
Display messages Possible causes/consequences and
M
MSolutions # The battery is not being charged.
A warning 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 attention to road and traf-
fic conditions, and switch off the engine.
X Secure the vehicle against rolling away ( Ypage 164).
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 Check eng. oil
lev. when next lev. when next
refuelling refuelling The engine oil level has dropped to the minimum level.
A warning tone also sounds.
X
Check the oil level when next refuelling, at the latest
(Y page 315).
X If necessary, top up the engine oil (Y page 316).
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 Reserve fuel level The fuel level has dropped into the reserve range.
Operation of the auxiliary heating is deactivated if 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. ¸
Please Please
replace
replace air
air
filter
filter Vehicles with a diesel engine: the engine air filter is dirty and must
be replaced.
X
Visit a qualified specialist workshop. 268
Display
messagesOn-board computer and displays

Display messages Possible causes/consequences and
M
MSolutions !
Clean Clean
the
thefuel
fuel fil‐
fil‐
ter
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. ¯
Refill AdBlue at Refill AdBlue at
workshop See Own‐ workshop See Own‐
er's Manual er's Manual The AdBlue
®
level has fallen below the reserve range. A warning
tone also sounds.
X Have AdBlue ®
refilled as soon as possible at a qualified spe-
cialist workshop. ¯
Refill AdBlue at Refill AdBlue at
workshop No start workshop No start
in .. km 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 Refill AdBlue at
workshop Eng. workshop Eng.
start not possible start not possible The AdBlue
®
tank is empty. A warning tone also sounds. You can
no longer start the engine.
X Consult a qualified specialist workshop immediately. ¯
Check AdBlue See Check AdBlue See
Owner's Manual Owner's Manual The AdBlue
®
system is malfunctioning. A warning tone also
sounds.
X Visit a qualified specialist workshop. ¯
Eng. Eng.
start
start not
notpos‐
pos‐
sible in ... km
sible in ... km The AdBlue
®
system is malfunctioning. A warning tone also
sounds.
X Visit a qualified specialist workshop immediately. ¯
Eng. Eng.
start
start not
notpos‐
pos‐
sible
sible 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
269On-board computer and displays Z

Display messages Possible causes/consequences and
M
MSolutions Park
Park
Assist
Assist inoper‐
inoper‐
ative
ative You have just carried out a large number of turning or parking
manoeuvres.
Active Parking Assist will become available again after approx-
imately ten minutes (Y
page 192).
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. Parking Guidance Parking Guidance
finished finished The vehicle is parked. A warning tone also sounds.
The display message disappears automatically.
DISTRONIC PLUS off DISTRONIC PLUS off DISTRONIC PLUS has been deactivated (Y
page 178). If it was
deactivated automatically, a warning tone also sounds. DISTRONIC PLUS
DISTRONIC PLUS
available again available again DISTRONIC PLUS is operational again after having been tempo-
rarily unavailable. You can now reactivate DISTRONIC PLUS
(Y
page 178). DISTRONIC DISTRONIC
PLUS
PLUScur‐
cur‐
rently
rently unavailable
unavailable
See Owner's Manual
See Owner's Manual DISTRONIC PLUS is temporarily inoperative. Possible causes:
R
the function is impaired due to heavy rain or snow.
R the sensors in the radiator trim and in the bumpers are dirty.
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.
R the system is outside the operating temperature range.
R the on-board voltage is too low.
A warning tone also sounds.
Once the causes listed above no longer apply, the display message
goes out.
DISTRONIC is operational again.
If 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 Secure the vehicle against rolling away ( Ypage 164).
X Clean the sensors in the radiator grille and the bumper
(Y page 321).
X Restart the engine. 274
Display
messagesOn-board computer and displays

Vehicle (4-button multifunction steering wheel)
Display messages Possible causes/consequences and
M
MSolutions To start engine,
To start engine,
shift to P or N shift to 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
P
Select Park (P) Select Park (P) You have switched off the engine with the Start/Stop button and
opened the driver's door.
You wanted to lock the vehicle.
A warning tone also sounds.
or
You have switched off the engine with the Start/Stop button and
opened the driver's door with the transmission in position N.
X Shift the transmission to position P.A The tailgate is open.
G WARNING
When the 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. ? Vehicles with an anti-theft alarm system: the bonnet is open. A
warning tone also sounds.
G WARNING
The open bonnet may then block your view when the vehicle is in
motion.
There is a risk of an accident.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 164).
X Close the bonnet. C At least one door is open. A warning tone also sounds.
X
Close all doors. 278
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
M
MSolutions Pwr. steering
Pwr. steering
malfunction malfunction The power steering assistance is faulty.
A warning tone also sounds.
G WARNING
You will need to use more force to steer.
There is a risk of an accident.
X Check whether 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. Top up Top up
washer fluid washer fluid The washer fluid level in the washer fluid reservoir has dropped
below the minimum.
X
Top up the washer fluid ( Ypage 317). Vehicle (12-button multifunction steering wheel)
Display messages Possible causes/consequences and
M MSolutions To start engine,
To start engine,
shift to either P shift to either P
or N 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 P
Select Park (P) Select Park (P) You have switched off the engine with the Start/Stop button and
opened the driver's door.
You wanted to lock the vehicle.
A warning tone also sounds.
or
You have switched off the engine with the Start/Stop button and
opened the driver's door with the transmission in position N.
X Shift the transmission to position P.A The tailgate is open.
G WARNING
When the 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. Display
messages
279On-board computer and displays Z

