Cadillac 2009 DTS Owner's Manual page 203

Light On Steady: An emission control system
malfunction has been detected on the vehicle.
Diagnosis and service might be required.
An emission system malfunction might be corrected by
doing the following:
•
Make sure the fuel cap is fully installed.
See Filling the Tank on page 5-7. 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.
•
If the vehicle has been driven through a deep puddle
of water, the vehicle's electrical system might be wet.
The condition is usually corrected when the electrical
system dries out. A few driving trips should turn the
light off.
•
Make sure to fuel the vehicle with quality fuel.
Poor fuel quality causes the engine not to run as
efficiently as designed and can cause: stalling after
start-up, stalling when the vehicle is changed into
gear, misfiring, hesitation on acceleration, or
stumbling on acceleration. These conditions
might go away once the engine is warmed up.
If one or more of these conditions occurs, change the
fuel brand used. It will require at least one full tank of
the proper fuel to turn the light off.
See Gasoline Octane on page 5-5.
If none of the above have made the light turn off, your
dealer/retailer can check the vehicle. The dealer/retailer
has the proper test equipment and diagnostic tools to
fix any mechanical or electrical problems that might have
developed.
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