to avoid 

overflow problems.

(D) The counters shall be made available to a generic scan tool in 

accordance with the SAE J1979/J1939 specifications and may be 

rescaled when transmitted, if required by the SAE specifications, from a 

resolution of one second per bit to no more than three minutes per bit.

(5.2.3) Specifications of EI-AECDs

(A) For purposes of section (h)(5.2.3), the following terms shall be defined as 

follows:

(i) “Purpose” is defined as the objective of the EI-AECD when it is 

activated (e.g., EGR valve protection);

(ii) “Action” is defined as a specific component/element act that is 

commanded when the EI-AECD is activated (e.g., EGR system is 

derated);

(iii) “Parameter” is defined as a component/element (e.g., ECT, oil 

temperature) used to determine when to activate the EI-AECD; and 

(iv) “Condition” is defined as the specific characteristic/state exhibited by 

the parameter (e.g., ECT above 100 degrees Celsius) that triggers 

activation of the EI-AECD. 

(B) Each unique combination of action, parameter, and condition within a 

purpose shall be tracked as a separate EI-AECD and increment the 

timer(s) at all times the condition necessary to activate the EI-AECD is 
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present.

(i) For EI-AECDs that implement an action of variable degree based on 

the varying characteristics of a parameter (e.g., derate EGR more 

aggressively as engine oil temperature continues to increase), the EIAECD shall be tracked by incrementing two separate timers within a 

single EI-AECD (e.g., EI-AECD #1 timer 1 and EI-AECD #1 timer 2) as 

follows:

a. The first of the two timers shall be incremented whenever the EIAECD is commanding some amount of reduced emission control

effectiveness up to but not including 75 percent of the maximum 

reduced emission control effectiveness that the EI-AECD is 

capable of commanding during in-use vehicle or engine operation. 

For example, an overheat protection strategy that progressively 

derates EGR and eventually shuts off EGR as oil temperature 

increases would accumulate time for the first timer from the time 

derating of EGR begins up to the time that EGR is derated 75 

percent. As a second example, an overheat protection strategy 

that advances fuel injection timing progressively up to a maximum 

advance of 15 degrees crank angle as the engine coolant 

temperature increases would accumulate time for the first timer 

from the time advance is applied up to the time that advance 

reaches 11.25 degrees (75 percent of the maximum 15 degrees).

b. The second of the two timers shall be incremented whenever the EIAECD is commanding 75 percent or more of the maximum reduced 

emission control effectiveness that the EI-AECD is capable of 

commanding during in-use vehicle or engine operation. For 

example, the second timer for the first example EI-AECD identified 

in section (h)(5.2.3)(B)(i) would accumulate time from the time that 

EGR is derated 75 percent up to and including when EGR is 

completely shut off. For the second example EI-AECD identified in 

section (h)(5.2.3)(B)(i), the second timer would accumulate time 

from the time fuel injection timing advance is at 11.25 degrees up 

to and including the maximum advance of 15 degrees.

(C) A manufacturer may request Executive Officer approval to combine 

multiple unique actions, parameters, and/or conditions to be tracked within 

a single EI-AECD. The manufacturer shall submit a plan for combining, 

tracking, and incrementing the EI-AECD to the Executive Officer for 

approval. Executive Officer approval of the plan shall be based on the 

effectiveness and the equivalence of the incrementing plan to determine 

the amount of EI-AECD activity per condition relative to the measure of 

EI-AECD activity under section (h)(5.2.3)(B). 

(D) For EI-AECDs that are activated solely due to elevation, the timer shall be 

incremented only for the portion of EI-AECD activation when the elevation 

is below 8000 feet (e.g., the timer for an EI-AECD that is activated when 

the elevation is above 5000 feet shall be incremented only when the EIAECD is active and the elevation is below 8000 feet).

(E) For EI-AECDs that are initially activated due to engine warm-up and are 

subsequently reactivated after the engine has warmed up, the timer shall 
123

be incremented only when the EI-AECD is active after the initial engine 

warm-up (e.g., an EI-AECD that turns off an emission control at low 

engine coolant temperature would not increment the timer during initial 

warm-up but would increment the timer if coolant temperature 

subsequently dropped below the low temperature and reactivated the EIAECD later in the drive cycle).

(F) If more than one EI-AECD is currently active, the timers for both EIAECDs shall accumulate time, regardless if there is overlap or 

redundancy in the commanded action (e.g., two different EI-AECDs 

independently but simultaneously commanding EGR off shall both 

accumulate time in their respective timers).

(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 

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 
124

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”.

(7) Exceptions to Standardization Requirements.

(7.1) For 2020 and subsequent model year alternate-fueled engines derived from a 

diesel-cycle engine, a manufacturer may meet the standardized requirements 

of section (h) that are applicable to diesel engines in lieu of the requirements 

applicable to gasoline engines.

(i) Monitoring System Demonstration Requirements for Certification.

(1) General.

(1.1) Certification requires that manufacturers submit emission test data from one 

or more durability demonstration test engines (test engines). 

(1.2) The Executive Officer may approve other demonstration protocols if the 

manufacturer can provide comparable assurance that the malfunction criteria 

are chosen based on meeting the malfunction criteria requirements and that 

the timeliness of malfunction detection is within the constraints of the 

applicable monitoring requirements.

(1.3) For flexible fuel engines capable of operating on more than one fuel or fuel 

combinations, the manufacturer shall submit a plan for providing emission 

test data to the Executive Officer for approval. The Executive Officer shall 

approve the plan if it is determined to be representative of expected in-use 

fuel or fuel combinations and provides accurate and timely evaluation of the 

monitored systems.

(2) Selection of Test Engines:

(2.1) Prior to submitting any applications for certification for a model year, a 

manufacturer shall notify the Executive Officer of the engine families and 

engine ratings within each family planned for that model year. The Executive 

Officer will then select the engine family(ies) and the specific engine rating 

within the engine family(ies) that the manufacturer shall use as demonstration 

test engines to provide emission test data. The selection of test vehicles for 

production vehicle evaluation, as specified in section (l)(2), may take place 

during this selection process.
125

(2.2) Number of test engines:

(2.2.1) For the 2010 model year, a manufacturer shall provide emission test data 

of a test engine from the OBD parent rating.

(2.2.2) For the 2011 and 2012 model years, a manufacturer certifying one to 

seven engine families in a model year shall provide emission test data of 

a test engine from one OBD child rating. A manufacturer certifying eight 

or more engine families in a model year shall provide emission test data of 

test engines from two OBD child ratings. The Executive Officer may 

waive the requirement for submittal of data of one or more of the test 

engines if data have been previously submitted for all of the OBD parent 

and OBD child ratings.

(2.2.3) For the 2013 and subsequent model years, a manufacturer certifying one 

to five engine families in a model year shall provide emission test data of 

a test engine from one engine rating. A manufacturer certifying six to ten 

engine families in a model year shall provide emission test data from test 

engines from two engine ratings. A manufacturer certifying eleven or 

more engine families in a model year shall provide emission test data of 

test engines from three engine ratings. The Executive Officer may waive 

the requirement for submittal of data of one or more of the test engines if 

data have been previously submitted for all of the engine ratings.

(2.2.4) For a given model year, a manufacturer may elect to provide emission 

data of test engines from more engine ratings than required by section 

(i)(2.2.1) through (2.2.3). For each additional engine rating tested in that 

given model year, the Executive Officer shall reduce the number of engine 

ratings required for testing in one future model year under sections 

(i)(2.2.2) through (2.2.3) by one. 

(2.3) Aging and data collection of diesel test engines:

(2.3.1) For 2010 through 2012 model year test engines, a manufacturer shall use 

an engine aged for a minimum of 125 hours plus exhaust aftertreatment 

emission controls aged by an accelerated aging process to be 

representative of full useful life. Manufacturers are required to submit for 

Executive Officer approval a description of the accelerated aging process 

and/or supporting data. The Executive Officer shall approve the process 

upon determining that the submitted description and/or data demonstrate 

that the process ensures that deterioration of the exhaust aftertreatment 

emission controls is stabilized sufficiently such that it is representative of 

the manufacturer’s best estimates for the performance of the emission 

control at the end of the useful life. The Executive Officer may not require 

manufacturers to provide actual in-use or high mileage data to verify or 

validate that the aging is equivalent to full useful life for purposes of 

section (i)(2.3.1).

(2.3.2) For 2013 through 2015 model year test engines:

(A) A manufacturer shall collect emission and deterioration data from an 

actual high mileage system(s) (consisting of the engine, engine emission 

controls, and aftertreatment) to validate its accelerated aging process. 

