Buick 2011 Lucerne Owner's Manual page 191

The engine coolant temperature warning light comes on
when the engine has overheated.
If this happens pull over and turn off the engine as soon
as possible. See Engine Overheating on page 6 35 for
more information.
This gauge shows the engine coolant temperature.
If the pointer moves towards the H (United States) or
shaded in thermostat symbol area (Canada), the engine
is too hot.
A temperature indicator light will turn on and a chime
will sound.
If the vehicle has been operating under normal driving
conditions, and the temperature indicator light comes
on, pull off the road, stop the vehicle and turn off the
engine as soon as possible.
This indicates that one or more of the tires is
significantly underinflated.
A tire pressure message in the Driver Information
Center (DIC), can accompany the light. See Driver
Information Center (DIC) on page 4 40 for more
information. Stop and check the tires as soon as it is
safe to do so. If underinflated, inflate to the proper
pressure. See Inflation - Tire Pressure on page 6 63
for more information.
For vehicles with a tire
pressure monitoring
system, this light comes
on briefly when the engine
is started. It provides
information about tire
pressures and the Tire
Pressure Monitoring
System.
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