
Fitting the adapter
X
Open the socket cover.
X Insert the connector with lug :into
groove ;on the socket and turn the con-
nector clockwise to the stop.
X Let the cover engage.
X If you are using an adapter cable, secure
the cable to the trailer with cable ties.
! Make sure that there is sufficien tcable
play so that the cable canno tbecome
detached when cornering. Towing
atrailer
227Driving an d parking Z

Safety systems
Display messages Possible causes/consequences and
M Solutions
!÷
currently unavail‐
able See Owner's
Manual G
Risk of accident
ABS, ESP ®
, BAS, PRE-SAFE ®
, the HOLD function, hill start assist
and ESP ®
trailer stabilisation are temporarily not available.
The adaptive brake lights, BAS PLUS and PRE-SAFE ®
Brake may
also have failed.
In addition, the ä,åand! warning lamps light up in
the instrument cluster.
For example, the on-board voltage may be insufficient.
ATTENTION ASSIST is deactivated.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
X Drive on carefully.
If the display message disappears, the functions mentioned
above are available again.
If the display message continues to be displayed:
X Drive on carefully.
X Visit a qualified specialist workshop. !÷
inoperative See
Owner's Manual G
Risk of accident
ABS, ESP ®
, BAS, PRE-SAFE ®
, the HOLD function, hill start assist
and ESP ®
trailer stabilisation are not available due to a malfunc-
tion.
The adaptive brake lights, BAS PLUS and PRE-SAFE ®
Brake may
also have failed.
In addition, the J,ä,åand! warning lamps light
up in the instrument cluster.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
ATTENTION ASSIST is deactivated.
X Drive on carefully.
X Visit a qualified specialist workshop immediately. 254
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
M Solutions
÷
inoperative See
Owner's Manual G
Risk of accident
ESP ®
, BAS, PRE-SAFE ®
, the HOLD function, hill start assist and
ESP ®
trailer stabilisation are no tavailable due to a malfunction.
The adaptive brake lights, BAS PLUS and PRE-SAFE ®
Brake may
also have failed.
In addition, the äandå warning lamps light up in the
instrument cluster.
ATTENTION ASSIST is deactivated.
The brake system continues to function normally, but without the
functions listed above.
X Drive on carefully.
X Visi taqualified specialist workshop. T!
÷
inoperative See
Owner's Manual G
Risk of accident
EBD (electronic brake force distribution), ABS, ESP ®
, BAS, PRE-
SAFE ®
, the HOLD function ,hill start assist and ESP ®
trailer stabi-
lisatio nare not available due to a malfunction.
The adaptive brake lights, BAS PLUS and PRE-SAFE ®
Brake may
also have failed.
In addition, the ä,åand! warning lamps light up in
the instrument cluster and a warning tone sounds.
ATTENTION ASSIST is deactivated.
The brake system continues to function normally, but withou tthe
functions listed above. The wheels could therefore lock if you
brake hard, for example.
X Drive on carefully.
X Visit a qualified specialist workshop immediately. J
Release parking
brake You are driving with the parking brake applied.
Awarning tone also
sounds.
X Release the parking brake. Display messages
255On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutions
6
Rear centre mal‐
function Consult
workshop G
Risk of injury
SRS has malfunctioned at the rear centre. The 6warning lamp
also lights up in the instrumen tcluster.
X Visit a qualified specialist workshop. 6
Left
windowbag mal‐
function Consult
workshop orRight
windowbag malfunc‐
tion Consult work‐
shop G
Risk of injury
There is a malfunction in the left-hand and/or right-hand window-
bag.
The 6 warning lamp also lights up in the instrumen tcluster.
X Visit a qualified specialist workshop. Lights
i Display messages about LEDs:
This display message will only appear if all LEDs have failed. Displa
ymessages Possible causes/consequences and
M Solutions
b
Left cornering
light or
Right cor‐ nering light The left or right-hand cornering light is faulty.
X
Chec kwhether you are permitted to change the bulb yourself
(Y page 129).
or
X Visit a qualified specialist workshop. b
Left dipped beam
or
Right dipped beam The left or right-hand dipped-beamh
eadlamp is faulty.
X Check whether you are permitted to change the bulb yourself
(Y page 129).
or
X Visit a qualified specialist workshop. b
Trailer left tail
lamp or
Trailer right tail lamp The left or right-hand trailer tail lamp is faulty.
X
Check whether you are permitted to change the bulb yourself.
or
X Visit a qualified specialist workshop. b
Trailer left indi‐
cator or
Trailer right indicator The left or right-hand trailer turn signal lamp is faulty.
X
Check whether you are permitted to change the bulb yourself.
or
X Visit a qualified specialist workshop. Display messages
259On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutions
b
Trailer brake lamp The trailer brake lamp is faulty.
X
Chec kwhether you are permitted to change the bulb yourself.
or
X Visit a qualified specialist workshop. b
Rear left indica‐
tor or
Rear right indicator The rear left-hand or rear right-hand turn signal is faulty.
X
Check whether you are permitted to change the bulb yourself
(Y page 129).
or
X Visit a qualified specialist workshop. b
Front left indica‐
tor or
Front right indicator The front left-hand or front right-hand turn signal is faulty.
X
Check whether you are permitted to change the bulb yourself
(Y page 129).
or
X Visit a qualified specialist workshop. b
Left
mirror indica‐
tor or
Right mir‐ ror indicator The turn signal in the left-hand or right-hand exterior mirror is
faulty.
X
Check whether you are permitted to change the bulb yourself
(Y page 129).
or
X Visit a qualified specialist workshop. b
Third brake lamp The third brake lamp is faulty.
X
Check whether you are permitted to change the bulb yourself
(Y page 129).
or
X Visit a qualified specialist workshop. b
Left-hand tail
lamp/brake lamp or
Right-hand tail lamp/brake lamp The left or right-hand tail lamp/brake lamp is faulty.
X
Check whether you are permitted to change the bulb yourself
(Y page 129).
or
X Visit a qualified specialist workshop. b
Left main beam
or
Right main beam The left or right-hand high beam is faulty.
X
Check whether you are permitted to change the bulb yourself
(Y page 129).
or
X Visit a qualified specialist workshop. 260
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
M Solutions
b
Intell. Light Sys‐
tem inoperative The Intelligent Light Syste
mis 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. Vehicles with trailer tow hitch: a fuse may have blown.
X
Check the fuses (Y page 359).
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. b
Switch off lights The lights are still switched on when you leave the vehicle. A
warning tone also sounds.
X
Turn the 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. 262
Display messagesOn-board computer and displays

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
_
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