The manufacturer shall collect the data from a 2010 or newer model year 

system that is the most representative of system designs planned for the 

2013 model year and has a minimum actual mileage of full useful life or 
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185,000 miles, whichever is lower. The manufacturer shall collect and 

report the data to ARB prior to the end of 2011. The manufacturer shall 

submit a plan for system selection, procurement, and data collection to 

the Executive Officer for approval prior to proceeding with the data 

collection. The Executive Officer shall approve the plan upon determining 

that the submitted description will result in the manufacturer gathering 

data necessary to quantify emission performance and deterioration of the 

system elements in a manner that will allow comparison to deterioration 

and performance levels achieved with the manufacturer’s accelerated 

aging process.

(B) For testing of 2013 through 2015 model year engines, a manufacturer 

shall use a system (engine, engine emission controls, and aftertreatment) 

aged by an accelerated aging process to be representative of full useful 

life. Manufacturers are required to submit for Executive Officer approval a 

description of the accelerated aging process and supporting data. The 

Executive Officer shall approve the process upon determining that the 

submitted description and data demonstrate that the aging process will 

result in a system representative of the manufacturer’s best estimates of 

the system performance at full useful life and that the manufacturer has 

utilized the data collected under section (i)(2.3.2)(A) to validate the 

correlation of the aging process to actual high mileage systems up to a 

minimum of full useful life or 185,000 miles.

(2.3.3) For 2016 and subsequent model year test engines:

(A) A manufacturer shall collect emission and deterioration data from an 

actual high mileage system(s) (consisting of the engine, engine emission 

controls, and aftertreatment) to validate its accelerated aging process. 

The manufacturer shall collect the data from a 2010 or newer model year 

system that is the most representative of system designs planned for the 

2016 model year and has a minimum actual mileage of full useful life. 

The manufacturer shall collect and report the data to ARB prior to the end 

of 2014. The manufacturer shall submit a plan for system selection, 

procurement, and data collection to the Executive Officer for approval 

prior to proceeding with the data collection. The Executive Officer shall 

approve the plan upon determining that the submitted description will 

result in the manufacturer gathering data necessary to quantify emission 

performance and deterioration of the system elements in a manner that 

will allow comparison to deterioration and performance levels achieved 

with the manufacturer’s accelerated aging process.

(B) For testing of 2016 and subsequent model year engines, a manufacturer 

shall use a system (engine, engine emission controls, and aftertreatment) 

aged by an accelerated aging process to be representative of full useful 

life. Manufacturers are required to submit for Executive Officer approval a 

description of the accelerated aging process and supporting data. The 

Executive Officer shall approve the process upon determining that the 

submitted description and data demonstrate that the aging process will 

result in a system representative of the manufacturer’s best estimates of 

the system performance at full useful life and that the manufacturer has 

utilized the data collected under section (i)(2.3.3)(A) to validate the 
127

correlation of the aging process to actual high mileage systems up to a 

minimum of full useful life.

(2.4) Aging of gasoline engines: For the test engine(s), a manufacturer shall use a 

certification emission durability test engine(s) system (i.e., consisting of the 

engine, engine emission controls, and aftertreatment), a representative high 

mileage engine(s) system, or an engine(s) system aged to the end of the full 

useful life using an ARB-approved alternative durability procedure (ADP).

(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: 

(3.1.1) Fuel System: The manufacturer shall perform a separate test for each 

malfunction limit established by the manufacturer for the fuel system 

parameters (e.g., fuel pressure, injection timing) and calibrated to the 

emission threshold malfunction criteria (e.g., 2.0 times the standard)

specified in sections (e)(1.2.1) through (e)(1.2.3). When performing a test 

for a specific parameter, the fuel system shall be operating at the 

malfunction criteria limit for the applicable parameter only. All other 

parameters shall be with normal characteristics. In conducting the fuel 

system demonstration tests, the manufacturer may use computer 

modifications to cause the fuel system to operate at the malfunction limit if 

the manufacturer can demonstrate to the Executive Officer that the 

computer modifications produce test results equivalent to an induced 

hardware malfunction.

(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).

(3.1.3) EGR System: The manufacturer shall perform a test at each flow, slow 

response, and cooling limit calibrated to the emission threshold

malfunction criteria (e.g., 2.0 times the standard) in sections (e)(3.2.1) 

through (3.2.3) and (e)(3.2.5). In conducting the EGR cooler performance 

demonstration test, the EGR cooler(s) being evaluated shall be 

deteriorated to the applicable malfunction criteria using methods 

established by the manufacturer in accordance with section (e)(3.2.9). In 

conducting the EGR system slow response demonstration tests, the 

manufacturer may use computer modifications to cause the EGR system 

to operate at the malfunction limit if the manufacturer can demonstrate to 

the Executive Officer that the computer modifications produce test results 

equivalent to an induced hardware malfunction or that there is no 

reasonably feasible method to induce a hardware malfunction.

(3.1.4) Boost Pressure Control System: The manufacturer shall perform a test at 
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each boost, response, and cooling limit calibrated to the emission 

threshold malfunction criteria (e.g., 2.0 times the FTP standard) in 

sections (e)(4.2.1) through (4.2.3) and (e)(4.2.4). In conducting the 

charge air undercooling demonstration test, the charge air cooler(s) being 

evaluated shall be deteriorated to the applicable malfunction criteria limit

established by the manufacturer in section (e)(4.2.4) using methods 

established by the manufacturer in accordance with section (e)(4.2.8).

(3.1.5) NMHC Catalyst: The manufacturer shall perform a separate test for each 

monitored NMHC catalyst(s) that is used for a different purpose (e.g., 

oxidation catalyst upstream of a PM filter, NMHC catalyst used 

downstream of an SCR catalyst). The catalyst(s) being evaluated shall be 

deteriorated to the applicable malfunction criteria limit(s) established by 

the manufacturer and calibrated to the emission threshold malfunction 

criteria (e.g., 2.0 times the standard) in section (e)(5.2.2)(A) and 

(e)(5.2.2)(B) using methods established by the manufacturer in 

accordance with section (e)(5.2.4). For each monitored NMHC 

catalyst(s), the manufacturer shall also demonstrate that the OBD system 

will detect a catalyst malfunction with the catalyst at its maximum level of 

deterioration (i.e., the substrate(s) completely removed from the catalyst 

container or “empty” can). Emission data are not required for the empty 

can demonstration.

(3.1.6) NOx Catalyst: The manufacturer shall perform a separate test for each 

monitored NOx catalyst(s) that is used for a different purpose (e.g., 

passive lean NOx catalyst, SCR catalyst). The catalyst(s) being evaluated 

shall be deteriorated to the applicable malfunction criteria limit(s)

established by the manufacturer and calibrated to the emission threshold 

malfunction criteria (e.g., 2.0 times the standard) in sections 

(e)(6.2.1)(A)(i), (e)(6.2.1)(B)(i), and (e)(6.2.2)(A) using methods 

established by the manufacturer in accordance with section (e)(6.2.3). 

For each monitored NOx catalyst(s), the manufacturer shall also 

demonstrate that the OBD system will detect a catalyst malfunction with 

the catalyst at its maximum level of deterioration (i.e., the substrate(s) 

completely removed from the catalyst container or “empty” can). 

Emission data are not required for the empty can demonstration.

(3.1.7) NOx Adsorber: The manufacturer shall perform a test using a NOx 

adsorber(s) deteriorated to the malfunction limit calibrated to the emission 

threshold malfunction criteria (e.g., 2.0 times the standard) in section 

(e)(7.2.1). The manufacturer shall also demonstrate that the OBD system 

will detect a NOx adsorber malfunction with the NOx adsorber at its 

maximum level of deterioration (i.e., the substrate(s) completely removed 

from the container or “empty” can). Emission data are not required for the 

empty can demonstration.

(3.1.8) PM Filter: The manufacturer shall perform a test using a PM filter(s) 

deteriorated to each applicable malfunction limit calibrated to the emission 

threshold malfunction criteria (e.g., 2.0 times the standard) in sections 

(e)(8.2.1), (e)(8.2.2), and (e)(8.2.4)(A). The manufacturer shall also 

demonstrate that the OBD system will detect a PM filter malfunction with 

the filter at its maximum level of deterioration (i.e., the filter(s) completely 
129

removed from the filter container or “empty” can). Emission data are not 

required for the empty can demonstration.

(3.1.9) Exhaust Gas Sensor: The manufacturer shall perform a test for each 

exhaust gas sensor parameter at the each malfunction limit calibrated to 

the emission threshold malfunction criteria (e.g., 2.0 times the FTP

standard) in sections (e)(9.2.1)(A)(i), (e)(9.2.1)(B)(i)a. through b., and 

(e)(9.2.2)(A)(i) through (ii). When performing a test, all exhaust gas 

sensors used for the same purpose (e.g., for the same feedback control 

loop, for the same control feature on parallel exhaust banks) shall be 

operating at the malfunction criteria limit for the applicable parameter only. 

All other exhaust gas sensor parameters shall be with normal 

characteristics.

