[Code of Federal Regulations]
[Title 40, Volume 17]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR86.099-17]

[Page 399-403]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 86_CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND 
ENGINES--Table of Contents
 
Subpart A_General Provisions for Emission Regulations for 1977 and Later 
 
Sec. 86.099-17  Emission control diagnostic system for 1999 and later 
light-duty vehicles and light-duty trucks.

    (a) All light-duty vehicles and light-duty trucks shall be equipped 
with an on-board diagnostic (OBD) system capable of monitoring, for each 
vehicle's useful life, all emission-related powertrain systems or 
components. All systems and components required to be monitored by these 
regulations shall be evaluated periodically, but no less frequently than 
once per Urban Dynamometer Driving Schedule as defined in Appendix I, 
paragraph (a), of this part, or similar trip as approved by the 
Administrator.
    (b) Malfunction descriptions. The OBD system shall detect and 
identify malfunctions in all monitored emission-related powertrain 
systems or components according to the following malfunction definitions 
as measured and calculated in accordance with test procedures set forth 
in subpart B of this part, excluding those test procedures described in 
Sec. 86.158-00. Paragraph (b)(1) of this section does not apply to 
diesel cycle light-duty vehicles or diesel cycle light-duty trucks, 
except where the catalyst is needed for NMHC control. Paragraphs (b)(2), 
(b)(3), and (b)(4) of this section do not apply to diesel cycle light-
duty vehicles or diesel cycle light-duty trucks.
    (1) Catalyst deterioration or malfunction before it results in an 
increase in NMHC emissions 1.5 times the NMHC standard, as compared to 
the NMHC emission level measured using a representative 4000 mile 
catalyst system.
    (2) Engine misfire resulting in exhaust emissions exceeding 1.5 
times the applicable standard for NMHC, CO or NOX; and any 
misfire capable of damaging the catalytic converter.
    (3) Oxygen sensor deterioration or malfunction resulting in exhaust 
emissions exceeding 1.5 times the applicable standard for NMHC, CO or 
NOX.
    (4) Any vapor leak in the evaporative and/or refueling system 
(excluding the tubing and connections between the purge valve and the 
intake manifold) greater than or equal in magnitude to a leak caused by 
a 0.040 inch diameter orifice; any absence of evaporative purge air flow 
from the complete evaporative emission control system. On vehicles with 
fuel tank capacity greater than 25 gallons, the Administrator may, 
following a request from the manufacturer, revise the size of the 
orifice to the smallest orifice feasible, based on test data, if the 
most reliable monitoring method available cannot reliably detect a 
system leak equal to a 0.040 inch diameter orifice.
    (5) Any deterioration or malfunction occurring in a powertrain 
system or component directly intended to control emissions, including 
but not necessarily limited to, the exhaust gas recirculation (EGR) 
system, if equipped, the secondary air system, if equipped, and the fuel 
control system, singularly resulting in exhaust emissions exceeding 1.5 
times the applicable emission standard for NMHC, CO or NOX 
For vehicles equipped with a secondary air system, a functional check, 
as described in paragraph (b)(6) of this section, may satisfy the 
requirements of this paragraph provided the manufacturer can demonstrate 
that deterioration of the flow distribution system is unlikely. This 
demonstration is subject to Administrator approval and, if the 
demonstration and associated functional check are approved, the 
diagnostic system shall indicate a malfunction when some degree of 
secondary airflow is not detectable in the exhaust system during the 
check. For vehicles equipped with positive crankcase ventilation (PCV), 
monitoring of the PCV system is not necessary provided the manufacturer 
can demonstrate to the Administrator's satisfaction that the PCV system 
is unlikely to fail.