Display messages Possible causes/consequences and
M
MSolutions ? Vehicles with an anti-theft alarm system: the bonnet is open. A
warning tone also sounds.
G WARNING
The open bonnet may then block your view when the vehicle is in
motion.
There is a risk of an accident.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Ypage 164).
X Close the bonnet. C At least one door is open. A warning tone also sounds.
X
Close all doors. &
inoperative Bat‐ inoperative Bat‐
tery low tery low The on-board voltage is too low. The auxiliary heating has switched
itself off or cannot be switched on (Y
page 137).
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 inoperative
Refuel
Refuel
vehicle
vehicle There is too little fuel in the fuel tank. The auxiliary heating cannot
be switched on (Y
page 137).
X Refuel at the nearest filling station. &
Inoperative See Inoperative See
Owner's Manual Owner's Manual The auxiliary heating has a temporary malfunction or is faulty.
X
When the vehicle is on a level surface and the engine has cooled
down, make up to four attempts to switch on the auxiliary heat-
ing, waiting several minutes between each attempt
(Y page 137).
X If the auxiliary heating does not switch on, consult a qualified
specialist workshop. 280
Display
messagesOn-board computer and displays

Display messages Possible causes/consequences and
M
MSolutions Key not detected
Key not detected
(Red display message) The KEYLESS-GO key is not in the vehicle.
A warning tone also sounds.
If the engine is switched off, you can no longer lock the vehicle
centrally or start the engine.
X
Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Ypage 164).
X Locate the KEYLESS-GO key. The KEYLESS-GO key is not detected while the engine is running
because there is interference from a strong source of radio waves.
A warning tone also sounds.
X
Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Ypage 164).
X Operate the vehicle with the key in the ignition lock if necessary. Key not detected Key not detected
(White display mes-
sage) The KEYLESS-GO key cannot be detected at present.
X
Change the location of the key with the KEYLESS-GO functions
in the vehicle.
If the KEYLESS-GO key is still not detected:
X Change the location of the key with the KEYLESS-GO functions
in the vehicle.
X Operate the vehicle with the key in the ignition lock if necessary. +
Key still in vehi‐ Key still in vehi‐
cle cle The KEYLESS-GO key has been detected inside the vehicle during
locking.
X
Remove the KEYLESS-GO key from the vehicle. +
Insert key Insert key KEYLESS-GO is temporarily malfunctioning or is defective. A warn-
ing tone also sounds.
X
Insert the key into the ignition lock and turn it to the desired
position.
X Visit a qualified specialist workshop. Close doors Close doors
to lock veh. to lock veh. At least one door is open. A warning tone also sounds.
X
Close all doors and lock the vehicle again. 282
Display
messagesOn-board computer and displays

Key (12-button multifunction steering wheel)
Display messages Possible causes/consequences and
M
MSolutions Â
Key does not Key does not
belong to vehicle belong to vehicle You have put the wrong key in the ignition lock.
X
Use the correct key. Â
Replace key Replace key The key needs to be replaced.
X
Visit a qualified specialist workshop. Â
Change key batter‐ Change key batter‐
ies ies The batteries of the KEYLESS-GO key are discharged.
X
Change the batteries ( Ypage 79). Â
Key not detected Key not detected
(red display message) The KEYLESS-GO key is not in the vehicle.
A warning tone also sounds.
If the engine is switched off, you can no longer lock the vehicle
centrally or start the engine.
X
Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Ypage 164).
(Y page 164).
X Locate the KEYLESS-GO key. The KEYLESS-GO key is not detected while the engine is running
because there is interference from a strong source of radio waves.
A warning tone also sounds.
X
Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Ypage 164).
X Operate the vehicle with the key in the ignition lock if necessary. Â
Key not detected Key not detected
(white display mes-
sage) The KEYLESS-GO key cannot be detected at present.
X
Change the location of the key with the KEYLESS-GO functions
in the vehicle.
If the KEYLESS-GO key is still not detected:
X Operate the vehicle with the key in the ignition lock if necessary. Â
Key still in vehi‐ Key still in vehi‐
cle cle The KEYLESS-GO key has been detected inside the vehicle during
locking.
X
Remove the KEYLESS-GO key from the vehicle. Display
messages
283On-board computer and displays Z