
X
Place the protective covering on the ball cou-
pling.
Opening the cover: X Turn handle :anti-clockwise and fold down
cover ;.
Unlocking and lowering the ball coupling:
X Pull out release wheel ?.
X Turn release wheel ?anti-clockwise.
The ball coupling unlocks and lowers. Indica-
tor lamp =flashes.
X Press the ball coupling in the direction of the
arrow until it engages behind the bumper.
Indicator lamp =goes out and the message
in the multifunction display disappears. Coupling up a trailer
X Make sure that the transmission is in position
P.
X Apply the parking brake.
X Position the trailer horizontally behind the
vehicle.
X Couple up the trailer.
X Establish the electric connection between the
vehicle and the trailer.
X Check that the trailer lighting system is work-
ing.
A connected trailer is only recognised when
the electrical connection is established cor-
rectly and when the lighting system is working
properly. The function of other systems, such
as ESP ®
, PARKTRONIC and Active Parking
Assist also depends on this. Uncoupling a trailer
G
WARNING
If you uncouple a trailer with an engaged over- run brake, you could trap your hand between
the vehicle and the trailer drawbar. This poses a risk of injury.
Do not uncouple a trailer with an engaged
overrun brake. G
WARNING
Vehicles with level control: If you disconnect the trailer cable, the vehicle
is lowered. This can cause you or others to
become trapped between the vehicle body
and tyres, or underneath the vehicle. This
poses a risk of injury.
Make sure that no-one is in the immediate
vicinity of the wheel arch or underneath the
vehicle when disconnecting the trailer cable.
! Do not disconnect a trailer with an engaged
overrun brake. Otherwise, your vehicle could
be damaged by the rebounding of the overrun
brake.
X Make sure that the transmission is in position
P.
X Apply the parking brake.
X Secure the trailer against rolling away.
X Remove the trailer cable and decouple the
trailer. Trailer power supply
! You can connect accessories to the perma-
nent power supply up to a maximum of 240 W.
You cannot charge a trailer battery using the
power supply.
X To switch the connected power supply on
or off: turn the key in the ignition lock to
position 2or 0respectively (Y page 132).
When it leaves the factory, your vehicle's trailer
socket is equipped with a permanent power
supply and a power supply that is switched on
via the ignition lock.
The permanent power supply is supplied via
trailer socket pin 9.
The power supply that is switched on via the
ignition lock is supplied via trailer socket pin 10.
The trailer's permanent power supply is
switched off in the event of low vehicle supply
voltage and after six hours at the latest.
You can find more information about fitting the
trailer electrics at a qualified specialist work-
shop. Failure check for LEDs
i If LED lamps are fitted in the trailer, a mal-
function message may appear in the multi- 204
Towing a trailerDriving and parking

function display even if there is no fault. The
reason for the error message may be that the
current has fallen below the minimum of
50 mA.
To ensure reliable indication of the failure, each LED chain in the trailer lighting must be guaran-
teed a minimum current of 50 mA. Trailer with 7-pin connector
General notes Trailer with 7-pin connector:
you can connect
to the 13-pin socket on the ball coupling using
an adapter or, if necessary, an adapter cable.
Both can be obtained at a qualified specialist
workshop.
Fitting the adapter !
Make sure that there is sufficient cable play
so that the cable cannot become detached
when cornering. X
Open the socket cover.
X Insert the plug connector with lug :into
groove =on the socket.
X Turn bayonet connection ;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. Towing a trailer
205Driving and parking Z

i
If you reset the values in the "ECO display",
the values in the "From start" trip computer
are also reset. If you reset the values in the
"From start" trip computer, the values in the
"ECO display" are also reset. Navigation menu
Displaying navigation instructions In the
Navi Navimenu, the multifunction display
shows navigation instructions.
Observe the additional information on naviga-
tion in the separate operating instructions for
the multimedia system.
X Switch on the multimedia system (see the
separate operating instructions).
X Press the =or; button on the steering
wheel to select the Navi
Navi menu.
Route guidance not active :
Direction of travel
; Current road
Route guidance active No change of direction announced
:
Distance to the destination
; Distance to the next change of direction
= Current road
? Symbol indicating "follow the road's course" Change of direction announced without a
lane recommendation :
Road to which the change of direction leads
; Distance to change of direction and visual
distance display
= Change-of-direction symbol
When a change of direction is announced, you
will see change-of-direction symbol =and dis-
tance graphic ;. This shortens towards the top
of the display as you approach the point of the
announced change of direction.
