Engine
Display messages Possible causes/consequences and
M Solutions
+
Top
up coolant See
Owner's Manual The coolant level is too low.
X
Top up the coolant, observing the warning notes when doing so
(Y page 324).
X If the coolant needs topping up more often than usual, have the
engine coolant system checked at a qualified specialist work-
shop. ?
Coolant Stop vehi‐
cle, Switch engine
off The coolant is too hot.
Aw
arning tone also sounds.
X Stop the vehicle immediately, paying attentio ntoroad and traf-
fic conditions, and switch off the engine.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by frozen slush.
X Wait until the display message disappears before restarting the
engine. 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 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
263On-board computer and displays Z
Display messages Possible causes/consequences and
M Solutions
# The battery is no
tbeing charged.
Aw arning tone also sounds.
Possible causes:
R faulty alternator
R torn poly-V-belt
R a malfunction in the electronics
X Stop the vehicle immediately, paying attentio ntoroad 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. 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 322).
X If necessary, top up the engine oil (Y page 323).
X Have the engine checked at a qualified specialist workshop if
the engine oil needs topping up more often than usual. 8
Reserve fuel level The fuel level has dropped into the reserve range.
Operation of the auxiliary heating is deactivated when the fuel level
drops into the reserve range.
X
Refuel at the nearest filling station. C There is only a very small amount of fuel in the fuel tank.
The auxiliary heating cannot be operated.
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. 264
Display messagesOn-board computer and displays
Display messages Possible causes/consequences and
M Solutions
!
Clean
the fuel fil‐
ter Vehicles with a diesel engine: there is water in the fuel filter. The
water mus
tbe drained off.
X Visit a qualified specialist workshop. ¯
Refill AdBlue at
workshop See Own‐
er's Manual The AdBlue
®
level has fallen below the reserve range. Awarning
tone also sounds.
X Have AdBlue ®
refilled as soon as possible at a qualified spe-
cialist workshop. ¯
Refill AdBlue at
workshop No start
in ..km The AdBlue
®
level is only sufficient for the indicated distance. A
warning tone also sounds.
X Have AdBlue ®
refilled as soon as possible at a qualified spe-
cialist workshop. ¯
Refill AdBlue at
workshop Eng.
start not possible The AdBlue
®
tan kis empty. Awarning tone also sounds. You can
no longer start the engine.
X Consult a qualified specialist workshop immediately. ¯
Check AdBlue See
Owner's Manual The AdBlue
®
system is malfunctioning. A warning tone also
sounds.
X Visi taqualified specialist workshop. ¯
AdBlue Eng. start
not possible
in ..km The AdBlue
®
system is malfunctioning. A warning tone also
sounds.
X Visit a qualified specialist workshop immediately. ¯
AdBlue Eng. start
not possible The AdBlue
®
system is malfunctioning. A warning tone also
sounds. You can no longer start the engine.
X Consult a qualified specialist workshop immediately. Display messages
265On-board computer and displays Z
Display messages Possible causes/consequences and
M Solutions
Blind Spot Assist
currently unavail‐
able See Owner's
Manual orActive
Blind Spot Assist
currently unavail‐
able See Owner's
Manual Blind Spot Assis
torActive Blind Spot Assist is temporarily inop-
erative .Possible causes:
R you have established the electrical connection between the
trailer and your vehicle.
R the sensors are dirty.
R function is impaired due to heavy rain or snow.
R the radar sensor system is outside the operating temperature
range.
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio sta-
tions or other sources of electromagnetic radiation.
The yellow 9indicator lamps also light up in the exterior mir-
rors.
X When towing a trailer, confirm the display message with a.
If you are driving without a trailer and the display message does
not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Apply the parking brake.
X Clean the sensors (Y page 330).
X Restart the engine.
If the system detects that the sensors are fully operational, the
display message disappears.
Blind Spot Assist or Active Blind Spot Assist is operational again. Blind Spot Assist
inopera‐
tive orActive Blind
Spot Assist inoper‐
ative Blind Spot Assist or Active Blind Spot Assist is faulty.
The yellow 9indicator lamps also light up in the exterior mir-
rors.
X Visit a qualified specialist workshop. Parking Guidance
inoperative Parking Guidance is malfunctioning (Y
page 203).
X Restart the engine.
