p.1 

OAR Box 1190 

Prepped by Candice Davis 

Document Number: 

40) ll-A-32 

Docket Number: 

A-90-28 

Printed 5/5/2008 9:13:51 AM Sheet 40 of 106 
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STATE OF CALIFORNIA—CALIFORNIA ENVIRONMENTAL PROTECTION AGENCY 

AIR RESOURCES BOARD 

2020 L STREET 

P.O. BOX 2815 

SACRAMENTO, CA 95814-2815 

PETE WILSON, Governor 

March 15, 1994 

Leila Holmes Cook 

Attorney/Advisor 

U.S.EPA 

Manufacturers Operations Division 

401 M Street S.W. (6405J) 

Washington D.C. 20460 

Dear Ms. Cook: 

Enclosed please find two copies of the Staff Report which was prepared for the 

September 1991 Board Meeting. Please feel free to contact our office if we 

can be of further assistance. 

Sincerely, 

Verda Haggerty" 

Office Technician 

Enclosures 

0 Printed on recycled paper 
P.3 

'»». -

California Air Resources Board 

Technical Status Update and Proposed Revisions to 

Malfunction and Diagnostic System Requirements 

Applicable to 1994 and Subsequent California 

Passenger Cars, Light-Duty Trucks, and 

Medium-Duty Vehicles - (OBD II) 

Staff Report I 

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Release Date: July 26,1991 

State of California 

Air Resources Board 

OUL g n w ii 

AUG I 51995 

EPA AIR DOCKET 

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P.4 

State of California 

AIR RESOURCES BOARD 

STAFF REPORT: INITIAL STATEMENT OF REASONS FOR RULEMAKING 

Technical Status Update and Proposed Revisions to Malfunction 

and Diagnostic System Requirements Applicable to 1994 and Subsequent 

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

- (OBD II) 

Date of Release: 7/26/91 

Scheduled for Consideration: 9/12/91 

Agenda Item No.: [ = - ] 

This report has been reviewed by the staff of 

the California Air Resources Board and approved for publication, 

Approval does not signify that the contents necessarily 

reflect the views and policies of the Air Resources Board, 

nor does mention of trade names or commercial products 

constitute endorsement or recommendation for use. 

J. 
P.5 

State of California 

AIR RESOURCES BOARD 

Staff Report: Initial Statement of Reasons 

for Proposed Rulemaking 

PUBLIC HEARING TO CONSIDER THE TECHNICAL STATUS UPDATE AND PROPOSED 

REVISIONS TO MALFUNCTION AND DIAGNOSTIC SYSTEM REQUIREMENTS APPLICABLE TO 

1994 AND SUBSEQUENT CALIFORNIA PASSENGER CARS, LIGHT-DUTY TRUCKS, AND 

MEDIUM-DUTY VEHICLES - (OBD II) 

Date of Release: 7/26/91 

Scheduled for Consideration: 9/12/91 

la Item No.: [___-_-_J 

I. 

Section 1968.1 of Title 13, California Code of Regulations (CCR), known 

as OBD II, was adopted by the Air Resources Board on September 14, 1989. 

The regulation requires manufacturers to implement new comprehensive onboard diagnostic systems, replacing the original on-board diagnostic 

requirements (OBD I) found in Title 13 CCR, Section 1968, beginning with the 

1994 model year. At the time of the Board hearing, some of the OBD II 

requirements were considered technology-forcing. Consequently, staff was 

instructed in Resolution 89-77 to report back to the Board in two years 

regarding progress of manufacturers in developing the required monitoring 

strategies. This report provides a summary of progress made by industry in 

overcoming the challenges posed by the OBD II regulation. 

Over the last two years staff has met with numerous vehicle, component, 

and emission control system manufacturers to discuss their OBD II 

developmental progress and concerns. While most manufacturers are 

continuing to refine their diagnostic strategies at this time, staff can now 

report that feasible solutions have been developed by industry for all of 

the adopted requirements, including those considered technology-forcing two 

years ago. Most manufacturers are now confident they will be able to 

implement their OBD II monitoring strategies in the 1994 to 1996 timeframe 

required by the regulations. 

Based on discussions with manufacturers and the Environmental 

Protection Agency (EPA), it has become evident that monitoring strategies 

for a few specific requirements could be revised to be more effective than 

currently required by the OBD II regulations. Accordingly, some regulatory 

modifications are being proposed, including appropriate lead-time 

adjustments, that will keep OBD II requirements consistent with the best 

capabilities of industry. 

1. 

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P.6 

Another factor necessitating modification of the adopted requirements 

was passage of the 1990 federal Clean Air Act Amendments (CAAA) directing 

the EPA to develop federal on-board diagnostic requirements. Given the 

specter of potentially different federal and California on-board diagnostics 

requirements, the CAAA requires EPA and California to coordinate the 

development of federal and state OBD regulations. Manufacturers have also 

strongly expressed the need to avoid developing separate systems to meet 

each regulation. To address this concern, the ARB and EPA have worked 

together to remove any inconsistencies that would make separate OBD systems 

necessary. 

In addition, other minor modifications have been proposed in response 

to issues which surfaced during discussions with manufacturers. For 

example, the requirements for signaling a malfunction have been made more 

consistent among the various monitoring requirements, and more time is being 

proposed in some cases to verify the presence of a malfunction before 

alerting the driver. Clarifications have also been made to regulatory 

language that has, at times, been misunderstood. 

II. BACKGROUND AND RATIONALE FOR OBD SYSTEMS 

On-board diagnostic systems reduce the time between occurrence of a 

malfunction and its detection and repair. This will not only reduce 

emissions caused by a malfunction but will minimize consequential damage to 

other vehicle components dr systems. 

Virtually all current motor vehicle emission control systems are 

integrated into a broad computer-based powertrain management system. By 

incorporating additional software to analyze data already available to the 

computer, and with addition of only a few electronic hardware components for 

providing additional information, an on-board diagnostic system can be 

developed to monitor the entire emission control system. When a malfunction 

is detected, the on-board diagnostic system would notify the driver by 

illuminating a Malfunction Indication Light (MIL) on the instrument panel. 

A code identifying the likely area of the malfunction would also be stored 

in the computer memory. 

On-board diagnostic regulations were originally adopted in California 

in 1985 for 1988 and later light- and medium-duty vehicles equipped with 

three-way catalysts and feedback fuel control systems. The regulation is 

now known as OBD I and was developed because increasing use of sophisticated 

electronic emission and powertrain control systems made it increasingly 

difficult for technicians to detect defective components through use 

of visual checks or diagnosis with test equipment which had been used on 

older vehicles. OBD I was seen as a promising mechanism for quickly 

identifying faulty electronic-based emission control system components in 

California's Smog Check Program. 

In OBD II, the ARB broadened the scope of OBD I by increasing the 

number of components and systems to be monitored by the system. When OBD I 

was adopted, technology did not exist or had not been identified to monitor 

2. ?r 
P.7 

some of the components now contained in OBD II such as catalyst and 

evaporative control system monitoring. OBD II requires that virtually every 

emission control system and electronic emission-related powertrain component 

be monitored. In addition to the foregoing, OBD II systems also require the 

detection of engine misfire. 

The underlying principle behind OBD II is that most malfunctions should 

be detected when the performance of a component or system deteriorates to 

the point that the vehicle's emissions exceed a threshold value tied to the 

applicable emission standard. This is in contrast to detecting malfunctions 

when the component or system is simply ne longer functioning. Under the OBD 

II approach, the vehicle operator will be notified at the time when the 

vehicle begins to marginally exceed emission standards. The regulation as 

adopted is specific regarding when the vehicle operator must be notified via 

the MIL to ensure prompt notification. 

In OBD II, the ARB also requires that additional information be 

provided to technicians for diagnosis and repair of emission-related 

problems. OBD II systems are required to use new standardized on-board 

vehiele communication systems to provide service technicians with detailed 

information about system performance and detected malfunctions. This 

information includes stored fault codes that will lead technicians to the 

likely area of the malfunction, and continuously updated information for 

somi angin© parameters to h®lp them isolat© the speeifie fault. The 

corranunication systems are to provide all of this information in a 

standardized format through a communication link similar to a telephone 

line. Specifications for this link have been developed hy the Society of 

Automotive Engineers (SAE). The SAE has also developed specifications for a 

low cost, hand held diagnostic scan tool that will be capable of 

communicating with all vehicle makes and models equipped with OBD II 

systems. Consequently, service centers will be able to access on-board 

diagnostic information without having to buy a separate piece of diagnostic 

equipment for every vehicle make they service. 

For various reasons, there exists a diversity of opinion concerning the 

value of on-board diagnostic systems. In an effort to develop an effective 

set of regulations for OBD II that were presented to the Board in 1989, the 

staff had extensively reviewed the technical details of advanced emission 

control systems and engaged in extensive discussions with industry. 

During these reviews and discussions, questions concerning the 

rationale for requiring OBD systems had been raised. Answers to these 

questions are set forth herein. 

1. 6iv®n That California Has Adopted Tough 1QQ.Q00 Mile Emission 

Standards, a Formidable In-Use Recall Program. Strong Warranty and 

Defects Reporting Requirements, and Other- Programs to Control In-Use 

Emissions. Why is QBD H Needed? 

Although each of these programs is aimed at assuring compliance of the 

vehicle fleet, on average, with emission standards over a 100,000 mile 

interval, there is still a need to better identify excess emissions from the 

3. 

6> 
P.8 

relatively small number of malfunctioning vehicles in this group. Further, 

there is an even greater need to address excess emissions from vehicles 

bevond 100,000 miles, the time when emission components are most likely to 

fail. When coupled with California's Smog Check Program, OBD II is aimed at 

assuring effective emission control from vehicles over their total lives. 

At a time when emission standards require progressively lower emission 

levels from vehicles, the current Smog Check Program is less able to detect 

malfunctions through idle emission tailpipe measurements and underhood 

inspections. As previously stated, emission control systems are 

increasingly governed by sophisticated electronic controls. OBD II is 

necessary to detect and properly repair malfunctions. 

The goal of on-board diagnostics is to alert the driver to the presence 

of a malfunction of the emission control system, and to identify the 

location of the problem in order to assist mechanics in properly performing 

repairs. Timely, effective repairs assure that in-use vehicles, including 

those with high mileage, maintain low emission levels. 

2. QBD II is a Complex Regulation Requiring State-of-the-Art Technology 

- But Will It Work? 

The adopted regulation and the proposed revisions have been developed 

to assure that vehicles retain emission control capability near that of 

certified emissions standards during in-use operation. To assure this, the 

regulation requires an up-front demonstration during vehicle certification 

on high mileage vehicles that the MIL illuminates when emissions exceed the 

applicable standards by a small threshold. As emission standards are 

reduced in coming years, the emission threshold will be reduced accordingly. 

Every emission-related component or system must be monitored, including the 

catalyst system, detection of misfiring cylinders, and even detection of 

extremely small leaks in the evaporative emission control system. The staff 

will also implant defective components in production vehicles to confirm 

that diagnostic systems perform as intended. Provisions also exist for 

recall of systems which do not function as required in-use. 

3. Can OBD II Take the Place of the Official Federal Test Procedure 

(FTP) for Measuring Emissions? 

Although OBD II requirements reflect state-of-the-art diagnostic 

system capability, there are limitations which apply to current techniques 

for detecting malfunctioning components. These limitations do not allow OBD 

II systems to take the place of the FTP test for measuring vehicle 

emissions. This is because monitoring systems in most cases can detect when 

components are functioning within their normal operating range, but are 

limited in the ability to determine if they are functioning accurately and 

precisely within the range. Some degree of rationality checking can be 

developed to determine if components are "stuck high" or "stuck low", but 

gaining additional information on how well a component performs within its 

normal operating range is often not feasible or practical. Fortunately, for 

some of the more critical components (such as the oxygen sensor), techniques 

are available to evaluate their proper performance. 

7 
P.9 

Components operating improperly within their normal operating range can 

cause emissions to exceed applicable standards before they can be detected 

as malfunctioning. Each of the OBD II requirements is aimed, however, at 

advancing the monitoring capability such that emission standards can be 

exceeded by only a small threshold before a malfunction must be signaled on 

an individual component basis (i.e., the threshold for a given component is 

determined assuming that all other components are operating normally). 

Should a number of components each operate with small inaccuracies within 

their normal range, however, they collectively could cause a vehicle to 

exceed the emission standards. In these instances, the appropriate 

detection threshold of each component would be even more difficult to 

establish than on an individual component basis. This latter concern is 

moderated, though, by requiring manufacturers to demonstrate that their 

malfunction criteria for individual components are suitable with respect to 

remaining within certain emission thresholds using a high mileage vehicle. 

At high mileage, all of the eraission control components are deteriorated to 

a moderate level (the demonstration vehicle will have accumulated 75,000-

100,000 miles). 

Except for catalyst and evaporative system monitoring, most other 

components are monitored such that a malfunction is signaled when emissions 

exceed 1.5 times the applicable standards. Thus, for a 0.25 g/mi 

hydrocarbon (HC) standard, a malfunction would be signaled when a component 

or system causes emissions to increase above about 0.4 g/mi HC whereas for 

an Ultra-Low Emission Vehiele meeting a 0.04 g/mi HC standard, malfunctions 

would b@ signaled when HC emissions exceed 0.06 g/mi. For catalyst systems, 

current capability permits detecting a loss of conversion efficiency of 

about 20 pereent or more, which may cause emissions to slightly exceed the 

threshold applicable for all other components. A small threshold increase 

in emissions ean be maintained, however, by judicious application of the 

catalyst monitoring technique. The regulatory changes being proposed would 

assure that strategies are employed which provide the earliest possible 

notice of eatalyst deterioration. Using the same example of a vehicle with 

emissions at the .25 g/mi HC standard, the proposed requirements would 

require detection of catalyst deterioration before .65 g/mi HC emissions is 

reached (i.e., when emissions increase by about 0.4 g/mi). For an Ultra-Low 

Emission Vehicle meeting a 0.04 g/mi HC standard, a catalyst malfunction 

would be noted when emissions reach approximately 0.08 g/mi HC. Thus, 

although OBD II cannot substitute for an FTP test, it is still extremely 

effective in identifying component deterioration when the vehicle is only 

marginally above the emission standards. 

4. Soffitflttfj@P_s_of Older-Vehicles With Diagnostic Systems Coma-lain That 

fch@JteIfimcftion Light Sometimes Comes Qn and Then 6oes Off, or That 

Ih^i£fi_ls_a_eieaF__}rahJ_iiEL^.g^ Driveahilitv). hut th@ Malfunction 

Light Does Mot Illuminate. This Results in the Owners Ignoring the 

System or Doubting Its Effectiveness. How Does QBD IX Address These 

Considerable effort has gone into establishing appropriate malfunction 

light illumination protocol. In general, the light is activated only after 

5. 
P.10. 

a fault has been verified during two successive driving trips, at which time 

a fault code is also stored in the computer to indicate the cause of the 

problem. Once the malfunction light is illuminated, it cannot automatically 

be extinguished unless the fault has disappeared for three trips in 

succession - a very unlikely situation if the problem was present for two 

trips in a row in the first place. Thus, it is likely that once the light 

is illuminated, it will not be extinguished unless a repair is made. 

Given the stringent monitoring threshold requirements for all emissionrelated components which are also integral to the engine control system, it 

is unlikely that a driveability problem could exist without being detected 

by the OBD II system. 

5. What Role Can QBD XI Play in Conjunction with California's Smog 

Check Program? 

For vehicles equipped with OBD II, the Smog Check Program could evolve 

into a check of the on-board computer for the presence of fault codes. 

There no longer would be a need for underhood inspections or tailpipe 

emission checks since the OBD II system would be a much better discriminator 

of emission-related faults. A vehicle with stored fault codes in its 

computer would need to be repaired before a Smog Check Certificate could be 

issued. Reliance on OBD II could also reduce the cost of performing a Smog 

Check since only a single inexpensive piece of equipment could be used to 

access fault codes for all makes of vehicles, and the check itself would not 

require any specific skill to perform. 

S. Cflt-ldiSL'fc the QBP_XX System be Tampered? I f Arc Qvmer Disconnects the 

BidOMEy-Md __li«r.wbv Erases Stored Fault Cedes in The Computer. 

Cflidda't the Vehiele Falsely Pass the Smog Cheek Test? 

OBD II contains measures to guard against tampering. Should the 

computer memory be cleared of trouble codes for any reason, the computer is 

required to signal that the vehicle must be driven until the monitoring 

system has had adequate time to interrogate all of the emission-related 

components (usually two moderate length trips would be needed). When the 

checking process is complete, a readiness code is stored in the computer. A 

Smog Check Test could not be conducted unless a readiness message is 

present. Tampering provisions are also required to protect the engine 

control computer from aftermarket reprogramming devices which could affect 

the OBD II system. 

7. ttottDaes the_QBD_XX_ Svstem Assist Mechanics in Repair of the Engine 

fil_ri.-Eji_Js_^i.Qn_,CQntrQl System? Can QBD XX Significantly Reduce the 

Cost of Repairs? 

By alerting the driver to the need for repair, early detection can 

prevent more extensive consequential damage that may result if a fault goes 

undetected. For example, OBD II will detect engine misfire well before most 

1 
P.11 

drivers could detect it through engine roughness. Early detection and 

correction could prevent serious damage to the catalytic converter, which 

would be expensive to replace. 

