Problems with the key
Problem
Possible causes/consequences and
M
MSolutions You can no longer lock
or unlock the vehicle
using the key. The key battery is discharged or nearly discharged.
X Check the key battery (Y page 94) and replace it if necessary
(Y page 94).
If this does not work: X Unlock (Y page 98) or lock (Y page 100) the vehicle using the
emergency key element. There is interference from a powerful source of radio waves.
X Unlock (Y page 98) or lock (Y page 100) the vehicle using the
emergency key element. The key is faulty.
X Unlock (Y page 98) or lock (Y page 100) the vehicle using the
emergency key element.
X Have the key checked at a qualified specialist workshop. You can no longer lock
or unlock the vehicle
using KEYLESS-GO. KEYLESS-GO was deactivated.
X Reactivate KEYLESS-GO (Y page 91). The key battery is discharged or nearly discharged.
X Check the key battery (Y page 94) and replace it if necessary
(Y page 94).
If this does not work: X Unlock (Y page 98) or lock (Y page 100) the vehicle using the
emergency key element. There is interference from a powerful source of radio waves.
X Unlock (Y page 98) or lock (Y page 100) the vehicle using the
emergency key element. There is a fault with KEYLESS-GO.
X Lock/unlock the vehicle using the remote control function of
the key.
X Have the vehicle and key checked at a qualified specialist work-
shop.
If the vehicle can also not be locked/unlocked using the remote
control function:
X Unlock (Y page 98) or lock (Y page 100) the vehicle using the
emergency key element.
X Have the vehicle and key checked at a qualified specialist work-
shop. Key
95Opening 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 416).
or
X Jump-start the vehicle (Y page 418).
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 94) and replace it if necessary
(Y page 94).
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 86).96
DoorsOpening and closing
The doors can then be opened from the inside
after the vehicle has been locked from the
outside. The anti-theft alarm system is trig-
gered if the door is opened from the inside.
Switch off the alarm (Y page 85).
All countries: G
WARNING
If children are left unsupervised in the vehicle, they could:
R open doors, thereby endangering other per-
sons or road users
R get out and be struck by oncoming traffic
R operate vehicle equipment and become
trapped, for example
In addition, the children could also set the
vehicle in motion, for example, if they:
R release the parking brake
R shift the automatic transmission out of park
position P or shift manual transmission into
neutral
R start the engine
There is a risk of an accident and injury.
When leaving the vehicle, always take the key with you and lock the vehicle. Never leave
children and animals unattended in the vehi-
cle. Keep the keys out of the reach of children.
Stow luggage or loads preferably in the boot.
Observe the loading guidelines (Y page 368).Unlocking and opening the doors
from the inside
Only for the United Kingdom: if the vehicle
has been locked with the key or with KEY-
LESS-GO, the double lock function is activa-
ted as standard. It is then not possible to open the doors from inside the vehicle. You can
deactivate the double lock function by deac-
tivating the interior motion sensor . The doors can then be opened from the inside after thevehicle has been locked from the outside. You
can only open the rear doors from inside the
vehicle if they are not secured by the child- proof locks (Y
page 73). The anti-theft alarm
system is triggered if the door is opened from
the inside. Switch off the alarm (Y page 85).
For all countries except the United King-
dom:
You can open a door from inside the vehicle
even if it has been locked. You can only open
the rear doors from inside the vehicle if they
are not secured by the child-proof locks
(Y page 73). If the vehicle has previously been
locked with the key or with KEYLESS-GO,
opening a door from the inside will trigger the
anti-theft alarm system. Switch off the alarm
(Y page 85). X
Pull door handle ;.
If the door is locked, locking knob :pops
up. The door is unlocked and opens. Centrally locking and unlocking the
vehicle from the inside
You can centrally lock and unlock the vehicle from the inside. The switches are on the
driver’s door. Doors
97Opening and closing Z
X
To unlock: press button :.
X To lock: press button ;.
If the front-passenger door is closed, the
vehicle locks.
This does not lock or unlock the fuel filler flap. You cannot unlock the vehicle centrally from
the inside if the vehicle has been locked with
the key or KEYLESS-GO.
For all countries except the United King-
dom:
The doors can be opened from the inside. You can only open the rear doors from inside the
vehicle if they are not secured by the child-
proof locks (Y page 73).
If the vehicle has previously been locked with the key or with KEYLESS-GO, opening a door
from the inside will trigger the anti-theft alarm system. Switch off the alarm (Y page 85).
