Air Repair: July 2002

              Air Repair July 2002 1
Volume 5 Number 3 July 2002
The on-board diagnostics (OBD)
test will become a mandatory part
of the pass/fail criteria for most
1996 and newer model year
vehicles, and will be phased in over
an 18 month period. Recently
passed legislation allows the Illinois
EPA to use the OBD test results to
pass the emissions test.
Most 1996 and newer vehicles
are equipped with a second-generation
on-board diagnostic
system (OBDII) that monitors all of
the equipment that controls emis-sions
systems in the vehicle to
ensure they are operating properly.
The OBD system notifies drivers as
soon as a problem is detected by
illuminating a malfunction indicator
light (MIL) on the dashboard. The
system can usually detect a prob-lem
well before the driver recog-nizes
symptoms of a problem, such
as poor fuel economy, lack of
performance, or increased emis-sions.
(Auto manufacturers can
only use the MIL for emission-related
problems.)
The OBD test will replace
traditional exhaust tests for most
1996 and newer vehicles. OBDII
systems are so technologically
advanced that they provide a better
way to perform emissions inspec-tions
than traditional exhaust tests.
OBD tests have been performed on
an advisory basis since December
1999.
OBD Test to be Part of Pass/Fail Criteria
The OBD test will be phased-in
because of the time needed to
change computer software and
accommodate the legislation. The
OBD full implementation will take
place over an 18-month period in
three phases:
Phase 1 from July to October
2002: 1996 and newer vehicles
that pass a gas cap pressure
test and an OBD test will
receive a compliance certificate
for the current test cycle and an
exhaust test will not be
performed. If the vehicle fails
or is rejected for an OBD test,
it will automatically receive the
appropriate exhaust test –
either IM240 or idle.
Phase 2 from October 2002 to
January 2004: Owners of 1996
and newer vehicles will be able
to decide whether to repair their
vehicle if it fails an OBD test,
or to be given a second chance
exhaust test.
Phase 3 beginning January 1,
2004: The emissions test for
most 1996 and newer vehicles
will consist of a gas cap
pressure test and an OBD test.
When a vehicle fails an OBD test
during Phase 1, the Vehicle Inspec-tion
Report will indicate the vehicle
failed for codes but will not indicate
which codes were present. The
Repair Diagnostics Report will
provide details of the IM240
exhaust test but will not report
details of the OBD test. Thus,
during this three-month period,
repair technicians will have to rely
on a scanner to access this critical
information. The details of failed
OBD tests will not be available until
Phase 2 is implemented.
During Phases 1 and 2, vehicles
that fail an OBD test and an
exhaust test must be repaired to
pass either the OBD test or the
appropriate exhaust test – IM240 or
idle depending on the make, model
and original design of the vehicle.
When Phase 3 is implemented, 1996
and newer vehicles will have to be
repaired to pass the OBD test.
An OBD test is relatively
simple to perform. After the gas
cap pressure test is performed, a
cable is attached to the OBD data
link connector (DLC). Inspectors
check to make sure the OBD
malfunction indicator lamp (MIL) is
working, and the test lane computer
looks for codes stored in the
vehicle’s powertrain control module.
Continued on page 5.
An inspector performs an OBD test.
This move from exhaust tests to
OBD tests represents a shift to
pollution prevention. OBDII is an