OBD II assists mechanics in repairing faulty components by identifying 

the problem area by means of standardized fault codes. For example, a 

faulty airflow meter would have assigned a particular numerical code which 

would be the same on any make of vehicle having such a component. Further, 

OBD II requires a standard access electrical connector which is identical 

for all makes of vehicles in California (and soon the entire United States). 

This means that a single inexpensive generic scan tool can be used to read 

out trouble codes and initialize automatic testing sequences on-board _mx_ 

mak@ of vehicle to help isolate the problem component. No longer will 

unique, expensive scan tools be needed for each make of vehicle being 

repaired. Unlike the manufacturer-specific scan tools, the OBD II generic 

scan tool will not require frequent updating to handle successive model-year 

vehicles. Less expensive repair tool requirements translate to lower costs 

of repairs. Being able to read out fault codes also enables mechanics to 

make correet repairs the first time, which can save money and greatly reduce 

the frustration of improper repairs. Since higher mileage vehicles are 

often repaired by independent facilities rather than dealerships, the 

availability of an inexpensive generic scan tool which connects to any make 

of vehicle with OBD II greatly improves the likelihood of proper, less 

expensive repairs. The generic scan tool can also read-out key engine 

control parameters to give mechanics a view into the computer operation to 

better understand the nature of an indicated problem. 

OBD II also includes "freeze frame" requirements, which means that the 

computer stores in memory the exact engine operating conditions when a fault 

occurred (including coolant temperature, vehiele speed, and engine load) so 

that intermittent faults ean be investigated by revisiting the same 

conditions at which th© problem occurred. Mechanics ean also verify that 

their repairs were correct by duplicating the driving conditions and 

ehecking to see if the fault code reappears. Faulty repairs will be quickly 

noticed because OBD II will alert the driver if a problem persists. 

Finally, OBD II includes requirements that repair information be made 

readily available at a reasonable price to anyone requesting the 

information. The repair procedures specified by manufacturers must 

reference use of the generic scan tool and commonly available repair tools 

in order to perform the repairs, although other procedures using more 

advanced manufacturer-specific equipment may also be available. 

By facilitating efficient, correct repairs with an inexpensive scan 

tool, by minimizing consequential damage through early detection of faults, 

and by permitting a less costly Smog Check, OBD II can save the owner time, 

frustration, and money. 

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incentive to design proper diagnostic systems, but enforcement action 

usually takes place after several years of production have occurred, and 

then additional iterations may be required before properly designed systems 

emerge. 

For these reasons, staff selected the more difficult and time 

consuming, but more effective approach of investigating technological 

feasibility and then setting minimum performance requirements up-front. In 

this way manufacturers will be unable to miss the intended goal, which has 

to be demonstrated through a series of emission tests with components that 

are at the manufacturer's criteria limit for signaling a malfunction. The 

demonstration occurs before vehicles can be certified for sale in 

California. 

III. TECHNOLOGICAL FEASIBILITY 

In 

two years 

monitoring 

the areas 

monitoring 

affected i 

activity i 

systems wh 

1989, the Board directed that an update be provided in 

concerning progress in developing technology to meet the adopted 

requirements. At that tirae there was uncertainty particularly in 

of catalyst monitoring, misfire detection, evaporative system 

and oxygen sensor monitoring. However, discussions with 

ndustry indicate that there has been considerable development 

n the last two years, and the design of effective monitoring 

ich meet all OBD II requirements now appears feasible. 

OBD II presently requires the monitoring of catalyst HC conversion 

efficiency. When conversion efficiency drops below a specified range, a 

malfunction is signaled. Industry has developed reliable monitoring 

strategies for assessing catalyst condition by evaluating data from oxygen 

sensors placed before and after a catalyst. 

While manufacturers have performed laboratory confirmation of the 

feasibility of eatalyst monitoring, on road evaluation has not been 

completed. Manufacturers are moving quickly to evaluate the oxygen sensorbased catalyst monitoring technique in a wide variety of exhaust system and 

catalyst configurations for different engine and vehicle types exposed to 

numerous environmental conditions. However, considerable testing is still 

needed to ensure that the monitoring system does not erroneously indicate 

faults due to unusual circumstances on the road. At this time a few 

manufacturers have expressed concern that reliable catalyst monitoring 

systems may not be ready for introduction in 1994, but most others have 

indicated that reliable catalyst monitoring can occur by then, at least on 

some portion of their product offerings. Thus, the staff does not believe i 

delay in the phase-in of catalyst monitoring, which begins in 1994, is 

needed. 

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testing requirements for new vehicles beginning in 1995 (Title 13 CCR, 

Section 1976). OBD II requirements are aimed at addressing the evaporative 

system defects found in in-use vehicles to assure that the new evaporative 

control systems remain highly effective. 

Because the monitoring approach suggested initially for OBD II might 

not meet the reliability levels sought by manufacturers in terms of avoiding 

false detection, and because small to moderate evaporative system leaks 

might not necessarily be detected, the staff reacted positively when an 

ilternative approach was suggested. The suggestion consisted of applying a 

small vacuum to the entire evaporative system followed by closing off the 

system and looking for a change in vacuum due to a leak. This concept is 

further described in section IV-2. Thus far, this approach enables 

detecting a leak from a hole as small as 0.040 inches in diameter. 

Additional coraponents required to carry out this monitoring approach include 

a pressure transducer in the fuel tank and a solenoid to close the vapor 

canister vent. These components themselves could be monitored for proper 

operation by the OBD II system through software logic evaluation of 

available electrical signal information. 

Because the new evaporative monitoring approach would be much more 

effective than the one suggested in the current regulation, a revised 

evaporative monitoring requirement is being proposed. Initial testing of 

this concept by EPA and some manufacturers has demonstrated it is feasible 

for incorporation into OBD II. With this rigorous evaporative monitoring 

requirement, in-use evaporative emission problems should be greatly reduced. 

4. flK__^__A^PJ_J__M_mMfi 

With OBD II, oxygen sensors must be monitored for their ability to 

properly eontrol the fuel system and their usefulness in detecting 

malfunctions in other components or systems (e.g., catalyst efficiency, 

secondary air systems, evaporative systems, etc.). Most manufacturers have 

now indicated that oxygen sensor deterioration can be detected before 

emission increases occur, at least for vehicles not meeting Low Emission 

Vehicle standards. Further, some manufacturers use a dual oxygen sensor 

arrangement both for fuel system control and catalyst monitoring. They use 

the more protected downstream oxygen sensor to compensate for deterioration 

and drift in the critical primary (upstream) oxygen sensor. Thus, emission 

control is retained despite a shift in the primary oxygen sensor switching 

point or some categories of deeline in its response rate. When this 

compensation increases beyond a predetermined threshold, a malfunction is 

signaled for the primary sensor. 

As a more simple, but very effective approach to evaluating oxygen 

sensors, other manufacturers observe the response rate of the oxygen sensor 

by cycling the fuel system rich and lean at a rate faster than an oxygen 

sensor is designed to follow. Good sensors can generate higher voltage 

amplitude under these conditions than can poor ones, which respond too 

slowly to the fuel changes. 

L 

11. 

K__EX 
_____> _ 

IV. PROPOSED CHANGES TO THE REGULATION! 

Two major rulemakings have precipitated the need for revisions to the 

adopted OBD II regulation: California's Low-Emission Vehicles/Clean Fuels 

regulation and the new federal CAAA. In addition, some technological 

developments have occurred which enable more effective monitoring 

requirements. The proposed changes primarily affect the catalyst monitoring 

and evaporative system requirements. Most of the remaining changes have 

been made to further reduce the likelihood of false indications of 

malfunctions, provide clarification of the language, permit added 

flexibility in the means of compliance, and incorporate updated Society of 

Automotive Engineers recommended practices. 

_. R@viseri_eata.ysfc MonitoriJit^RggHirefaefits 

The current OBD II regulation calls for steady-speed monitoring of 

only the front catalyst or catalysts in a system for deterioration in HC 

conversion efficiency to a 40 to 50 percent level (Section (b)(1)). The 

relatively low conversion efficiency criterion was adopted to ensure that 

initial catalyst monitoring efforts would not falsely identify a catalyst in 

good condition as malfunctioning. Changes to the catalyst monitoring 

requirement are being proposed for a number of reasons: 

Manufacturers have found that steady-speed monitoring for 

catalyst conversion efficiency of 40 to 50 percent using the dual 

oxygen sensor approach is difficult to accomplish with adequate 

certainty, but that monitoring for efficiency in the range of 60 

to 80 percent could be done reliably. 

In catalyst systems incorporating small volume front catalysts, a 

reliable means of assessing conversion efficiency is not yet 

certain, although some promising approaches are being pursued. 

EPA is proposing malfunction criteria for catalyst systems which 

are based on exceeding prescribed emission threshold increases. 

For HC emissions, the allowable increase would be 0.4 g/mi. This 

approach permits manufacturers to monitor the catalyst system as 

a single unit, thereby avoiding the problem cited above (if small 

volume catalysts are damaged, the remaining catalyst system would 

still be likely to avoid a HC increase greater than the 0.4 g/mi 

HC threshold). 

EPA catalyst monitoring developments indicate that a more 

reliable assessment of catalyst condition can be gained by 

monitoring under a variety of driving conditions rather than 

solely monitoring under steady-speed conditions. Accordingly, 

EPA is requiring that catalyst monitoring be accomplished within 

a Federal Test Procedure (FTP) driving cycle. 

12. 
P.17 

- With adoption of the ARB Low Emission Vehicle/Clean Fuels 

Regulation, more timely detection of catalyst malfunction would 

be required for Low Emission Vehicles than for non-Low Emission 

vehicles. 

In view of the above considerations, some changes to monitoring 

requirements are being proposed. First, for vehicles employing steady-speed 

monitoring, the malfunction criteria would be increased to a deterioration 

in HC conversion efficiency to 60 - 80 percent. This would improve the 

reliability and timeliness in detecting a malfunction. To address the 

second and third issues, staff proposes to allow monitoring of the catalyst 

system as a single unit for non-Low Emission Vehicles, since techniques for 

monitoring small volume catalysts independently are not yet assured. This 

change would also permit design of a single catalyst monitoring system to 

satisfy requirements being proposed by the EPA as well. 

Staff further proposes a change to the current regulation to phase in 

the FTP-based catalyst monitoring approach, although, as noted above, the 

current regulation calls for evaluation of catalyst HC conversion efficiency 

during a steady-speed driving condition, which is relatively easy to 

accomplish. More sophisticated catalyst monitoring has been studied by both 

industry and the EPA. Development of catalyst monitoring by the EPA has 

shown that catalyst condition can be evaluated during the FTP driving cycle 

by assembling brief segments of data over a variety of engine operating 

conditions. These data are filtered and evaluated statistically to arrive 

at an accurate determination of catalyst efficiency. The FTP-based 

evaluation would yield a more timely, accurate assessment of catalyst 

condition than monitoring under steady-speed conditions, and would allow inuse compliance testing of catalyst monitoring systems over a standard test 

cycle. The proposed change would require indication of a malfunction when 

catalyst HC conversion efficiency based on an FTP test reaches 50 to 60 

percent for Low Emission Vehicles. EPA estimated that this criterion is 

equivalent to the steady-speed criterion of 60 to 80 percent conversion 

efficiency. For non-Low Emission Vehicles, the FTP-based criterion would be 

an increase of 1.5 times the HC standard (which translates to the same 

increase being proposed by the EPA) for signaling a malfunction. 

However, since many manufacturers have developed steady-speed 

monitoring strategies for implementation in 1994, the regulation would allow 

this approach to be used for the first two to three years. Thereafter, an 

1. The ARB is basing the criterion for non-Low Emission Vehicles on a 1.5 

times the applicable HC standard, as opposed to EPA's 0.4 g/mi HC increase, 

because OBD II applies to medium-duty trucks up to 14,000 lbs test weight. 

EPA requirements, on the other hand, would apply only to light-duty 

vehicles. Since California medium-duty trucks must meet numerically higher 

HC standards than light-duty trucks, an accompanying increase in the 

malfunction criteria is appropriate. 

13. 
evaluation of catalyst efficiency over the FTP cycle would be phased-in. 

This change is also being proposed because EPA plans to require FTP-based 

catalyst monitoring in federal OBD requirements, and industry has asked that 

the ARB and EPA coordinate the monitoring requirements to minimize 

development efforts in complying with both regulations. 

As a result of the Low-Emission Vehicles/Clean Fuels regulation, 

staff concluded that catalyst monitoring requirements should be split into 

two categories: non-Low Emission Vehicles and Low Emission Vehicles. The 

issue is that as emission standards decrease to very low levels, the 

approach to catalyst monitoring would need to change in order to provide an 

earlier indication of malfunction .consistent with the lower emission 

levels. Under the proposed change to the regulation, manufacturers of nonLow Emission Vehicles (certified to a .25 g/mi HC, 3.4 g/mi CO, 0.4 g/mi NOx 

standard) would be permitted to monitor the entire catalyst system as a 

single unit. A malfunction would be signaled when an emission increase of 

0.4 g/mi HC occurs due to catalyst deterioration anywhere within the system. 

This approach may be easier to implement in some cases than the one being 

proposed for Low Emission Vehicles, and provides industry with initial 

experience in catalyst monitoring before tackling more difficult systems. 

Low Emission Vehicles require earlier notice of malfunction when catalyst 

system deterioration in conversion efficiency occurs compared to a non-Low 

Emission Vehicle (allowing a HC increase of 0.4 g/mi before signaling a 

malfunction for a vehicle designed to meet a 0.04 g/mi HC standard, (i.e., 

10 times the emission standard), would not be acceptable). Therefore, staff 

is proposing that the regulation be revised for Low Emission Vehicles to 

require monitoring primarily the front catalyst alone. At lower emission 

levels, the front catalyst is much more critical to achieving low emissions 

than at the non-Low Emission Vehicle emission levels. It would also be the 

first catalyst to show deterioration. Providing warning of deterioration of 

the front catalyst alone signals a malfunction much earlier than waiting for 

the entire catalyst system to deteriorate to a level causing an increase of 

0.4 g/mi HC. 

A keystone in adopting the Low Emission Vehicle regulation was the 

promise exhibited by electrically heated catalysts in greatly reducing cold 

start emissions. These catalysts are heated electrically either before or 

subsequent to engine starting to more quickly achieve catalyst operating 

temperature for greater conversion of cold start emissions. Accordingly, 

staff is proposing in Section (b)(2) new monitoring requirements for heated 

catalyst systems should manufacturers ultimately choose to use this 

technology for meeting very low emission standards. Heated catalysts would 

be monitored independently of other catalysts, both for proper HC conversion 

efficiency and proper function of the heating system. 

14. 

ll 
P.19 

2. Revised .Evaporative Monitorina Requiremaafca 

Beeause of the large emission impact of evaporative system defects, 

ARB and EPA staff concluded that more rigorous evaporative system monitoring 

requirements are needed in the on-board diagnostic regulations. As 

described earlier, Section (b)(3) of the adopted regulation (Section (b)(4) 

with the proposed changes) calls for a functional check of the evaporative 

system which would verify that HC vapor flows into the engine when canister 

purge is activated. While this approach can detect malfunction of electromechanical components and large evaporative system leaks, small to moderate 

size leaks might not be detected. Thus, the proposed change to the 

monitoring requirement would require the more rigorous approach of verifying 

there are no leaks in the evaporative system. The suggested strategy would 

be a vacuum or pressure leakdown test. The presence of a leak would cause 

the trapped vaeuum or pressure to decay; if the- decay rate exceeds a 

specified threshold, a malfunction would be indicated. A very small leak, 

as small as a "pinhole", can be detected by this vary effective monitoring 

system. 

The proposed change to the evaporative monitoring requirement 

constitutes a significant departure from the current monitoring approach. 

Accordingly, under the proposed amendment, industry would be permitted 

additional lead time for implementation. Additional lead time is required 

because each vehiele model will require calibration and testing based on 

evaporative system volume and configuration (including fuel tank size and 

optional fuel tank availability), evacuation time for various fuel fill 

levels, sensitivity to ambient temperature and fuel properties such as vapor 

pressure, fuel sloshing in the tank, and other design considerations. It is 

proposed that this new approach be phased-in in accordance with revised 

evaporative systems designed to meet ARB's recently adopted high 

temperature, 3-day evaporative emission testing procedure. These new 

evaporative monitoring systems would then be phased-in during the 1995-1998 

model years. 

While it is proposed that evaporative monitoring systems will not be 

required until the high temperature evaporative requirements are met, it 

should be noted that all electronic evaporative system components would 

eontinue to require monitoring. Output components, such as the purge valve 

must be monitored for proper function in response to computer commands. 

3. Other Changas 

Most of the remaining changes, listed below, constitute refinements 

to the regulation and are generally non-controversial. Further explanation 

of these modifications can be found in the accompanying Technical Support 

Document. 

In order to further ensure against false malfunction indications, 

more tirae for the diagnostic system to determine that a misfire is 

present (except when misfire conditions are likely to cause immediate 

 

15. 

If 

______ 
P.20 

catalyst damage) would be provided. More time for monitoring 

evaluation would also be given for long-term fuel trim malfunctions 

for similar reasons. 

Because ARB testing indicates that proper secondary air flow is 

critical for vehicles to meet Low Emission Vehicle standards, 

enhanced secondary air system monitoring is being proposed. The 

regulation would require the diagnostic system to quantify actual 

flowrate rather than perform a functional check only (unless it can 

be shown that the air delivery system cannot corrode, in which case a 

functional check would suffice). 

