
A check which periodically establishes a radio
connection between the vehicle and the key
determines whether a valid key is in the vehi- cle. This occurs, for example:
R when starting the engine
R whilst driving
R when using HANDS-FREE ACCESS
R when the external door handles are
touched
R during convenience closing X
To unlock the vehicle: touch the inner
surface of the door handle.
X To lock the vehicle: touch sensor sur-
face :or;.
Make sure that you do not touch the inner
surface of the door handle.
X Convenience closing feature: touch
recessed sensor surface ;for an exten-
ded period.
For further information on the convenience closing feature (Y page 101).
Deactivating If you do not intend to use a key for an exten-
ded period of time, you can deactivate the
KEYLESS-GO function of the key. The key will
then use very little power, thereby conserving battery power. For the purposes of activa-
tion/deactivation, the vehicle does not have
to be nearby. X
To deactivate: press the&button on
the key twice in rapid succession.
The battery check lamp of the key flashes
twice briefly and lights up once, then KEY-
LESS-GO is deactivated .
X To activate: press any button on the key or
insert the key into the ignition lock.
KEYLESS-GO and all of its associated fea-
tures are available again. KEYLESS-GO start function
Bear in mind that the engine can be started by any of the vehicle occupants if there is a key
in the vehicle. Changing the settings of the locking
system
You can change the settings of the locking
system. This means that only the driver's door and the fuel filler flap are unlocked when the
vehicle is unlocked. This is useful if you fre-
quently travel alone.
X To change the setting: press and hold
down the %and& buttons simulta-
neously for about six seconds until the bat- tery indicator lamp flashes twice
(Y page 88).
i If the setting of the locking system is
changed within the signal range of the vehi- cle, pressing the &or% button:
R locks or
R unlocks the vehicle
The key now functions as follows:
X To unlock the driver's door: press the
% button once.
X To unlock centrally: press the%but-
ton twice.
X To lock centrally: press the&button. 86
KeyOpening and closing 

The KEYLESS-GO function is changed as fol-
lows:
X To unlock the driver's door: touch the
inner surface of the door handle on the
driver's door.
X To unlock centrally: touch the inner sur-
face of the front-passenger door handle.
X To lock centrally: touch the outer sensor
surface on one of the door handles.
X To restore the factory settings: press
and hold down the %and& buttons
simultaneously for approximately six sec-
onds until the battery check lamp flashes
twice (Y page 88). Emergency key element
General notes If the vehicle can no longer unlocked with the
key or KEYLESS-GO, use the emergency key
element.
If you use the emergency key element to
unlock and open the driver's door, the anti-
theft alarm system will be triggered. Switch
off the alarm (Y page 80).
If you unlock the vehicle using the emergency
key element, the fuel filler flap will not be
unlocked automatically.
X To unlock the fuel filler flap: insert the
key into the ignition lock.
Removing the emergency key element X
Push release catch :in the direction of
the arrow and, at the same time, remove
emergency key element ;from the key.
For further information about: R unlocking the driver's door (Y page 93)
R unlocking the boot (Y page 98)
R locking the vehicle (Y page 93)
Inserting the emergency key element X
Push emergency key element ;com-
pletely into the key until it engages and
release catch :is back in its basic posi-
tion. Battery of the key
Important safety notes G
WARNING
Batteries contain toxic and corrosive substan- ces. If batteries are swallowed, it can result in
severe health problems. There is a risk of fatal injury.
Keep batteries out of the reach of children. If
a battery is swallowed, seek medical attention immediately. H
Environmental note Batteries contain pollutants.
It is illegal to dispose of them
with the household rubbish.
They must be collected sep-
arately and disposed of in anenvironmentally responsible
recycling system. Dispose of batteries in an
environmentally responsible
manner. Take discharged
batteries to a qualified spe-
cialist workshop or to a col-
lection point for used batter-
ies. Key
87Opening and closing Z 