[[Page 400]]

    (6) Any other deterioration or malfunction occurring in an 
electronic emission-related powertrain system or component not otherwise 
described above that either provides input to or receives commands from 
the on-board computer and has a measurable impact on emissions; 
monitoring of components required by this paragraph shall be satisfied 
by employing electrical circuit continuity checks and rationality checks 
for computer input components (input values within manufacturer 
specified ranges), and functionality checks for computer output 
components (proper functional response to computer commands) except that 
the Administrator may waive such a rationality or functionality check 
where the manufacturer has demonstrated infeasibility; malfunctions are 
defined as a failure of the system or component to meet the electrical 
circuit continuity checks or the rationality or functionality checks.
    (7) Oxygen sensor or any other component deterioration or 
malfunction which renders that sensor or component incapable of 
performing its function as part of the OBD system shall be detected and 
identified on vehicles so equipped.
    (8) Alternatively, for model years 1999 and 2000, engine families 
may comply with the malfunction descriptions of Sec. 86.098-17(a) and 
(b) in lieu of the malfunction descriptions in paragraphs (a) and (b) of 
this section. This alternative is not applicable after the 2000 model 
year.
    (c) Malfunction indicator light. The OBD system shall incorporate a 
malfunction indicator light (MIL) readily visible to the vehicle 
operator. When illuminated, it shall display ``Check Engine,'' ``Service 
Engine Soon,'' a universally recognizable engine symbol, or a similar 
phrase or symbol approved by the Administrator. A vehicle shall not be 
equipped with more than one general purpose malfunction indicator light 
for emission-related problems; separate specific purpose warning lights 
(e.g. brake system, fasten seat belt, oil pressure, etc.) are permitted. 
The use of red for the OBD-related malfunction indicator light is 
prohibited.
    (d) MIL illumination. The MIL shall illuminate and remain 
illuminated when any of the conditions specified in paragraph (b) of 
this section are detected and verified, or whenever the engine control 
enters a default or secondary mode of operation considered abnormal for 
the given engine operating conditions. The MIL shall blink once per 
second under any period of operation during which engine misfire is 
occurring and catalyst damage is imminent. If such misfire is detected 
again during the following driving cycle (i.e., operation consisting of, 
at a minimum, engine start-up and engine shut-off) or the next driving 
cycle in which similar conditions are encountered, the MIL shall 
maintain a steady illumination when the misfire is not occurring and 
shall remain illuminated until the MIL extinguishing criteria of this 
section are satisfied. The MIL shall also illuminate when the vehicle's 
ignition is in the ``key-on'' position before engine starting or 
cranking and extinguish after engine starting if no malfunction has 
previously been detected. If a fuel system or engine misfire malfunction 
has previously been detected, the MIL may be extinguished if the 
malfunction does not reoccur during three subsequent sequential trips 
during which similar conditions are encountered (engine speed is within 
375 rpm, engine load is within 20 percent, and the engine's warm-up 
status is the same as that under which the malfunction was first 
detected), and no new malfunctions have been detected. If any 
malfunction other than a fuel system or engine misfire malfunction has 
been detected, the MIL may be extinguished if the malfunction does not 
reoccur during three subsequent sequential trips during which the 
monitoring system responsible for illuminating the MIL functions without 
detecting the malfunction, and no new malfunctions have been detected. 
Upon Administrator approval, statistical MIL illumination protocols may 
be employed, provided they result in comparable timeliness in detecting 
a malfunction and evaluating system performance, i.e., three to six 
driving cycles would be considered acceptable.
    (e) Storing of computer codes. The emission control diagnostic 
system shall record and store in computer memory diagnostic trouble 
codes and

[[Page 401]]