The need for checking the rationality of input signals to the onboard computer would be clarified. 

Certification demonstration tests for FTP-based catalyst monitoring, 

^fter-start catalyst heating systems, and secondary air systems are 

being proposed to demonstrate the appropriateness of the criteria 

selected for determining a malfunction. 

A statement concerning the availability of repair information that 

references the generic scan tool is proposed to assure that the tool 

is fully effective for diagnosis and repair of emission-related 

malfunctions. 

Based on the progress of the SAE committees responsible for 

finalizing the recommended practices referenced in the regulations, 

staff has modified the OBD II regulations to reference the most 

recent versions of these practices. However, a number of the 

practices have not been finalized. The regulatory language will be 

modified to reference the final versions once they have been 

completed. One of the recommended practices, J1930, 

"Electrical/Electronic Systems Diagnostic Terms, Definitions, 

Abbreviations and Acronyms", is also referenced in Section 1977 of 

Title 13 and will be updated as well to maintain consistency. This 

update has been requested by industry. 

Other non-substantive changes have also been included to clarify the 

requirements. 

V. COORDINATION WITH THE ENVIRONMENTAL PROTECTION AGENCY 

The federal CAAA directs the EPA to develop a set of OBD regulations 

which must include, at a minimum, requirements to monitor the oxygen sensor 

and the catalytic converter. These requirements are to be implemented 

beginning with the 1994 model year. The amendments also require 

coordination with California's OBD II program. 

In order to ensure that an OBD system can be designed that will meet 

both agencies' requirements, the ARB and EPA worked together to develop the 

16. 

i1 

.-
P.21 

most appropriate and effective diagnostic system requirements. The OBD II 

regulations, with the proposed modifications, reflect a consensus on the 

best diagnostic approaches. 

The EPA is currently in the process of proposing regulatory language 

to satisfy the federal CAAA, The EPA is proposing a general performance 

requirement applicable to all emission-related systems. The failure or 

deterioration of an emission-related system or component that will cause 

emissions to increase beyond a specified emission threshold must be detected 

by the OBD system. Except for misfire, oxygen sensor and catalyst 

monitoring, manufacturers would be responsible for determining which 

components and systems need monitoring, which failure modes would be 

critical, and how the failure would be detected. The EPA would rely 

strongly on in=use testing and recall to ensure that OBD systems are 

effective. California, on the other hand, emphasizes more comprehensive 

requirements with more emphasis placed on an up-front demonstration of 

monitoring system effectiveness. California also requires that _U_L 

emission-related components be monitored to better ensure that high mileage 

vehicles perform at eraission levels in the vicinity of the standards. 

Based on discussions between ARB and EPA staff, it appears that a 

reasonable approach to ensuring proper OBD coordination and implementation 

would be for EPA to accept California OBD II systems as complying with 

federal requirements in the early years, and then for California to accept 

federal OBD systems as meeting California requirements for non-Low Emission 

Vehicles (0.25 g/mi HC, 3.4 g/mi CO, and 0.4 g/mi NOx) after 1998. By then, 

most of these vehicles will be phasing-out in California as the number of 

Low Emission Vehicles increases (which will all have California OBD II 

systems). Therefore, the staff will be strongly recommending to EPA that it 

accept California OBD II-equipped vehicles nationwide at least through the 

1998 model year. Under this proposal, after 1998, manufacturers would be 

able to design systems that meet the EPA requirements for 49 state vehicles, 

although it is expected that no major design changes would be necessary to 

comply with the federal requirements at that time. Similarly, California 

would accept any federal OBD systems after 1998 as satisfying non-Low 

Emission Vehicl© California OBD II requirements. Because the malfunction 

criteria proposed by EPA are independent of the vehicle's certified emission 

levels, ARB staff feels it would not be appropriate to accept Low Emission 

Vehicles in California that are equipped with federal OBD systems. 

Otherwise, as mentioned previously, a malfunction would probably not be 

detected until the vehicle's emission levels were several times the 

standards. 

VI. EXPANDED APPLICABILITY QF THE REOUIRFMFNTS 

Adopted OBD II regulations apply to vehicles with feedback fuel 

control systems, (Title 13, CCR Section 1968.1 (a) (1.0)), which covers 

virtually all vehicles for sale in California at this time with the 

exception of diesels. Although diesel engine emission control systems do 

not yet incorporate oxygen sensor-based feedback control systems, there is 

17. 
P^2 

expanding use of advanced electronic controls in order to meet lower 

emission standards. Given the expanding role of electronics in diesels, OBD 

II requirements should be implemented to the extent feasible. Since the 

California Smog Check Program is expected to evolve into a check of the onboard diagnostic system, and the use of advanced electronic systems is 

needed to meet more stringent emission standards, diagnostic system 

requirements should apply to all vehicles. EPA is also planning to include 

all vehicles under federal OBD rules. 

Because inclusion of diesels was decided late relative to ARB's 

regulatory process for the OBD II changes being proposed, there was little 

opportunity to discuss this issue with industry. Staff consulted, however, 

with the major manufacturers of diesel engines in early June to determine 

the extent to which diesel engines could comply with OBD II requirements, 

and whether inclusion of all diesel vehicles in OBD II was practical within 

the 1994-96 timeframe. After some discussion, staff and industry generally 

agreed on the extent of monitoring requirements feasible for diesel engines. 

Because diesel engines lack full feedback fuel system control and do not 

utilize oxygen sensors, many of the OBD II requirements for feedback fuel 

system vehicles eannot apply. Nonetheless, most of the emission-related 

components and systems can be monitored by the diagnostic system with the 

exception of the catalyst, which is used for different purposes on a diesel 

engine than for other engines. Diesel engine catalysts primarily control 

particulate emissions, and are less efficient in obtaining HC or carbon 

monoxide (CO) reductions than current gasoline engine designs. 

Because oxygen sensors are not used to control the system, there 

presently is no feasible means of detecting loss of catalyst particulate 

conversion efficiency. Components/systems which can be monitored include 

the electronic fuel injection system, exhaust gas recirculation system 

function, wastegate, electronically-controlled transmission components, and 

others. 

The diesel engine manufacturers agreed to include diagnostic 

capability in their electronically controlled engines. Due to the lateness 

of this proposed change, full compliance with OBD II would be delayed until 

1996 in California for diesels. ARB staff and manufacturers agreed that a 

monitoring plan should be submitted by each manufacturer for approval by the 

Executive Offieer. The plan would indicate the emission-related components 

and systems that are feasible to monitor at a cost comparable to other 

engines meeting the OBD II requirements. All other applicable requirements, 

including implementation of the diagnostic link, demonstration testing, 

etc., would also be met. Most of the diesel engines affected by this 

requirement are outfitted in medium-duty trucks built by General Motors, 

Ford (Navistar), and Chrysler (Cummins) and in a few models in the lightduty class, primarily from European manufacturers. Most of these vehicles 

include a moderate level of diagnostic capability already, but would require 

additional development to comply with OBD II. 

18. 

.2/ 
P.23 

VII. AIR CONDITIONING SYSTEM MONITORING 

Resolution 89-77 directs ARB staff to review the OBD II requirement 

to detect the leakage of chlorofluorocarbons (CFCs) from vehicle air 

conditioning systems in view of other monitoring programs regarding the use 

of CFCs. 

The Montreal Protocol, with its 1990 amendments, calls for reductions 

in the amount of CFCs produced throughout the 1990's, with complete 

elimination of CFC production by the year 2000. 

The OBD II air conditioning monitoring requirement has provided 

vehicle manufacturers an incentive to phase out the use of CFCs in 1996 by 

waiving the monitoring requirement in such a case. At this time, ARB staff 

is unaware of any manufacturers which will develop air conditioning 

monitoring systems; all will phase-out the use of CFCs by the 1996 model 

year. While the phase-out of CFC use in California vehicles in itself would 

probably have little impact on CFC emissions worldwide, ARB staff believes 

it is a positive step in the direction of promoting a more accelerated 

phase-out of CFC production. As has happened with past requirements, other 

states/countries may follow the lead of the ARB, which in turn could cause 

the demand for CFCs to drop below predicted future levels. Therefore, it is 

suggested that this requirement should remain as part of the OBD II 

regulations. 

VXH . ISSUES OF CONTROVERSY 

Despite unprecedented amounts of time spent with manufacturers in 

developing the OBD II regulations and the proposed changes, there are a few 

remaining issues for which agreement was not achieved. 

1. 3fc£iflflanev .of Emission Thresholds 

Except for eatalyst monitoring and a few other monitoring 

requirements, the regulation generally specifies that a malfunction is to be 

signaled when emissions exceed 1.5 times the applicable standards (thus, for 

a .25 HC level, a malfunction would be signaled before emissions reach 0.4 

g/mi, whereas for a NOx standard of 0.4 g/mi a malfunction would be signaled 

before emissions reach 0.6 g/mi). Some manufacturers believe these emission 

thresholds are too stringent. They maintain that some components cannot be 

diagnosed as malfunctioning until an emission increase larger than the 

allowable threshold has occurred or that trying to meet too small a 

threshold could falsely trigger a malfunction indication. Obviously, 

manufacturers would neither want to annoy owners by illuminating the MIL 

unnecessarily early, nor would they want to pay unnecessary warranty 

expense. 

In response to this concern, staff reexamined the behavior of 

feedback fuel control systems with adaptive learning capabilities and 

19. 
concluded that at least at the non-Low Emission Vehicle emission level, the 

thresholds being proposed are reasonable. Except for the catalyst system, 

exhaust gas recirculation (EGR) and secondary air system, most other 

electronic emission control components govern the fuel control system. By 

design, the feedback control system automatically compensates and adapts in 

response to component deterioration, and the degree of control covers a very 

wide range. As long as the fuel control system maintains precisely the 

air/fuel ratio needed by the catalytic converter to operate at maximum 

conversion efficiency (stoichiometric), emissions below the standards should 

also be maintained. Given the wide compensation capability of the fuel 

control system, an individual component deteriorated enough to drive the 

fuel system to its range of authority limit should be relatively easy to 

discern from an otherwise normally operating component. Taking the oxygen 

sensor as an example (the most critical component in the fuel system) some 

manufacturers indicated that this component could be nearly failed, and 

emissions would likely remain below the emission standards at the non-Low 

Emission Vehicle level, because the fuel system still has sufficient 

corrective capability to maintain a stoichiometric air/fuel ratio. 

Similarly, some manufacturers have indicated that complete failure of the 

EGR system would be unlikely to cause an increase in NOx above the proposed 

emission threshold since EGR is used more for minimizing knock and improving 

fuel economy than for substantial NOx control. In these cases, a reliable 

check should be possible, since the monitoring criteria could approach the 

crudeness of a functional check only and provide a reliable indication of 

malfunction. At this time, it appears that failure of many components would 

not necessarily cause emissions to exceed the standards ains. an emission, 

threshold. Until manufacturers provide convincing evidence that the 

established criteria are too stringent, the staff has no basis for proposing 

a change. 

For Low Emission Vehicles, espeeially for the Ultra-Low Emission 

Vehicle category, there may be some basis for concern, though no one has 

sufficient data to be certain a change in the threshold is needed. For this 

reason, for Low Emission Vehicles, the staff is proposing that in cases 

where a manufacturer using both the best monitoring techniques and the most 

advanced adaptive learning strategies for the fuel system can demonstrate 

that significant errors of commission would occur using the specified 

threshold, the Executive Officer may revise the threshold upward. In the 

case of misfire detection, for example, staff has already limited the 

threshold for detecting misfire since little benefit would be gained in 

detecting misfire any earlier for a Low Emission Vehicle than for a non-Low 

Emission Vehicle (where misfire will be detected at about the 1 to 2 percent 

misfire level). 

In order to maintain the maximum effectiveness of OBD II even at the 

Low Emission Vehicle level, it is desirable to maintain pressure on industry 

to develop improved monitoring strategies for detecting deteriorating 

components. In order to maintain emissions from high mileage vehicles near 

the emission standards, an effective OBD II system is necessary. Setting an 

emission threshold at 2 or 3 times the standard would seriously undermine 

emission reduction goals. Judging from staff's experience with ARB's own 

20. 

^3 
P.25 

Ultra Low Emission Vehicles, maintaining the emission 

emission levels will not be significantly more likely 

illumination of the MIL than at the higher emission 1 

eurrent emission systems already control emissions to 

warmed-up normal operating conditions because of the 

control systems and catalysts. Also, most of the add 

emissions for Low Emission Vehicles comes from heated 

eatalyst performance threshold is not tied to the 1.5 

a percent conversion efficiency that has already been 

threshold at low 

to cause erroneous 

evels. The best 

near zero under 

excellent adaptive fuel 

itional reduction in 

catalyst systems whose 

factor, but rather to 

shown to be feasible. 

.2. Insufficient lead Tim® For Implementing Som© QBD XI Monitoring 

In discussions with numerous manufacturers concerning progress in 

developing OBD II monitoring strategies, it has become clear some companies 

have been more aggressive in finding solutions than others. This is 

evidenced by the faet that a few manufacturers believe they do not have 

sufficient time to implement some requirements by 1994, particularly the 

catalyst requirements. While nearly all manufacturers agree that catalyst 

monitoring is feasible based on some laboratory and limited on-road testing, 

a few believe there is still insufficient time remaining before 1994 

introduction to test these systems. They still need to ensure their 

monitoring strategies work properly under all driving conditions and across 

a wide variety of vehicles, particularly at higher mileages. Others, 

however, have expressed confidence that implementation of catalyst 

monitoring on at least a portion of their product line can be accomplished 

by 1994. 

Based on discussions with some of the manufacturers which appear able 

to implement catalyst monitoring for the few engine families likely to begin 

phase-in of OBD II in 1994, the on-road development phase may not prove as 

troublesome as some may suggest. Much of this concern seems to originate 

from the lack of experience with these systems to date. On the other hand, 

some manufacturers may be willing to accept more risk than others. 

Nevertheless, the ARB does not want unreliable OBD systems in the field 

either, and recommends that the staff report back to the Board in November, 

1992, to determine if a delay until 1995 in the eatalyst monitoring 

requirement or some other particular requirement would be warranted. 

Reporting to the Board at that time would permit manufacturers to make lastminute, software changes to delete a particular requirement, if necessary, in 

time for 1994 production. 

3. Some QBD II Requirements May Limit Dus.qp FUlflMIHiy 

A few manufacturers have been critical of some of the catalyst 

efficiency monitoring requirements contained in the proposed OBD II 

revisions. In particular, they have been critical of the requirement for 

Low Emission Vehicles that any front catalyst shall be monitored for proper 

conversion efficiency. The problem stems from the inability of 

21. 
JEL2__-

manufacturers to develop a method of reliably detecting catalyst conversion 

efficiency when the catalyst is a very small volume unit. Manufacturers 

sometimes prefer to use small volume "light-off" catalysts because they heat 

up quickly due to their low mass when exposed to exhaust gas, and can 

provide effective control of cold start eraissions. Unfortunately, however, 

these catalysts are located close to the engine and are less able to 

dissipate heat as quickly as larger catalysts. They are therefore more 

prone to damage, particularly if malfunctions such as misfire take place. 

Manufacturers may gamble on the use of these small catalysts for 

controlling emissions during the first 75,000 miles of vehicle use after 

which time their in-use liability ends. Before 75,000 miles is also when 

catalyst damaging malfunctions are probably unlikely (high energy ignition 

systems in current vehicles and unleaded gasoline permit spark plugs to last 

beyond 60,000 miles). However, vehicles remain in use well beyond this 

point and become increasingly subject to malfunctions. The staff is not 

necessarily opposed to use of these small catalysts so long as their failure 

will be detected by the OBD II system. 

In addition, the staff believes that it may be possible to combine a 

small volume catalyst with another small volume catalyst in series as one 

way of increasing the overall volume to enable reliable monitoring. This 

arrangement is also particularly effective at improving light-off 

characteristics, compared to use of only one small front catalyst followed 

by a large volume catalyst. Since there are ways of achieving quick warm-up 

with minimal revisions to the catalyst system and still be able to detect a 

damaged small volume catalyst, staff believes that the restrictions on 

inadequate designs are warranted. 

X. COST AND COST EFFECTIVENESS 

The added cost per vehicle to implement the proposed OBD II 

modifications, above the cost of the previously adopted OBD II system, is 

estimated to be about $18, retail price equivalent. This cost is attributed 

to the addition of the necessary hardware to meet the new evaporative system 

monitoring requirements, and includes the cost of a pressure sensor, a 

solenoid for closing the canister vent, and the associated wiring and 

mounting hardware. 

Based on an analysis of the emission benefit from the enhanced 

evaporative system monitoring requirement, the estimated cost effectiveness 

is $1.11 per pound of diurnal and hot soak evaporative hydrocarbons. 

Because of limited data, no evaporative emission reduction was calculated 

for running loss emissions which would be prevented by detection and 

correction of evaporative control system malfunctions. Therefore, ARB staff 

believes that the above cost effectiveness is very conservative. Data 

obtained for the EMFAC7E running loss emission factors indicate that running 

losses may increase by a factor of 10 to 20 on current technology vehicles 

when evaporative system malfunctions are present. 

22. 