Problem
Possible causes/consequences and
M
MSolutions The engine cannot be
started using the key. the on-board voltage is too low
X Switch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work: X Check the starter battery and charge it if necessary
(Y page 364).
or
X Jump-start the vehicle (Y page 366).
or
X Consult a qualified specialist workshop. The engine cannot be
started using the Start/
Stop button. The key is
in the vehicle. The vehicle is locked.
X Unlock the vehicle and try to start the vehicle again. The key battery is discharged or nearly discharged.
X Check the key battery (Y page 88) and replace it if necessary
(Y page 88).
If this does not work: X Start your vehicle with the key in the ignition lock. There is interference from a powerful source of radio waves.
X Start your vehicle with the key in the ignition lock. You have lost a key. X
Have the key deactivated at a qualified specialist workshop.
X Report the loss immediately to the vehicle insurers.
X If necessary, have the locks changed as well. You have lost the emer-
gency key element. X
Report the loss immediately to the vehicle insurers.
X If necessary, have the locks changed as well. Doors
Important safety notes
United Kingdom only: G
WARNING
When the double locks are activated, the
doors can no longer be opened from the
inside. People in the vehicle can no longer get out, e.g. in hazardous situations. There is a
risk of injury. Therefore, do not leave any people unsuper-
vised in the vehicle, particularly children, eld- erly people or people in need of special assis-
tance. Do not activate the double lock when
people are in the vehicle.
If the vehicle has been locked from the out-
side, the double lock function is activated as
standard. It is then not possible to open the
doors from inside the vehicle. You can deac-
tivate the double lock function by deactivat-
ing the interior motion sensor (Y page 82).90
DoorsOpening and closing 

When the auxiliary heating is switched on,
make sure that:
R no flammable materials come into contact
with hot vehicle components
R the exhaust gas can escape from the
exhaust pipe unhindered
R the exhaust gas does not come into contact
with flammable materials.
The auxiliary heating and the exhaust gas out-
let are situated behind the right-hand front
wheel.
! Operating the auxiliary heating/ventila-
tion draws on the vehicle battery. After you
have heated or ventilated the vehicle a
maximum of two times, drive for a longer
distance.
Switch the auxiliary heating on regularly once
a month for about ten minutes.
The auxiliary heating heats the air in the vehi-
cle interior to the set temperature. This
occurs without using the heat of the running
engine. The auxiliary heating is operated
directly using the vehicle's fuel. For this rea-
son, the tank content must be at least at
reserve fuel level to ensure that the auxiliary
heating functions.
The auxiliary heating or auxiliary ventilation
automatically adjusts to changes in temper-
ature and weather conditions. For this rea-
son, the auxiliary heating could switch from
ventilation mode to heating mode or from
heating mode to ventilation mode.
The auxiliary heating switches off when the
engine is switched off. The auxiliary ventila-
tion switches off when you turn the key to key position 2(Y page 161).
The auxiliary heating switches off automati-
cally after 50 minutes. This time limit can be
altered. To do this, visit a qualified specialist
workshop.
You cannot use the auxiliary ventilation to
cool the vehicle interior to a temperature
lower than the outside temperature. Before switching on X
Turn the key to position 2in the ignition
lock (Y page 161).
X Set the desired temperature using the
w rocker switch on the front control
panel or using COMAND Online (see the
separate operating instructions).
If you do not alter the temperature before
switching on the auxiliary heating or auxiliary
ventilation, the last temperature setting will
be adopted.
Auxiliary heating or auxiliary ventilation can
also be switched on if the manually set cli-
mate control is activated. Optimum comfort
can be attained when the system is set to
automatic mode. Set the temperature to
22 †.
You can switch the auxiliary heating or auxil-
iary ventilation on or off:
R using the rocker switch on the centre con-
sole (Y page 150)
R using the remote control (Y page 151)
The on-board computer can be used to spec-
ify up to three departure times, one of which
may be preselected:
R using the remote control (Y page 151)
R using COMAND Online (see the separate
operating instructions)
Switching the auxiliary heating/venti-
lation on or off using the centre console
rocker switch 150
Operating the climate control systemClimate control 

Key
Display messages
Possible causes/consequences and
M
M Solutions Â
Key does not Key does not
belong to vehicle belong to vehicle You have put the wrong key in the ignition lock.
X Use the correct key. Â
Replace key Replace key The key needs to be replaced.
X Consult a qualified specialist workshop. Â
Change key batter‐ Change key batter‐
ies ies The key battery is discharged.
X Replace the battery (Y page 88).Â
Key not detected Key not detected
(white display mes-
sage) The key is currently undetected.
X Change the location of the key in the vehicle.
If the key still cannot be detected: X Insert the key into the ignition lock and turn it to the desired
position. Â
Key not detected Key not detected
(red display message) The 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 to prevent it from rolling away (Y page 181).
X Locate the key.
X Press aon the steering wheel to confirm the display mes-
sage. Display
messages
301On-board computer and displays Z