Warning/
indicator
lampNSignal type
Possible causes/consequences and M
Solutions
?NThe red coolant warning lamp comes on while the engine is running.
The coolant level is too low.
If the coolant level is correct, the airflow to the engine radiator may be blocked or
the electric engine radiator fan may be defective.
The coolant is too hot and the engine is no longer being cooled sufficiently.
XObserve the additional display messages in the multifunction display.
XPull over and stop the vehicle safely and switch off the engine, paying attention
to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 154).
XLeave the vehicle and keep a safe distance from the vehicle until the engine has cooled down.
XCheck the coolant level and add coolant, observing the warning notes
(Ypage 309).
XIf you have to add coolant frequently, have the engine cooling system checked.
XMake sure that the air supply to the engine radiator is not blocked, e.g. by snow,
slush or ice.
XDo not start the engine again until the coolant temperature is below 248 ‡
(120 †). Otherwise, the engine could be damaged.
XDrive to the nearest qualified specialist workshop.
XAvoid heavy loads on the engine as you do so, e.g. driving in mountainous terrain
and stop-and-go traffic.
?N The red coolant warning lamp comes on while the engine is running. A warning
tone also sounds.
The coolant temperature has exceeded 248 ‡(120 †). The airflow to the engine
radiator may be blocked or the coolant level may be too low.
GWARNING
The engine is not being cooled sufficiently and may be damaged.
Do not drive when your engine is overheated. This can cause some fluids which
may have leaked into the engine compartment to catch fire.
Steam from the overheated engine can also cause serious burns which can occur
just by opening the hood.
There is a risk of injury.
XObserve the additional display messages in the multifunction display.
XPull over and stop the vehicle safely and switch off the engine, paying attention
to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 154).
XLeave the vehicle and keep a safe distance from the vehicle until the engine has
cooled down.
XCheck the coolant level and add coolant, observing the warning notes
(Ypage 309).
XIf you have to add coolant frequently, have the engine cooling system checked.
XMake sure that the air supply to the engine radiator is not blocked, e.g. by snow,
slush or ice.
264Warning and indicator lamps in the instrument cluster
On-board computer and displays
Where possible, let the engine cool down andtouch only the components described in the
following.
GWARNING
The engine compartment contains moving
components. Certain components, such as
the radiator fan, may continue to run or start
again suddenly when the ignition is off. There is a risk of injury.
If you need to do any work inside the engine
compartment:
Rswitch off the ignition
Rnever reach into the area where there is a
risk of danger from moving components,
such as the fan rotation area
Rremove jewelry and watches
Rkeep items of clothing and hair, for exam-
ple, away from moving parts
GWARNING
The cooling system is pressurized, particularly
when the motor is warm. If you open the cap,
you could be scalded if hot coolant sprays out.
There is a risk of injury.
Let the engine cool down before you open the
cap. Wear gloves and eye protection. Slowly
open the cap to relieve pressure.
GWARNING
Opening the hood when the engine is over-
heated or when there is a fire in the engine
compartment could expose you to hot gases
or other service products. There is a risk of
injury.
Let an overheated engine cool down before
opening the hood. If there is a fire in the
engine compartment, keep the hood closed
and contact the fire department.
Checking coolant level
Checking the coolant level (example)
XPark the vehicle on a level surface.
Only check the coolant level when the vehicle
is on a level surface and the engine has cooled
down.
XTurn the SmartKey to position 2in the igni-
tion lock (Ypage 132).
or
XPress the Start/Stop button twice on vehicles
with KEYLESS-GO or the KEYLESS-GO start
function (
Ypage 133).
XCheck the coolant temperature display in the
instrument cluster (Ypage 36).
The coolant temperature must be below
158 ‡ (70 †).
XTurn the SmartKey to position gin the igni-
tion lock (Ypage 132).
or
XPress the Start/Stop button once on vehicles with KEYLESS-GO or the KEYLESS-GO start
function (
Ypage 133).
XSlowly turn cap :half a turn counter-clock-
wise and allow excess pressure to escape.
XTurn cap :further counter-clockwise and
remove it.
If the coolant is at the level of marker bar =
in the filler neck when cold, there is enough
coolant in coolant expansion tank ;.
If the coolant level is approximately 0.6 in
(1.5 cm) above marker bar =in the filler neck
when warm, there is enough coolant in expan-
sion tank ;.
XIf necessary, add coolant that has been tested
and approved by Mercedes-Benz.
XReplace cap :and turn it clockwise as far as
it will go.
For further information on coolant, see
(
Ypage 368).
Engine compartment309
Maintenance and care
Z