If the display message continues to be displayed:
X Visit a qualified specialist workshop. Display messages
269On-board computer and displays Z
Display messages Possible causes/consequences and
M Solutions
Parking Guidance
cancelled Parking Guidance is deactivated. Possible causes:
R
the vehicle is skidding.
R the sensors are dirty.
R A malfunction has occurred.
Aw arning tone also sounds.
X Reactivate Parking Guidance late r(Y page 203).
If the parking space symbol does not appear in the multifunction
display at speeds below 30 km/h:
X Clean the sensors (Y page 330).
X Restart the engine.
If the parking space symbol still does not appear in the multifunc-
tion display at speeds below 30 km/h:
X Visit a qualified specialist workshop. Parking Guidance has been deactivated because you are no longer
following the recommended path.
X
Park again and, while doing so, observe the display messages
in the multifunction display. Parking Guidance
finished The vehicle is parked.
Awarning tone also sounds.
The display message disappears automatically. DISTRONIC PLUS
off DISTRONIC PLU
Shas been deactivated (Y page 185). If it was
deactivated automatically, a warning tone also sounds. DISTRONIC PLUS
available again DISTRONIC PLU
Sis operational againa fter having beentempo-
rarily unavailable. You can now reactivate DISTRONIC PLUS
(Y page 185). 270
Display messagesOn-board computer and displays
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 Apply the parking brake.
X Clean the DISTRONIC PLUS cover in the radiator grille
(Y page 330).
X Clean the bumpers (Y page 330).
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 and PRE-SAFE
®
Brake may
also have failed.
Aw arning tone also sounds.
X Visi taqualified specialist workshop. DISTRONIC PLUS
suspended 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 185). DISTRONIC PLUS and
SPEEDTRONIC
inoperative DISTRONIC PLUS and SPEEDTRONIC are faulty. A warning tone
also sounds.
X Visit a qualified specialist workshop. Display messages
271On-board computer and displays Z
Vehicle
Display messages Possible causes/consequences and
M Solutions
To start engine,
shift to either P
or N You have attempted to start the engine with the transmission in
position
Ror D.
X Shift the transmission to position Por N. P
Select Park (P) Vehicles with automatic transmission with a selector lever:
You have switched off the engine with the Start/Stop button and
opened the driver's door.
You wanted to lock the vehicle.
Aw arning tone also sounds.
or
You have switched off the engine with the Start/Stop butto nand
opened the driver's door with the transmission in position N.
X Shift the transmission to position P. Vehicles with automatic transmission with a selecto
rlever:
While the HOLD function or DISTRONIC PLUS is active, you have:
R opened the driver's door and released the seat belt or
R switched off the engine or
R opened the bonnet
At one may also sound at regular intervals. The tone becomes
louder if you attempt to lock the vehicle.
You cannot start the engine.
X Shift the transmission to position P.
You can restart the engine. Auxiliary battery
malfunction The auxiliary battery for the automatic transmission is no longer
being charged.
X
Visit a qualified specialist workshop. Apply brake to
deselect Park (P)
position You have attempted to move the transmission selector lever to
position D,Ror Nwithout depressing the brake pedal.
X Depress the brake pedal. Vehicle
not in position P Vehicles with DIRECT SELECT lever:
The driver's door is open and the transmission is in position
R,N
or D.
Aw arning tone also sounds.
X Shift the transmission to position P.
X Apply the parking brake. Display messages
275On-board computer and displays Z
Display messages Possible causes/consequences and
M Solutions
_
Rear left seat
backrest not
locked or
Rear right seat back‐
rest not locked G
Risk of injury
Saloon with through-loading feature in the rear bench seat:
The backrest in the rear is no tengaged on the left-hand and/or
right-hand side .Awarning tone also sounds.
X Push the backres tback until it engages. j
Check trailer
hitch lock G
Ris
kofa ccident
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 Apply the parking brake.
X Allow the trailer tow hitch ball coupling to engage in the end
position (Y page 223). D
Power
steering mal‐
function See Own‐
er's Manual G
Risk of accident
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. &
inoperative Bat‐
tery low The on-board voltage is too low. The auxiliary heating has switched
itself off or cannot be switched on (Y page 145).
X Drive for a longer distance.
The battery is being charged. The auxiliary heating is operational
again as soon as the on-board electrical system voltage is suf-
ficient. &
inoperative
Refuel
vehicle The fuel level in the fuel tank is too low. The auxiliary heating can-
not be switched on (Y page 145).
X Refuel at the nearest filling station. Display messages
277On-board computer and displays Z