
Display messages Possible causes/consequences and
M Solutions
b
Reversing light The reversing lamp is faulty.
X
Chec kwhether you are permitted to replace the bulb yourself
(Y page 103).
or
X Visit a qualified specialist workshop. b
Left tail lamp
or
Right tail lamp The left or right-hand tail lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 103).
or
X Visit a qualified specialist workshop. b
Left daytime driv‐
ing lamp
or
Right daytime driving lamp The left or right-hand daytime driving lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 103).
or
X Visit a qualified specialist workshop. b
Intell. Light Sys‐
tem inoperative The Intelligent Light System is faulty. The lights remain available
without the Intelligent Light System.
X
Visit a qualified specialist workshop. b
Malfunction See
Owner's Manual The exterior lighting is faulty.
X
Visit a qualified specialist workshop. b
Malfunction See
Owner's Manual The exterior lighting is faulty.
X
Visit a qualified specialist workshop. Vehicles with trailer tow hitch: a fuse may have blown.
X
Check the fuses (Y page 287).
X If necessary, replace the blown fuse. Observe the warning notes
as you do so.
If the display message continues to be displayed:
X Visit a qualified specialist workshop. b
AUTO
lights inoper‐
ative The light sensor is faulty.
X
Visit a qualified specialist workshop. 218
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
M Solutions
b
Switch off lights The lights are still switched on when you leave the vehicle. A
warning tone also sounds.
X Tur nthe light switch to Ã. Adaptive Main-beam
Assist inoperative Adaptive Highbeam Assist is faulty.
X
Visit a qualified specialist workshop. Adaptive Main-beam
Assist currently
unavailable See
Owner's Manual Adaptive Highbeam Assist is deactivated and temporarily inoper-
ative. Possible causes:
R
the windscreen is dirty in the camera's field of vision.
R visibility is impaired due to heavy rain, snow or fog.
X Cleant he windscreen.
If the system detects that the camera is fully operational again,
the Adaptive Main-beam Assist available again message
is displayed.
Adaptive Highbeam Assist is operational again. Engine
Display messages Possible causes/consequences and
M Solutions
+
Top
up coolant See
Owner's Manual The coolant level is too low.
!
Avoid making long journeys with too little coolant in the engine
cooling system. The engine will otherwise be damaged.
X Top up the coolant, observing the warning notes before doing
so (Y page 265).
X If the coolant needs topping up more often than usual, have the
engine coolant system checked at a qualified specialist work-
shop. ? The fan motor is faulty.
X
If the coolant temperature is less than 120 †, you can continue
driving to the nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving on
mountain roads and stop-start traffic. Display messages
219On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutions
?
Coolant Stop vehi‐
cle Switch engine
off The coolan
tis too hot.
Aw arning tone also sounds.
G WARNING
Do no tdrive when youre ngine is overheated. Thi scan cause some
fluids which may have leaked into the engine compartmen tto
catch fire.
Stea mfrom the overheated engine can also cause serious burns
which can occur just by opening the bonnet.
There is a risk of injury.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Engage the electric parking brake.
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by frozen slush.
X Do not start the engine again until the display message goes out
and the coolant temperature is under 120 †. The engine may
otherwise be damaged.
X Pay attention to the coolant temperature display.
X If the temperature increases again, visit a qualified specialist
workshop immediately.
The reading may rise up to 120 †undernormal driving conditions
if the coolant has been filled correctly. # The battery is not being charged.
Possible causes:
R
faulty alternator
R torn poly-V-belt
R a malfunction in the electronics
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Open the bonnet.
X Check whether the poly-V-belt is torn.
If the poly-V-belt is torn:
! Do not continue driving. The engine could otherwise overheat.
X Consult a qualified specialist workshop.
If the poly-V-belt is OK:
X Visit a qualified specialist workshop immediately. 220
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
M Solutions
4
Check eng. oil
lev. when next
refuelling The engine oil level has dropped to the minimum level.
Aw
arning tone also sounds.
X Chec kthe oil level when next refuelling, at the latest
(Y page 263).
X If necessary, top up the engine oil (Y page 264).
X Have the engine checked at a qualified specialist workshop if
the engine oil needs topping up more often than usual. æ
Reserve fuel level The fuel level has dropped into the reserve range.
X
Refuel at the nearest filling station. ç There is only a very small amount of fuel in the fuel tank.
X
Refuel at the nearest filling station without fail. ¸
Replace
air cleaner Vehicles with a diesel engine: the engine air filter is dirty and must
be replaced.
X
Visit a qualified specialist workshop. !
Clean
the fuel fil‐
ter Vehicles with a diesel engine: there is water in the fuel filter. The
water must be drained off.
X
Visit a qualified specialist workshop. Driving systems
Display messages Possible causes/consequences and
M Solutions
À
Attention Assist:
Drowsiness detec‐
ted Based on certain criteria, ATTENTION ASSIST has detected fatigue
or
alack of concentration on th epart of th edriver. A warning tone
also sounds.
X If necessary, take a break.
During long journeys, take regular breaks in good time so you get
enough rest. À
Attention Assist
inoperative ATTENTION ASSIST is inoperative.