2<f 
P.27 

XI. CONCLUSION 

The automobile industry has demonstrated innovative and progressive 

engineering skills in finding solutions to the OBD II requirements adopted 

in 1989. Although some work remains before implementing these solutions 

into production vehicles, effective and reliable monitoring strategies have 

been demonstrated for all of the requirements both in the laboratory and in 

limited testing of on-road vehicles with prototype systems. 

During the last two years, staff has met regularly with industry to 

monitor progress and to develop improvements to the regulation where 

improved effectiveness, greater reliability, lower cost, corrections or 

other changes would be indicated. Staff has made every effort to 

accommodate requests by manufacturers to meet and openly discuss OBD II 

issues and concerns. The proposed changes to the adopted regulation are a 

result of this lengthy process, and are expected to result in a highly 

effective tool for properly controlling in-use vehicle emissions. OBD II 

systems should also provide important benefits to vehicle owners. 

Since ARB must maintain as its highest priority the protection of 

public health, the proposed requirements are tough and continue to require 

the best that industry is judged capable of achieving. Thus, while industry 

may sometimes estimate their capability differently than ARB, there is good 

agreement that most of the numerous technical requirements in OBD II are 

both worthwhile and feasible. 

23. 
P.28 

1968.1 Malfunction 

Model-Year Passenger 

Diagnostic System Requirements—1994 and Subsequent 

, Light-Duty Trucks, and Medium-Duty Vehicles W4fch 

feedback Fae4 GeRfcFe4 Systems 

(a) GENERAL REQUIREMENTS 

(1.0) All 1994 and subsequent model-year passenger cars, light-duty 

trucks, and medium-duty vehicles with feedback fuel control 

systems shall be equipped with a malfunction indicator light (MIL) 

located on the instrument panel that will automatically inform the 

vehicle operator in the event of a malfunction of any efa4ss4eRpe4afee_ powertrain components which can affect emissions that 

provide input to, or receive output from, the on-board computer(s) 

or of the malfunction of the on-board computer(s) itself. The MIL 

shall not be used for any other purpose. 

(1.1) The MIL shall be of sufficient illumination and location to be 

readily visible under all lighting conditions. The MIL shall 

illuminate in the engine-run key position before engine cranking 

to indicate that the MIL is functional and shall, when 

illuminated, display the phrase "Check Engine" or "Service Engine 

Soon". The word "Powertrain" may be substituted for "Engine" in 

the previous phrases. 

(1.2) All 1994 and subsequent model-year passenger cars, light-duty 

trucks, and medium-duty vehicles w4feh feedbaek ?ue4 eeRfeFe4 

required to have MIL pursuant to (1.0) above shall also be 

equipped with an on-board diagnostic system capable of identifying 

the likely area of the malfunction by means of fault codes stored 

in computer memory. These vehicles shall be equipped with a 

standardized electrical connector to provide access to the stored 

fault codes. Specific performance requirements are listed below. 

A glossary of terms is contained in subsection (n) at the end of 

this section. 

(1.3. Manufacturers of diesel engines utilizing computer-based 

eleetronie powertrain control systems shall submit a plan for 

eomplvino with these reguirements to the Executive Officer for 

approval* Ths plan shall bs appr.p_yftri-ba.ssd, pn monitoring all 

powertrain components vhich pan affect emissions and for which 

reliable monitoring techniques are available at costs comparable 

to other engines meeting these requirements, and on meeting all 

other applicable requirements (e.g.. storing freeze frame 

conditions, meeting standardization reguirements. etc.). 

(1.4) For Low Emission Vehicles fLEV.. the Executive Officer shall 

revise the emission threshold for a malfunction on anv check if 

the most reliable monitoring method developed requires a higher 

threshold to prevent significant errors of commission in detecting 

a.malfunction, 

(1.5) For every case in which a malfunction is to be noted when an 

emission threshold is exceeded (e.g.. emissions in excess of 1.5 

^ 
times the standard), the manufacturer may perform onlv a 

functional check of a specific component or svstem if complete 

failure of such would not cause the vehicle's emissions to exceed 

the emission threshold. 

(1.6) After the 1998 model vear. for Non-LEVs. fulfillment of federal 

On-Board Diagnostic (QBD) requirements shall be deemed to be an 

acceptable option for the manufacturer for the purpose of meeting 

these reguirements. 

(b) MONITORING REQUIREMENTS 

(1.0) CATALYST MONITORING 

(1.1) Requirement: 

(1.1JL) LEVs: The diagnostic system shall individually monitor 

the front catalyst or catalysts (except bypass eata4ysts) (i.e.. 

any catalvst(s) 64esest te the en§4Re which receive engine-out 

untreated exhaust gasl_. except that front catalysts mav be 

monitored in combination with the next catalvst downstream if it 

can be demonstrated that a malfunction will be indicated when the 

front catalvst is alone malfunctioning (see (b) (1.2.1)). Sueh 

e£ata!ysts arranged in parallel with the same inlet and outlet in 

a single exhaust pipe shall be considered as one catalyst. A_ 

separate catalvst incorporated into the same container as a front 

catalvst shall be considered a downstream catalvst. 

(1.1.2) If the front catalvst is a small volume catalvst (see (b) 

(1.2.2)). the diagnostic svstem shall also monitor the next 

catalvst downstream of the small volume catalvst either 

independently of. or (if the conditions in section (1.1.1) are 

met) in combination with, the small volume catalvst. 

(1.1.3) Manufacturers mav submit other monitoring strategies, 

subject to Executive Officer approval, based on eoual timeliness 

and reliability in detecting a catalvst malfunction as these 

requirements. 

(1.1.4) Non LEYS! The diagnostic svstem shall monitor the 

catalvst svstem for proper performance. 

(1.2) Malfunction Criteria: 

(1.2.1) LEVs: Each monitored catalvst. or combination of 

catalysts, shall be considered malfunctioning when average Federal 

Test Procedure (FTP) total hydrocarbon (HC) conversion efficiency 

falls between 40 fee SO 50 to 60 percent wM4e 4R neFma4 e4esed 

4eep epepat4eR. The efficiency determination shall be based on a 

steady state test an FTP test wherein a malfunction is noted when 

the cumulative total HC emissions. eeReen.Fa.4en measured at the 

outlet of the monitored catalvst(s) is more than 60 te 69 40 to 50 

percent of the cumulative total engine-out emission! 6eneeRtFafe4eR 

measured at the inlet of the catalvst(s). In addition, if a front 

A-2 

_7 
catalvst is monitored in combination with a downstream catalvst, 

the front catalvst shall be considered malfunctioning when its 

efficiency has deteriorated between 40 to 50 Percent from Its 4QQ0 

mile average FTP total HC efficiency. The E»eeut4ve 9ff4eeF sha44 

Fev4se the te4@FaRee SR the eheek 4? the raest Fe44ab4e raeR4teF4n§ 

raethed deve4eped peq_4pes a w4dep te4epaflee te pFeveRt s4gR4f4eaRt 

eppeFS ef 6emm4ss4eR 4R deteet4R§ a raa4fHRet4eR4R§ eata4yst-

(1.2.2) She_4d a sraa44 waFm-ap eata4yst be _sedT the raaRHfaetdFeF 

§R_4 4 SHBRW . a p4an fe? apppeva4 by the EseeuUve 9f£4seF i-e 

a©R4tep @ash sues wapra-_p sata4yst 4RdepefldeRfe4y ©f- aRy ©thep 

s_ta4yslv ep 4R 6emb4Rat4eR w4th the Rest eafea4yst 4 R sep4esT QF 

by aRethep method te 4deRt4fy eata4yst eff4e4eRey 4ess- AppF©va4 

sha44 be gpanted 4? the raaflafaefeapep pp©v4des an equa44y Fe44ab4e 

and t4rae4y 4Rd4eat4en ef raa4?_Rst4ea as fep eafea4yst systems 4R 

(_T2._4T For LEVs. each small volume catalvst (i.e., those_ 

designed with a conversion efficiency too low to be practically 

monitored for 50 to 60 percent average FTP total HC efficiency) 

monitored independently shall be considered malfunctioning when 

its average FTP conversion efficiency has deteriorated bv between 

__-_-^_-IQ_jmrcent from its 4000 mile conversion efficiency,. 

(1.2.3) Non-LEVs: The catalvst svstem shall be considered 

malfunctioning when its conversion capability decreases to the 

point that HC emissions increase bv more than 1.5 times the 

standard over an FTP test from a test run with a representative 

4000 mile catalvst svstem. 

(1.2.4) For LEVs and Non-LEVs. as an option to monitoring the 

eatalvst during FTP driving conditions, for 1994 and 1995 model 

vear vehicles onlv. manufacturers mav monitor the front catalvst 

independently of. or in combination with, the next catalvst 

diMlSJXaafl. Each monitored catalvst or eatalvst combination shall 

be, considered malfunctioning when total HC conversion efficiency 

f*_ Ls .between. 60 to 80 percent while in normal closed loop 

MflCfl-LiPD, The efficiency determination shall be based on a 

steady state test wherein a malfunction is noted when the total HC 

emission concentration measured at the outlet of the monitored 

catalvst(s) is more than 20 to 40 percent of the cumulative total 

engine-out emissions measured at the inlet of the catalvst(s). 

1994 and 1995 model vear vehicles certified to this option shall 

incorporate FTP based monitoring no later than the 1997 model vear 

/vehicles initially complying with section 1968.1 in the 1996 

model vear shall utilize an FTP based catalvst monitoring svstem). 

(1.3) Monitoring Conditions: 

•(1.3.1) A catalvst monitoring check shall occur at least once per 

trip except for vehicles utilizing steady state monitoring, which 

Shall Comply with Section (1,3,2), "Trio" is defined in section 

(n) (S.Q).—This trip definition applies throughout section 

___________ 

A-3 

Earn 
(1.3..2) If steady state efficiency is being monitored (sefi-

^e^tion (b) (1.2.4)). Tthe manufacturer shall choose a non-closed 

throttle, reasonably steady speed condition for monitoring the 

catalyst with the constraints that the check shall (i) occur 

between 20 mph and 50 mph, (ii) take no more than a 20 second 

interval to determine both that the vehicle is operating in a 

proper window to perform the check and to actually perform the 

check, and (iii) be conducted at the earliest such condition 

encountered after the beginning of closed-loop operation for each 

driving cycle. Performance of the check may be delayed after 

engine startup until stabilized coolant temperature is achieved 

and/or a suitable cumulative time interval of non-closed throttle 

vehicle operation has elapsed to ensure the catalyst is warmed-up 

for properly performing the monitoring check. The specified 

cumulative time interval shall begin from the first non-closed 

throttle operation either after achieving a stabilized coolant 

temperature or after engine starting and shall not exceed 180 

seconds. These monitoring constraints and conditions may be 

altered, subject to Executive Officer Approval. Such approval 

shall be granted if the manufacturer submits data and an 

engineering evaluation justifying the need for the exception and 

demonstrates that the requested alteration would yield improved 

catalyst monitoring. 

(£-3-2) "Reasonably steady" speed interval in this instance means 

a 20 second period where all accelerations and decelerations are 

of an average magnitude of 0.5 mph/second or less over any two 

second interval during this period. The manufacturer may abort 

the check if the engine operating conditions change during the 

check so that the vehicle exceeds the speed or acceleration/ 

deceleration tolerances before the end of the checking interval. 

The manufacturer may base performance of the catalyst check upon 

engine RPM and load conditions equivalent to the above monitoring 

conditions. If a manufacturer develops a means of monitoring 

catalvst efficiency which cannot utilize a steady state monitoring 

period (e.g.. examining time vs. temperature during catalvst 

warmup). it mav present a monitoring proposal to the Executive 

Pfflsex for ap.Br.oYa_ based on equivalent accuracy and timeliness 

as the steady state monitoring protocol in detecting a 

malfunctionincL-cafca-yst. 

(4v3.3} At the _4ssFet4en ©f- the taanufaetupePy any seeendapy a4p 

4njest4©n raay be d4sab4ed _HP4R§ a sata4yst sheeky but ne mape 

than thpee sash eheeks sha44 be 6©ndueted pep dp4v4n§ eye4e-

(i-3*4) If a raanufastHFep deve4eps a means ef men4t©p4n§ eata4yst 

eff4s4ensy wh4eh eannet ut444ie a steady state meR4tep4R§ pep4ed 

(e-§-7 e«ara4a4R§ t4me vs- tempepatupe dup4R§ eata4yst wapmup^T 4t 

may ppesent a men4t©p4R§ pp©pesa4 te the Eae6at4ve 9ff4eep f©F 

appp©va4- ?he Eae6ut4ve 9f?4eep sha44 apppeve sueh a ppepesa4 4f4t ppev4des equ4va4ent aeeupaey and fe4me44ness as the steady state 

men4t©p4n§ ppst©6©4 4n deteet4R§ a ma4funet4en4R§ eata4yst-

(1.4) MIL Illumination and Fault Code Storage: 

A-4 

3/ 
P.32 

(1.4.1) Except as noted below, upon detection of. a_cata1vst 

malfunction, the diagnostic svstem shall store _a fault COde and. 

^ MI L shall be illuminated no later..than the end .of-the next 

trio if the malfunction js again present. 

(1.4._2) For steady state eatalvst eff iciencv _che.c__s__ Uupon 

detection of catalyst efficiency between 49 fifl to 59 SQ percent, 

the diagnostic system may perform up to two successive monitoring 

checks prior to informing the vehicle operator of a malfunction. 

These monitoring checks need not occur on the same driving cycle, 

but shall be performed as soon as proper monitoring conditions 

occur. If catalyst efficiency remains between 49 6fl to 59 gfl 

percent or less for the three sequential checks, a fault code 

shall be stored and the MIL shall then be activated. 

(1.4.21) The diagnostic system shall temporarily disable catalyst 

monitoring when a malfunction exists which could affect the proper 

evaluation of catalyst efficiency. 

(1.4.34J The monitoring method for the eatalyst(s) shall be 

capable of detecting when a catalyst trouble code has been cleared 

(exeept diagnostic system self-clearing), but the catalyst has not 

been replaced (e.g., eatalyst overteraperature approaches may not 

be acceptable). 

(2.0) HEATED CATALYST MONITORING 

(2..1) RegHi£e_ie__;_ 

(2.1.1) The diagnostic svstem shall monitor all heated catalvst 

systems for proper heating. 

(2.1.2) In addition to the non-heated catalvst requirements in 

se_ctiofl_(b) (1). the HC conversion efficiency of all heated 

catalysts shall each be monitored. Manufacturers mav monitor 

heated catalysts in combination with another catalvst if it can be 

demonstrated that a malfunction will be indicated when the heated 

catalvst is malfunctioning. Otherwise, the heated catalvst shall 

be monitored independently. If a heated catalvst is a small 

volume front catalvst. the diagnostic svstem shall also monitor 

the next eatalvst downstream either independently of. or (if the 

conditions above are met) in combination with, the small volume 

heated catalvst. 

(2.2) Malfunction Criteria: 

X_-__-JJ Pre-Start Heated Catalvst Systems: The svstem shall be 

considered malfunctioning when the designated ore-start catalvst 

temperature is not attained before engine starting. 

1Z.Z.Z) After-Start Heated Catalvst Systems: The svstem shall be 

cojLS_Mei_ed_malfunctioninq when the eatalvst does not reach its 

des_Lg__at_;d_ heat ino temperature within a reguisite time period 

alter engine.Starting. The time period is to be determined bv the 

A-5 

32 
P.33 

manufacturer subject to the reguirement that the SVStem Shall 

detect a heating svstem malfunction causing emissions from a 

vehicle equipped with the heated catalvst svstem to exceed 1.5 

times anv of the applicable FTP standards. 

(2.2.3) Manufacturers using other heating or monitoring 

strategies mav submit an alternate plan for approval bv the 

Executive Officer to monitor heated catalvst systems based on 

comparable reliability and timeliness to these reguirements in 

detecting a catalvst heating malfunction. 

(2.2.4) Except as noted in section (b) (1.2.4). the diagnostic 

system shall use the malfunction criteria specified in section (b) 

(1.2.1) or section (b) (1.2.2). whichever is applicable, when 

monitoring the conversion efficiency of a heated catalvst. 

(2.3) Monitoring Conditions: 

(2.3.1) Pre-Start Heated Catalvst Systems: The diagnostic svstem 

shall monitor the heating svstem for proper operation once per 

trip. Manufacturers may disable the monitoring system for one 

engine start if during the previous driving cvcle the vehicle 

traveled less than one mile. 

(2.3.2) After-Start Heated Catalvst Systems: The diagnostic 

svstem shall monitor the heating svstem for proper operation once 

per trip. 

(2.3.3) Except as noted in section (b) (1.2.4). the diagnostic 

svstem shall monitor the conversion efficiency of all heated 

catalysts at least once per trip. 

(2.4) MIL Illumination and Fault Code Storage: 

(2.4.1) Uoon detection of a catalvst heating malfunction, the 

diagnostic svstem shall store a fault code and the MIL shall be 

illuminated no later than the end of the next trip if the 

malfunction is again present. 

(2.4.2) For heated catalvst efficiency malfunctions, the MIL 

Shall be illuminated, and a fault code stored according to section 

(b) (1.4). 

(22.0) MISFIRE MONITORING 

(22-1) Requirement: The diagnostic system shall monitor engine misfire 

and shall identify the specific cylinder experiencing misfire. 

