United States Air and Radiation EPA420-F-98-045
Environmental Protection November 1998
Agency
Office of Mobile Sources
v>EPA Regulatory
Announcement
Modification of Federal On-board
Diagnostic (OBD) Regulations
The Environmental Protection Agency (EPA) is issuing a final
rulemaking to harmonize certain aspects of the federal On-Board
Diagnostic (OBD) program with California OBDII regulations which, in
general, are more stringent. This final rulemaking also allows for
additional lead time for alternate fuel vehicle manufacturers to
implement federal OBD on such vehicles.
Background
On February 19, 1993, the EPA published a final rule requiring manufac-
turers of light-duty vehicles (LDVs) and light-duty trucks (LDTs) to
install OBD systems beginning with the 1994 model year. OBD systems
monitor emission control components for any malfunction or deteriora-
tion that cause emission limits to be exceeded. OBD systems alert the
driver of the need for repair via a dashboard light when the diagnostic
system has detected a problem. The rulemaking also requires that, when
a malfunction occurs, diagnostic information be stored in the vehicle's
computer to assist the technician in diagnosis and repair.
On May 28, 1997, EPA published a Notice of Proposed Rulemaking that
proposed changes to the federal OBD requirements starting with the
1999 model year.
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of
EPA is finalizing modifications to the
federal OBD regulations, including:
« Harmonizing the emission levels above
which a component or system is consid-
ered malfunctioning (i.e., the malfunc-
tion thresholds) with California's OBD
II requirements.
• Mandating that EPA OBD systems fully
evaluate the entire emission control
system, including the evaporative emis-
sion control system.
« Indefinitely extending the allowance of
deficiencies for federal OBD vehicles.
Indefinitely extending the allowance of
optional compliance with the California
OBD II requirements for federal OBD
certification while also updating the
allowed version of those California OBD
II regulations to the most recently
published version.
Providing flexibility to alternate fueled
vehicles through the 2004 model year.
Benefits
OBD systems provide substantial ozone
benefits by notifying the driver of a prob-
lem before the vehicle's emissions have
increased significantly. If the vehicle is
taken to a repair shop in a timely fashion, it
can be properly repaired before any signifi-
cant emission increase occurs. OBD sys-
tems also provide automobile manufactur-
ers with valuable feedback from their
customers' vehicles that can be used to
improve vehicle and emission control
system designs. This final rule will not
change the environmental benefits of the
OBD program.
for
This rule provides flexibility to industry by
allowing automobile manufacturers to
design and implement one OBD system
that will meet the requirements of both
federal OBD regulations and California
OBD II regulations. Additionally, one of
the modifications finalized by this rule will
reduce the burden on alternate fuel vehicle
manufacturers by extending the lead-time
they will have to comply with this regula-
tion.
For
Additional documents on OBD are avail-
able electronically from the EPA Internet
server at:
www.epa.gov/oms/ld-hwy.htm
For further information on this final rule,
please contact Holly Pugliese at:
U.S. Environmental Protection Agency
Office of Mobile Sources
2000 Traverwood Drive
Ann Arbor, MI 48105
(734)214-4288
pugliese.holly@epa.gov
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