(3.1.10) VVT System: The manufacturer shall perform a test at each target error 

limit and slow response limit calibrated to the emission threshold 

malfunction criteria (e.g., 2.0 times the FTP standard) in sections 

(e)(10.2.1) and (e)(10.2.2). In conducting the VVT system demonstration 

tests, the manufacturer may use computer modifications to cause the VVT 

system to operate at the malfunction limit if the manufacturer can 

demonstrate to the Executive Officer that the computer modifications 

produce test results equivalent to an induced hardware malfunction.

(3.1.11) Cold Start Emission Reduction Strategy: The manufacturer shall perform 

a test at the malfunction limit calibrated to the emission threshold 

malfunction criteria (e.g., 2.0 times the standard) for the system or for 

each component monitored according to section (e)(11.2.2).

(3.1.12) For each of the testing requirements of section (i)(3.1), if the 

manufacturer has established that only a functional check is required 

because no failure or deterioration of the specific tested system could 

result in an engine’s emissions exceeding the emission threshold

malfunction criteria (e.g., 2.0 times any of the applicable standards), the 

manufacturer is not required to perform a demonstration test; however the 

manufacturer is required to provide the data and/or engineering analysis 

used to determine that only a functional test of the system(s) is required. 

(3.2) Required testing for Gasoline/Spark-Ignited Engines:

(3.2.1) Fuel System:

(A) For engines with adaptive feedback based on the primary fuel control 

sensor(s), the manufacturer shall perform a test with the adaptive

feedback based on the primary fuel control sensor(s) at the rich limit(s) 

and a test at the lean limit(s) established by the manufacturer and 

calibrated to the emission threshold malfunction criteria (e.g., 1.5 times 

the standard) in section (f)(1.2.1)(A) to detect a malfunction before 

emissions exceed 1.5 times the applicable standards. For purposes of 

fuel system testing, the fault(s) induced may result in a uniform distribution 

of fuel and air among the cylinders. Non-uniform distribution of fuel and 

air used to induce a fault may not cause misfire.

(B) For engines with feedback based on a secondary fuel control sensor(s) 

and subject to the malfunction criteria in section (f)(1.2.1)(B), the 

manufacturer shall perform a test with the feedback based on the 

secondary fuel control sensor(s) at the rich limit(s) and a test at the lean 
130

limit(s) established by the manufacturer and calibrated to the emission 

threshold malfunction criteria (e.g., 1.5 times the standard) in section 

(f)(1.2.1)(B) to detect a malfunction before emissions exceed 1.5 times 

the applicable standards.

(C) For engines subject to the malfunction criteria in section (f)(1.2.1)(C) 

(monitoring of air-fuel ratio cylinder imbalance faults), the manufacturer 

shall perform a test at the malfunction limit(s) calibrated to the emission 

threshold malfunction criteria (e.g., 1.5 times the standard) in section 

(f)(1.2.1)(C). The manufacturer shall perform the test at the rich limit and 

another test at the lean limit with a fault induced on the worst case 

cylinder for each limit. The manufacturer shall submit data and/or 

analysis demonstrating that a fault of the cylinder(s) will result in the worst 

case emissions for each malfunction limit.

(C)(D) For other fuel metering or control systems, the manufacturer shall 

perform a test at the criteria limit(s).

(D)(E) For purposes of fuel system testing, the fault(s) induced may result in 

a uniform distribution of fuel and air among the cylinders. Non-uniform 

distribution of fuel and air used to induce a fault may not cause misfire. In 

conducting the fuel system demonstration tests, the manufacturer may 

use computer modifications to cause the fuel system to operate at the 

malfunction limit if the manufacturer can demonstrate to the Executive 

Officer that the computer modifications produce test results equivalent to 

an induced hardware malfunction.

(3.2.2) Misfire: The manufacturer shall perform a test at the malfunction criteria

limit calibrated to the emission threshold malfunction criteria (e.g., 1.5 

times the standard) specified in section (f)(2.2.2). 

(3.2.3) EGR System: The manufacturer shall perform a test at each flow limit 

calibrated to the emission threshold malfunction criteria (e.g., 1.5 times 

the standard) in sections (f)(3.2.1) and (f)(3.2.2).

(3.2.4) Cold Start Emission Reduction Strategy: The manufacturer shall perform a 

test at the malfunction limit calibrated to the emission threshold 

malfunction criteria (e.g., 1.5 times the standard) for each component 

monitored according to section (f)(4.2.1)(A) or (f)(4.2.2)(B).

(3.2.5) Secondary Air System: The manufacturer shall perform a test at each flow 

limit calibrated to the emission threshold malfunction criteria in sections 

(f)(5.2.1) and (f)(5.2.2). 

(3.2.6) Catalyst: The manufacturer shall perform a test using a catalyst system 

deteriorated to the emission threshold malfunction criteria (e.g., 1.5 times 

the standard) in section (f)(6.2.1) using methods established by the 

manufacturer in accordance with section (f)(6.2.2). The manufacturer 

shall also demonstrate that the OBD system will detect a catalyst system 

malfunction with the catalyst system at its maximum level of deterioration 

(i.e., the substrate(s) completely removed from the catalyst container or 

“empty” can). Emission data are not required for the empty can 

demonstration.

(3.2.7) Exhaust Gas Sensor: 

(A) The manufacturer shall perform a test with all primary oxygen sensors 

(conventional switching sensors and wide range or universal sensors) 
131

used for fuel control simultaneously possessing a response rate 

deteriorated to the malfunction criteria limit calibrated to the emission 

threshold malfunction criteria (e.g., 1.5 times the standard) in section 

(f)(8.2.1)(A). For conventional switching sensors, the manufacturer shall 

perform a test for each of the following malfunctions (1) the single worst 

case response rate malfunction among all symmetric and asymmetric 

patterns required by section (f)(8.2.1)(A), and (2) the worst case 

asymmetric response rate malfunction that results in delays during 

transitions from rich-to-lean or lean-to-rich sensor output. For wide range 

or universal sensors, the manufacturer shall perform a test for each of the 

following malfunctions: (1) the single worst case response rate 

malfunction among all symmetric and asymmetric patterns required by 

section (f)(8.2.1)(A), and (2) the symmetric response rate malfunction that 

results in delays during transitions from rich-to-lean and lean-to-rich 

sensor output. For systems where the same response rate pattern meets 

the criteria of (1) and (2) above, only one demonstration test is required.

For the response rate patterns not tested, the manufacturer is required to 

provide the data and/or engineering analysis used to determine that the 

tested response pattern for criterion (1) will result in the worst case 

emissions compared to all the other response rate malfunctions. 

Manufacturers shall also perform a test for any other oxygen sensor 

parameter under sections (f)(8.2.1)(A) and (f)(8.2.2)(A) that can cause 

engine emissions to exceed the emission threshold malfunction threshold

criteria (e.g., 1.5 times the applicable standards due to a shift in air/fuel 

ratio at which oxygen sensor switches, decreased amplitude). When 

performing additional test(s), all primary and secondary (if applicable) 

oxygen sensors used for fuel control shall be operating at the malfunction 

criteria limit for the applicable parameter only. All other primary and 

secondary oxygen sensor parameters shall be with normal characteristics.

(B) For engines utilizing sensors other than oxygen sensors for primary fuel 

control (e.g., hydrocarbon sensors), the manufacturer shall submit, for 

Executive Officer approval, a demonstration test plan for performing 

testing of all of the sensor parameters that can cause engine emissions to 

exceed the emission threshold malfunction threshold criteria (e.g., 1.5 

times the applicable standards). The Executive Officer shall approve the 

plan if it is determined that it will provide data that will assure proper 

performance of the diagnostics of the sensors, consistent with the intent 

of section (i).

(3.2.8) VVT System: The manufacturer shall perform a test at each target error 

limit and slow response limit calibrated to the emission threshold 

malfunction criteria (e.g., 1.5 times the FTP standard) in sections (f)(9.2.1) 

and (f)(9.2.2). In conducting the VVT system demonstration tests, the 

manufacturer may use computer modifications to cause the VVT system 

to operate at the malfunction limit if the manufacturer can demonstrate to 

the Executive Officer that the computer modifications produce test results 

equivalent to an induced hardware malfunction.

(3.2.9) For each of the testing requirements of section (i)(3.2), if the manufacturer 

has established that only a functional check is required because no failure 
132

or deterioration of the specific tested system could result in an engine’s 

emissions exceeding the emission threshold malfunction criteria (e.g., 1.5 

times any of the applicable standards), the manufacturer is not required to 

perform a demonstration test; however the manufacturer is required to

provide the data and/or engineering analysis used to determine that only a 

functional test of the system(s) is required.

(3.3) Required Testing for All Engines:

(3.3.1) Other Emission Control Systems: The manufacturer shall conduct 

demonstration tests for all other emission control components (e.g., 

hydrocarbon traps, adsorbers) designed and calibrated to an emission 

threshold malfunction criteria (e.g., 1.5 times the applicable emission

standards) under the provisions of section (g)(4).