Change of direction announced with a
lane recommendation :
Road to which the change of direction leads
; Distance to change of direction and visual
distance display
= Lanes not recommended
? Recommended lane and new lane during a
change of direction
A Change-of-direction symbol
On multilane roads, new lane recommendations
can be displayed for the next change of direction
if the digital map supports this data. During the change of direction, new lanes may be added.
Lane not recommended =: you will not be able
to complete the next change of direction if you
stay in this lane.
Recommended lane and new lane during a
change of direction ?: in this lane you will be
able to complete the next two changes of direc- tion without changing lane. 210
Menus and submenusOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions Vehicles with trailer tow hitch: a fuse may have blown.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Safeguard the vehicle against rolling away (Y page 150).
X Check the fuses (Y page 310).
X If necessary, replace the blown fuse. Observe the warning notes as
you do so.
If the multifunction display still shows the display message:
X Consult a qualified specialist workshop. b
AUTO lights inoper‐ AUTO lights inoper‐
ative ative The light sensor is faulty.
X
Consult a qualified specialist workshop. b
Switch off lights Switch off lights You are leaving the vehicle and the lights are switched on. A warning
tone also sounds.
X Turn the light switch to the Ãposition. Adaptive Highbeam
Adaptive Highbeam
Assist Plus cur‐ Assist Plus cur‐
rently unavailable rently unavailable
See Owner's Manual See Owner's Manual Adaptive Highbeam Assist Plus is deactivated and temporarily inop-
erative.
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 Clean the windscreen.
If the system detects that the camera is fully operational again, the Adaptive Highbeam Assist Plus available again Adaptive Highbeam Assist Plus available again message is
displayed.
Adaptive Highbeam Assist Plus is operational again. Adaptive Highbeam Adaptive Highbeam
Assist Plus inoper‐ Assist Plus inoper‐
ative ative Adaptive Highbeam Assist Plus is faulty.
X Consult a qualified specialist workshop. 230
Display
messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions Lane
Lane
Keeping
Keeping Assist
Assist
currently unavaila‐
currently unavaila‐
ble ble See
SeeOwner's
Owner's Man‐
Man‐
ual
ual orActive LaneActive Lane
Keeping Assist cur‐
Keeping Assist cur‐
rently unavailable
rently 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 have been no lane markings for an extended 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 Safeguard the vehicle against rolling away (Y page 150).
X Clean the windscreen. Lane Lane
Keeping
Keeping Assist
Assist
inoperative
inoperativeorActive Active
Lane
Lane Keeping
Keeping Assist
Assist
inoperative
inoperative Lane Keeping Assist or Active Lane Keeping Assist is faulty.
X Consult a qualified specialist workshop. Blind Spot Assist
Blind Spot Assist
currently unavaila‐ currently unavaila‐
ble ble
See
SeeOwner's
Owner's Man‐
Man‐
ual
ual orActive BlindActive Blind
Spot Assist cur‐
Spot Assist cur‐
rently unavailable rently unavailable
See Owner's Manual See Owner's Manual Blind Spot Assist or Active Blind Spot Assist is temporarily inoperative.
Possible causes:
R the radar sensor system is outside the operating temperature range
R the radar sensor system is temporarily inoperative, e.g. due to elec-
tromagnetic radiation emitted by nearby TV or radio stations or
other sources of electromagnetic radiation
The yellow 9indicator lamps also light up in the exterior mirrors.
Once the causes listed above no longer apply, the display message
goes out.
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 Safeguard the vehicle against rolling away (Y page 150).
X Restart the engine. Blind Spot Assist Blind Spot Assist
not available when not available when
towing a trailer towing a trailer
See Owner's Manual See Owner's Manual Blind Spot Assist or Active Blind Spot Assist is deactivated while tow-
ing a trailer.
You have established the electrical connection between the trailer and
your vehicle.
X Press aon the steering wheel to confirm the display message. Display
messages
235On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions j
Check Check
trailer
trailer hitch
hitch
lock
lock The trailer tow hitch is not correctly engaged.
A warning tone also sounds.
G WARNING
If the ball coupling is not engaged, the trailer may come loose. There
is a risk of an accident.
X Stop the vehicle immediately, paying attention to road and traffic
conditions, and switch off the engine.
X Apply the parking brake.
X Engage the trailer coupling's ball coupling in the end position
(Y page 203). &
inoperative inoperative
Battery
Battery
Low
Low The on-board voltage is too low. The auxiliary heating has switched
itself off or cannot be switched on (Y page 124).
X Drive for a considerable distance.
The battery charges. The auxiliary heating is operational again as
soon as the on-board electrical system voltage is sufficient. &
inoperative Refuel inoperative Refuel
vehicle vehicle There is too little fuel in the fuel tank. The auxiliary heating cannot be
switched on (Y page 124).