United Kingdom only: if the vehicle has
been locked with the key or with KEYLESS-
GO, 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 86). It
is then possible to operate the doors as fol-
lows. The doors can be opened from the
inside. You can only open the rear doors from
inside the vehicle if they are not secured by
the child-proof locks (Y page 73).
When a locked door is opened from inside the vehicle, the previous unlocking process will
be observed if the vehicle has been:
R locked with the locking button for the cen-
tral locking or
R locked automatically
The vehicle will be fully unlocked if it had pre- viously been fully unlocked. Only the door
which has been opened form the inside is
unlocked if only the driver's door had been
previously unlocked. Automatic locking feature
X
To deactivate: press and hold button :
for approximately five seconds until a tone sounds.
X To activate: press and hold button ;for
approximately five seconds until a tone
sounds.
If you press one of the two buttons and do not hear a tone, the relevant setting has already
been selected.
The vehicle is locked automatically when the
ignition is switched on and the wheels are
turning.
Therefore, you could be locked out if:
R the vehicle is being pushed.
R the vehicle is being towed.
R the vehicle is being tested on a dynamom-
eter.
i You can also activate and deactivate the
automatic locking function via COMAND
Online or Audio 20 (see the separate oper-
ating instructions). Unlocking the driver's door (emer-
gency key element)
If the vehicle can no longer be locked or
unlocked with the key or KEYLESS-GO, use
the emergency key element.
X Take the emergency key element out of the
key (Y page 93).
Vehicles with KEYLESS-GO: 98
DoorsOpening and closing
X
Insert the tip of the emergency key element
into the slit on the cover of the driver's doorlock and turn it until the cover is released. X
Insert the emergency key element into the
lock of the driver's door as far as it will go.
X Turn the emergency key element anti-
clockwise as far as it will go to position 1.
The locking knob pops up and the door
unlocks.
On right-hand-drive vehicles, turn the emer-
gency key element clockwise.
X Turn the emergency key element back and
remove it.
X Insert the emergency key element into the
key.
X Hold the cover over the lock of the driver's
door with the thicker end towards the front of the vehicle and press to secure. Then
make sure that the slit of the cover is hor-
izontal.
Vehicles without KEYLESS-GO: X
Insert the emergency key element into
opening :in the protective cap.
X Pull and hold the door handle.
X Pull the protective cap on the emergency
key as straight as possible away from the
vehicle until it releases.
X Release the door handle. X
Insert the emergency key element into the
lock of the driver's door as far as it will go.
X Turn the emergency key element anti-
clockwise as far as it will go to position 1.
The locking knob pops up and the door
unlocks.
On right-hand-drive vehicles, turn the emer-
gency key element clockwise. X Turn the emergency key element back and
remove it.
X Insert the emergency key element into the
key (Y page 93).
X Carefully press the protective cap onto the
lock cylinder until it engages and is seated firmly. Do not pull the door handle when
doing so.
All vehicles:
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 85). Doors
99Opening and closing Z
Locking the vehicle (emergency key
element)
If the vehicle can no longer be locked with the key or KEYLESS-GO, use the emergency key
element.
X Open the driver's door.
X Close the front-passenger door, the rear
doors and the boot lid.
X Press the locking button (Y page 97).
X Check whether the locking knobs on the
front-passenger door and the rear doors
are still visible. Press down the locking
knobs by hand, if necessary.
X Close the driver's door.
X Take the emergency key element out of the
key (Y page 93).
Vehicles with KEYLESS-GO:
X Insert the tip of the emergency key element
into the slit on the cover of the driver's door lock and turn it until the cover is released. X
Insert the emergency key element into the
lock of the driver's door as far as it will go.
X Turn the emergency key element clockwise
as far as it will go to position 1.
The locking knob drops down and the driv- er's door is locked.
On right-hand-drive vehicles, turn the emer-
gency key element anti-clockwise.
X Turn the emergency key element back and
remove it.
X Insert the emergency key element into the
key. X
Make sure that the doors and the boot lid
are locked.
X Hold the cover over the lock of the driver's
door with the thicker end towards the frontof the vehicle and press to secure. Then
make sure that the slit of the cover is hor-
izontal.
Vehicles without KEYLESS-GO: X
Insert the emergency key element into
opening :in the protective cap.
X Pull and hold the door handle.
