
Display messages
Possible causes/consequences and
0050
0050Solutions 0099
Eng. Eng.
start
start not
notpos‐
pos‐
sible in ..km
sible in ..km The DEF system is malfunctioning. A warning tone also sounds.
X Visit a qualified specialist workshop immediately. 0099
Eng. Eng.
start
start not
notpos‐
pos‐
sible
sible The DEF system is malfunctioning. A warning tone also sounds.
You can no longer start the engine.
X Consult a qualified specialist workshop immediately. Driving systems
Display messages
Possible causes/consequences and
0050 0050Solutions 00AD
Attention Assist: Attention Assist:
Take a break! Take a break! 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 you get enough rest. 00AD
Attention Assist Attention Assist
Inoperative Inoperative ATTENTION ASSIST is inoperative.
X Visit a qualified specialist workshop. 00D9
Off Off The HOLD function is deactivated. The vehicle is skidding.
A warning tone also sounds.
X Reactivate the HOLD function later (Y page 184). The HOLD function is deactivated. When the brake pedal is firmly
depressed, an activation condition is not fulfilled.
A warning tone also sounds.
X Check the activation conditions for the HOLD function
(Y page 184). Radar Radar
Sensors
Sensors Deac‐
Deac‐
tivated See Opera‐
tivated See Opera‐
tor's Manual tor's Manual The radar sensor system is deactivated.
X Switch on the radar sensor system (Y page 233). Display
messages
251On-board computer and displays Z

Display messages
Possible causes/consequences and
0050
0050Solutions Blind Spot Assist
Blind Spot Assist
Currently Unavail‐ Currently Unavail‐
able See Opera‐ able See Opera‐
tor's Manual tor's Manual
or
Active Blind Spot
Active Blind Spot
Assist Currently Assist Currently
Unavailable See Unavailable See
Operator's Manual Operator's Manual Blind Spot Assist or Active Blind Spot Assist is temporarily inop-
erative. Possible causes are:
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 0063indicator lamps also light up in the exterior mir-
rors.
When the causes stated above no longer apply, the display mes-
sage disappears.
Blind Spot Assist or Active Blind Spot 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 (Y page 168).
X Clean the sensors (Y page 309).
X Restart the engine. 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 defective.
The yellow
0063indicator lamps also light up in the exterior mir-
rors.
X Visit a qualified specialist workshop. Park Assist Can‐ Park Assist Can‐
celed celed 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 that the multi-
function steering wheel is not touched unintentionally. The vehicle has started to skid and ESP
®
has intervened.
X Use Active Parking Assist again later (Y page 189). Display
messages
253On-board computer and displays Z

Display messages
Possible causes/consequences and
0050
0050Solutions Park
Park
Assist
Assist Inoper‐
Inoper‐
ative
ative You have just carried out a large number of turning or parking
maneuvers.
Active Parking Assist will become available again after approx-
imately ten minutes (Y
page 189).
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 defective.
X Visit a qualified specialist workshop. Park Assist Park Assist
switched off switched off 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 176). 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 176). DISTRONIC DISTRONIC
PLUS
PLUSCur‐
Cur‐
rently
rently Unavailable
Unavailable
See
See Operator's
Operator's Man‐
Man‐
ual
ual DISTRONIC PLUS is temporarily inoperative. Possible causes are:
R function is impaired due to heavy rain or snow.
R the sensors in the radiator trim and the bumper 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.
When the causes stated above no longer apply, the display mes-
sage disappears.
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 (Y page 168).
X Clean the sensors in the radiator grill and the bumper
(Y page 309).
X Restart the engine. 254
Display
messagesOn-board computer and displays

Vehicle
Display messages
Possible causes/consequences and
0050
0050Solutions Shift
Shift
to
to'P'
'P' or
or'N'
'N'
to Start Engine
to Start Engine You have attempted to start the engine with the transmission in
position Ror D.
X Shift the transmission to position Por N. Risk of rolling
Risk of rolling
Select Park (P) Select Park (P) You have attempted to stop the engine with the Start/Stop button
while the transmission was not in position P.
G WARNING
The vehicle may roll away.
There is a risk of an accident. X Shift the transmission to position P.
X Secure the vehicle against rolling away (Y page 168).0065 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. 0066 The hood is open.
G WARNING
The open hood may 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 168).
X Close the hood. 0051 At least one door is open.
X Close all the doors. 258
Display messagesOn-board computer and displays