If more than one cylinder is misfiring, a separate code shall 

, indicate that multiple cylinders are misfiring (specifying the 

individual misfiring cylinders under this condition is optional, 

however, identifying only one misfiring cylinder shall not occur 

when a multiple misfire code is stored). 

A-6 

53 
fr 

(22.2) Malfunction Criteria: The manufacturer shall specify in the 

documentation provided for certification (see subsection (g) 

and (h) infra.) a percentage of misfires out of the total number 

of firing events necessary for determining a malfunction for each 

of the conditions listed below. 

XAJ.T The percent misfire evaluated in 200 revolution increments 

for each engine speed and load condition which would result in 

eatalyst damage. The manufacturer shall submit in the 

certification documentation catalyst temperature data versus 

percent misfire over the full range of engine speed and load 

conditions. The data shall be obtained from a representative 

cross section of a manufacturer's engine offerings from small to 

large displacements. Up to three such engine evaluations shall be 

documented per manufacturer, though a manufacturer may submit more 

data if desired. An engineering evaluation shall be provided for 

establishing malfunction criteria for the remainder of engine 

families in 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; 

IBX* The percent misfire evaluated in 1000 revolution increments 

which would cause emissions frora a durability demonstration 

vehicle to fa44 exceed an FTP test by raepe thafl 1.5 times anv of 

the applicable £I£ standard! if the degree of misfire were present 

from the beginning of the test. If the level of misfire 

determined under this reguirement is significantly lower for an 

LEV as opposed to a Non-LEV with a similar engine design, the 

manufacturer may re_me_i_ approval from the Executive Officer to 

use a higher percentage of misfire as the malfunction criteria for 

the LEV, not to exceed the level of the Non-LEV. For the purpose 

of establishing the percent misfire, the manufacturer shall 

eonduet the demonstration test(s) with the misfire events 

occurring at equally spaced complete engine eyele intervals, 

across randomly selected cylinders throughout each 1000 revolution 

increment. However, the percent misfire established shall be 

applicable for any misfire eondition (e.g. random, continuous, 

equally spaced, etc.) for the purpose of identifying a 

malfunction. This criterion shall be used for all vehicles with 

engines containing the same number of cylinders as the 

demonstration vehicle. The number of misfires in 1000 revolution 

increments which was determined for the durability demonstration 

vehicle malfunction criterion may be used to establish the 

corresponding percent misfire malfunction criteria for engines 

with other numbers of cylinders. The malfunction criteria for a 

manufacturer's product line shall be updated when a new durability 

demonstration vehicle is tested which indicates more stringent 

criteria are necessary than previously established to remain 

within the above emission limit; 

X.CJ.-S- The degree of misfire evaluated in 1000 revolution increments 

which would cause a durability demonstration vehiele to fail an 

Inspection and Maintenance program tailpipe emission test. This 

A-7 

^v 

, _.._• 
criterion shall apply to vehicles with the same number of 

cylinders as the demonstration vehicle. The number of misfires in 

1000 revolution increments which was determined for the durability 

demonstration vehicle malfunction criterion may be used to 

establish the corresponding percent misfire malfunction criteria 

for engines with other numbers of cylinders. The malfunction 

criteria for a manufacturer's product line shall be updated when a 

new durability demonstration vehicle is tested which indicates 

more stringent criteria are necessary than previously established 

to ensure passing an Inspection and Maintenance test, or when the 

Inspection and Maintenance test is revised. 

(22.3) Monitoring Conditions: Misfire shall be monitored continuously 

and under all positive torque engine speeds and conditions. With 

Executive Officer approval, the manufacturer may disable misfire 

monitoring when misfire cannot be distinguished from other effects 

when using the best available monitoring technology or the method 

of detection is not operable under some identifiable conditions. 

The manufacturer shall present data and an engineering evaluation 

to the Executive Officer to justify the proposed action (e.g. ase 

sf an ©aygen sensep 4s QR© petent4a4 means ef assess4n§ ra4s£4Febut 4t ean de se en4y when 41 has wapraed-up). 

(22-4) MIL Illumination and Fault Code Storage: 

(22.4.1) Except as provided below in subsection (22.4.22), upon 

detection of any ©£ the spes4f4ed 4eve4§ ef- a4sf4p_ the level of 

misfire specified in subsection (3.2) (A), the MIL shall blink 

once per second during actual misfire conditions and remain 

continuously illuminated otherwise. In vehicles which provide 

fuel shutoff and default fuel control to prevent overfueling_ 

during misfire conditions, the MIL neeti not blink and mav instead 

illuminate continuously upon detection of misfire provided that 

the fuel shutoff and default control shall be activated as soon as 

misfire is detected. Fuel shutoff and default fuel control mav be 

deactivated only to permit fueling outside of the misfire rangiL, 

(3.4.2) Upon detection of the misfire levels specified in 

subsection (3.2) (B) or (C). the MIL shall be illuminated and a 

fault code stored no later than the end of the next driving cvcle 

in which misfire is detected, unless driving conditions similar to 

those under which misfire was originally detected have been 

encountered (see section (3.4.3)) without an indication of 

misfire,, in which case the initial temporary code and stored 

conditions mav be erased. Furthermore, if similar driving 

conditions are not encountered during.80 trios subsequent to the 

initial detection of a malfunction, the initial temporary code and 

stored conditions mav be erased. 

(3,4.3) Upon detection of misfire, manufacturers shall store the 

engine speed, load, and warm-up status (i.e.. cold or warmed-up) 

under which the first misfire event was detected. A trio or 

driving cvcle shall be considered to have similar conditions if 

t_ie_ stored engine speed conditions are encountered within 375 rom. 

A-8 

35^ 
P.36 

load conditions within 10 percent, and the same warm-HP status 13, 

present. With Executive Officer approval, other strategies for 

determining if similar conditions have begr__encountereri mav he.. 

employed. Approval shall be based on comparable timeliness and 

reliability in detecting similar conditions^ 

(2*4-2} Sn veh4s4es wh4eh pp©v4de fae4 shateff and defaa4t fae4 

eentp©4 t© ppevent ev©pfa©44R§ dup4R§ m4s?4pe e©Rd4t4©RSv the MIL 

Reed net fe44nk aRd may instead 444am4nate 6©nt4nH©as4y apen 

_etest4©n sf ra4sf4pe ppsv4ded that the fae4 shuteff and defaa4t 

sentp©4 sha44 be aet4vated as seen as K?4S£4F@ 4 S dete6tedT and may 

be deast4vated ©n4y te pepm4t fae44n§ aats4de sf the sa4sf4pe 

(2T4T3 ) Upen deteet4©R sf the spee4?4ed 4eve4s ef ra4sf4FeT a 

faa4t eede sha44 be steped 4Rd4eat4R§ wh4eh ey44Rdep 4s ra4sf4F4n§ 

ep that mu4t4p4e ra4sf4Fes ape eseaFF4R§-

(31.0) EVAPORATIVE PURGE SYSTEM MONITORING 

(34.1) Requirement: 

(4.1.1) The diagnostic system shall raen4t©p the ppepep 

fan©t4en4R§ ©f the evap©pat4ve papge system aRd sha44 verify puF§e 

_UT flow from the complete evaporative svstem a44 6aR4steF(s4 

(4ne4ud4n§ ©an4steps _es4§ned fsp pefa@44n§ vapsp peeevepy) ©R the 

veh4s4e. In addition, the diaqnostic_svstem shall also monitor the 

evaporative svstem for the loss of HC vaoor into the atmosphere bv 

performing a pressure or vacuum check of the complete evaporative 

svstem. 

(4.1.2) Manufacturers mav temporarily disable the evaporative 

purge svstem to perform a check. 

(4.1.3) Manufacturers mav reguest Executive Officer approval to 

abort an evaporative svstem check under specific conditions if it 

can be demonstrated that a reliable check cannot be made when 

theSA J; .0 ad IJLI ons-e x.i s t, 

(4.1.4) Subject.to Executive Officer approval, other monitoring. 

strategies may•bfL.i-seri. provided the manufacturer provides a 

description of the strategy and supporting data showing eguivalent 

monitoring reliability and timeliness in detecting an evaporative 

svstem malfunction or leak. 

(4.1.5) Implementation of this requirement is not mandatory until 

vehicles are designed to comply with the reguirements of Title 13. 

California Code of Regulations. Section 1976. "Standards and Test 

Procedures for Motor Vehicle Fuel Evaporative Emissions." for 1995 

and subseouent model vear vehicles. 

(34.2) Malfunction Criteria: An evap©Fat4ve puF§e system sha44 be 

6©Rs4deped ma4faRsfe4©R4n§ when hydeFeaFben f4ew 4flte the eng4ne 4s 

net deteetab4e when the eafl4step p_F§e 4s ast4vated aRd a 

A-9 

3£ 
P.37 

pequ4s4te amount ef hydFeeaFben vap©F 4s pFesenfe 4n the 6an4steF 

te pepfepm the eheekr An evaporative svstem shall be considered 

malfunctioning when no air flow from the svstem can be detected. 

or when a svstem leak is detected that is greater than or equal in 

magnitude to a leak caused bv a 0.040 inch diameter orifice.—Ihfi_ 

Executive Officer shall revise the size of the orifice if the most 

reliable monitoring method available cannot reliably detect a 

svstem leak of this magnitude. 

(34.3) Monitoring Conditions: The monitoring svstem shall monitor the 

evaporative svstem at least once per trio. Subject to Executive 

Officer approval, if performance of the check causes vehicles to 

exceed applicable emission standards when using the best available 

technology, manufacturers mav perform evaporative svstem 

monitoring during a steadv-soeed condition, as defined in section 

(b) (1.3.2). between 20 and 50 moh. 

(3-3-i) {Rtegpated Refue44n§ Vapep Re6evepy Systems* A eheek feF 

' ma4fuR6t4eR sha44 S66UF en the dp4v4ng eye4e 4mmed4ate4y f©44ew4R§ 

each pefae44R§ eveRt wh4eh 4eads the 6an4step w4th fae4 vapep se 

that a men4tep4ng 6heek ef the evapepat4ve papge system eaR be 

made (e-g- the eheek may be 4nfee§pated w4th a F©qu4s4te ©haRge 4R 

the fue4 gauge pead4n§)-

(3-3-2) N©R-Refae44n§ Vapep Reeevepy (Evapp©at4ve 9n4y4 Systems. 

A m©R4t©p4ng 6heek ef the pupge system sha44 eeeap at 4east enee 

pep tp4p-

(3-3.3) Nen-integpated Refue44ng Vapep ReeeveFy Systems. The 

pefue44n§ vapep P66©vepy system aRd the evap©pat4ve e©Rtp©4 system 

sha44 be m©n4t©ped sepapate4y ae©©Fd4R§ te (3-3-1) aRd (3-3.2) 

Fespeet4ve4yT 

(34.4) MIL Illumination and Fault Code Storage: 

(4.4.1) Upon detection of an evaporative system malfunction, the 

diagnostic svstem shall store a fault code and the MIL shall 

illuminate no later than the end of the next trip if the 

malfunction is again detected. 

(4.4.2) If the diagnostic svstem is capable of discerning that a 

svstem leak is being caused bv a missing or improperly secured 

fuel cap, the manufacturer mav notify the vehicle operator through 

the use of an indicator light other than the MIL. The 

manufacturer is not required to store a fault code in this case. 

The indicator light shall conform to the requirements outlined 

in section (a) (1.1) for location and illumination. As another 

option, the manufacturer mav extinguish the MIL, provided no other 

malfunctions have been detected, and mav erase the fault code 

corresponding to the problem once the on-board diagnostic svstem 

has verified that the fuel cap specifically has been securely 

fastened. Other eouivalent strategies shall be considered bv the 

Executive Officer. 

A-10 

*1 
(3-4-1) integrated Refae44n§ Vapep ReeeveFy Systems* Fe44ew4n§ a 

sa4tab4@ pefue44n§ event and apen detest4en ef a ma4fan6t4eRT the 

d4a§R©st4© system sha44 stepe a faa4t sede and the M_L sha44 

444ura4nate ne 4atep than the eRd ef the Rest dp4v4ng sye4e (net 

nest tp4p) 4f papge HG f4ew 4§ st444 net detested? 

(3-4v_) Nen-Refae44ng Vapep Reeevepy (Ivap©pat4ve 9n4y) Systems* 

S4th@p a s4ng4©-stage ©P a twe-stage sheek fsp ma4fanet4sn may be 

made? Sf aftep tw® geqaent4a4 tp4ps a sheets fsp evap©pat4ve 

em4ss4©ns 4nd4sates a pp©b4era (s4n§4e-sta§e sheek) SP petent4a4 

pp©b4@m (tws-stage cheek)-? a eede wh4sh 4nd4eates e4thep the 

pp@s@ne@ sf a ma4faR6t4en (s4§ne4=sta§© sheek) SF that a seseRd 

stage eheek ef the eafi4step papge system 4s tak4n§ p4aee (twestage eheek) sha44 be steped- IR a twe-stage eheekr the pupge 

system may be deaet4vated dap4n§ the neat tw© tp4ps (©P 4©R§ep 4f 

a manafaetapep demanstpates sabjeet te Eaesat4ve 9ff4eep appF©va4 

that a 4©R§@ P p@p4ed 4s neeessapy te av©4d fa4se eedes) 4R ©pdep 

te f4fla44y eva4aate the eaR4step pupge systemT as 4©R§ as a eheek 

4s made fep the ppesenee ef pupge at 4east evepy ten m44es ef 

veh4e4e epepat4en SF as sesn aftep eaeh ten m44e 4ntepva4 ef 

dp4v4n§ as en§4ne ©p©pat4n§ 6©nd4t4©ns ape en6©anteped wh4eh 

pepm4t a pe44ab4e eheek fep papge f4ew- The f4Ra4 eheek fep 

ma4fan6t4en sha44 be eemp4eted ne 4atep than the eRd ©f the tp4p 

f©44©w4n§ the end sf pupge system deaet4vat4en- Sheu4d fue4 vapep 

be detested dap4n§ a sesewd stage ehe6kT the steped twe-stage 

eheek eede may be epassd and n©praa4 papge pesaraed? if the 

manafaetapep makes a peqaest and pp©v4des a©6eptab4e sappept4n§ 

data t© the _Heeat4v© 9ff4eep. the E8@6Ht4vs 9ff4eep sha44 pepm4t 

the papge system eheek ts be temp©pap44y d4sab4ed aRdep 6©Rd4t4©RS 

wh4sh may 4ead t© fa4s© ©sdes. A faa4t ©ede sha44 be steped and 

the MSL sha44 444am4nate w4th4n § seeends sf dete©t4n§ a paFge 

system ma4fanet4©n fep systems us4ng e4thep the ©Re-stage ©P the 

twe-stage shesk ppseedape? Sabjest te _aeeat4ve 9ff4sep appp©va4T 

a4tepnate men4t©p4Rg ppesedapes may bs ased pp©v4ded the 

manafaetapep sabm4ts a men4t©p4R§ stpategy demenstpated te have 

equ4va4ent Pe44ab444ty and t4me44ness 4R dete©t4R§ ma4fan©t4©R as 

the ppeeedap© 4R th4s papagpaph-

(3.4*3) N©R-lRte§pated Refae44n§ Vapep ReeeveFy Systems* MJL 

444am4Rat4sn and faa4t stepage ep4tep4a fep the pefue44n§ vapeF 

peesvepy system aRd the evap©pat4ve 6©Rtp©4 system sha44 be 

a©6©Pd4R§ te (3x4-4) aRd (3.4-2) Fespeet4ve4y-

(45.0) SECONDARY AIR SYSTEM MONITORING 

(45.1) Requirement: Any vehicle equipped with any form of secondary air 

delivery system shall have the diagnostic system monitor the 

proper functioning of (i) the secondary air delivery system and 

(ii) any air switching valve. 

(4j_.2) Malfunction Criteria: 

(4JL.2JJ The diagnostic system shall indicate secondary air 

delivery system malfunction when seme degFee ©f seeandaFy a4Ff4ew 

A-11 
P.39 

4s net deteetab4e 4n the exhaust system dup4ng a ehe6k ef the 

se6©ndapy a4p d©44v©py system the flow rate falls below the 

manufacturer's specified low flow limit such that a vehicle would 

exceed 1.5 times anv of the applicable FTP emission standards. 

(5.2.2) Manufacturers demonstrating that deterioration of the 

flow distribution svstem is unlikely mav reouest Executive Officer 

approval to perform onlv a functional check of the svstem.—L_L_ 

such a case, the diagnostic svstem shall indicate a malfunction 

when some degree of secondary airflow is not detectable in the 

exhaust svstem during a check. 

(45.3) Monitoring Conditions: The monitoring of the secondary air 

delivery system and the air switching valve shall occur once per 

trip. 

(45.4) MIL Illumination and Fault Code Storage: The diagnostic system 

shall store a fault code w4th4n 5 seeaRds ef deteet4Rg a 

ma4fun6t4en. and the MIL shall illuminate no later than the end of 

the next trip if the malfunction is again detected. 

(5fi.O) AIR CONOITIONING SYSTEM REFRIGERANT MONITORING 

(Sfi.l) Requirement: 

(Sfi.1.1) The diagnostic system shall monitor air conditioning 

systems for loss of refrigerants which could harm the 

stratospheric ozone layer or are reactive in forming atmospheric 

ozone. Any sensor used for such monitoring shall itself be 

monitored for proper circuit continuity and proper range of 

operation. A provision for ensuring that a leak has been 

corrected before extinguishing the MIL shall be provided. 