X Refuel at the nearest filling station. &
inoperative inoperative
See
SeeOwn‐
Own‐
er's Man.
er's Man. The auxiliary heating is temporarily malfunctioning or 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 heating,
waiting several minutes between each attempt (Y page 124).
X If the auxiliary heating does not switch on, consult a qualified spe-
cialist workshop. Telephone Telephone
No
Noservice
service Your vehicle is outside the network provider's transmitter/receiver
range.
X Wait until the mobile phone operational readiness symbol appears
in the multifunction display. 244
Display
messagesOn-board computer and displays

Safety
Seat belts Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ü
N
Only for certain countries: the red seat belt warning lamp lights up for 6 seconds
after the engine starts.
The seat belt warning lamp reminds the driver and front passenger to fasten their
seat belts.
X Fasten your seat belt (Y page 39).ü
N
Only for certain countries: the red seat belt warning lamp lights up after the
engine starts. In addition, a warning tone sounds for up to 6 seconds.
The driver's seat belt is not fastened.
X Fasten your seat belt (Y page 39).
The warning lamp goes out and the warning tone ceases. ü
N
The red seat belt warning lamp lights up after the engine starts, as soon as the
driver's or the front-passenger door is closed.
The driver or passenger has not fastened their seat belt.
X Fasten your seat belt (Y page 39).
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. ü
N
The red seat belt warning lamp flashes and an intermittent audible warning
sounds.
The driver or passenger has not fastened their seat belt. At the same time, you are
driving faster than 25 km/h or have briefly driven faster than 25 km/h.
X Fasten your seat belt (Y page 39).
The warning lamp goes out and the intermittent warning tone ceases.
There are objects on the front-passenger seat. At the same time, you are driving
faster than 25 km/h or have briefly driven faster than 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
247On-board computer and displays Z

X
Select a favourite.
X Add a favourite at the desired position.
If a favourite has already been added at this
position, it will be overwritten.
Adding your own favourite
X Select Vehicle
VehicleQ Climate control
Climate control.
X Press and hold the òbutton until the
favourites are displayed.
X Add a favourite at the desired position.
If a favourite has already been added at this
position, it will be overwritten. Navigation mode
Important safety notes G
WARNING
Operating the integrated information systems and communications equipment in the vehicle
while driving will distract you from traffic con-
ditions. You could then lose control of the
vehicle. There is a risk of an accident.
Only operate these devices if road traffic con-
ditions permit. If you are unsure about the
surrounding conditions, pull over to a safe
location and make entries only while the vehi-
cle is stationary.
You must observe the legal requirements for the country in which you are currently driving whenoperating the navigation system.
General notes Correct functioning of the navigation system
depends, amongst other things, on GPS recep-
tion. In certain situations, GPS reception may be
impaired, there may be interference or there
may be no reception at all, e.g. in tunnels or
multi-storey car parks.
Audio 20 is equipped with Garmin ®
MAP PILOT
(see the manufacturer's operating instructions).
The Garmin ®
MAP PILOT operating instructions
are stored on the SD memory card as a PDF file. The SD card box contains a quick guide.
The following descriptions apply to navigation
with COMAND Online. Further information can
be found in the Digital Owner's Manual. Selecting a route type and route options Multimedia system:
X Select Navi NaviQNavigationNavigation.
The map displays the current vehicle position.
X Slide 6the controller.
X Select Options
OptionsQ Route settings
Route settings .
Notes for route types:
R Eco route
Eco route
R Dynamic route
Dynamic route
Traffic reports on the route for the route guid-
ance are taken into account.
R Dynamic route only after request Dynamic route only after request
You can decide whether or not current traffic
reports should be taken into account for route
calculation.
R Calculate alternative routes
Calculate alternative routes
Different routes are being calculated. In order
to do so, instead of Start Start, select the menu
item Continue
Continue .
Notes for route options:
R Use toll roads
Use toll roads
The route calculation includes roads which
require you to pay a usage fee (toll).
R Use vignette roads Use vignette roads (not available in all
countries)
The route calculation includes roads which
require you to pay a time-based fee (vignette). A vignette allows temporary use of the route
network, e. g. 10 days or 1 year.
Entering an address Multimedia system:
X Select Navi NaviQNavigationNavigation.
The map displays the current vehicle position.
X Slide 6the controller.
X Select Destination
DestinationQ Address entry
Address entry.
Enter an address, e.g. as follows:
R town or postcode, street, house number
R country, town or postcode
R town or postcode, centre
R street, town or postcode, junction
X Select Town
Town.
The town in which the vehicle is currently
located (current vehicle position) is at the top.
Below this, you will see locations for which
route guidance has already been carried out. 258
Operating systemMultimedia system