Cadillac 2004 CTS - Manual (Page 164)

Engine Coolant Temperature Gage
This gage shows the
engine coolant
temperature. If the gage
pointer moves into
the shaded area, the
engine is too hot.
That reading means the same thing as the warning
light – the engine coolant is very hot. See
Engine
Overheating on page 5-30.
Malfunction Indicator Lamp
Check Engine Light
Your vehicle is equipped
with a computer which
monitors operation of the
fuel, ignition and emission
control systems.
This system is called OBD II (On-Board Diagnostics-
Second Generation) and is intended to assure that
emissions are at acceptable levels for the life of
the vehicle, helping to produce a cleaner environment.
The Check Engine light comes on to indicate that
there is a problem and service is required. Malfunctions
often will be indicated by the system before any
problem is apparent. This may prevent more serious
damage to your vehicle. This system is also designed to
assist your service technician in correctly diagnosing
any malfunction.
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