
the power output of the engine, and conse-
quently the vehicle's gradient-climbing capa-
bility, decrease with increasing altitude.
Folding the ball coupling in/out
Folding out the ball coupling G
WARNING
If the ball coupling is not correctly engaged,
the trailer can detach. There is a risk of an
accident.
Always engage the ball coupling as described. G
WARNING
If you release the ball coupling or it does not
engage correctly when folding in, it will swing out. Within pivoting range of the ball coupling,
there is an increased risk of an accident and
injury.
Only release the ball coupling if the pivoting
range is unobstructed. Always make sure that the ball coupling engages when folding in.
Before you can tow a trailer with your vehicle,
you must fold out the ball coupling. The release wheel is located behind the left-
hand side trim panel in the boot.
Opening the cover:
X Turn handle :around anti-clockwise and
fold cover ;down. Unlocking and folding out the ball coupling:
X Pull out release wheel ?.
X Turn release wheel ?anti-clockwise until the
ball coupling releases and folds out from
under the rear bumper. Indicator lamp =
flashes. X
Pull the ball coupling in the direction of the
arrow until it engages in a vertical position.
The trailer power socket is integrated into the ball coupling and swivels out with it.
Indicator lamp =goes out.
The multifunction display shows the
Trailer hitch Check lock mech. Trailer hitch Check lock mech. mes-
sage until the ball coupling is engaged.
X Remove the protective covering from the ball
coupling and store it in a safe place.
X Make sure that the ball of the ball coupling is
clean and greased.
HYBRID vehicles : make sure that you read the
"HYBRID" Supplement included in the vehicle
literature. Otherwise, you may not recognise
dangers. 210
Towing a trailerDriving an
d parking

Folding in the ball coupling
i
Fold the ball coupling back in if you are not
using the trailer tow hitch.
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 139).
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. Towing a trailer
211Driving and parking Z

Failure check for LEDs
i If LED lamps are fitted in the trailer, a mal-
function message may appear in the multi-
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. 212
Towing a trailerDriving and pa
rking

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 157).
X Check the fuses (Y page 318).
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. Display
messages
237On-board computer and displays Z

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 157).
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 157).
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. 242
Display
messagesOn-board computer and displays

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 210). &
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 132).
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 132).
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 132).
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. Ð
Power steering mal‐ Power steering mal‐
function See Own‐ function See Own‐
er's Manual er's Manual 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. Display
messages
251On-board computer and displays Z

X
Use clear water and a soft cloth to clean cam-
era lens :.
Cleaning the exhaust tail pipes G
WARNING
The exhaust tail pipe and tail pipe trim can
become very hot. If you come into contact
with these parts of the vehicle, you could burn
yourself. There is a risk of injury.
Always be particularly careful around the
exhaust tail pipe and the tail pipe trim. Allow
these components to cool down before touch-
ing them.
! Do not clean the exhaust pipe with acid-
based cleaning agents, such as sanitary
cleanser or wheel cleaner.
Impurities combined with the effects of road grit and corrosive environmental factors may cause
flash rust to form on the surface. You can
restore the original shine of the exhaust pipe by
cleaning it regularly, especially in winter and
after washing.
X Clean the exhaust pipe with a care product
tested and approved by Mercedes-Benz.
Cleaning the trailer tow hitch H
Environmental note
Dispose of oily and greasy cloths in an envi-
ronmentally-responsible manner.
! Do not clean the ball coupling with a high-
pressure cleaner. Do not use solvents.
! Please note the care instructions in the
trailer coupling manufacturer's operating
instructions. The ball coupling must be cleaned if it becomes
dirty or corroded.
X Remove rust, e.g. with a wire brush.
X Remove dirt with a clean, lint-free cloth or a
brush.
X After cleaning, lightly oil or grease ball cou-
pling :.
X Check that the vehicle's trailer tow hitch is
working properly.
i You can also have the maintenance work on
the ball coupling and the trailer tow hitch car-
ried out by a qualified specialist workshop. Interior care
Cleaning the display !
For cleaning, do not use any of the following:
R alcohol-based thinner or petrol
R abrasive cleaning agents
R commercially-available household cleaning
agents
These may damage the display surface. Do
not put pressure on the display surface when
cleaning. This could lead to irreparable dam-
age to the display.
X Before cleaning the display, make sure that it
is switched off and has cooled down.
X Clean the display surface using a commer-
cially available microfibre cloth and TFT/LCD
display cleaner.
X Dry the display surface using a dry microfibre
cloth. Care
301Maintenance and care Z

X
Slide cover :of positive terminal ;in the direction of the arrow.
X Connect positive terminal ;on your vehicle to positive terminal =of donor battery Busing the
jump lead, always beginning with positive terminal ;on your own vehicle first.
X Start the engine of the donor vehicle and run it at idling speed.
X Connect negative terminal ?of donor battery Bto earth point Aof your vehicle using the jump
lead, connecting the jump lead to donor battery Bfirst.
X Start the engine.
X Before disconnecting the jump leads, let the engines run for several minutes.
X First, remove the jump leads from earth point Aand negative terminal ?, then from positive
clamp ;and positive terminal =. Begin each time at the contacts on your own vehicle first.
X Close cover :of positive clamp ;after removing the jump leads.
X Have the battery checked at a qualified specialist workshop.
Jump-starting is not considered to be a normal operating condition.
i Jump-starting cables and further information regarding jump-starting can be obtained at any
qualified specialist workshop. Towing away and tow-starting
Important safety notes
G
WARNING
Safety relevant functions are restricted or no
longer available if:
R the engine is not running
R the brake system or power steering is mal-
functioning
R there is a malfunction in the voltage supply
or the vehicle's electrical system
When your vehicle is towed away or towed
started, you may require considerably more
effort to steer and brake. There is a risk of an
accident.
In such cases use a rigid towing bar. Before
being towed away or tow started, make sure
the steering moves freely. G
WARNING
When towing or tow-starting another vehicle
and its weight is greater than the permissible gross weight of your vehicle, the:
R towing eye may be torn off
R car/trailer combination may swerve or
even overturn
There is a risk of an accident. When towing or tow-starting another vehicle,
its weight should not be greater than the per-
missible gross weight of your vehicle.
Details on the permissible gross vehicle weight
of your vehicle can be found on the vehicle iden-
tification plate (Y page 336).
! When COLLISION PREVENTION ASSIST
PLUS, DISTRONIC PLUS or the HOLD function is activated, the vehicle brakes automatically
in certain situations.
To avoid damage to the vehicle, deactivate
these systems in the following or similar sit-
uations:
R when towing away
R in a car wash
! Only secure the tow cable or tow bar to the
towing eyes or, if available, to the trailer tow
hitch. You could otherwise damage the vehi-
cle.
! Observe the following points when towing
with a tow rope:
R Secure the tow rope on the same side on
both vehicles.
R Make sure that the tow rope is not longer
than legally permitted. Mark the tow rope in
the middle, e.g. with a white cloth
(30 x 30 cm). This will make other road
users aware that a vehicle is being towed.
R Only secure the tow cable to the towing
eyes or, if available, to the trailer tow hitch. Towing away and tow-starting
315Breakdown assistance Z