Chevrolet GMC 2002 Owner's Manual Supplement page 14

If the Light Comes On
This light should come on, as a check to show you it is
working, when the ignition is on and the engine is not
running. If it doesn't, have it repaired. This light will
also come on if an emission control system malfunction
has been detected on your vehicle. Dealer or qualified
service center diagnosis and service may be required.
You also may be able to correct the emission system
malfunction by considering the following:
Did you just drive through a deep puddle of water?
If so, your electrical system may be wet. The condition
will usually be corrected when the electrical system
dries out. A few driving trips should turn the light off.
Are you low on fuel?
As your engine starts to run out of fuel, your engine may
not run as efficiently as designed since small amounts of
air are sucked into the fuel line. The system can detect
this. Adding fuel should correct this condition. It will
take a few driving trips to turn the light off.
If none of the above steps have made the light turn off,
have your dealer or qualified service center check the
vehicle. Your dealer has the proper test equipment and
diagnostic tools to fix any mechanical or electrical
problems that may have developed.
Emissions Inspection and Maintenance Programs
Some state/provincial and local governments have or may
begin programs to inspect the emission control equipment
on your vehicle. Failure to pass this inspection could
prevent you from getting a vehicle registration.
Here are some things you need to know in order to help
your vehicle pass an inspection.
Your vehicle will not pass this inspection if the
SERVICE ENGINE SOON light is on or not
working properly.
Your vehicle will not pass this inspection if the OBD
-
(on board diagnostic) system determines that critical
emission control systems have not been completely
diagnosed by the system. The vehicle would be
considered not ready for inspection. This can happen if
you have recently replaced your battery or if your battery
has run down. The diagnostic system is designed to
evaluate critical emission control systems during normal
driving. This may take several days of routine driving.
If you have done this and your vehicle still does not
pass the inspection for lack of OBD system readiness,
see your dealer or qualified service center to prepare the
vehicle for inspection.
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