(3.3.2) For each of the testing requirements of section (i)(3.3), if the manufacturer 

has established that only a functional check is required because no failure 

or deterioration of the specific tested system could result in an engine’s 

emissions exceeding the emission threshold malfunction criteria (e.g., 1.5 

times any of the applicable standards), the manufacturer is not required to 

perform a demonstration test; however the manufacturer is required to 

provide the data and/or engineering analysis used to determine that only a 

functional test of the system(s) is required.

(3.4) The manufacturer may electronically simulate deteriorated components if the 

manufacturer can demonstrate to the Executive Officer that the computer 

modifications produce test results equivalent to an induced hardware 

malfunction but may not make any engine control unit modifications (unless 

otherwise provided above or exempted pursuant to this section) when 

performing demonstration tests. All equipment necessary to duplicate the 

demonstration test must be made available to ARB upon request. A 

manufacturer may request Executive Officer approval to electronically 

simulate a deteriorated component with engine control unit modifications. 

The Executive Officer shall approve the request upon determining the 

manufacturer has submitted data and/or engineering analysis demonstrating 

that is technically infeasible, very difficult, and/or resource intensive to implant 

the fault with modifications external to the engine control unit.

(3.5) For each of the testing requirements of (i)(3), when performing a test, all 

components or systems used in parallel for the same purpose (e.g., separate 

VVT actuators on the intake valves for Bank 1 and Bank 2, separate NOx 

converting catalysts on parallel exhaust banks) shall be simultaneously 

deteriorated to the malfunction criteria limit. Components or systems in 

series or used for different purposes (e.g., upstream and downstream 

exhaust gas sensors in a single exhaust bank, separate high pressure and 

low pressure EGR systems) may not be simultaneously deteriorated to the 

malfunction criteria limit. 

(3.6) For each of the testing requirements under section (i)(3), if the manufacturer 

has established that only a functional check is required because no failure or 

deterioration of the specific tested system could result in an engine’s 

emissions exceeding the emission threshold malfunction criteria (e.g., 1.5 

times the standards), the manufacturer is not required to perform a 

demonstration test; however the manufacturer is required to provide the data 
133

and/or engineering analysis used to determine that only a functional test of 

the system(s) is required.

(4) Testing Protocol:

(4.1) Preconditioning:.The manufacturer may request Executive Officer approval to 

use a preconditioning cycle prior to conducting each of the above emission 

tests. The Executive Officer shall approve the request upon determining that 

a manufacturer has provided data and/or engineering evaluation that 

demonstrate that the preconditioning is necessary to stabilize the emission 

control system. The manufacturer may also request Executive Officer 

approval to use an additional identical preconditioning cycle following a 20 

minute hot soak after the initial preconditioning cycle. The Executive Officer 

shall approve the request upon determining that a manufacturer has provided 

data and/or engineering evaluation that demonstrate that the additional 

preconditioning is necessary to stabilize the emission control system. The 

manufacturer may not require the test engine to be cold soaked prior to 

conducting preconditioning cycles in order for the monitoring system testing 

to be successful. If a second preconditioning cycle is permitted, the 

manufacturer may adjust the system or component to be tested before 

conducting the second preconditioning cycle. The manufacturer may not 

replace, modify, or adjust the system or component after the last 

preconditioning cycle has taken place.

(4.2) Test Sequence:

(4.2.1) The manufacturer shall set the system or component on the test engine 

for which detection is to be tested at the malfunction criteria limit(s) prior 

to conducting the applicable emission test (or preconditioning, if 

approved). 

(4.2.2) The test engine shall be operated over the first engine start of the FTP 

emission test (i.e., the cold start) or a SET cycle to allow for the initial 

detection of the tested system or component malfunction. If required by 

the designated monitoring strategy, an additional cold soak and first 

engine start of the FTP cycle (i.e., the cold start) may be performed prior 

to conducting this test cycle (e.g., for two-trip monitors that only run during 

cold starts). 

(4.2.3) The test engine shall then be operated over the second engine start of the 

FTP emission test (i.e., the hot start) or an SET emission test. The 

second SET cycle may be omitted from the testing protocol if it is 

unnecessary (e.g., one-trip fault detection strategies that run on the SET).

(4.3) Test Data Collection: 

(4.3.1) During the test sequence of section (i)(4.2), the manufacturer shall collect 

data immediately prior to each engine shut-down (e.g., the end of each 

preconditioning cycle in section (i)(4.2.1), the end of the cold start FTP 

cycle in section (i)(4.2.3), the end of the warm start FTP cycle in section 

(i)(4.2.3)). If the data cannot be collected immediately prior to engine 

shut-down, the data shall be collected immediately after engine shutdown.

(4.3.2) The manufacturer shall be required to collect the following data:

(A) Approximate time on the test cycle (in seconds after engine start) when 

the MIL illuminates (e.g., MIL illuminated at 402 seconds into the cold start 
134

FTP cycle);

(B) All data required by sections (h)(4.1) through (h)(4.9) and (h)(5) including 

readiness status, current data stream values, fault code(s), freeze frame 

data, test results, CAL ID, CVN, VIN, ESN, ECU Name, in-use 

performance ratios, and engine run time tracking data.

(4.4) A manufacturer required to test more than one test engine (section (i)(2.2)) 

may utilize internal calibration sign-off test procedures (e.g., forced cool 

downs, less frequently calibrated emission analyzers) instead of official test 

procedures to obtain the emission test data required in section (i) for all but 

one of the required test engines. The manufacturer may elect this option if 

the data from the alternative test procedure are representative of official 

emission test results. Manufacturers using this option are still responsible for 

meeting the malfunction criteria specified in sections (e) through (g) when 

emission tests are performed in accordance with official test procedures.

(4.5) A manufacturer may request Executive Officer approval to utilize an alternate 

testing protocol for demonstration of MIL illumination if the engine 

dynamometer emission test cycle does not allow all of a monitor’s enable 

conditions to be satisfied. A manufacturer may request the use of an 

alternate engine dynamometer test cycle or the use of chassis testing to 

demonstrate proper MIL illumination. In evaluating the manufacturer's 

request, the Executive Officer shall consider the technical necessity for using 

an alternate test cycle and the degree to which the alternate test cycle 

demonstrates that in-use operation with the malfunctioning component will 

properly result in MIL illumination.

(5) Evaluation Protocol:

(5.1) Full OBD engine ratings subject to sections (d)(7.1.1), (d)(7.2.2), or (d)(7.3) 

shall be evaluated according to the following protocol. 

(5.1.1) For all tests conducted under section (i), the MIL shall be illuminated upon 

detection of the tested system or component malfunction before the end 

of the emission test specified in (i)(4.2.3) in accordance with the 

requirements of sections (e) through (g).

(5.1.2) If the MIL illuminates prior to emissions exceeding the applicable emission 

threshold malfunction criteria specified in sections (e) through (g), no 

further demonstration is required. With respect to the misfire monitor 

demonstration test, if a manufacturer has elected to use the minimum 

misfire malfunction criteria of one percent as allowed in sections 

(e)(2.2.2)(A) and (f)(2.2.2)(A), no further demonstration is required if the 

MIL illuminates with misfire implanted at the malfunction criteria limit.

(5.1.3) If the MIL does not illuminate when the system or component is set at its 

limit(s), the criteria limit or the OBD system is not acceptable.

(A) Except for testing of the catalyst (i.e., components monitored under 

sections (e)(5.2.2), (e)(6.2.1), (e)(7.2.1), and (f)(6.2.1)) or PM filter system

(i.e., (e)(8.2.1) and (e)(8.2.4)), iIf the MIL first illuminates after emissions 

exceed the applicable emission threshold malfunction criteria specified in 

sections (e) through (g), the test engine shall be retested with the tested 

system or component adjusted so that the MIL will illuminate before

without emissions exceeding the applicable emission threshold 

malfunction criteria specified in sections (e) through (g). If the system or 
135

component cannot be adjusted to meet this criterion because a default 

fuel or emission control strategy is used when a malfunction is detected 

(e.g., open loop fuel control used after an oxygen sensor malfunction is 

determined), the test engine shall be retested with the system or 

component adjusted to the worst acceptable limit (i.e., the applicable 

monitor indicates the system or component’s is performanceing is passing 

but at the closest possible value relative to the monitor threshold value at 

which a fault would be detected that would invoke the default strategy and 

illuminate the MILor slightly better than the malfunction criteria). The 

manufacturer may request the Executive Officer to accept test data when 

the system or component’s performance is at the worst acceptable limit 

within a margin of error necessary to accommodate testing variability 

and/or other practical limitations in setting the performance at the absolute 

worst acceptable limit. The Executive Officer shall accept the test data 

upon determining that the test data adequately demonstrate that 

emissions do not exceed the applicable malfunction criteria at the tested 

worst acceptable limit and that emissions will not exceed the applicable 

emission threshold malfunction criteria before performance exceeds the 

monitor threshold for fault detection. When tested with the component

adjusted to the worst acceptable limit, the MIL must not illuminate during 

the test and the engine emissions must be below the applicable 

malfunction criteria specified in sections (e) through (g). These provisions 

shall only apply to testing of the catalyst (i.e., components monitored 

under sections (e)(5.2.2), (e)(6.2.1), (e)(7.2.1), and (f)(6.2.1)) or PM filter 

system (i.e., (e)(8.2.1) and (e)(8.2.4)) if the on-board computer invokes a 

default fuel or emission control strategy upon detection of the relevant 

catalyst malfunction. Otherwise, the provisions of section (i)(5.1.3)(B) 

shall apply to testing of the catalyst or PM filter system.

