Chevrolet 2010 Impala Owner's Manual page 176

If it does not, have the vehicle serviced by the dealer.
If the system is working normally the indicator light
goes off.
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
more information.
4-30
This light comes on briefly
while starting the vehicle.
for
This gauge shows the engine coolant temperature.
If the gauge pointer moves toward the H
(United States) or torward the shaded thermostat
(Canada), it means that the engine coolant has
overheated. If the vehicle has been operating under
normal driving conditions, pull off the road, stop the
vehicle and turn off the engine as soon as possible.
See
information.
for more