Mercedes-Benz SL 2008 Owner's Manual page 239

Practical advice
Troubleshooting
Problem
D The red coolant warning
lamp comes on while the
engine is running.
D The red coolant warning
lamp comes on while the
engine is running.
D The red coolant warning
lamp comes on while the
engine is running. You will
also hear a warning tone.
236
Possible cause/consequence
The coolant level is too low.
The coolant is too hot and the
engine is no longer being cooled
sufficiently.
If the coolant level is correct, the
airflow to the radiator may be
blocked or the radiator fan may
be malfunctioning.
The coolant is too hot and the
engine is no longer being cooled
sufficiently.
The coolant level is too low.
The coolant temperature has
exceeded 120 †. The engine is
not being cooled sufficiently and
may be damaged.
Suggested solutions
Stop the vehicle. Pay attention to traffic conditions as you do so.
X
Allow the engine and coolant to cool.
X
Check the coolant level ( page 180). Observe the warning notes.
X
Y
Top up the coolant if necessary.
Have the coolant system checked at a qualified specialist work-
X
shop if the coolant needs topping up more often than usual.
Make sure that the airflow to the radiator is not blocked, e.g. by
X
snow, slush or ice.
If the coolant temperature is less than 120†, you can continue
X
driving to the nearest qualified specialist workshop.
Avoid heavy loads on the engine (e.g. driving in mountainous ter-
X
rain) and stop-and-go driving.
Stop the vehicle. Pay attention to traffic conditions as you do so.
X
Allow the engine and coolant to cool.
X
Check the coolant level ( page 180). Observe the warning notes.
X
Y
Top up the coolant if necessary.
Have the coolant system checked at a qualified specialist work-
X
shop if the coolant needs topping up more often than usual.