GMC 2004 Yukon XL, Owner'S Manual, Page: 209 / 554

If the Light is Flashing
The following may prevent more serious damage to
your vehicle:
•
Reducing vehicle speed
•
Avoiding hard accelerations
•
Avoiding steep uphill grades
•
If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible
If the light stops flashing and remains on steady,
see “If the Light Is On Steady” following.
If the light continues to flash, when it is safe to do so,
stop the vehicle. Find a safe place to park your vehicle.
Turn the key off, wait at least 10 seconds and restart
the engine. If the light remains on steady, see “If the
Light Is On Steady” following. If the light is still flashing,
follow the previous steps, and see your dealer for
service as soon as possible.
If the Light Is On Steady
You may be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully
install the cap. See Filling Your Tank on page 5-9.
The diagnostic system can determine if the fuel cap has
been left off or improperly installed. A loose or missing
fuel cap will allow fuel to evaporate into the atmosphere.
A few driving trips with the cap properly installed
should turn the light off.
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.
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