(B) Except as provided for in section (i)(5.1.3)(A), iIn testing the catalyst (i.e.,

components monitored under sections (e)(5.2.2), (e)(6.2.1), (e)(7.2.1), 

and (f)(6.2.1)) or PM filter system (i.e., (e)(8.2.1) and (e)(8.2.4)), if the MIL 

first illuminates after emissions exceed the applicable emission

threshold(s) malfunction criteria specified in sections (e) and (f), the tested 

engine shall be retested with a less deteriorated catalyst/PM filter system 

(i.e., more of the applicable engine out pollutants are converted or

trapped). Adjustment and testing of the catalyst or PM filter system’s 

performance may be repeated until successful results are obtained. For 

the OBD system to be approved, testing shall be continued until either of 

the following conditions are must be satisfied by the test results:

(i) The MIL is illuminated and emissions do not exceed the emission 

thresholds malfunction criteria specified in sections (e) or (f); or 

(ii) The manufacturer demonstrates that the MIL illuminates within the 

upper and lower limits of the threshold malfunction criteria identified 

below. The manufacturer shall demonstrate acceptable limits by 

continuing testing until The demonstration shall be deemed 

appropriate when the test results show:

a. The MIL is illuminated and emissions exceed the emission 

thresholds malfunction criteria specified in sections (e) or (f) by 10
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20 percent or less of the applicable standard (e.g., emissions are 

less than 1.85 2.2 times the applicable standard for an emission 

threshold malfunction criterion of 1.75 2.0 times the standard); and

b. The MIL is not illuminated and emissions are below the emission 

thresholds malfunction criteria specified in sections (e) or (f) by no 

more than 20 percent of the standard (e.g., emissions are between 

1.55 1.8 and 1.75 2.0 times the applicable standard for an emission 

threshold malfunction criterion of 1.75 2.0 times the standard).

(5.1.4) If an OBD system is determined unacceptable by the above criteria, the 

manufacturer may recalibrate and retest the system on the same test 

engine. In such a case, the manufacturer must confirm, by retesting, that 

all systems and components that were tested prior to recalibration and are 

affected by the recalibration function properly under the OBD system as 

recalibrated.

(5.2) OBD child ratings subject to sections (d)(7.1.2) or (d)(7.2.3) (i.e., extrapolated 

OBD) shall be evaluated according to the following protocol. 

(5.2.1) For all tests conducted under section (i), the MIL shall be illuminated upon 

detection of the tested system or component malfunction before the end 

of the emission test specified in (i)(4.2.3) in accordance with the 

malfunction criteria established by the manufacturer under sections 

(d)(7.1.2) and (d)(7.2.3).

(5.2.2) Except for testing of the catalyst or PM filter system, if the MIL first 

illuminates after the tested component or system significantly exceeds the 

applicable malfunction criteria established by the manufacturer, the test 

engine shall be retested with the tested system or component adjusted so 

that the MIL will illuminate at the applicable malfunction criteria 

established by the manufacturer.

(5.2.3) In testing the catalyst or PM filter system, if the MIL first illuminates after 

the tested component or system significantly exceeds the applicable 

malfunction criteria established by the manufacturer, the tested engine 

shall be retested with a less deteriorated catalyst/PM filter system (i.e., 

more of the applicable engine out pollutants are converted or trapped). 

For the OBD system to be approved, testing shall be continued until either 

of the following conditions are satisfied:

(A) The MIL is illuminated and the tested component or system is at the 

applicable malfunction criteria established by the manufacturer; or 

(B) The manufacturer demonstrates that the MIL illuminates within the upper 

and lower limits of the threshold identified below. The manufacturer shall 

demonstrate acceptable limits by continuing testing until the test results 

show:

(i) The MIL is illuminated and monitoring results indicate the tested 

component or system exceeds the malfunction criteria established by 

the manufacturer by 10 percent or less of the monitored parameter; 

and

(ii) The MIL is not illuminated and monitoring results indicate the tested 

component or system is below the malfunction criteria established by 

the manufacturer by 10 percent or less of the monitored parameter.

(6) Confirmatory Testing:
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(6.1) ARB may perform confirmatory testing to verify the emission test data 

submitted by the manufacturer under the requirements of section (i) comply 

with the requirements of section (i) and the malfunction criteria identified in 

sections (e) through (g). This confirmatory testing is limited to the engine 

rating represented by the demonstration engine(s).

(6.2) ARB or its designee may install appropriately deteriorated or malfunctioning 

components (or simulate a deteriorated or malfunctioning component) in an 

otherwise properly functioning test engine of an engine rating represented by 

the demonstration test engine(s) in order to test any of the components or 

systems required to be tested in section (i). Upon request by the Executive 

Officer, the manufacturer shall make available an engine and all test 

equipment (e.g., malfunction simulators, deteriorated components) necessary 

to duplicate the manufacturer’s testing. The Executive Officer shall make the 

request within six months of reviewing and approving the demonstration test 

engine data submitted by the manufacturer for the specific engine rating.

(j) Certification Documentation.

(1) When submitting an application for certification of an engine, the manufacturer 

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

standardized for all of a manufacturer’s engines, the manufacturer may, for each 

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

of its engines.

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

manufacturer may propose to the Executive Officer that it be allowed to 

submit documentation for certification from one engine that is representative 

of other engines. The Executive Officer shall approve the engine as 

representative if the engine possesses the most stringent exhaust emission 

standards and OBD monitoring requirements and covers all of the emission 

control devices for the engines covered by the submitted documentation. 

Upon approval, this grouping shall be known as an “OBD certification 

documentation group”.

(1.2) With Executive Officer approval, one or more of the documentation 

requirements of section (j) may be waived or modified if the information 

required would be redundant or unnecessarily burdensome to generate.

(1.3) To the extent possible, the certification documentation shall use SAE J1930 

or J2403 terms, abbreviations, and acronyms.

(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:

(2.1) A description of the functional operation of the OBD system including a 

complete written description for each monitoring strategy that outlines every 

step in the decision-making process of the monitor. Algorithms, diagrams, 

samples of data, and/or other graphical representations of the monitoring 

strategy shall be included where necessary to adequately describe the 

information.

(2.2) A table, in the standardized format detailed in Attachment C of ARB Mail-Out 

#MSC 09-22 July 7, 2009, incorporated by reference.
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(2.2.1) The table must include the following information for each monitored 

component or system (either computer-sensed or -controlled) of the 

emission control system:

(A) Corresponding fault code

(B) Monitoring method or procedure for malfunction detection

(C) Primary malfunction detection parameter and its type of output signal

(D) Fault criteria limits used to evaluate output signal of primary parameter

(E) Other monitored secondary parameters and conditions (in engineering 

units) necessary for malfunction detection

(F) Monitoring time length and frequency of checks

(G) Criteria for storing fault code

(H) Criteria for illuminating malfunction indicator light

(I) Criteria used for determining out-of-range values and input component 

rationality checks

(2.2.2) Wherever possible, the table shall use the following engineering units:

(A) Degrees Celsius (°C) for all temperature criteria

(B) KiloPascals (KPa) for all pressure criteria related to manifold or 

atmospheric pressure

(C) Grams (g) for all intake air mass criteria

(D) Pascals (Pa) for all pressure criteria related to evaporative system vapor 

pressure

(E) Miles per hour (mph) for all vehicle speed criteria

(F) Relative percent (%) for all relative throttle position criteria (as defined in 

SAE J1979/J1939)

(G) Voltage (V) for all absolute throttle position criteria (as defined in SAE 

J1979/J1939)

(H) Milligrams per stroke (mg/stroke) for all fuel quantity-based per ignition 

event criteria for diesel engines, and Pper crankshaft revolution (/rev) for 

all other changes per ignition event based criteria (e.g., airflow in g/rev 

instead of g/stroke or g/firing) for gasoline and diesel engines

(I) Per second (/sec) for all changes per time based criteria (e.g., g/sec)

(J) Percent of nominal tank volume (%) for all fuel tank level criteria

(2.3) A logic flowchart describing the step-by-step evaluation of the enable criteria 

and malfunction criteria for each monitored emission-related component or 

system.

(2.4) Emission test data, a description of the testing sequence (e.g., the number 

and types of preconditioning cycles), the data required to be collected in 

section (i)(4.3), and a description of the modified or deteriorated components 

used for fault simulation with respect to the demonstration tests specified in 

section (i). The Executive Officer may approve conditional certification of an 

engine prior to the submittal of this data for ARB review and approval. 

