Pontiac 2005 Grand Prix - Manual (Page 319)

If an overheat warning occurs without any sign of
steam, try this for a minute or so:
1. In heavy traffic, let the engine idle in NEUTRAL (N)
while stopped. If it is safe to do so, pull off the road,
shift to PARK (P) or NEUTRAL (N) and let the
engine idle.
2. Set the heater at the highest setting and the fan at
the highest speed and open the windows as
necessary.
If the overheat warning no longer exists, the vehicle can
be driven. Just to be safe, drive slower for about
10 minutes. If the warning does not come back on, the
vehicle can be driven normally.
If the warning continues, and you have not stopped, pull
over, stop, and park the vehicle right away.
If there is still no sign of steam, idle the engine for three
minutes while parked. If the warning is still there, turn
off the engine and get everyone out of the vehicle until it
cools down. Also, see “Overheated Engine Protection
Operating Mode” later in this section.
You may decide not to lift the hood but to get service
help right away.
Overheated Engine Protection
Operating Mode
The overheated engine protection operating mode
allows the vehicle to be driven to a safe place in an
emergency situation. If an overheated engine condition
exists, this protection mode alternates firing groups
of cylinders to help prevent engine damage. In
this mode, there will be a significant loss in power and
engine performance. The engine coolant temperature
gage indicator will move to the shaded area, and
the engine coolant temperature warning light will come
on, showing that an overheated engine condition
exists. Driving extended miles (km) and/or towing a
trailer in the overheated engine protection mode should
be avoided.
Notice: After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any
repair. The engine oil will be severely degraded.
Repair the cause of coolant loss, change the oil and
reset the oil life system. See Engine Oil on page 5-14.
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