diagnostic readiness codes indicating the status of the emission control 
system. These codes shall be available through the standardized data 
link connector per SAE J1979 specifications incorporated by reference in 
paragraph (h) of this section.
    (1) A diagnostic trouble code shall be stored for any detected and 
verified malfunction causing MIL illumination. The stored diagnostic 
trouble code shall identify the malfunctioning system or component as 
uniquely as possible. At the manufacturer's discretion, a diagnostic 
trouble code may be stored for conditions not causing MIL illumination. 
Regardless, a separate code should be stored indicating the expected MIL 
illumination status (i.e., MIL commanded ``ON,'' MIL commanded ``OFF'').
    (2) For a single misfiring cylinder, the diagnostic trouble code(s) 
shall uniquely identify the cylinder, unless the manufacturer submits 
data and/or engineering evaluations which adequately demonstrate that 
the misfiring cylinder cannot be reliably identified under certain 
operating conditions. The diagnostic trouble code shall identify 
multiple misfiring cylinder conditions; under multiple misfire 
conditions, the misfiring cylinders need not be uniquely identified if a 
distinct multiple misfire diagnostic trouble code is stored.
    (3) The diagnostic system may erase a diagnostic trouble code if the 
same code is not re-registered in at least 40 engine warm-up cycles, and 
the malfunction indicator light is not illuminated for that code.
    (4) Separate status codes, or readiness codes, shall be stored in 
computer memory to identify correctly functioning emission control 
systems and those emission control systems which require further vehicle 
operation to complete proper diagnostic evaluation. A readiness code 
need not be stored for those monitors that can be considered 
continuously operating monitors (e.g., misfire monitor, fuel system 
monitor, etc.). Readiness codes should never be set to ``not ready'' 
status upon key-on or key-off; intentional setting of readiness codes to 
``not ready'' status via service procedures must apply to all such 
codes, rather than applying to individual codes. Subject to 
Administrator approval, if monitoring is disabled for a multiple number 
of driving cycles (i.e., more than one) due to the continued presence of 
extreme operating conditions (e.g., ambient temperatures below 40 
[deg]F, or altitudes above 8000 feet), readiness for the subject 
monitoring system may be set to ``ready'' status without monitoring 
having been completed. Administrator approval shall be based on the 
conditions for monitoring system disablement, and the number of driving 
cycles specified without completion of monitoring before readiness is 
indicated.
    (f) Available diagnostic data. (1) Upon determination of the first 
malfunction of any component or system, ``freeze frame'' engine 
conditions present at the time shall be stored in computer memory. 
Should a subsequent fuel system or misfire malfunction occur, any 
previously stored freeze frame conditions shall be replaced by the fuel 
system or misfire conditions (whichever occurs first). Stored engine 
conditions shall include, but are not limited to: engine speed, open or 
closed loop operation, fuel system commands, coolant temperature, 
calculated load value, fuel pressure, vehicle speed, air flow rate, and 
intake manifold pressure if the information needed to determine these 
conditions is available to the computer. For freeze frame storage, the 
manufacturer shall include the most appropriate set of conditions to 
facilitate effective repairs. If the diagnostic trouble code causing the 
conditions to be stored is erased in accordance with paragraph (d) of 
this section, the stored engine conditions may also be erased.
    (2) The following data in addition to the required freeze frame 
information shall be made available on demand through the serial port on 
the standardized data link connector, if the information is available to 
the on-board computer or can be determined using information available 
to the on-board computer: Diagnostic trouble codes, engine coolant 
temperature, fuel control system status (closed loop, open loop, other), 
fuel trim, ignition timing advance, intake air temperature, manifold air 
pressure, air flow rate, engine RPM, throttle position sensor output 
value, secondary air status (upstream,

[[Page 402]]