Factors to be considered by the Executive Officer in approving the late 

submission of information identified in section (j)(2.4) shall include the reason 

for the delay in the data collection, the length of time until data will be 

available, and the demonstrated previous success of the manufacturer in 

submitting the data prior to certification.

(2.5) For gasoline engines, data supporting the misfire monitor, including:
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(2.5.1) The established percentage of misfire that can be tolerated without 

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

conditions.

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

misfire monitoring system over the full engine speed and load operating 

range as detailed in ARB Mail-Out #MSC 09-22 for the following misfire 

patterns: random cylinders misfiring at the malfunction criteria established 

in section (f)(2.2.2), one cylinder continuously misfiring, and paired 

cylinders continuously misfiring.

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

the FTP. For every disablement that occurs during the cycles, the data 

shouldshall 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 FTP 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 #MSC 09-22. 

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

to collect the misfire data for sections (j)(2.5.1) through (2.5.3).

(2.6) Data supporting the limit for the time between engine starting and attaining 

the designated heating temperature for after-start heated catalyst 

systems.For diesel engines subject to the monitoring requirements of section 

(e)(2.2.2), data supporting the misfire monitor, including:

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

misfire monitoring system as detailed in ARB Mail-Out #MSC 09-22 over the 

required engine speed and load operating range for the following misfire 

patterns: random cylinders misfiring at the malfunction criteria specified in 

section (e)(2.2.2), one cylinder continuously misfiring, and paired cylinders 

continuously misfiring.

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

the EPA Urban Dynamometer Driving Schedule for Heavy-Duty Vehicles 

specified in 40 CFR Part 86, Appendix I (d). For every disablement that 

occurs during the cycle, 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 #MSC 09-22.

(2.7) Data supporting the criteria used to detect a malfunction of the fuel system, 

EGR system, boost pressure control system, catalyst, NOx adsorber, PM 

filter, cold start emission reduction strategy, secondary air, evaporative 

system, VVT system, exhaust gas sensors, and other emission controls 

which causes emissions to exceed the applicable malfunction criteria 

specified in sections (e), (f), and (g). For diesel engine monitors in sections 
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(e) and (g) that are required to indicate a malfunction before emissions 

exceed an emission threshold based on any applicable standard (e.g., 1.5 

times any of the applicable standards), the test cycle and standard 

determined by the manufacturer to be the most stringent for each applicable 

monitor in accordance with section (d)(6.1) and the adjustment factors 

determined by the manufacturer for each applicable monitor in accordance 

with section (d)(6.2). 

(2.8) A listing of all electronic powertrain input and output signals (including those 

not monitored by the OBD system) that identifies which signals are monitored 

by the OBD system. For input and output signals that are monitored as 

comprehensive components, the listing shall also identify the specific fault 

code for each malfunction criteria (e.g., out of range low, out of range high, 

open circuit, rationality low, rationality high).

(2.9) A written description of all parameters and conditions necessary to begin 

closed-loop/feedback control of emission control systems (e.g., fuel system, 

boost pressure, EGR flow, SCR reductant delivery, PM filter regeneration, 

fuel system pressure).

(2.10) A written identification of the communication protocol utilized by each engine 

for communication with an SAE J1978/J1939 scan tool.

(2.11) A pictorial representation or written description of the diagnostic connector

and its location including any covers or labels.

(2.12) A written description of the method used by the manufacturer to meet the 

requirements of section (g)(2) for CV system monitoring including diagrams or 

pictures of valve and/or hose connections.

(2.13) A written description of each AECD utilized by the manufacturer including the 

sensor signals and/or calculated values used to invoke each AECD, the 

engineering data and/or analysis demonstrating the need for such an AECD, 

the actions taken when each AECD is activated, the expected in-use 

frequency of operation of each AECD, the expected emission impact from 

each AECD activation, and , for diesel engines, the identification of each 

AECD that has been determined by the manufacturer to be an EI-AECD and 

the assignment by the manufacturer to the data required to be tracked and 

reported in the standardized format specified in section (h)(6) (e.g., the AECD 

of “engine overheat protection as determined by coolant temperature greater 

than...” is an EI-AECD and is reported as EI-AECD #1 to a generic scan 

tool).

(2.14) A written description of each NOx and PM NTE deficiency and emission 

carve-out utilized by the manufacturer including the sensor signals and/or 

calculated values used to invoke each NTE deficiency or carve-out, the 

engineering data and/or analysis demonstrating the need for such an NTE 

deficiency or carve-out, the actions taken when each NTE deficiency or 

carve-out is activated, the expected in-use frequency of operation of each 

NTE deficiency or carve-out, and the expected emission impact from each 

NTE deficiency or carve-out activation.

(2.15) Build specifications provided to engine purchasers or chassis manufacturers 

detailing all specifications or limitations imposed on the engine purchaser 

relevant to OBD requirements or emission compliance (e.g., allowable MIL 

locations, connector location specifications, cooling system heat rejection 
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rates). A description of the method or copies of agreements used to ensure 

engine purchasers or chassis manufacturers will comply with the OBD and 

emission relevant build specifications (e.g., signed agreements, required 

audit/evaluation procedures). 

(2.16) A cover letter identifying all concerns and deficiencies applicable to the 

equivalent previous model year engine, and the changes and/or resolution of 

each concern or deficiency for the current model year engine, and all other 

known issues that apply to the current model year engine (e.g., concerns or 

deficiencies of another engine that also apply to this engine).

(2.17) A checklist of all the malfunction criteria in sections (e), (f), and (g) and the 

corresponding diagnostic noted by fault code for each malfunction criterion. 

The formats of the checklists are detailed in Attachments G and H of ARB 

Mail-Out #MSC 09-22, July 7, 2009, incorporated by reference.

(2.18) Any other information determined by the Executive Officer to be necessary to 

demonstrate compliance with the requirements of this regulation. A list of all 

components/systems required to track and report in-use performance under 

section (d)(3.2.1), the corresponding diagnostic(s) noted by fault code used to 

increment the numerator for each component/system, and a description of 

the incrementing specifications for the in-use monitor performance numerator 

and denominator for each diagnostic.

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

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

(2.20) A timeline showing the start of engine production and the start of vehicle 

production for the engine family, and the required deadlines for production 

vehicle evaluation testing of the standardized requirements (according to 

section (l)(1.2)) and the monitoring requirements (according to 

section (l)(2.1)).

(2.18)(2.21) Any other information determined by the Executive Officer to be 

necessary to demonstrate compliance with the requirements of this 

regulation.

(k) Deficiencies.

(1) The Executive Officer, upon receipt of an application from the manufacturer, may 

certify OBD systems installed on engines even though the systems do not 

comply with one or more of the requirements of title 13, CCR section 1971.1. In 

granting the certification, the Executive Officer shall consider the following 

factors: the extent to which the requirements of section 1971.1 are satisfied 

overall based on a review of the engine applications in question, the relative 

performance of the resultant OBD system compared to systems fully compliant 

with the requirements of section 1971.1, and a demonstrated good-faith effort on 

the part of the manufacturer to: (1) meet the requirements in full by evaluating 

and considering the best available monitoring technology; and (2) come into 

compliance as expeditiously as possible. The Executive Officer may not grant 

certification to an engine in which the reported noncompliance for which a 

deficiency is sought would be subject to ordered recall pursuant to section 

1971.5(d)(3)(A).

(2) For 2013 and subsequent model year engines, manufacturers of OBD systems 

for which deficiencies have been granted are subject to fines pursuant to section 
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43016 of the California Health and Safety Code. The specified fines apply to: (1) 

the third and subsequently identified deficiency(ies), ordered according to section 

(k)(3), and (2) a monitoring system deficiency where a required monitoring 

strategy is completely absent from the OBD system.

(3) The fines for engines specified in section (k)(2) above are in the amount of $50 

per deficiency per engine for non-compliance with any of the monitoring 

requirements specified in sections (e), (f), and (g)(4), and $25 per deficiency per 

engine for non-compliance with any other requirement of section 1971,1. In 

determining the identified order of deficiencies, deficiencies subject to a $50 fine 

are identified first. Total fines per engine under section (k) may not exceed $500 

per engine and are payable to the State Treasurer for deposit in the Air Pollution 

Control Fund.

(4) Manufacturers must re-apply for Executive Officer approval of a deficiency each 

model year. In considering the request to carry-over a deficiency, the Executive 

Officer shall consider the factors identified in section (k)(1) including the 

manufacturer’s progress towards correcting the deficiency. Except as provided 

for in sections (k)(4.1) and (k)(4.2) below, tThe Executive Officer may not allow 

manufacturers to carry over monitoring system deficiencies for more than two 

model years unless it can be demonstrated that substantial engine hardware 

modifications and additional lead time beyond two years would be necessary to 

correct the deficiency, in which case the Executive Officer shall allow the 

deficiency to be carried over for three model years.

