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368 Practical hints
What to do if …
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•Coolant
Stop, turn engine
offThe coolant is too hot.
Among other possible causes,
the poly-V-belt could be broken.Stop the vehicle in a safe location or as soon as it is
safe to do so.
Turn off the engine.
Apply the parking brake (page 59).
Check the poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise, the engine will
overheat due to an inoperative water pump which
may result in damage to the engine. Contact an
authorized Mercedes-Benz Center.
If it is intact:
Wait for the message to disappear before restarting
the engine.
Doing otherwise could result in serious engine
damage that is not covered by the Mercedes-Benz
Limited Warranty.
(Continued on next page)
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369 Practical hints
What to do if …
During severe operating conditions, e.g.
stop-and-go traffic, the coolant tempera-
ture may rise close to 248°F (120°C).
Display symbolDisplay messagePossible cause/consequencePossible solution
Observe the coolant temperature display
(
page 127).
If the temperature rises again:
Contact an authorized Mercedes-Benz
Center immediately.
Warning!G
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 and can occur just by opening
the hood. Stay away from the engine if you
see or hear steam coming from it.
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°F (120°C).
Doing so may cause serious engine damage
which is not covered by the Mercedes-Benz
Limited Warranty.
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370 Practical hints
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•The cooling fan for the coolant is
malfunctioning.Observe the coolant temperature display
(
page 127).
If the coolant temperature is below 120°C,
you may continue driving to the nearest
specialist workshop.
Avoid heavy loads on the engine (e.g. by
driving uphill) as well as stop-and-go traffic.
Have the fan replaced as soon as possible.
/Top up coolant
See Oper. ManualThe coolant level is too low.Add coolant (page 300).
Comply with all warnings while doing so.
If you have to add coolant frequently,
have the cooling system checked by an au-
thorized Mercedes-Benz Center.
Warning!G
Do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts. You could be seriously burned.
!Do not ignore the low engine coolant level
warning. Extended driving with this message and
symbol displayed may cause serious engine
damage not covered by the Mercedes-Benz
Limited Warranty. Do not drive without sufficient
amount of coolant in the cooling system. The
engine will overheat, causing major engine
damage.
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371 Practical hints
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±Display malfunction
Drive to workshopCertain electronic systems are un-
able to relay information to the con-
trol system. The following systems
may have failed:
Coolant temperature display
Tachometer
Cruise control display
Have the electronic systems checked by an
authorized Mercedes-Benz Center.
JYou are driving with one or more
doors open.Close the doors.
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372 Practical hints
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NCheck oil level
when next refuelingSLK 280 and SLK 350 only:
The engine oil level has dropped to
a critical level.Check the engine oil level (page 296) and
add engine oil as required (
page 299).
If you must add engine oil frequently, have
the engine checked for possible leaks.
USA only:
Add 1 qt. engine oil
when next refueling
Canada only:
Add 1 liter engine oil
when next refueling
SLK 55 AMG only:
The engine oil level is too low.Add engine oil (page 299) and check the
engine oil level (
page 296).
Cannot measure
motor oil levelSLK 55 AMG only:
The measuring system is malfunc-
tioning.Have the measuring system checked by an
authorized Mercedes-Benz Center.
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373 Practical hints
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When the message Add 1 qt. (Canada:
1 liter) engine oil when next
refueling
(SLK 55 AMG) or Check oil
level when next refueling
(SLK 280,
SLK 350) appears while the engine is run-
ning and at operating temperature, the en-
gine oil level has dropped to approximately
the minimum level.
When this occurs, the warning will first
come on intermittently and then stay on if
the oil level drops further.Visually check for oil leaks. If no obvious oil
leaks are noted, drive to the nearest
service station where the engine oil should
be topped to the required level with an
approved engine oil. For information on
approved engine oils, refer to the Factory
Approved Service Products pamphlet
(USA only) or contact an authorized
Mercedes-Benz Center.
Display symbolDisplay messagePossible cause/consequencePossible solution
NEngine oil level
Reduce oil levelSLK 55 AMG only:
You have added too much engine
oil. There is a risk of damaging the
engine or the catalytic converter.Have oil siphoned or drained off.
Observe all legal requirements with respect
to its disposal.
Engine oil level
Stop, turn engine offThere is no oil in the engine. There
is a danger of engine damage.Stop the vehicle in a safe location or as soon
as it is safe to do so.
Turn off the engine.
Apply the parking brake (page 59).
Add engine oil (page 299) and check the
engine oil level (
page 296).
!The engine oil level warnings should not be
ignored. Extended driving with the symbol
displayed could result in serious engine damage
that is not covered by the Mercedes-Benz
Limited Warranty.
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AReserve fuelThe fuel level has dropped below the
reserve mark.Refuel at the next gas station (page 291).
4Gas cap
is openA loss of pressure has been detected
in the fuel system. The fuel cap may
not be closed properly or the fuel
system may be leaky.Check the fuel cap (page 291).
If it is not closed properly:
Close the fuel cap.
If it is closed properly:
Have the fuel system checked by an autho-
rized Mercedes-Benz Center.
KRetractable roof
Open/Close completelyYou are driving with the retractable
hardtop not properly locked.Stop the vehicle in a safe location. Observe
the traffic situation around you.
Push the retractable hardtop switch forward
or rearward until the retractable hardtop is
completely closed or open (
page 240).
Retractable roof
being openedThe retractable hardtop is not com-
pletely opened or closed. The roof
hydraulics will start to lose pressure.Make sure the retractable hardtop is com-
pletely opened or closed (
page 240).
Retractable roof
locked
while vehicle is
movingYou have attempted to open the
retractable hardtop while driving.Stop the vehicle in a safe location and try to
open the hardtop again.
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OYou are driving with the hood open.Risk of accident!
Stop the vehicle in a safe location or as soon
as it is safe to do so.
Apply the parking brake (page 59).
Close the hood (page 294).
IPlease
get a new keyThe SmartKey is malfunctioning.Contact an authorized Mercedes-Benz
Center.
Remove keyYou have forgotten to remove the
SmartKey from the starter switch.Remove the SmartKey from the starter
switch.
.3rd brake lampThe high mounted brake lamp is
malfunctioning. This message will
only appear if a critical number of
LEDs have stopped working.Contact an authorized Mercedes-Benz
Center as soon as possible.
AUTO-Light
inoperativeThe light sensor is malfunctioning.
The headlamps switch on automati-
cally.Contact an authorized Mercedes-Benz
Center as soon as possible.
To switch off the headlamps (U.S. vehicles only):
In the control system, set lamp operation to
manual mode (
page 143).
Switch off headlamps using the exterior
lamp switch (
page 109).