(6fi.l.2) Manufacturers of a model vehicle which will phase out 

the use of sueh pefp4gepants chlorofluorocarbons in its air 

conditioning systems by the 1996 model-year or which will use 

federally-approved refrigerants with substantially less 

atmospheric ozone depleting potential than CFC-12 need not comply 

with this requirement for that model. 

(Ifi.2) Malfunction Criteria: Manufacturers shall provide a monitoring 

strategy for approval by the Executive Officer for monitoring a 

refrigerant leak. The approval shall be based on timeliness and 

reliability in detecting a leak. 

(Sfi.3) Monitoring Conditions: The diagnostic system shall monitor the 

air conditioning system at least once per trip. 

(Sfi.4) MIL Illumination and Fault Code Storage: The diagnostic system 

shall store a fault code w4th4n S se6©nds ef deteet4Rg a pe.en.4a4 

ma4fun6t4enT and the MIL shall illuminate no later than the end of 

the next trip if the malfunction is again present. The diagnostic 

system shall not clear a fault code and the MIL shall not turn off 

unless the leak has been corrected. 

A-12 

«*? 
P.40 

(62.0) FUEL SYSTEM MONITORING 

(61.1) Requirement: The diagnostic system shall monitor the fuel 

delivery system for its ability to provide compliance with 

emission standards. 

(62.2) Malfunction Criteria: The manufacturer shall establish 

malfunction criteria to monitor the fuel delivery system such that 

a vehicle's emissions would not exceed 1.5 times any of the 

applicable FTP era4ss4en standards before a fault is detected. If 

the vehicle is equipped with fuel trim eireuitry, the manufacturer 

shall include as one of the malfunction criteria the condition 

where the trim circuitry has used up all of the trim adjustment 

allowed within the manufacturer's selected limit(s). 

Manufacturers may compensate the criteria limit(s) appropriately 

for changes in altitude or for temporary introduction of large 

amounts of purge vapor or for other similar identifiable operating 

conditions when they occur. 

(62-3) Monitoring Conditions: The fuel system shall be monitored 

continuously for the presence of a malfunction. 

(62.4) MIL Illumination and Fault Code Storage: 

(62.4.1) For fuel systems with short-term trim only capability, 

the diagnostic system shall store a fault eode after the fuel 

system has attained the criteria limit for a manufacturer-defined 

time interval sufficient to determine a malfunction. The M_L 

sha44 444am4nat© 4If the malfunction criteria limit and time 

interval are exceeded, the MIL shall be illuminated and a fault 

e_?dji_Ata___t__p later than the end of the next driving cycle in 

whieh the criteria and interval are again exceeded, unless driving 

conditions similar to those under whieh the problem was originally 

detected have been encountered (see section (7.4.3)) without such 

an-fi__eeeri_mce. in which case the initial temporary code and stored 

conditions mav be erased. Furthermore, if similar driving 

conditions are not encountered during §0 trj-as .subsequent to the 

initial detection of a malfunction, the initial temporary code and 

stored conditions mav be erased, en tw© ssnsesat4ve dF4v4n§ ©y©4es 

©p en tw© eye4es WRSF S the speed aRd 4ead e©Rd4t4ens ©f the seeeRd 

eye4© ap@ w4th4n _9 p©P6ent ©f the eend4t4©RS that ea4sted dap4Rg 

the f4pst ma4faRet4©n (the t4me 4ntepva4 fep detepm4n4Rg a 

ma4faR6t4en 4s pestp4eted based en dem©nstpat4en test4ng Fequ4Fed 

4R sabseet4©R (§))-

(62.4.2) For fuel systems with long-term fuel trim capability, 

upon attaining a long-term based malfunction criteria limit 

independent of. or in combination with, the short-term trim svstem 

status, the MIL shall be illuminated and a fault code stored no 

later than the end of the next trio in which the malfunction is 

again detected, unless driving conditions similar to those under 

which the problem was originally detected have been encountered 

(see subsection (7.4.3)) without an indication of a malfunction. 

in Which case the initial temporary code and stored conditions mav 

A-13 

YO 
P.41 

be erased. Furthermore, if similar driving conditions are not 

encountered during 80 trips subsequent to the initial detection of 

a malfunction, the initial temporary code and stored conditions 

may be erased, the d4agnest4e system sha44 stepe a fau4t cede aRd 

the MIfc sha44 444um4nate w4th4n 6 seeeRds ef atta4n4ng a 4©Rg-teFm 

based ma4fanet4en 6P4tep4a 44m4t 4ndependent SF T SP 4R eemb4Rat4eR 

w4thT the shept-tepm tp4m system status-

(7.4.3) Upon detection of a fuel svstem malfunction, manufacturers 

shall store the engine speed, load and warm-uo status (i.e.. cold 

or warmed-up) under which the malfunction was detected. A trio or 

driving cvcle shall be considered to have similar conditions if 

the stored engine speed is encountered within 375 rpm. load 

conditions within 10 percent, and the same warm-up status is 

present. With Executive Officer approval, other strategies for 

determining if similar conditions have been encountered mav be 

employed. Approval shall be based on comparable timeliness and 

reliability in detecting similar conditions. 

(72.0) OXYGEN SENSOR MONITORING 

(76.1) Requirement: 

(78.1.1) The diagnostic system shall monitor, at a minimum, the 

output voltage and response rate of all primary (fuel control) 

oxygen (lambda) sensors for malfunction. It shall also monitor 

all secondary oxygen sensors (fuel trim control or use as a 

monitoring device) for proper output voltage and/or response rate. 

Response rate is the time required for the oxygen sensor to switch 

from lean-to-rich once it is exposed to a richer than 

stoichiometric exhaust gas or vice versa (measuring oxygen sensor 

switching frequency 4s may not b£ an adequate indicator of oxygen 

sensor response rate, particularly at low speeds). 

(75.1.2) Either the lean-to-rich or both the lean-to-rich and 

rich-to-lean response rates shall be checked. Response rate 

checks shall evaluate the portions of the sensor's dynamic signal 

that are most affected by sensor malfunctions such as aging or 

poisoning. 

(7-1-3) Fep 6©Rvent4ena4 SSRSSPS w4th a nem4na4 ISFB te ens v©4t 

s4gna4T the pespeRse pate detepm4Rat4©R a4g©p4thm may net ase a 

beg4nR4Rg ep en_4R§ s4gna4 4eve4 fep the 4ead 44m4t abeve 159 

m4444v©4ts- A4tepnat4ve4yT mManufacturers may observe the voltage 

envelope of the sensor when cycled at a frequency of 1.5 Hertz or 

greater, as determined by the manufacturer, to evaluate a slow 

response rate sensor (i.e. a slow sensor cannot achieve maximum 

and/or minimum voltage as will a good sensor given a properly 

chosen switching frequency and fuel step change for the check). 

With Executive Officer approval, manufacturers may use other 

voltage requirements/fuel-air switching frequencies or monitoring 

strategies based on a determination of accurate and timely 

evaluation of the sensor. 

A-14 

H 
(71.1.42) For sensors with different characteristics, the 

manufacturer shall submit data and an engineering evaluation to 

the Executive Officer for approval based on showing equivalent 

evaluation of the sensor. 

(71.1.54) For vehicles equipped with heated oxygen sensors, the 

heater circuit shall be monitored for proper current or voltage 

drop (note: a continuity check of oxygen sensors is not required). 

Other heater cireuit monitoring strategies would require approval 

by the Executive Officer based on equally reliable and timely 

indication of malfunction as current or voltage-based monitoring. 

(72.2) Malfunction Criteria: 

(72.2.1) An oxygen sensor shall be considered malfunctioning when 

the voltage and/or response rate criteria are exceeded and causes 

emissions from a dapab444ty deraanstpat4©n vehicle equipped with 

the sensor(s) to exceed an FTP test by map© than 1.5 times any of 

the applicable £IR standards, or when the voltage and/or response 

rate criteria of sensors for use as a diagnostic system monitoring 

deviee (e.g., for catalyst efficiency monitoring) are exceeded. 

(71.2.2) For heated oxygen sensors, the heater circuit shall be 

considered malfunctioning when the current or voltage drop in the 

circuit is no longer within the manufacturer's specified limits 

for proper operation. Subject to Executive Officer approval, 

other monitoring strategy malfunction criteria for detection of 

heater circuit malfunctions may be used provided the manufacturer 

submits data showing monitoring reliability and timeliness to be 

equivalent to the stated criteria in this paragraph. 

(?2.3) Monitoring Conditions: 

(72.3.1) For primary oxygen sensor(s) used for fuel control, the 

response rate and output voltage shall be monitored for 

malfunction before the end of the first idle period after the 

vehicle has commenced elosed-loop operation, if the necessary 

eheeking condition for acceptable oxygen sensor(s) performance has 

been encountered. The performance of the sensor can only be 

judged acceptable by one or more of the following means: within 

any 20 second reasonably steady speed condition (-peassnab4y 

steady- 4s ___ defined in X_U (1.3.2), within any deceleration of 3 

seconds or more, or during the first idle period of at least 20 

seconds after closed loop operation begins (i.e., not during an 

acceleration condition); heweveF not withstanding, unacceptable 

performance ean be determined at any time. Other monitoring 

conditions may be used provided the manufacturer provides a 

monitoring strategy and supporting data showing equivalent 

monitoring reliability and timeliness in detecting a 

malfunctioning sensor compared to the above monitoring conditions 

and the Executive Officer approves. 

A-15 
P.43 

(72.3.2) For secondary oxygen sensors used for catalyst monitoring 

and/or fuel system trim, the response rate and/or output voltage 

shall be monitored for malfunction at least once per trip. 

(72-3.3) For heated oxygen sensors, the heater circuit shall be 

monitored for malfunction at least once per trip. 

.) MIL Illumination and Fault Code Storage: Upon detection of any 

oxygen sensor malfunction, the diagnostic system shall store a 

fault code and the MIL shall illuminate no later than the end of 

the next trip if the malfunction is again present. 

(28.5) Other (non^lambda) Oxygen Sensors: 

(72.5.1) For vehicles equipped with universal exhaust gas oxygen 

sensors (i.e. sensors which provide an output proportional to 

exhaust gas oxygen concentration), the diagnostic system shall 

provide a response rate check (the time required to respond to a 

specific change in fuel/air ratio) at least once per trip and an 

out-of-range check for which monitoring shall be continuous. For 

malfunctions, MIL illumination and fault code storage shall be as 

in (72.4). 

(72.5.2) If a manufacturer utilizes other types of oxygen 

sensors, the manufacturer shall submit a monitoring plan to the 

Executive Officer for approval based on equivalent monitoring with 

conventional sensors. 

(82.0) EGR SYSTEM MONITORING 

(02-1) Requirement: 

X-LJ-JL). The diagnostic system shall monitor the EGR system on 

vehicles so-equipped for low and high flow rate malfunctions. 

(9.1.2) Manufacturers mav request Executive Officer approval to 

temporarily disable the EGR svstem check under specific conditions 

if it can be demonstrated that a reliable check cannot be made 

when these conditions exist. 

(82-2) Malfunction Criteria: The EGR system shall be considered 

malfunctioning when one or both of the following occurs: (1) any 

component of the system fails to perform within manufacturer 

specifications., or X_Li the EGR flow rate exceeds the 

manufacturer's specified low and sx high flow limits such that a 

vehicle would exceed 1.5 times _myL_Ql the applicable FTP emission 

standards. 

(82.3) Monitoring Conditions: The diagnostic system shall monitor the 

EGR system at least once per trip. 

(82.4) MIL Illumination and Fault Code Storage: The diagnostic system 

shall store a fault code w4th4n f4ve seeends ef deteet4Rg a 

A-16 

HS 
raa4fuRet4©R- ?_u__L£he MIL shall illuminate no later than the end 

of the next trip if the malfunction is again present. 

(912.0) COMPREHENSIVE COMPONENT MONITORING 

(912.1) Requirement: 

(912.1.1) Input Components: 

(A) The diagnostic system shall monitor for malfunction any 

electronic era4ss4©R-pe4ated powertrain component/system which can 

affect eraissions not otherwise described above that provides input 

directly or indirectly to the on-board computer. 

(B) Such monitoring shall be based at a minimum on proper circuit 

continuity and out of range values (which includes rationality 

Checking (logic evaluation of available information to determine 

if a component is operating properly within its normal range), to 

ensure prpper operation of the input device (e.g.. indicating a 

malfunction in the ease of high fuel tank pressure when the 

coolant temperature is low, an aeeelerometer output indicating 

continuous rough road conditions, etc.)). 

(C) Input components ___y include, but are not limited to, the 

vehicle speed sensor, crank angle sensor, knock sensor, throttle 

position sensor, coolant temperature sensor, cam position sensor, 

fuel composition sensor (e.g. methanol flexible fuel vehicles), 

transmission electronic components such as sensors, modules, and 

solenoids which provide signals to the en§4ne management 

powertrain control system (see section (b) (10.5)). 

(D) The coolant temperature sensor shall be monitored for 

achieving a stabilized minimum temperature level which is needed 

to achieve closed-loop operation within a manufacturer-specified 

time interval after starting the engine. The Executive Officer 

shall allow disablement of this check under extremely low ambient 

temperature conditions provided a manufacturer submits data 

demonstrating non-attainment of a stabilized minimum temperature. 

(912.1.2) Output Components: 

(A) The diagnostic system shall monitor for proper functional 

response to eaeh computer command, any era4ss4©n-pe4ated powertrain 

output component/system receiving commands from the computer 

either directly or indirectly which can affect emissions and which 

is not otherwise monitored as a component/system in the above 

monitoring requirements. 

(B) Components for which functional monitoring is not feasible 

shall be monitored, at a minimum, for proper circuit continuity 

and out of range values, if applicable. 

(C) Output components may include, but are not limited to, the 

automatic idle speed motor, emission-related electronic only 

A-17 
P.45 

transmission controls, heated fuel preparation systems, and a 

warmup catalyst bypass valve (see section (b) (10.5)). 

(912.2) Malfunction Criteria: 

(912.2.1) Input Components: Input components/systems shall be 

considered malfunctioning when, at a minimum, lack of circuit 

continuity or manufacturer-specified out-of-range values occur. 

Additionally, the coolant temperature sensor shall be considered 

malfunctioning if it does not achieve a stabilized minimum 

temperature necessary for closed-loop operation within a 

manufacturer-speeified time interval after starting the engine. 

(912.2.2) Output Components: Output components/systems shall be 

considered malfunctioning when a proper functional response to 

each computer command does not occur. Should a functional check 

for malfunction not be feasible, then an output component/system 

shall be considered malfunctioning when, at a minimum, lack of 

circuit continuity or manufacturer-specified out-of-range values 

oceur. 

(912.3) Monitoring Conditions: Components/systems in this subsection 

shall be monitored continuously. 

(912.4) MIL Illumination and Fault Code Storage: Upon detecting a 

malfunction, the diagnostic system shall store a fault code w4th4R 

5 seeends and the MIL shall illuminate no later than the end of 

the next trip if the malfunction is again detected. 

(912.5) Component Determination: The manufacturer shall determine 

whether an powertrain input or output component not otherwise 

covered 4s era4ss4en-pe4ated can affect emissions. If the 

Executive Officer reasonably believes that a manufacturer has 

incorrectly determined that a component 4s net em4ss4en-pe4ated 

cannot affect emissions, the Executive Officer shall require the 

manufacturer to provide emission data showing that such a 

component, when faulty and installed in a suitable test vehicle, 

does not have an emission effect. 

(c) ADDITIONAL MIL ILLUMINATION AND FAULT CODE STORAGE PROTOCOL 

(1.0) MIL ILLUMINATION For all emission-related components/systems, 

upon final determination of malfunction, the MIL shall remain 

continuously illuminated (except that it shall blink as indicated 

previously for misfire detection). If any malfunctions are 

identified in addition to misfire, the misfire condition shall 

take precedence, and the MIL shall blink aceordingly. The 

diagnostic system shall store a fault code for MIL illumination 

whenever the MIL is illuminated. The diagnostic system shall 

illuminate the MIL and shall store a code whenever the engine 

control enters a default or "limp home" mode of operation. The 

diagnostic system shall illuminate the MIL and shall store a code 

whenever the engine control system fails to enter closed-loop 

operation within a manufacturer specified minimum time interval. 

A-18 

«f 
(2.0) EXTINGUISHING THE MIL 

(2.1) Misfire and Fuel System Malfunctions: For misfire or fuel system 

malfunctions, the MIL may be extinguished if the fault does not 

recur when monitored during tw© three subsequent sequential 

driving cyeles in which conditions are s4raa4taneeus4y w4th4n 19 

pepeent ©f the speed and 4ead 6©nd4t4ens similar to those under 

which e»4sted when the malfunction was first determined (see 

sections_(b) (3.4.3) and (b) (7.4.3U. 

(2.2) All Other Malfunctions: Except as noted in section (b) (6.4). 

fPor all other faults, the MIL may be extinguished after three 

subsequent sequential trips in which the malfunction has not 

recurred and no other malfunction has been identified that would 

independently illuminate the MIL according to the requirements 

outlined above. 