(4.1) For deficiencies first granted in the 2010 model year, the Executive Officer 

may allow manufacturers to carry over the deficiency into the 2013 model 

year unless it can be demonstrated that substantial engine hardware 

modifications and additional lead time beyond the 2013 model year would be 

necessary to correct the deficiency, in which case the Executive Officer shall 

allow the deficiency to be carried over into the 2014 model year.

(4.2) For deficiencies first granted in the 2011 model year, the Executive Officer 

may allow manufacturers to carry over the deficiency into the 2014 model 

year.

(5) Except as allowed in section (k)(6), deficiencies may not be retroactively granted 

after certification.

(6) Request for retroactive deficiencies

(6.1) During either the first 6 months after commencement of the start of engine 

production or the first 36 months after commencement of the start of vehicle 

production, whichever is later, manufacturers may request that the Executive 

Officer grant a deficiency and amend an engine’s certification to conform to 

the granting of the deficiencies for each aspect of the monitoring system: (a) 

identified by the manufacturer (during testing required by section (l)(2) or any 

other testing) to be functioning different than the certified system or otherwise 

not meeting the requirements of any aspect of section 1971.1; and (b) 

reported to the Executive Officer. If the Executive Officer grants the 

deficiency(ies) and amends the certification, the approval would be 

retroactive to all affected engines within the engine family. 

(6.2) Executive Officer approval of the request for a retroactive deficiency shall be 

granted provided that the conditions necessary for a pre-certification 

deficiency determination are satisfied (see section (k)(1)) and the 
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manufacturer could not have reasonably anticipated the identified problem 

before commencement of production.

(6.3) In granting the amended certification, the Executive Officer shall include any 

approved post-production deficiencies together with all previously approved 

deficiencies in computing fines in accordance with section (k)(2).

(7) For 2013 through 2015 model year engines that utilize PM sensors for PM filter 

filtering performance monitoring (section (e)(8.2.1)), in cases where the 

deficiency is for a monitor required to detect malfunctions of the PM filter filtering 

performance (section (e)(8.2.1)), the PM sensor (section (e)(9.2.2)), or the PM 

sensor heater (section (e)(9.2.4)), the deficiency shall be exempt from the 

specified fines of section (k)(3) and the deficiency shall not be included in the 

count of deficiencies used in (k)(2) to determine the number of deficiencies 

subject to fines.

(8) For hybrid vehicles:

(8.1) For 2014 model year hybrid vehicles previously certified with deficiencies for 

the 2013 model year, the 2014 model year shall be considered the first model 

year for the deficiency with regards to the carry-over provisions in section 

(k)(4).

(8.2) For deficiencies related to issues with the implementation of the hybrid 

system or of the hybrid system itself on 2013 through 2015 model year 

engines, two additional deficiencies shall be exempt from the specified fines 

of section (k)(3) and the deficiencies shall not be included in the count of 

deficiencies used in (k)(2) to determine the number of deficiencies subject to 

fines.

(9) Any OBD system installed on a production engine/vehicle that fails to conform with 

the certified OBD system for that engine/vehicle or otherwise fails to meet the 

requirements of section 1971.1 and has not been granted a deficiency pursuant 

to the provisions of section (k)(1) through (k)(6) are considered non-compliant. 

The engines/vehicles are subject to enforcement pursuant to applicable 

provisions of the Health and Safety Code and title 13, CCR section 1971.5.

(l) Production Engine/Vehicle Evaluation Testing.

(1) Verification of Standardized Requirements.

(1.1) Requirement: Manufacturers shall perform testing to verify that 2013 and 

subsequent model year production engines installed in vehicles meet the 

requirements of section (h)(3) and (h)(4) relevant to proper communication of 

required emission-related messages to an SAE J1978/J1939 scan tool.

(1.2) Selection of Test Vehicles:

(1.2.1) Engine manufacturers shall perform this testing every model year on ten 

unique production vehicles (i.e., engine rating and chassis application 

combination) per engine family. If there are less than ten unique 

production vehicles for a certain engine family, the manufacturer shall test 

each unique production vehicle in that engine family. Manufacturers shall 

perform this testing no later than either three months after the start of 

engine production or one month after the start of vehicle production, 

whichever is later. Manufacturers may request Executive Officer approval 

to group multiple production vehicles together and test one representative 

vehicle per group. The Executive Officer shall approve the request upon 
144

finding that the software and hardware designed to comply with the 

standardization requirements of section (h) (e.g., communication protocol 

message timing, number of supported data stream parameters, engine 

and vehicle communication network architecture) in the representative 

vehicle are identical to all others in the group and that any differences in 

the production vehicles are not relevant with respect to meeting the 

criteria in section (l)(1.4).

(1.2.2) For 2016 and subsequent model year engines, the Executive Officer shall 

reduce the maximum required number of vehicles to be tested from ten 

per engine family to five per engine family for a manufacturer based on 

the demonstrated previous success of the manufacturer to meet the 

requirements of section (l)(1). For purposes of this requirement, a

manufacturer shall be determined to be successful in meeting the 

requirements of section (l)(1) if zero vehicles fail the testing required by 

section (l)(1) for two consecutive years.

(1.2.3) For 2019 and subsequent model year engines, the Executive Officer shall 

further reduce the maximum required number of vehicles to be tested to 

three per engine family for a manufacturer based on the demonstrated 

previous success of the manufacturer to meet the requirements of section 

(l)(1). For purposes of this requirement, a manufacturer shall be 

determined to be successful in meeting the requirements of section (l)(1) if

zero vehicles fail the testing required by section (l)(1) for three 

consecutive years.

(1.2.4) The Executive Officer may waive the requirement for submittal of data 

from one or more of the production vehicles if data have been previously 

submitted for all of the production vehicles. Manufacturers may request 

Executive Officer approval to carry over data collected in previous model 

years. The Executive Officer shall approve the request upon finding that 

the software and hardware designed to comply with the standardization 

requirements of section (h) are identical to the previous model year and 

no other hardware or software changes that affect compliance with the 

standardization requirements have been made.

(1.3) Test Equipment: For the testing required in section (l)(1), manufacturers shall 

utilize an off-board device to conduct the testing. Prior to conducting testing, 

manufacturers are required to request and receive Executive Officer approval 

of the off-board device that the manufacturer will use to perform the testing.

(1.3.1) For vehicles using the ISO 15765-4 protocol for the standardized functions 

required in section (h), the Executive Officer shall approve the request 

upon determining that the manufacturer has submitted data, 

specifications, and/or engineering analysis that demonstrate that the offboard device meets the minimum requirements to conduct testing 

according to SAE J1699-3 using the software developed and maintained 

for the SAE J1699-3 committee and available through

www.sourceforge.net and SAE J2534 compliant hardware configured 

specifically for SAE J1699-3 testing.

(1.3.2) For vehicles using the SAE J1939 protocol for the standardized functions 

required in section (h), the Executive Officer shall approve the request 

upon determining that the manufacturer has submitted data, 
145

specifications, and/or engineering analysis that demonstrate that the offboard device is able to verify that vehicles tested are able to perform all of 

the required functions in section (l)(1.4) with any other off-board device 

designed and built in accordance with the SAE J1978/J1939 generic scan 

tool specifications. 

(1.4) Required Testing:

(1.4.1) The testing shall verify that communication can be properly established 

between all emission-related on-board computers and any SAE 

J1978/J1939 scan tool designed to adhere strictly to the communication 

protocols allowed in section (h)(3);

(1.4.2) The testing shall verify that all emission-related information is properly 

communicated between all emission-related on-board computers and any 

SAE J1978/J1939 scan tool in accordance with the requirements of 

section (h) and the applicable ISO and SAE specifications including 

specifications for physical layer, network layer, message structure, and 

message content.

(1.4.3) The testing shall further verify that the following information can be 

properly communicated to any SAE J1978/J1939 scan tool:

(A) The current readiness status from all on-board computers required to 

support readiness status in accordance with SAE J1979/J1939-73 and 

section (h)(4.1) in the key on, engine off position and while the engine is 

running;

(B) The MIL command status while the MIL is commanded off and while the 

MIL is commanded on in accordance with SAE J1979/J1939 and section 

(h)(4.2) in the key on, engine off position and while the engine is running, 

and in accordance with SAE J1979/J1939 and sections (d)(2.1.2) during 

the MIL functional check and, if applicable, (h)(4.1.36) during the MIL 

readiness status check while the engine is off;

(C) All data stream parameters required in section (h)(4.2) in accordance with 

SAE J1979/J1939 including, if applicable, the proper identification of each 

data stream parameter as supported in SAE J1979 (e.g., Mode/Service 

$01, PID $00);

(D) The CAL ID, CVN, ESN, and VIN in accordance with SAE J1979/J1939 

and sections (h)(4.6) through (4.8);

(E) An emission-related fault code (permanent, confirmed, pending, MIL-on, 

and previously MIL-on) in accordance with SAE J1979/J1939-73 

(including correctly indicating the number of stored fault codes and MIL 

command status (e.g., Mode/Service $01, PID $01, Data A for SAE 

J1979)) and section (h)(4.4) for each diagnostic and emission critical 

electronic powertrain control unit;

(1.4.4) The testing shall also verify that the on-board computer(s) can properly 

respond to any SAE J1978/J1939 scan tool request to clear emissionrelated fault codes and reset readiness status in accordance with section 

(h)(4.10).

