
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 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
level level 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
cleaner
cleaner Vehicles with a diesel engine: the engine air filter is dirty and must
be replaced.
X
Visit a qualified specialist workshop. Display
messages
265On-board computer and displays Z

Engine (12-button multifunction steering wheel)
Display messages Possible causes/consequences and
M
MSolutions +
Top Top
up upcoolant
coolant See
See
Owner's Manual
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 316).
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 below 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 in
mountainous terrain and stop-start traffic. ?
Coolant Stop vehi‐ Coolant Stop vehi‐
cle Switch engine cle Switch engine
off off The coolant is too hot.
A warning tone also sounds.
G WARNING
Never drive with an overheated engine. Driving when your engine
is overheated can cause some fluids which may have leaked into
the engine compartment to catch fire.
Steam from an overheated engine can 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 Secure the vehicle against rolling away (Y page 164).
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 below 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.
Under normal operating conditions and with the specified coolant
level, the coolant temperature may rise to 120 †. Display messages
267On-board computer and displays Z

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

Driving systems (12-button multifunction steering wheel)
Display messages Possible causes/consequences and
M
MSolutions À
Attention Assist: Attention Assist:
Drowsiness detec‐ Drowsiness detec‐
ted ted Based on certain criteria, ATTENTION ASSIST has detected fatigue
or a lack of concentration on the part of the driver. A warning tone
also sounds.
X
If necessary, take a break.
During long journeys, take regular breaks in good time so that you
get enough rest. À
Attention Assist Attention Assist
inoperative inoperative ATTENTION ASSIST is inoperative.
X
Visit a qualified specialist workshop. Ã
Inoperative Inoperative DSR (Downhill Speed Regulation) is deactivated due to a fault.
X
Have DSR checked at a qualified specialist workshop. Speed Speed
Limit
Limit Assist
Assist
currently unavail‐
currently unavail‐
able See Owner's able See Owner's
Manual Manual Speed Limit Assist is deactivated and temporarily inoperative.
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.
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 windscreen.
If the system detects that the camera is fully operational, the dis-
play message disappears.
Speed Limit Assist is operational again. Speed Limit Speed Limit
Assist: Unavaila‐ Assist: Unavaila‐
ble ble
in
inthis
this country
country Speed Limit Assist is only available in certain countries.
X
Drive on.
Speed Limit Assist is available again when you drive in a country
in which its use is approved. Speed Speed
Limit
Limit Assist
Assist
inoperative
inoperative Speed Limit Assist is faulty.
X
Visit a qualified specialist workshop. ë
Off Off The HOLD function is deactivated. The vehicle is skidding.
A warning tone also sounds.
X
Reactivate the HOLD function later (Y page 186). Display
messages
271On-board computer and displays Z

Display messages Possible causes/consequences and
M
MSolutions Lane Keeping
Lane Keeping
Assist currently Assist currently
unavailable See unavailable See
Owner's Manual Owner's Manual
or
Active Lane Keep‐
Active Lane Keep‐
ing Assist cur‐ ing Assist cur‐
rently rently unavailable
unavailable
See Owner's Manual
See Owner's Manual Lane Keeping Assist or Active Lane Keeping Assist is deactivated
and temporarily inoperative. 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.
R there are no lane markings for a longer period.
R the lane markings are worn, dark or covered, e.g. by dirt or snow.
Once the causes listed above no longer apply, the display message
goes out.
Lane Keeping Assist or Active Lane Keeping Assist 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 windscreen. Lane Keeping Lane Keeping
Assist inopera‐ Assist inopera‐
tive tive
orActive
Active
Lane Keeping
Lane Keeping
Assist inoperative Assist inoperative Lane Keeping Assist or Active Lane Keeping Assist is faulty.
X
Visit a qualified specialist workshop. Blind Spot Assist Blind Spot Assist
inoperative inoperative
or
Active Blind Spot
Active Blind Spot
Assist inoperative Assist inoperative 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. Park Park
Assist
Assist cancel‐
cancel‐
led
led The driver's door is open and the driver's seat belt has not been
fastened.
X
Repeat the parking process with the seat belt fastened and the
driver's door closed. You have inadvertently touched the multifunction steering wheel
while steering intervention was active.
X
While steering intervention is active, make sure not to touch the
multifunction steering wheel. The vehicle has started to skid and ESP
®
has intervened.
X Use Active Parking Assist again later (Y page 192). Display
messages
273On-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

Tyres (4-button multifunction steering wheel)
Display messages Possible causes/consequences and
M
MSolutions Check
Check
tyres
tyres The tyre pressure loss warning system has detected a significant
loss in pressure.
A warning tone also sounds.
G WARNING
With tyre pressures which are too low, there is a risk of the fol-
lowing hazards:
R the tyres may burst, especially as the load and vehicle speed
increase.
R the tyres may wear excessively and/or unevenly, which may
greatly impair tyre traction.
R the driving characteristics, as well as steering and braking, may
be greatly impaired.
There is a risk of an accident.
X Stop the vehicle without making any sudden steering or braking
manoeuvres. Pay attention to the traffic conditions as you do
so.
X Secure the vehicle against rolling away (Y page 164).
X If there is a flat tyre, inspect the tyres (Y page 329).
X Check the tyre pressures and, if necessary, correct the tyre
pressure.
X Restart the tyre pressure loss warning system when the tyre
pressure is correct (Y page 355).Check tyres Check tyres
Restart system
Restart system 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 355).Run Flat Indicator Run Flat Indicator
Inoperative
Inoperative The tyre pressure loss warning system is faulty.
X
Visit a qualified specialist workshop. 276
Display
messagesOn-board computer and displays

Tyres (12-button multifunction steering wheel)
Display messages Possible causes/consequences and
M
MSolutions Tyre pressure
Tyre pressure
Check tyres Check tyres The tyre pressure loss warning system has detected a significant
loss in pressure.
A warning tone also sounds.
G WARNING
With tyre pressures which are too low, there is a risk of the fol-
lowing hazards:
R the tyres may burst, especially as the load and vehicle speed
increase.
R the tyres may wear excessively and/or unevenly, which may
greatly impair tyre traction.
R the driving characteristics, as well as steering and braking, may
be greatly impaired.
There is a risk of an accident.
X Stop the vehicle without making any sudden steering or braking
manoeuvres. Pay attention to the traffic conditions as you do
so.
X Secure the vehicle against rolling away (Y page 164).
X If there is a flat tyre, inspect the tyres (Y page 329).
X Check the tyre pressures and, if necessary, correct the tyre
pressure.
X Restart the tyre pressure loss warning system when the tyre
pressure is correct (Y page 355).Run Flat Indicator Run Flat Indicator
then restart Run then restart Run
Flat Indicator 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 355).Run Flat Indicator Run Flat Indicator
inoperative
inoperative The tyre pressure loss warning system is faulty.
X
Visit a qualified specialist workshop. Display
messages
277On-board computer and displays Z