Page 377 of 474
376 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
/Top Up Coolant
See Operator’s 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. 
     
        
        Page 378 of 474
377 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
±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.
NCheck oil level
when next refueling
.
SLK 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. 
     
        
        Page 379 of 474

378 Practical hints
What to do if …
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 is at first 
intermittent and then remains on if the oil 
level drops further.Visually check for oil leaks. If there are no 
obvious oil leaks, drive to the nearest 
service station to refill the engine oil 
should be topped to the required level. 
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
NUSA 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
Engine Oil LevelSLK 55 AMG only:
The measuring system is malfunc-
tioning.Have the measuring system checked by an 
authorized Mercedes-Benz Center.
!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. 
     
        
        Page 380 of 474

379 Practical hints
What to do if …
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 off.There 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).
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 detect-
ed 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. 
     
        
        Page 381 of 474

380 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
KRetractable Roof Operation
Please WaitThe on-board voltage is too low.Start the engine.
The hardtop drive system was 
shut down for safety reasons after 
multiple, consecutive attempts to 
raise or lower the hardtop.After about 10 minutes you can open or 
close the retractable hardtop.
Switch on the ignition (page 37).
Repeat the opening or closing 
procedure.
Retractable Roof
LoweringThe retractable hardtop is not 
completely opened or closed. The 
roof hydraulics will start to lose 
pressure.Make sure the retractable hardtop is 
completely opened or closed 
(
page 240).
Retractable Roof
Operation Only At StandstillYou have attempted to open the 
retractable hardtop while driving.Stop the vehicle in a safe location and try 
to open the hardtop again.
Retractable Roof Not
Opened/Closed CompletelyYou are driving with the retract-
able hardtop not properly locked.Stop the vehicle in a safe location. Ob-
serve the traffic situation around you.
Push the retractable hardtop switch for-
ward or rearward until the retractable 
hardtop is completely closed or open 
(
page 240). 
     
        
        Page 382 of 474
381 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
IPlease
get a new key.The 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). 
     
        
        Page 383 of 474

382 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
.Brake-/Tail Lamp
LeftThe left brake lamp is malfunction-
ing. This message will only appear if 
a critical number of LEDs have 
stopped working.Contact an authorized Mercedes-Benz 
Center as soon as possible.
Brake-/Tail Lamp
RightThe right brake lamp is malfunction-
ing. This message will only appear if 
a critical number of LEDs have 
stopped working.Contact an authorized Mercedes-Benz 
Center as soon as possible.
Front Foglamp
LeftThe left front fog lamp is malfunc-
tioning.Contact an authorized Mercedes-Benz 
Center as soon as possible.
Front Foglamp
RightThe right front foglamp is malfunc-
tioning.Contact an authorized Mercedes-Benz 
Center as soon as possible.
Rear Foglamp
Auxiliary Bulb OnThe rear fog lamp on the driver’s 
side is malfunctioning. A backup 
bulb has been brought into use.Replace the bulb as soon as 
possible (
page 400).
High Beam
LeftThe left high beam lamp (halogen 
headlamps)/high beam flasher 
lamp (Bi-Xenon* headlamps) is 
malfunctioning.Replace the bulb as soon as 
possible (
page 400). 
     
        
        Page 384 of 474
383 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
.High Beam
RightThe right high beam lamp (halogen 
headlamps)/high beam flasher 
lamp (Bi-Xenon* headlamps) is 
malfunctioning.Replace the bulb as soon as 
possible (
page 400).
License Plate Lamp
LeftThe left license plate lamp is 
malfunctioning.Replace the bulb as soon as 
possible (
page 400).
License Plate Lamp
RightThe right license plate lamp is 
malfunctioning.Replace the bulb as soon as 
possible (
page 400).
Reverse Lamp
LeftThe left backup lamp is malfunc-
tioning.Replace the bulb as soon as 
possible (
page 400).
Reverse Lamp
RightThe right backup lamp is malfunc-
tioning.Replace the bulb as soon as 
possible (
page 400).
Low Beam
LeftThe left low beam lamp is malfunc-
tioning.Halogen headlamp:
Replace the bulb as soon as 
possible (
page 400).
Bi-Xenon* headlamp:
Contact an authorized Mercedes-Benz 
Center as soon as possible.