Display messages
Possible causes/consequences and
0050
0050Solutions 00AF
Don't Forget Your Don't Forget Your
Key Key The display message is shown for a maximum of 60 seconds and
is only a reminder.
You have opened the driver's door with the engine switched off.
The KEYLESS-GO key is not in the ignition lock.
X Remember to take the KEYLESS-GO key with you when you
leave the vehicle. 00AF
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 (Y page 168).
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 (Y page 168).
X Operate the vehicle with the SmartKey in the ignition lock. 00AF
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 SmartKey with the KEYLESS-GO
functions in the vehicle.
If the KEYLESS-GO key is still not detected:
X Operate the vehicle with the SmartKey in the ignition lock. 00AF
Remove Remove
'Start'
'Start' But‐
But‐
ton and Insert Key
ton and Insert Key The KEYLESS-GO key can continuously not be detected.
KEYLESS-GO is temporarily malfunctioning or is defective. A warn-
ing tone also sounds.
X Insert the SmartKey into the ignition lock and turn it to the
desired position.
X Visit a qualified specialist workshop. 260
Display
messagesOn-board computer and displays

Warning and indicator lamps in the instrument cluster
Seat belts
Problem
Possible causes/consequences and
0050
0050Solutions 00E9
After starting the
engine, the red seat
belt warning lamp lights
up for 6 seconds. The seat belt warning lamp reminds the driver and front passenger
to fasten their seat belts.
X Fasten your seat belt (Y page 58).00E9
After starting the
engine, the red seat
belt warning lamp lights
up. In addition, a warn-
ing tone sounds for up
to 6 seconds. The driver's seat belt is not fastened.
X Fasten your seat belt (Y page 58).
The warning tone ceases. 00E9
The red seat belt warn-
ing lamp lights up after
the engine starts, as
soon as the driver's or
the front-passenger
door is closed.
The driver or front passenger has not fastened their seat belt.
X Fasten your seat belt (Y page 58).
The warning lamp goes out. There are objects on the front-passenger seat.
X Remove the objects from the front-passenger seat and stow
them in a secure place.
The warning lamp goes out. 00E9
The red seat belt warn-
ing lamp flashes and an
intermittent audible
warning sounds. The driver or front passenger has not fastened their seat belt. The
vehicle is being driven faster than 15 mph (25 km/h) or has briefly been driven faster than 15 mph (25 km/h).
X Fasten your seat belt (Y page 58).
The warning lamp goes out and the intermittent warning tone
ceases. There are objects on the front-passenger seat. The vehicle is being
driven faster than 15 mph (25 km/h) or has briefly been driven
faster than 15 mph (25 km/h).
X Remove the objects from the front-passenger seat and stow
them in a secure place.
The warning lamp goes out and the intermittent warning tone
ceases. Warning and indicator lamps in the instrument cluster
261On-board computer and displays Z

Safety systems
Problem
Possible causes/consequences and
0050
0050Solutions 0027
(USA only)
004D (Canada only)
The red brake system
warning lamp comes on while the engine is run-
ning. A warning tone
also sounds. There is not enough brake fluid in the brake fluid reservoir.
G WARNING
The braking effect may be impaired.
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. Do not continue driving
under any circumstances.
X Secure the vehicle against rolling away (Y page 168).
X Do not add brake fluid. Adding more will not remedy the mal-
function.
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction
display. 0025
The yellow ABS warning
lamp is lit while the
engine is running. ABS (Anti-lock Braking System) is deactivated due to a malfunc-
tion. BAS (Brake Assist), BAS PLUS, ESP ®
(Electronic Stability
Program), PRE‑ SAFE®
, PRE‑SAFE ®
Brake, the HOLD function, hill
start assist and ESP ®
trailer stabilization are therefore also deac-
tivated, for example.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the functions listed above. The wheels could therefore lock if you
brake hard, for example.
The steerability and braking characteristics may be severely affec-ted. The braking distance in an emergency braking situation can
increase.
If ESP ®
is not operational, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop.
If the ABS control unit is faulty, there is also a possibility that other
systems, such as the navigation system or the automatic trans-
mission, will not be available. 262
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Problem
Possible causes/consequences and
0050
0050Solutions 0025
The yellow ABS warning
lamp is lit while the
engine is running. ABS is temporarily unavailable. BAS, BAS PLUS, ESP
®
, EBD (elec-
tronic brake force distribution), PRE‑SAFE ®
, PRE‑SAFE ®
Brake, the
HOLD function, hill start assist and ESP ®
trailer stabilization are
therefore also deactivated, for example.
Possible causes are:
R Self-diagnosis is not yet complete.
R The on-board voltage may be insufficient.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the functions listed above. The front and rear wheels could therefore
lock if you brake hard, for example.
The steerability and braking characteristics may be severely affec-ted. The braking distance in an emergency braking situation can
increase.
If ESP ®
is not operational, ESP ®
is unable to stabilize the vehicle.
There is a risk of an accident.
X Carefully drive a suitable distance, making slight steering move-
ments at a speed above 12 mph (20 km/h).
The functions mentioned above are available again when the
warning lamp goes out.
If the warning lamp is still on: X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
263On-board computer and displays Z