Cadillac 2007 XLR Owner's Manual page 197

This system is called OBD II (On-Board
Diagnostics-Second Generation) and is intended
to assure that emissions are at acceptable
levels for the life of the vehicle, helping to produce
a cleaner environment. The check engine light
comes on to indicate that there is a problem and
service is required. Malfunctions often will be
indicated by the system before any problem is
apparent. This may prevent more serious damage
to your vehicle. This system is also designed to
assist your service technician in correctly
diagnosing any malfunction.
Notice: If you keep driving your vehicle with
this light on, after awhile, your emission
controls may not work as well, your fuel
economy may not be as good, and your engine
may not run as smoothly. This could lead to
costly repairs that may not be covered by your
warranty.
Notice: Modifications made to the engine,
transmission, exhaust, intake, or fuel system
of your vehicle or the replacement of the
original tires with other than those of the same
Tire Performance Criteria (TPC) can affect your
vehicle's emission controls and may cause
this light to come on. Modifications to these
systems could lead to costly repairs not
covered by your warranty. This may also result
in a failure to pass a required Emission
Inspection/Maintenance test. See Accessories
and Modifications on page 363.
This light should come on briefly, as a check to
show you it is working, as you start the engine. If
the light does not come on, have it repaired.
This light will also come on during a malfunction in
one of two ways:
•
Light Flashing — A misfire condition has
been detected. A misfire increases vehicle
emissions and may damage the emission
control system on your vehicle. Diagnosis and
service may be required.
•
Light On Steady — An emission control
system malfunction has been detected on your
vehicle. Diagnosis and service may be
required.
197