[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]