(3.0) ERASING A FAULT CODE The diagnostic system may erase a fault 

code if the same fault is not re-registered in at least 40 engine 

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

_______ 

(d) TAMPERING PROTECTION Computer-coded engine operating parameters 

shall 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 Offieer approval, manufacturers 

may exempt from this requirement those product lines which are unlikely to 

require protection. Criteria to be evaluated in making an exemption 

include, but are not limited to, current availability of performance chips, 

high performance capability of the vehiele, and sales volume. Any 

reprogrammable computer code system (e.g. EEPROM) shall include proven 

write-proteet features whieh may include copyrightable executable routines 

or other methods. 

(e) READINESS/FUNCTION CODE If a diagnostic eheek of all monitored 

components and systems has not been completed since the computer memory was 

last cleared, the manufacturer shall store a code indicating the need for 

additional mixed eity and highway driving to complete the check. 

The diagnostic system eheek for continuous monitoring of misfire and 

fuel system faults shall be considered complete for purposes of determining 

the readiness indication if malfunctions are not detected in these areas by 

the time all other diagnostic system checks are complete. Ppepep epepat4eR 

sf an integpated Refae44ng Vapep ReeeveFy System ep the Fefae44Rg p©pt4eR ef 

a Nen-lRtegpated Refea44R§ Vapep Reeevepy System sha44 net be eeRs4deped 4R 

deteFm4n4R§ d4a§R©st4e system Fead4Ress- FSP Evap©pat4ve 9n4y Systems? a 

pead4ness sheek sha44 be esRs4deped eemp4ete aftep a f4pst stage eheek 4s 

eamp4ete. If monitoring is temporarily disabled under conditions which may 

lead to false codes for any system, that check shall not be considered in 

determining diagnostic system readiness. The diagnostic system shall also 

include a code or acknowledge message indicating that the diagnostic system 

itself is functioning properly. 

A-19 

•.•_,_.__._ _ 
(f) STORED ENGINE CONDITIONS F©F a fue4 system ma4fanet4©R ©P f©F 

R,45f4FeT wh4ehevep eeeups f4pstT Upon detection of the first malfunction of 

anv component or svstem. "freeze frame" engine conditions present at the 

time a fau4t cede 4s peg4steped shall be stored in computer memory. Should 

a subseguent fuel svstem or misfire malfunction occur, anv previously Stored 

freeze frame conditions shall be replaced bv the fuel svstem or misfire 

conditions (whichever occurs first). Stored engine conditions shall 

include, but are not limited to, calculated load value (4f ava44ab4e), 

engine RPM, fuel trim value(s), fuel pressure (if available), vehicle speed 

(if available), coolant temperature, intake manifold pressure (if 

available), closed- or open-loop operation, and the fault code which caused 

the data to be stored. The manufacturer shall may choose the most 

appropriate set of conditions facilitating effective repairs for freeze 

frame storage when the fau4t eeeuFS. Only one frame of data is required. 

Manufacturers may at their discretion choose to store additional frames 

provided that at least the required frame can be read by a generic scan tool 

meeting SAE specifications established in Draft SAE Recommended Practices on 

"Generic Scan Tool" (J1978), FebFHapy __JH£ 198921, and "Diagnostic Test 

Modes" (J1979), June 198921, which are incorporated by reference herein. If_ 

the fault code causing the conditions to be stored is erased in accordance 

with section (c) (3.0). the stored engine conditions mav be cleared as well. 

(g) DURABILITY DEMONSTRATION VEHICLE 

(1.0) REQUIREMENT Each year a manufacturer shall provide emission test 

data for one certification durability vehicle that has not been 

used previously for purposes of this section. The Executive 

Officer shall waive this requirement if a manufacturer does not 

have a certification durability vehicle available which is 

suitable for this demonstration in a given year, provided a 

manufacturer submits other data from a representative high mileage 

vehicle or vehicles acceptable to the Executive Officer to 

demonstrate that malfunction criteria are based on emission 

performance. The ARB shall determine the demonstration vehicle. 

Each manufacturer shall notify the Executive Officer prior to 

running a California durability vehicle in order to allow possible 

selection as the demonstration vehicle for a given model year 

unless a vehicle has previously been chosen for the given model 

year. Demonstration tests shall be conducted on the certification 

durability vehicle at the end of the required mileage 

accumulation. The demonstration test for the EGR system, however, 

may be conducted at 50,000 miles until there is a standard for NOx 

emissions applicable for more than 50,000 miles. In the case of 

NOx testing past 50,000 miles, NOx standards may be applied at the 

end of mileage accumulation based on the 0-50,000 mile 

deterioration rate. Upon adoption of a NOx standard applicable 

for a higher mileage interval, the EGR system demonstration shall 

also take place on the certification durability vehicle at the end 

of its mileage accumulation period. 

(1.1) Flexible fuel vehicles shall perform each demonstration test using 

85 percent methanol and 15 percent gasoline, and gasoline 

PJ_JX For vehicles capable of operating on other fuel 

combinations, the manufacturer shall submit a plan for performing 

A-20 

V7 
P.48 

demonstration testing for approval bv the ExecutLlY.fi Officer on the 

basis of providing accurate and timely evaluation of the monitored 

-_y_ttJ_D-L_ 

(2.0) APPLICABILITY The manufacturer shall perform single-fault testing 

based on the FTP test cycle with the following components/systems 

at their malfunction criteria limits as determined by the 

manufacturer: 

(2.1) Oxygen Sensors. The manufacturer shall conduct two demonstration 

tests: Th© first test involves testing all primary and secondary 

(if equipped) oxygen sensors used for fuel control simultaneously 

possessing normal output voltage but response rate deteriorated to 

the malfunction criteria limit (secondary oxygen sensors for which 

response rate is not monitored shall be with normal response 

characteristics). The second test..shall include testing with all 

primary and secondary (if equipped) oxygen sensors used for fuel 

control simultaneously possessing output voltage at the 

malfunction criteria limit. The Executive Officer may approve 

other demonstration protocols if the manufacturer can show 

comparable assurance that the malfunction criteria are chosen 

based on meeting emission requirements. 

(2.2) EGR System: The manufacturer shall conduct only one flow rate 

demonstration test at the low flow limit. 

(2.3) Fuel Metering System: 

(2.3.1) For vehicles with short-term or long-terra fuel trim 

circuitry, the manufacturer shall conduct one demonstration test 

at the border of the rich limit and one demonstration test at the 

border of the lean limit established by the manufacturer for 

emission compliance. 

(2.3.2) For other systems, the manufacturer shall conduct a 

demonstration test at the criteria limit(s). F4e»4b4e fae4 

veh4e4es sha44 pepfepm the dem©RStpat4en test en 86 pepeent 

methan®4 and IS pepeent §ase44ne? and ©n §as©44ne en4y- Fep 

veh4e4es sapab4e ef ©peFat4ng en sthep fae4 eemb4nat4enST the 

raanafaetapep sha44 sabm4t a p4aR fep p©pf©pm4R§ the dem©RStpat4©R 

f©p appp©va4 by the _aeeat4ve 9ff4eep en the bas4s ef pp©v4d4Rg 

aeeapate aRd t4me4y eva4aat4en ef fae4 system faa4ts-

(2.3.3) For purposes of the demonstration, the fault(s) induced 

may result in a uniform distribution of fuel and air among the 

cylinders (sevepe d4stp4bat4en pp©b4eras w444 a4t4raate4y be 

detested when ra4sf4p4R§ eeeaps). Non-uniform distribution of fuel 

and air used to induce a fault shall not cause an indication of 

misfire. The manufacturer shall describe the fault(s) induced in 

the fuel system causing it to operate at the criteria limit(s) for 

the demonstration test (e.g., restricted or increased flow fuel 

injectors, an altered output signal airflow meter, etc.). 

Computer modifications to cause the fuel system to operate at the 

A-21 

Yr 

EMU J 
P.49 

adaptive limit for malfunction shall not be allowed for the 

demonstration tests. 

(2.4) Misfire: The manufacturer shall conduct one FTP demonstration 

test at the criteria limit specified in (b)(3.1)(B) for 

malfunction and a second demonstration test showing that the 

vehicle is capable of passing a California Inspection/Maintenance 

test when operating at the misfire criteria limit. 

(2.5) Secondary Air Svstem: The manufacturer shall conduct a flow rate 

demonstration test at the low flow limit, unless onlv a functional 

check is permitted. 

(2.6) Catalvst Efficiency: 

(2.6.1) Non-LEVs: The manufacturer shall conduct a baseline FTP 

test with a representative 4000 mile catalvst followed bv one FTP 

demonstration test using a catalvst svstem deteriorated to its 

malfunction limit. If a manufacturer is employing a steady state 

catalvst efficiency check in accordance with section (b) (1.2.4). 

demonstration of the catalvst monitoring svstem is not required. 

(2.6.2) LEVs: The manufacturer shall conduct a catalvst 

efficiency demonstration using a catalvst deteriorated to within 

the malfunction criteria. If two substrates are integrated into 

the same container, onlv the upstream substrate shall be 

deteriorated for the demonstration. 

(2.7) Heated Catalyst Systems; For heated catalvst systems that use an 

after start heating strategy, the manufacturer shall conduct a 

demonstration test where the designated heating temperature is 

reached at the time limit for malfunction after engine starting. 

(2.8) Manufacturers mav electronically simulate deteriorated components. 

but mav not make anv vehicle control unit modifications when 

Performing demonstration teStS. All equipment necessary to 

duplicate the demonstration test must be made available to the ARB 

upon request. 

(3.0) PRECONDITIONING The manufacturer shall use one CVS-72 fu44 FTP 

driving cycle (thpee -bags.- tw© en§4ne stapts) (two "bags." one 

engine start) for preconditioning before each of the above 

emission tests... 4n 44ea ef the 6VS-72 dp4v4ng 6ye4e (tw© -ba§sT-

©Re eng4ne stapt) n©Fma44y ased fep ppeeend4t4en4ng fap an FTP 

em4ss4en test- If a manufacturer can demonstrate that additional 

preconditioning is necessary to stabilize the emission control 

system, the Executive Officer shall allow an additional 

preconditioning CVS-7S2__ driving cvcle. or a Federal Highway Fuel 

Economy Driving Cvcle. following a ten-minute hot soak after the 

intial preconditioning cycle. 

(4.0) EVALUATION PROTOCOL 

A-22 
,1) With the exception of short-term trim only vehicles aRd 

f©p ra4sf4p©, the manufacturer shall set the system or component at 

the criteria limit(s) from the beginning of and throughout the 

preconditioning eyele and FTP test. 

.2) For short-term trim only vehicles, the fuel system shall operate 

at the criteria limit frora the beginning of closed-loop operation 

for the manufacturer-defined time interval for determining 

malfunction (and normally otherwise) for both the preconditioning 

and FTP test cycles. M4sf4pe sha44 be sat at 4ts sp4tep4a 44m4t 

as §p©e4f4ed papsaant t© sabseet4en(b)(2.2)(B) fpera the beg4RR4R§ 

®f th© FTP test ©n4y-

(4.3) For misfire demonstration, misfire shall be set at Jts criteria 

limit as specified pursuant to section (b) (3.2) (B) 

throughout the preconditioning cvcle and FTP test. 

(4.34) For all demonstrations, eaeept these spee4f4ea44y neted be4ewT 

the MIL shall be illuminated by the ©Rd ef the ppeeeRd4t4eR4Rg 

sye4© before the hot start portion of the FTP test in accordance 

with requirements of subsection (b): 

(4?3?4) F©F a shept-tepm tp4m-©n4y fae4 system? the MIL sha44 be 

444am4nated dap4n§ the FTP testes?! ) FS P an EGR 

th© FTP testsystem the MSL sha44 444am4nate by the end ©f 

(4-3-3) Fep the m4sf4pe dem©nstpat4©n th© MSL sha44 444am4nate 

aftep 299 te 1999 eng4ne p©v©4at4ens fpem the beg4nn4ng ef the FTP 

test (SP aftep 299 te 1999 eng4R@ p@v©4at4ens fpem the be§4na4R§ 

sf e4esed-4eep spepat4eR 4f an esygen sens8P 4s used fep m4sf4pe 

(4.34-1) If the MIL does not illuminate when the systems or 

components are set at their lirait(s), the criteria limit or the 

OBD system is not acceptable. 

(4.34.52) Except for catalvst efficiency demonstration. „if the 

MIL illuminates and emissions do not exceed 1.5 times any of the 

applicable FTP emission standards, no further demonstration shall 

be required.0 

(4.34-62) Except for catalvst efficiency demonstration. ?if the 

MIL illuminates and emissions exceed 1.5 times any of the 

applicable FTP emission standards, the vehicle shall be retested 

with the component's malfunction criteria limit value reset such 

that vehicle emissions are reduced bv no more than 30 percent te 

w4th4n f4fteen peFeeflt ef 4ts ma4fanet4en ep4teF4a 44ra4t va4ae 

(4-e-7 w4th4n 85 te 199 pepeent ef the 44ra4t va4ue). Limit value 

at a minimum includes, in the case of oxygen sensors, response 

rate and voltage; for EGR systems, EGR flow rate; for secondary 

air systems, air flow rate: for short-term fuel trim-only 

systems, time interval at the fuel system range of authority 

A-23 

aMm 
P.51 

limit; for long-term fuel trim systems, shift in the base fuel 

calibration: for heated catalvst systems, the time limit between 

engine starting and attaining the designated heating temperature 

(if an after-start heating strategy is used): and for misfire, 

percent misfire. For the OBD system to be approved, the vehicle 

must then meet the above emission levels when tested with the 

faulty components. The MIL shall not illuminate during this 

demonstration. 

(4.4.4) For Non-LEV catalvst efficiency demonstration, if 

HC emissions do not increase bv more than 1.5 times the standard 

from the baseline FTP test and the MIL is illuminated, no further 

demonstration shall be required. However, if HC emissions 

increase bv more than 1.5 times the standard from the baseline FTP 

test and the MIL is illuminated, the vehicle shall be retested 

with the average FTP HC conversion capability of the catalvst 

svstem increased bv no more than 10 percent (i.e.. 10 percent more 

engine out hydrocarbons are converted). For the OBD svstem to be 

approved, the vehicle must then meet the above emission levels 

when re-tested. The MIL shall not illuminate during this 

demonstration. 

(4.4.5) For LEV catalvst efficiency demonstration, if catalvst 

efficiency is within the malfunction criteria range over the FTP 

test and the MIL is illuminated, no further demonstration is 

required. If catalyst efficiency falls outside of the malfunction 

criteria range, the catalyst's efficiency shall be adjusted, or 

the catalvst shall be replaced with another deteriorated catalvst. 

and the system re-tested. If catalyst efficiency is within the 

malfunction criteria range over the FTP test and the MIL is not 

illuminated, the catalvst mav be deteriorated further but not 

below the lower limit of the malfunction criteria range, and the 

System retested. If the catalyst's efficiency is below the lower 

limit of the malfunction criteria range and the MIL is not 

illuminated, the OBD svstem is not acceptable. 

(4.5) If an OBD svstem is determined unacceptable bv the above criteria. 

the manufacturer mav re-calibrate and re-test the svstem on the 

Same DDV. Anv affected monitoring systems demonstrated prior to 

-. the re-calibration shall be re-verified. 

. (h) CERTIFICATION DOCUMENTATION The manufacturer shall submit the 

following documentation for each engine family at the tirae of certification: 

(1) A written description of the functional operation of the 

diagnostic system to be included in Section 8 of manufacturers' 

certification applications. 

(2) A table providing the following information for each monitored 

component or system (either computer-sensed or -controlled) of the 

emission control system: 

i. corresponding fault code 

ii. monitoring method or procedure for malfunction detection 

A-24 
P.52 

iii. primary malfunction detection parameter and its type of 

output signal 

iv. fault criteria limits used to evaluate output signal of 

primary parameter 

v. other monitored secondary parameters and conditions (in 

engineering units) necessary for malfunction detection 

vi. monitoring time length and frequency of checks 

vii. criteria for storing fault code 

viii. criteria for illuminating malfunction indicator light 

ix. criteria used for dpt,arm1n<nP

 oufc o f rang e values and input 

component rationalitv.Jtififiks. 

(3) A logic flowchart describing the general method of detecting 

malfunctions for each monitored emission-related component or 

system. To the extent possible, abbreviations in Society of 

Automotive Engineers' (SAE) J1930 "Diagnostic Acronyms, Terms, and 

Definitions for Electrical/Electronic Systems", June, 198821, 

shall be used. J1930 is incorporated by reference herein. The 

information required in the chart under (2) above may instead be 

included in this flow chart, provided all of the information 

required in (2) is included. 

(4) A listing and block diagram of the input parameters used to 

calculate or determine calculated load values and the input 

parameters used to calculate or determine fuel trim values. 

(5) A scale drawing of the MIL? and the fuel cap indicator light. 

if present, which specifies location in the instrument panel, 

wording, color, and intensity. 

(6) Emission test data specified in subsection (g). 

(7) Data supporting the selected degree of misfire which can be 

tolerated without damaging the eatalyst. 

(8) Data sapp©pt4n§ the m4n4mam fae4 f444 needed te ensape 

adeqaate san4step vapep 4ead4ng fsp men4tep4n§ the ©vap©pat4ve 

pup§@ system fep veh4e4es eqa4pped w4th en-beapd p©fae44R§ vapep 

peeevepy systems Data supporting the limit for the time between 

engine starting and attaining the designated heating temperature 

for after-start heated catalvst systems. 

