Cadillac 2013 ATS Owner's Manual page 251

If the decision is made not to lift the
bonnet when this warning appears,
get service help right away.
If the decision is made to lift the
bonnet, make sure the vehicle is
parked on a level surface.
Then check to see if the engine
cooling fan is running. If the engine
is overheating, the fan should be
running. If it is not, do not continue
to run the engine. Have the vehicle
serviced.
Notice: Running the engine
without coolant may cause
damage or a fire. Vehicle damage
would not be covered by the
warranty.
If Steam Is Coming from the
Engine Compartment
WARNING
Steam from an overheated engine
can burn you badly, even if you
just open the bonnet. Stay away
from the engine if you see or hear
steam coming from it. Just turn it
off and get everyone away from
the vehicle until it cools down.
Wait until there is no sign of
steam or coolant before you open
the bonnet.
If you keep driving when the
engine is overheated, the liquids
in it can catch fire. You or others
could be badly burned. Stop the
engine if it overheats, and get out
of the vehicle until the engine
is cool.
Vehicle Care
If No Steam Is Coming from
the Engine Compartment
If an engine overheat warning is
displayed but no steam can be seen
or heard, the problem may not be
too serious. Sometimes the engine
can get a little too hot when the
vehicle:
Climbs a long hill on a hot day.
Stops after high-speed driving.
Idles for long periods in traffic.
If the overheat warning is displayed
with no sign of steam:
1. Turn the air conditioning off.
2. Turn the heater on to the highest
temperature and to the highest
fan speed. Open the windows as
necessary.
3. In heavy traffic, let the engine
idle in N (Neutral) for an
automatic transmission or
Neutral for a manual gearbox
while stopped. If it is safe to do
so, pull off the road, shift to
P (Park) or N (Neutral) for an
10-15