downstream, or atmosphere), calculated load value, vehicle speed, and 
fuel pressure. The signals shall be provided in standard units based on 
SAE specifications incorporated by reference in paragraph (h) of this 
section. Actual signals shall be clearly identified separately from 
default value or limp home signals.
    (3) For all emission control systems for which specific on-board 
evaluation tests are conducted (catalyst, oxygen sensor, etc.), the 
results of the most recent test performed by the vehicle, and the limits 
to which the system is compared shall be available through the 
standardized data link connector per SAE J1979 specifications 
incorporated by reference in paragraph (h) of this section.
    (4) Access to the data required to be made available under this 
section shall be unrestricted and shall not require any access codes or 
devices that are only available from the manufacturer.
    (g) The emission control diagnostic system is not required to 
evaluate systems or components during malfunction conditions if such 
evaluation would result in a risk to safety or failure of systems or 
components. Additionally, the diagnostic system is not required to 
evaluate systems or components during operation of a power take-off unit 
such as a dump bed, snow plow blade, or aerial bucket, etc.
    (h) Incorporation by reference materials. The emission control 
diagnostic system shall provide for standardized access and conform with 
the following Society of Automotive Engineers (SAE) standards and/or the 
following International Standards Organization (ISO) standards. The 
following documents are incorporated by reference. This incorporation by 
reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
inspected at Docket No. A-90-35 at EPA's Air docket (LE-131), room 1500 
M, 1st Floor, Waterside Mall, 401 M St., SW., Washington, DC, or at the 
National Archives and Records Administration (NARA). For information on 
the availability of this material at NARA, call 202-741-6030, or go to: 
http://www.archives.gov/federal--register/code--of--federal--
regulations/ibr--locations.html.
    (1) SAE material. Copies of these materials may be obtained from the 
Society of Automotive Engineers, Inc., 400 Commonwealth Drive, 
Warrendale, PA 15096-0001.
    (i) SAE J1850 July 1995, ``Class B Data Communication Network 
Interface,'' shall be used as the on-board to off-board communications 
protocol. All emission related messages sent to the scan tool over a 
J1850 data link shall use the Cyclic Redundancy Check and the three byte 
header, and shall not use inter-byte separation or checksums.
    (ii) Basic diagnostic data (as specified in Sec. 86.094-17(e) and 
(f)) shall be provided in the format and units in SAE J1979 July 1996, 
E/E Diagnostic Test Modes.
    (iii) Diagnostic trouble codes shall be consistent with SAE J2012 
July 1996, ``Recommended Practices for Diagnostic Trouble Code 
Definitions.''
    (iv) The connection interface between the OBD system and test 
equipment and diagnostic tools shall meet the functional requirements of 
SAE J1962 January 1995, ``Diagnostic Connector.''
    (2) ISO materials. Copies of these materials may be obtained from 
the International Organization for Standardization, Case Postale 56, CH-
1211 Geneva 20, Switzerland.
    (i) ISO 9141-2 February 1994, ``Road vehicles--Diagnostic systems--
Part 2: CARB requirements for interchange of digital information,'' may 
be used as an alternative to SAE J1850 as the on-board to off-board 
communications protocol.
    (ii) [Reserved]
    (i) Deficiencies and alternate fueled vehicles. Upon application by 
the manufacturer, the Administrator may accept an OBD system as 
compliant even though specific requirements are not fully met. Such 
compliances without meeting specific requirements, or deficiencies, will 
be granted only if compliance would be infeasible or unreasonable 
considering such factors as, but not limited to, technical feasibility 
of the given monitor, lead time and production cycles including phase-in 
or phase-out of engines or vehicle designs

[[Page 403]]

and programmed upgrades of computers, and if any unmet requirements are 
not carried over from the previous model year except where unreasonable 
hardware or software modifications would be necessary to correct the 
non-compliance, and the manufacturer has demonstrated an acceptable 
level of effort toward compliance as determined by the Administrator. 
Furthermore, EPA will not accept any deficiency requests that include 
the complete lack of a major diagnostic monitor (``major'' diagnostic 
monitors being those for the catalyst, oxygen sensor, engine misfire, 
and evaporative leaks), with the possible exception of the special 
provisions for alternate fueled vehicles. For alternate fueled vehicles 
(e.g., natural gas, liquefied petroleum gas, methanol, ethanol), 
beginning with the model year for which alternate fuel emission 
standards are applicable and extending through the 2004 model year, 
manufacturers may request the Administrator to waive specific monitoring 
requirements of this section for which monitoring may not be reliable 
with respect to the use of the alternate fuel. At a minimum, alternate 
fuel vehicles shall be equipped with an OBD system meeting OBD 
requirements to the extent feasible as approved by the Administrator.
    (j) Demonstration of compliance with California OBD II requirements 
(Title 13 California Code Sec. 1968.1), as modified pursuant to 
California Mail Out 97-24 (December 9, 1997), shall satisfy the 
requirements of this section, except that compliance with Title 13 
California Code Secs. 1968.1(b)(4.2.2), pertaining to evaporative leak 
detection, and 1968.1(d), pertaining to tampering protection, are not 
required to satisfy the requirements of this section, and the deficiency 
fine provisions of 1968.1(m)(6.1) and (6.2) shall not apply.

[63 FR 70694, Dec. 22, 1998]