X Visi taqualified specialist workshop. Display messages
221On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutions
Park Assist
inoperative You have just carried out a large number of turning or parking
manoeuvres.
Active Parking Assis
twill become available again after approx-
imately ten minutes (Y page 166).
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Switch off and restart the engine.
If the display message continues to be displayed:
X Visit a qualified specialist workshop. PARKTRONIC is faulty.
X
Visit a qualified specialist workshop. DISTRONIC PLUS
off DISTRONIC PLUS has been deactivated (Y
page 154). If it was
deactivated automatically, a warning tone also sounds. DISTRONIC PLUS
available again DISTRONIC PLUS is operational again after having been tempo-
rarily unavailable. You can now reactivate DISTRONIC PLUS
(Y
page 154). Display messages
225On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutions
DISTRONIC PLUS
currently unavail‐
able See Owner's
Manual DISTRONIC is deactivated and temporarily inoperative. Possible
causes:
R
the DISTRONIC PLUS cover in the radiator grille is dirty.
R function is impaired due to heavy rain or snow.
R the sensors in the bumpers are dirty.
R the rada rsensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio sta-
tions or other sources of electromagnetic radiation.
R the system is outside the operating temperature range.
R the on-board voltage is too low.
Aw arning tone also sounds.
If the display message does no tdisappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Engage the electric parking brake.
X Clean the DISTRONIC PLUS cover in the radiator grille
(Y page 270).
X Clean the bumpers (Y page 270).
X Restar tthe engine.
If the system detects that the sensors are fully operational, the
display message disappears.
DISTRONIC is operational again. DISTRONIC PLUS
inoperative DISTRONIC PLUS is faulty. BAS PLUS (Brake Assist PLUS) may
also have failed.
Aw
arning tone also sounds.
X Visi taqualified specialist workshop. DISTRONIC PLUS
inactive You have depressed the accelerator pedal. DISTRONIC PLUS is no
longer controlling the speed of the vehicle.
X
Remove your foot from the accelerator pedal. DISTRONIC PLUS
--- km/h An activation condition for DISTRONIC PLUS is not fulfilled.
X
Check the activation conditions for DISTRONIC PLUS
(Y page 156). DISTRONIC PLUS and
SPEEDTRONIC
inoperative DISTRONIC PLUS and SPEEDTRONIC are faulty. A warning tone
also sounds.
X
Visit a qualified specialist workshop. 226
Display messagesOn-board computer and displays

Tyres
Display messages Possible causes/consequences and
M Solutions
Tyre pressure
Check tyres The tyre pressure loss warning system has detected a significant
loss in pressure.
Aw
arning tone also sounds.
G WARNING
Underinflated or overinflated tyres pose the following risks:
R they may burst, especially as the load and vehicle speed
increase.
R they may wear excessively and/or unevenly, whic hmay greatly
impair tyre traction.
R the driving characteristics, as well as steering and braking, may
be greatly impaired.
There is a ris kofaccident.
X Stop the vehicle withou tmaking any sudde nsteering or braking
manoeuvres .Pay attentio nto the traffic conditions as you do
so.
X If there is a flat tyre, inspect the tyres (Y page 276).
X Check the tyre pressures and, if necessary, set to the correct
tyre pressure.
X Restart the tyre pressure loss warning system when the tyre
pressure is correc t(Ypage 297).
For further information on tyre pressure, see (Y page 295).Check tyre pres‐
sures
then restart Run
Flat Indicator The tyre pressure loss warning system generated a display mes-
sage and has not been restarted since.
X
Set the correct tyre pressure in all four tyres.
X Restart the tyre pressure loss warning system (Y page 297).Run Flat Indicator
inoperative The tyre pressure loss warning system is faulty.
X
Visit a qualified specialist workshop. 228
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
M Solutions
A The tailgate is open.
G WARNING
Whe nthe engine is running, exhaust gases can enter the vehicle
interior if the tailgate is open.
There is a risk of poisoning.
X Close the tailgate. ? The bonnet is open.
G WARNING
The open bonnet may block your view when the vehicle is in
motion.
There is a risk of accident.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Engage the electric parking brake.
X Close the bonnet. C At least one door is open.
Awarning tone also sounds.
X Close all doors. j
Check trailer
hitch lock The trailer tow hitch is no
tcorrectly engaged.
Aw arning tone also sounds.
X Stop the vehicle immediately, paying attentio ntoroad and traf-
fic conditions, and switch off the engine.
X Engage the electric parking brake.
X Allow the trailer tow hitch ball coupling to engage in the end
position (Y page 183).
Otherwise, the trailer may detach itself. D
Power
steering mal‐
function See Own‐
er's Manual The power steering assistance is faulty. You will need to use more
force to steer.
Aw
arning tone also sounds.
X Chec kwhether you are able to apply the extra force required.
X If you are able to steer safely: carefully drive on to a qualified
specialist workshop.
X If you are unable to steer safely: do not drive on. Contact the
nearest qualified specialist workshop. 230
Display messagesOn-board computer and displays