(9) For LEVs. Bdata supporting the criteria used by the diagnostic 

system for establishing a 49 t© 59 50 to 60 percent catalyst 

total HC efficiency level, or a 40 to 5Q percent -rieterioration 

!___§! (ep ethep t©4epanee 4eve4 peqa4ped by the Eseeat4ve 

/IQ) For Non-LEVs, data supporting the criteria used to indicate a 

malfunction when cataLvsJL-ctetedioration leads to a 1.5 .times the 

standard increase in H(Lg-J__sJ,o__s,. if a steady state catalvst 

efficiency check is employed in accordance with section (b) 

q_2_4-. data supporting the criteria used bv the diagnostic 

A-25 
=_____-

system for establishing a 60 to 80 percent catalVSt efflCienCYlevel shall be provided instead.,. 

(11) Data supporting the criteria used to detect evaporati-itpuroe svstem leaks. 

(192) A description of the modified or deteriorated component used 

for the fault simulation to drive the fuel system to the criteria 

limit(s) for demonstrating fuel system compliance with the 

requirements of subsection (g). 

(112) Any other information determined by the Executive Officer to 

be necessary to demonstrate compliance with the requirements of 

this section. 

(r) IN-USE RECALL TESTING PROTOCOL The manufacturer shall adhere to the 

following procedures for vehicles subject to in-use recall testing required 

by the ARB: 

(1) If the MIL illuminates during a test cycle or during a preconditioning 

cycle, the fault causing the illumination may be identified and repaired 

following published procedures readily available to the public including the 

independent service sector. 

(2) The test may be rerun, and the results from the repaired vehicle may be 

used for emission reporting purposes. 

(3) If a vehicle contains a part which is operating outside of design 

specifications with no MIL illumination, the part shall not be replaced 

prior to emission testing. 

(4) Failure of a vehiele, or vehicles on average, to meet applicable 

emission standards with no illumination of the MIL shall not by itself be 

grounds for requiring the OBD system to be recalled for recalibration or 

repair since the OBD system eannot predict precisely when vehicles exceed 

emission standards. 

(5) A decision to recall the OBD system for recalibration or repair will 

depend on factors including, but not limited to, level of emissions above 

applicable standards, presence of identifiable faulty or deteriorated 

components which affect emissions with no MIL illumination, and systematic 

erroneous activation of the MIL. 

(j) CONFIRMATORY TESTING The ARB may perform confirmatory testing of 

manufacturers' diagnostic systems for compliance with requirements of this 

section in accordance with malfunction criteria submitted in the 

manufacturer's approved certification documentation. The ARB or its 

designee may install appropriately deteriorated or malfunctioning components 

in an otherwise properly functioning test vehicle of an engine family 

represented by the demonstration test vehicle(s) (or simulate a deteriorated 

or malfunctioning component response) in order to test the fuel system, 

misfire detection system, oxygen sensor, secondary air svstem. catalvst 

efficiency monitoring svstem. heated catalvst svstem. and EGR system 

malfunction criteria for compliance with the applicable emission 

constraints in this section. Confirmatory testing to verify that 

malfunction criteria are set for compliance with emission requirements of 

this section shall be limited to vehicles in engine families derived from 

A-26 

- S-3 
P.54 

the demonstration vehicle(s). Diagnostic systems of a representative sample 

of vehicles which uniformly fail to meet the requirements of this section 

may be recalled for correction. 

(k) STANDARDIZATION Standardized access to emission-related fault 

codes, emission-related powertrain test information (i.e., parameter values) 

as outlined in subsection (1), emission rel ated _d_i_ignosti.c _aEP_cedureS», and 

stored freeze frame data shall be incorporated based on SAE specifications. 

(1.0) ______§£ «31859 SAE Recommended Practice J185Q. "Class B Data 

Communieation Network Interface" (J18S9), Neverabep _______ 198821, 

or ISO 9141 CARB. "Road vehicles - Diagnostic. SvsJAems - CARB 

Requirements for Interchange of Digital InformatlPJL__ which 4s ___£ 

incorporated by reference, shall be used as the on-board to offboard network communieations protocol. All emission related 

messages, sent to the J1978 scan tool ave___a__U__5Q data link Shall 

use the Cyclic Redundancy Check and the three bvte head.e___-a____ 

shall not use inter-bvte separation or checksums. 

(lrl) Th© Gye44s Redandaney Sheek (6RS) and aeknew4edge byte ept4sns 4R 

.1859 sha44 be eempat4b4e w4th the eemman4eat4en messages 

pefepsneed 4n J1978 and J1979? 9th@p J1859 ©pt4©ns may b© 

p@pm4tted by th© Eaeeat4v© Qff4ssp based apen a p©v4ew ef 

eerap4©H4ty and eest 4mpa6t en the §enep4e sean te©4-

(1T2 ) If Intepnat4ena4 StandaFds 9p§an4iat4en (£S8) 9141 beeemes 

8©8§4st©nt w4th SAi ^1962T «31978y J1979? aRd J2912 saeh that en4y 

®n® pp©t©e©4 weu4d eent4na@ te b@ needed t© at444_e the sean tee4T 

the S„.sat4vs 9ff4eep may a44ew the pev4sed _S9 9141 te be ased as 

as _4!@pnat© phys4ea4 4ayep and b4t peppes@ntat4©n fep th4s 

i©^mun4eat4©nT Th© appp©va4 sha44 b© based ©n t4m@4y ava44ab444ty 

®f ISO 9141 fep 4ntegpat4en 4nte th© genep4e sean ts©4 w4th 

K34a4raa4 add4t4ena4 eest ep eemp4en4ty? 

(2.0) .1978 & .1979 Standardization of the message content (including 

test modes and test messages) as well as standardization of the 

downloading protocol for fault codes, parameter values and their 

units, and freeze frame data are set forth in Draft SAE 

Recommended Practices on "Generic Scan Tool" (J1978), FebpaaFy, 

198921, and "Diagnostic Test Modes" (J1979), June, 198921, which 

have been incorporated by reference. Fault codes, parameter 

values, and freeze frame data shall be eapable of being downloaded 

to a generic scan tool meeting these SAE specifications. 

(2.1) 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 

r_efl_-ij-s to be performed using onlv the J1978 Generic Scan Tool and 

commonly available, non-microorocessor based tools. In addition 

to these .procedures, manufacturers mav publish repair procedures 

referencing the use of manufacturer specific or enhanced 

ei-UP-_.e_3.t-. 

A-27 
(2.2) The J1978 scan tool shall be capable of notifying the user when 

one or more of the required monitoring systems are not included as 

part of the OBD svstem. 

(3.0) .20X2 _________ Uniform fault codes based on SAE specifications 

shall be employed. SAE Draft Information Report "Recommended 

Format and Messages for Diagnostic Trouble Codes" (J2012), 

FebFaapy June. 198921, is incorporated by reference. 

(4.0) _1962 A standard data link connector in a standard location in 

each vehicle based on SAE specifications shall be incorporated. 

Any pins in the standard connector that provide any electrical 

power shall be properly fused to protect the integrity and 

usefulness of the diagnostic connector for diagnostic purposes. 

The SAE Draft Recommended Practice "Diagnostic Connector" (J1962), 

Fefepaapy _______ 198921, is incorporated by reference. 

(1) SIGNAL ACCESS 

(1.0) The following signals in addition to the required freeze frame 

information shall be made available on demand through the serial 

port on the standardized data link connector: calculated load 

value (4f ava44ab4e), diagnostic trouble codes, engine coolant 

temperature, fuel control system status (open loop, closed loop, 

other), fuel trim (if equipped), fuel pressure (if available), 

ignition timing advance, intake air temperature (if equipped), 

manifold air pressure (if equipped), air flow rate from mass air 

flow meter (if equipped), engine RPM, throttle position sensor 

output value (if equipped), secondary air status (upstream, 

downstream, or atmosphere; if equipped), and vehicle speed (if 

equipped). The signals shall be provided in standard units based 

on the SAE specifications incorporated by reference in this 

regulation, and actual signals shall be clearly identified 

separately from default value or limp home signals. 

(2.0) The manufacturer shall publish in factory service manuals a normal 

range for the calculated load value and mass air flow rate at 

idle, and at 2500 RPM (no load, in neutral or park). If the total 

fuel command trim is made up by more than one source (e.g. shortterm trim and long-term trim), all fuel trim signals shall be 

available. The signals shall be provided in standard units based 

on the incorporated SAE specifications, and actual signals shall 

be clearly identified separately from default value or limp home 

signals. 

(3.0) A sepapate ana4e§ s4gna4 fep sash egygen sensep ased sha44 be 

ava44ab4© 4n th© data 44nk ssnneetsp ©geept as neted be4ew- The 

4eeat4en 4n th© standapd data 44nk eenneetep fep ap te feap egygeR 

sensep s4gna4s7 4f needed? sha44 be deteFm4ned by SAE 

spe64f46at4en 4n J1962- The s4gna4 4ev©4 sha44 be R©m4Ra44y zeFe 

te ©R© ve4t. b@ 4se4ated fFera the 6entpe4 e4pea4t (4-e- baffeFed 

s4gna4)T and sha44 aeeupate4y FepFeseRt the egygen senseF s4gna4s 

4n pespense pate and f4de44ty (4-e- ne smeeth4n§)- In 44ea ef the 

abeveT egygen sensep data may be pp©v4ded thFeagh the data 44Rk 

A-28 

_r~ 
sp©64f4ed 4n SAE J1979 4f an eff-beapd egygen sensep eva4uat4en 

pp©v4des eqaa4 ©p bettep d4sep4m4Rat4en ef ma4fanet4eRS thaR the 

©R-b©apd cheek- Oxvgen sensor data that will allow diagnosis of 

malfunctioning oxvoen sensors shall he provided through the data 

link. Such data shall be transmitted in accordance with J1979, 

Alternative methods shall be approved by the Executive Officer if, 

in the judgment of the Executive Officer, they provide for an 

standapd4ied equivalent off-board evaluation of the oxygen 

sensor(s). 

(m) IMPLEMENTATION SCHEDULE 

(1.0) These OBD II requirements, except evaporative puree svstem 

monitoring (see seetion (b) (4.1.5). shall be implemented 

beginning with the 1994 model year. 

(2.0) The Executive Officer shall grant an extension for compliance with 

the requirements of these subsections with respect to a specific 

vehicle model or engine family if the vehicle model or engine 

family meets previously applicable on-board diagnostic system 

requirements and a manufacturer demonstrates that it cannot modify 

a present electronic control system by the 1994 model-year because 

major design system changes not consistent with the manufacturer's 

projected changeover schedule would be needed to comply with 

provisions of these subsections. 

(2.21) The manufacturer which has received an extension from the 

Executive Officer shall comply with these regulations when 

modification of the electronic system occurs in accordance with 

the manufacturer's projected changeover schedule or in the 1996 

model year, whichever first occurs. 

(2.32) Any manufacturer requesting an extension shall, no later than 

October 15, 1991, submit to the Executive Officer an application 

specifying the period for which the extension is required. 

(3.0) Small volume manufacturers as defined in (n) (16.0) shall meet 

these requirements by the 1996 model year. 

(4.0) Manufacturers may at their discretion implement a portion of these 

regulations prior to the required implementation date provided 

that the system complies with previously applicable on-board 

diagnostic system requirements. 

(5.0) Vehicles certified to run on alternate fuels, and diesel vehicles. 

shall meet these requirements bv the 19 % model vear. 

(n) GLOSSARY For purposes of this section: 

(1.0) "Malfunction" means the inability of an emission-related component 

or system to remain within design specifications. Further, 

malfunction refers to the deterioration of any of the above 

components or systems to a degree that would likely cause the 

emissions of an average certification durability vehicle with the 

A-29 

Sir 

I. 
deteriorated components or systems present at the beginning of a 

CVS-75 test to exceed by more than 1.5 times anv of the emission 

standards, unless otherwise specified, applicable pursuant to 

Subchapter 1 (commencing with Section 1900), Chapter 3 of 

Title 13. 

(2-9) -Bypass eata4yst- pefeps te a eata4yst pp4map44y ut444zed te 

deepeass era4ss4ens dap4Rg ee4d stapt eend4t4ens- When the eng4ne 

peaehes a ra4n4raara epepat4ng tempepatap© (as detepm4ned by teh 

manafa6tapep)T the eghaust gas 4s pe-peated se that 4t dees Ret 

pass thpeagh th4s 6ata4yst dup4ng eapmed-ap epeFat4en-

(32.0) "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. 

(42.0) "Engine misfire" means lack of combustion in the cylinder due to 

absence of spark, poor fuel metering, poor compression, or any 

other cause. 

(54.0) Oxygen sensor "response rate" refers to the delay (measured in 

milliseconds) between a switch of the sensor from lean to rich or 

vice versa in response to a change in fuel/air ratio above and 

below stoichiometric. 

(62.0) A "trip" means vehicle operation (following an engine-off period) 

of duration and driving mode such that all components and 

systems are monitored at least once by the diagnostic system 

except catalvst efficiency or evaporative svstem monitoring when 

a steadv-soeed check is used, subject to the limitation that the 

manufacturer-defined trip monitoring conditions shall all be 

encountered at least once during a CVS-752 cycle. 

(72-0) A "warm-up cycle" means sufficient vehicle operation (fe44ew4ng 

an eng4ne-eff pep4ed whepe eee4aRt tempeFatape has stab444zed at 

the amb4eRt tempepatape 4eve4) such that a m4R4mum eee4aRt 

tempeFatape ef 169 degpees FahFenhe4t 4s aeh4eved- the coolant 

temperature has risen bv at least 40 degrees Fahrenheit from 

engine starting and reaches a minimum temperature of 160 degrees 

Eflhrenheit. 

(82.0) A "driving cycle" consists of engine startup, vehicle operation 

beyond the beginning of closed loop operation, and engine 

shutoff. 

(9-9) -iRtegFated pefae44R§ vapep p'eeevepy system- meaRS a system 

eeRta4n4ng ene 6an4step fep eaptap4ng evapepat4ve em4ss4ens fFem 

any veh4e4e seapee and fpem pefae44Rg as we44-

(19-9) -NeR-4RtegFated Fefae44flg vapep FeeeveFy system- raesns a system 

seRta4R4R§ 6RS ean4step fep eaptap4Rg pefae44ng vapeps and anetheF 

ean4step(s) fep eaptap4ng veh4e4e evapFeat4ve em4ss4eRSA-30 

57 
P.58 

(112-0) "Continuous monitoring" means sampling at a rate no less than 

two samples per second. 

(122-0) "Fuel trim" refers to feedback adjustments to the base fuel 

schedule. Short-term fuel trim refers to raepe dynamic or 

instantaneous adjustments. Long-term fuel trim refers to sh4fts 

te much more gradual adjustments to the fuel calibration 

schedule (SP spee4f4e va4ues) that w444 be tempepap44y 

sabst4tated fep th© base seheda4© (ep va4aes)T and th4s ppeeess 

typ4ea44y essaps maeh mep© gpadaa44y than short-term trim 

adjustments. These long terra adjustments compensate for vehicle 

differences and gradual changes-that occur over time. 

(1312.0) "Base Fuel Schedule" refers to the fuel calibration schedule 

programmed into the Powertrain Control Module or PROM when 

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

to anv learned on-board correction. 

(14H.0) "Calculated load value" refers to the f4Ra4 va4ue. afteF a44 

e©ppeet4ens ap© detepm4ned by the Peweptpa4n G©Rtp©4 Msda4e te 

peppesent th© 4nstaRtaR©©as a4p f4ew7 wh4eh 4s then ased te 

s@4eet SP ea4ea4ate the apppepp4ate fae4 f4ew fpem the base 

fa©4 seheda4e- an indication of the current airflow divided bv 

peak airflow, where peak airflow is corrected for altitude, if 

available. This definition provides a unitless number that is 

not engine specific, and provides the service technician with 

an indication of the percent engine capacity that is being used 

(with wide open throttle as 100%). 

Purrent airflow Atm. pressure (. sea level) 

CLV X 

Peak airflow (9 Sea level) Barometric pressure 

(1512-0) "Medium-duty vehicle" is defined in Title 13, Section 1900 

(b)(9). 

(1612.0) "Small volume manufacturer" is any manufacturer with California 

sales not exceeding 3,000 new motor vehicles per model year. 

.14.0) "Low Emission Vehiele" refers to a vehicle certified in 

California as a Transitional Low Emission Vehicle, a Low emission 

Vehicle, or an Ultra Low Emission Vehicle. These vehicle 

categories are further defined in Title 13. sections 1956.8 and 

1960.1. 

A-31 
P.59 

Seetioini 1977. Cert Ifl cut loo and Service Docuraents=1993 and Subsequent Model 

M@.@ P Veto.eles. 

(a) In addition to all other requirements, all documents required by 

Caifornia certification procedures including emission-related vehicle and 

engine service procedures shall conform to the emission related nomenclature 

and abbreviations provided in the Society of Automotive Engineers' procedure 

J1930, -B4a§n®st4s Aepenyms? T©pmsT and Def4n4t4ens fep 

_4@6tp4ea4j*i4©6tp©n46 Systems"? Seet4en 6T Jane 1988 "Electrical/Electronic 

Systems Diagnostic Terms. Definitions. Abbreviations and Acronyms". June 

1591. which is incorporated herein by reference. 

(b) Subsection (a) shall apply to all new documents printed or updated 

by a manufacturer starting with the 1993 model year. 

I, 

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