Overheated Engine Protection; Operating Mode; Engine Fan - GMC 2012 Sierra Denali Owner's Manual

If the temperature overheat gauge
is no longer in the overheat zone or
an overheat warning no longer
displays, the vehicle can be driven.
Continue to drive the vehicle slowly
for about 10 minutes. Keep a safe
vehicle distance from the vehicle in
front. If the warning does not come
back on, continue to drive normally.
If the warning continues, pull over,
stop, and park the vehicle
right away.
If there is no sign of steam, idle the
engine for three minutes while
parked. If the warning is still
displayed, turn off the engine until it
cools down. Also, see Overheated
Engine Protection Operating Mode
later in this section.
Overheated Engine
Protection

Operating Mode

If an overheated engine condition
exists and the ENGINE POWER IS
REDUCED message is displayed,
an overheat protection mode which
alternates firing groups of cylinders
helps prevent engine damage. In
this mode, a loss in power and
engine performance will be noticed.
This operating mode allows the
vehicle to be driven to a safe place
in an emergency. Driving extended
distances and/or towing a trailer in
the overheat 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 10 7.
Vehicle Care

Engine Fan

The vehicle has electric cooling
fans. The fans spinning at low
speed during most everyday driving
might be heard. The fans can turn
off if no cooling is required. Under
heavy vehicle loading, trailer towing,
and/or high outside temperatures,
or if operating the air conditioning
system, the fans can change to high
speed and an increase in fan noise
might be heard. This is normal and
indicates that the cooling system is
functioning properly. The fans
change to low speed when
additional cooling is no longer
required.
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