GMC 2007 Acadia - Manual (Page 227)

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 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 could damage the emission
control system on your vehicle. Diagnosis and
service might be required.
• Light On Steady — An emission control
system malfunction has been detected on
your vehicle. Diagnosis and service might be
required.
If the Light is Flashing
The following can prevent more serious damage
to your vehicle:
• Reduce vehicle speed.
• Avoid hard accelerations.
• Avoid 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 the 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/retailer
for service as soon as possible.
If the Light Is On Steady
You might 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 the Tank on page 390.
The diagnostic system can determine if the
fuel cap has been left off or improperly installed.
A loose or missing fuel cap allows fuel to
evaporate into the atmosphere. A few driving
trips with the cap properly installed should
turn the light off.
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