Mercedes-Benz 2011 SL550 Roadster Operator's Manual page 266

What to do if ...
264
Problem
? The red coolant
temperature
warning lamp
comes on when
the engine is
running and an
acoustic
warning sounds.
G
Warning!
Driving when your engine is overheated can
cause some fluids which may have leaked into
the engine compartment to catch fire. You
could be seriously burned.
Steam from an overheated engine can cause
serious burns which can occur just by opening
the engine hood. Stay away from the engine
if you see or hear steam coming from it.
Possible causes/consequences and M Solutions
The coolant temperature has exceeded 248‡ (120†).
X
Stop in a safe location as soon as possible and allow the engine
and coolant to cool down.
Stop the vehicle in a safe location away from
other traffic. Turn off the engine, get out of the
vehicle and do not stand near the vehicle until
the engine has cooled down.
! The engine should not be operated with
the coolant temperature above 248‡
(120†). Doing so may cause serious
damage which is not covered by the
Mercedes-Benz Limited Warranty.