(1.5) Reporting of Results:

(1.5.1) The manufacturer shall submit to the Executive Officer the following, 

based on the results of testing:
146

(A) If a variant meets all the requirements of section (l)(1.4), the test results 

(i.e., the test log file) and a statement specifying that the variant passed all 

the tests, or

(B) If any variant does not meet the requirements of section (l)(1.4), a written 

report to the Executive Officer for approval within one month of testing the 

specific variant. The written report shall include the problem(s) identified 

and the manufacturer’s proposed corrective action (if any) to remedy the 

problem(s). Factors to be considered by the Executive Officer in 

approving the proposed corrective action shall include the severity of the 

problem(s), the ability of the vehicle to be tested in a California inspection 

program (e.g., roadside inspection, fleet self-inspection program), the 

ability of service technicians to access the required diagnostic information, 

the impact on equipment and tool manufacturers, and the amount of time 

prior to implementation of the proposed corrective action.

(1.5.2) Upon request of the Executive Officer, a manufacturer shall submit a 

report of the results of any testing conducted pursuant to section (l)(1) to 

the Executive Officer for review.

(1.5.3) In accordance with section (k)(6), manufacturers may request Executive 

Officer approval for a retroactive deficiency to be granted for items 

identified during this testing.

(1.6) Alternative Testing Protocols. Manufacturers may request Executive Officer 

approval to use other testing protocols. The Executive Officer shall approve 

the protocol if the manufacturer can demonstrate that the alternate testing 

methods and equipment provide an equivalent level of verification of 

compliance with the standardized requirements to the requirements of section 

(l)(1).

(2) Verification of Monitoring Requirements.

(2.1) No later than either six months after the start of engine production or three six 

months after the start of vehicle production, whichever is later, manufacturers 

shall conduct a complete evaluation of the OBD system of one or more 

production vehicles (test vehicles) and submit the results of the evaluation to 

the Executive Officer.

(2.2) Selection of test vehicles:

(2.2.1) For each engine selected for monitoring system demonstration in section 

(j), the manufacturer shall evaluate one production vehicle equipped with 

an engine from the same engine family and rating as the demonstration 

engine. The Executive Officer shall select the specific production 

vehicle(s) to be tested.

(2.2.2) A manufacturer required to test more than one test vehicle may test an 

engine in lieu of a vehicle for all but one of the required test vehicles.

(2.2.3) The Executive Officer may waive the requirements for submittal of 

evaluation results from one or more of the test vehicles if data have been 

previously submitted for all of the engine ratings and variants.

(2.3) Evaluation requirements:

(2.3.1) The evaluation shall demonstrate the ability of the OBD system on the 

selected production vehicle to detect a malfunction, illuminate the MIL, 

and, where applicable, store an appropriate fault code readable by a scan 
147

tool conforming to SAE J1978/J1939 when a malfunction is present and 

the monitoring conditions have been satisfied for each individual 

diagnostic required by title 13, CCR section 1971.1.

(2.3.2) The evaluation shall verify that malfunctions detected by non-MIL 

illuminating diagnostics of components used to enable any other OBD 

system diagnostic (e.g., fuel level sensor) will not inhibit the ability of other 

OBD system diagnostics to properly detect malfunctions.

(2.3.3) The evaluation shall verify that the software used to track the numerator 

and denominator for purposes of determining in-use monitoring frequency 

correctly increments as required in section (d)(4).

(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. For monitors that are required to indicate 

a malfunction before emissions exceed an emission threshold based on 

any applicable standard (e.g., 2.0 times any of the applicable standards), 

manufacturers are not required to use malfunctioning 

components/systems set exactly at their malfunction criteria limits. 

Emission testing to confirm that the malfunction is detected before the 

appropriate emission standards emission threshold malfunction criteria 

(e.g., 2.0 times the standard) are exceeded is not required.

(2.3.5) Manufacturers shall submit a proposed test plan for Executive Officer 

approval prior to evaluation testing being performed. The test plan shall 

identify the method used to induce a malfunction for each diagnostic. If 

the Executive Officer determines that the requirements of section (l)(2) are 

satisfied, the proposed test plan shall be approved.

(2.3.6) Subject to Executive Officer approval, manufacturers may omit 

demonstration of specific diagnostics. The Executive Officer shall 

approve a manufacturer's request if the demonstration cannot be 

reasonably performed without causing physical damage to the vehicle 

(e.g., on-board computer internal circuit faults) or jeopardizing the safety 

of personnel performing the demonstration.

(2.3.7) For evaluation of test vehicles selected in accordance with section (l)(2.2), 

manufacturers are not required to demonstrate diagnostics that were 

previously demonstrated prior to certification as required in section (i).

(2.4) Manufacturers shall submit a report of the results of all testing conducted 

pursuant to section (l)(2) to the Executive Officer for review. This report shall 

identify the method used to induce a malfunction in each diagnostic, the MIL 

illumination status, and the fault code(s) stored.

(2.5) In accordance with section (k)(6), manufacturers may request Executive 

Officer approval for a retroactive deficiency to be granted for items identified 

during this testing.

(3) Verification and Reporting of In-use Monitoring Performance.

(3.1) Manufacturers are required to collect and report in-use monitoring 

performance data representative of production vehicles (i.e., engine rating 

and chassis application combination). Manufacturers shall collect and report 

the data to ARB within twelve months after the production vehicles were first 

introduced into commerce.
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(3.2) Manufacturers shall separate production vehicles into monitoring 

performance groups, as defined by sections (l)(3.2.1) and (3.2.2) below, and 

submit data representative of each group:

(3.2.1) Emission architecture. Engines shall be separated by emission 

architecture. All engines that use the same or similar emission control 

architecture and monitoring system shall be in the same emission 

architecture category.

(3.2.2) Monitoring performance group. Within an emission architecture category, 

engines shall be separated by vehicle application. The separate

monitoring performance groups shall be based on three classifications: 

engines intended primarily for line-haul chassis applications, engines 

intended primarily for urban delivery chassis applications, and all other 

engines.

(3.3) Manufacturers may request Executive Officer approval to use an alternate 

grouping method to collect representative data. Executive Officer approval 

shall be granted upon determining that the proposed groupings include 

production vehicles using similar emission controls, OBD strategies, 

monitoring condition calibrations, and vehicle application driving/usage 

patterns such that they are expected to have similar in-use monitoring 

performance. If approved by the Executive Officer, the manufacturer may 

submit one set of data for each of the approved groupings.

(3.4) For each group, the data must include all of the in-use performance tracking 

data reported through SAE J1979/J1939 (i.e., all numerators, denominators, 

the general denominator, and the ignition cycle counter), the engine model

year, the engine manufacturer, the engine family, the engine serial number, 

the engine HP rating (for diesels), the engine torque rating (for diesels), the 

date the data were collected, the odometer reading, the vehicle/chassis VIN, 

the monitoring performance group, and the ECM software calibration 

identification number and be in the standardized format detailed in 

Attachments D and E of ARB Mail-Out #MSC 09-22.

(3.5) Manufacturers shall submit a plan to the Executive Officer for review and 

approval that details the types of production vehicles in each group, the 

number of vehicles per group to be sampled, the sampling method, the time 

line to collect the data, and the reporting format. The Executive Officer shall 

approve the plan upon determining that it provides for effective collection of 

data from a sample of vehicles that, at a minimum, is fifteen vehicles per 

group, will likely result in the collection and submittal of data within the 

required time frame, will generate data that are representative of California 

drivers and temperatures, and does not, by design, exclude or include 

specific vehicles in an attempt to collect data only from vehicles with the 

highest in-use performance ratios.

(3.6) Upon request of the manufacturer, the Executive Officer may for good cause 

extend the twelve month time requirement set forth in section (l)(3.1) up to a 

maximum of eighteen months. In granting additional time, the Executive 

Officer shall consider, among other things, information submitted by the 

manufacturer to justify the delay, sales volume of the group(s), and the 

sampling mechanism utilized by the manufacturer to procure vehicles for data 

collection. If an extension beyond twelve months is granted, the 
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manufacturer shall additionally be required to submit an interim report within 

twelve months for data collected up to the time of the interim report.

(4) Verification of In-Use Compliance

(4.1) As a condition for certification, manufacturers are required to perform 

compliance testing on in-use engines as specified in California Code of 

Regulations, title 13, section 1971.5(c).

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

43104, 43105, 43105.5, and 43106, 43154, 43211, and 43212, 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.