X Pull the protective cap on the emergency
key as straight as possible away from the
vehicle until it releases.
X Release the door handle. X
Insert the emergency key element into the
lock of the driver's door as far as it will go.
X Turn the emergency key element clockwise
as far as it will go to position 1.
The locking knob drops down and the driv- er's door is locked.
On right-hand-drive vehicles, turn the emer-
gency key element anti-clockwise. 100
DoorsOpening and closing
X
Turn the emergency key element back and
remove it.
X Insert the emergency key element into the
key (Y page 93).
X Make sure that the doors and the boot lid
are locked.
X Carefully press the protective cap onto the
lock cylinder until it engages and is seated
firmly. Do not pull the door handle when
doing so.
All vehicles:
If you lock the vehicle as described above, the fuel filler flap is not locked. The anti-theft
alarm system is not primed. Boot
Important safety notes
G
WARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Exhaust
gases can enter the vehicle interior if the boot
lid is open when the engine is running, espe-
cially if the vehicle is in motion. There is a risk of poisoning.
Always switch off the engine before opening
the boot lid. Never drive with the boot lid
open. G
WARNING
If objects, luggage or loads are not secured or not secured sufficiently, they could slip, tip
over or be flung around and thereby hit vehicle
occupants. There is a risk of injury, especially when braking or abruptly changing directions.
Always store objects so that they cannot be
flung around. Secure objects, luggage or
loads against slipping or tipping before the
journey.
! The boot lid swings upwards when
opened. Therefore, make sure that there is sufficient clearance above the boot lid. The opening dimensions on the boot lid can
be found in the "Vehicle data" section
(Y
page 476).
i You can limit the opening angle of the
boot lid in COMAND Online or Audio 20
(see the separate operating instructions).
Do not leave the key in the boot. You could
otherwise lock yourself out.
Stow luggage or loads preferably in the boot.
Observe the loading guidelines (Y page 368). Obstacle detection with boot lid
reversing feature
Vehicles with boot lid remote closing fea- ture: the boot lid is equipped with automatic
obstacle detection with reversing function. If
a solid object blocks or restricts the boot lid
when automatically opening, this procedure
is stopped. If a solid object blocks or restricts the boot lid when automatically closing, the
boot lid opens again automatically. The auto- matic obstacle recognition with reversing
function is only an aid. It is not a substitute for
your attentiveness when opening and closing the boot lid. G
WARNING
The reversing function does not react:
R to soft, light and thin objects, e.g. small fin-
gers
R over the last 8 mm of the closing path
This means that the reversing feature cannot
prevent someone being trapped in these sit-
uations. There is a risk of injury.
When closing make sure that no parts of the
body are in the closing area.
If someone is trapped:
R press the Fbutton on the key, or
R press the remote operating switch on the
driver's door, or
R press the closing or locking button on the
boot lid, or
R pull the boot lid handle Boot
101Opening and closing Z
Vehicles with HANDS-FREE ACCESS:
it is
also possible to stop the closing process by
performing a kicking movement under the
rear bumper. Opening/closing from the outside
Opening X
Press the Fbutton on the key.
or X Pull handle :.
The boot lid opens.
Closing X
Pull the boot lid down using recess :and
push it closed.
X If necessary, lock the vehicle with the &
button on the key or with KEYLESS-GO
(Y page 91). Opening/closing automatically from
the outside
Important safety notes G
WARNING
Parts of the body could become trapped dur-
ing automatic closing of the boot lid. More-
over, people, e.g. children, may be standing in the closing area or may enter the closing area
during the closing process. There is a risk of
injury.
Make sure that nobody is in the vicinity of the closing area during the closing process.
Use one of the following options to stop the
closing process:
R Press the Fbutton on the key.
R Press the remote operating switch on the
driver's door.
R Press the closing or locking button on the
boot lid.
R Pull the boot lid handle.
Vehicles with HANDS-FREE ACCESS: it is
also possible to stop the closing process by
performing a kicking movement under the
rear bumper.
! The boot lid swings upwards when
opened. Therefore, make sure that there is sufficient clearance above the boot lid.
The opening dimensions of the boot lid can be
found in the "Vehicle data" section
(Y page 476).
Opening You can open the boot lid automatically using
the key or the handle in the boot lid.
X Press and hold the Fbutton on the key
until the boot lid opens.
or
X If the boot is unlocked, pull the boot lid
handle and release it again immediately. 102
BootOpening and closing