What does this warning light on my dash mean ?

What do i do ?
Check Engine / Service Engine Soon

Todays GM vehicles use many sensor, switches, solenoids, and other
electrical components to control or monitor every aspect of the engine.
From controlling the fuel and ignition systems, to monitoring the emissions.
A problem in any of these systems, or subsystems, can cause the check
engine light to come on.

The first step in any diagnosis of the check engine light is to get the
computer (PCM or ECM)
scanned for codes. Any time this warning comes
on, a code is stored in the computer memory along with many data
parameters that were present at the time of the fault.

A simple
code reader that can be purchased at any automotive supplier
can retrieve these codes. Many of the large national parts store chains will
scan the system at no charge. The code will give an indication as to what
system has / had a problem. The more expensive scanners will also show
live data, and allow further diagnosis by being able to control parts of a
particular system.
Some repair questions and answers.
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