2012 MERCEDES-BENZ A CLASS lock

A visual and audible alarm is triggered if the
alarm system is primed and you open:
R
the vehicle with the emergency key ele-
ment
R a door
R the tailgate
R the bonnet
X To stop the alarm: insert the key into the
ignition lock.
The alarm is switched off.
or
X Press the % or & button on the key.
The alarm is switched off.
The alarm is not switched off, even if you
close the open door that has triggered it, for
example. Tow-away protection
Function An audible and visual alarm is triggered if your
vehicle's angle of inclination is altered while
tow-away

protection is primed. This can occur
if the vehicle is jacked up on one side, for
example.
Activating X
Make sure that:
R
the doors are closed.
R the tailgate is closed.
Only then is the tow-away protection
primed.
X Lock the vehicle with the key.
Tow-away protection is primed after
approximately

60 seconds.
Deactivating X
Unlock the vehicle with the key.
or
X Insert the key into the ignition lock.
Tow-away protection is switched off auto-
matically. Deactivating
X
Remove the key from the ignition lock.
X Press button :.
Indicator lamp ; lights up briefly.
X Lock the vehicle with the key.
Tow-away protection is deactivated.
Tow-away protection remains deactivated
until:
R the vehicle is unlocked again
R a door is opened and closed again
R the vehicle is locked again
To prevent a false alarm, deactivate the tow-
away protection if you lock your vehicle and
it:
R is being transported
R is being loaded onto a ferry or car trans-
porter, for example
R is parked on a movable surface, e.g. in a
split-level garage Interior motion sensor
Function When the interior motion sensor is primed, a
visual

and audible alarm is triggered if move-
ment is detected in the vehicle interior. This
can occur if someone reaches into the vehicle
interior, for example. 70
Anti-theft systems
Safety

Activating
X
Make sure that:
R
the side windows are closed.
R the panorama sliding sunroof is closed.
R there
are no objects, e.g. mascots, hang-
ing on the rear-view mirror or on the grab
handles on the roof trim.
This will prevent false alarms.
X Make sure that:
R
the doors are closed.
R the panorama sliding sunroof is closed.
R the tailgate is closed.
Only then is the interior motion sensor
primed.
X Lock the vehicle with the key.
The interior motion sensor is primed after
approximately

30 seconds.
Deactivating X
Unlock the vehicle with the key.
or
X Insert the key into the ignition lock.
The interior motion sensor is switched off
automatically.
Deactivating X
Remove the key from the ignition lock.
X Press button :.
Indicator lamp ; flashes briefly.
X Lock the vehicle with the key.
The interior motion sensor is deactivated. The interior motion sensor remains deactiva-
ted until:
R
the vehicle is unlocked again
R a door is opened and closed again
R the vehicle is locked again
To prevent a false alarm, deactivate the inte-
rior motion sensor if you lock your vehicle
and:
R people or animals remain in the vehicle.
R the panorama sliding sunroof remains
open.
R the side windows remain open.
i UK only: your vehicle is equipped with a
double lock function. The doors cannot be
opened from the inside if the vehicle has
been locked with the key ( Y page 80).
Deactivate the interior motion sensor
before you lock the vehicle with the key.
The doors can then be opened from the
inside after the vehicle has been locked
from

the outside with the key. Observe the
"Important safety notes" (Y page 79). Anti-theft systems
71
Safety Z

Useful information
i This Owner's Manual describes all mod-
els,
series and optional equipment for your
vehicle that were available at the time of
going to press. National variations are pos-
sible. Note that your vehicle may not be
equipped with all of the functions descri-
bed. This is also the case for systems and
functions relevant to safety.
i Read the information on qualified special-
ist workshops: (Y page 24). Key
Important safety notes
G
WARNING
If children are left unsupervised in the vehicle,
they could:
R open the doors, thus endangering other
people or road users.
R get out and disrupt traffic.
R operate the vehicle's equipment.
Additionally, children could set the vehicle in
motion if, for example, they:
R release the parking brake.
R shift the automatic transmission out of
parking position P.
R shift the 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 or animals unattended in the vehicle.
Always keep the key out of reach of children. G
WARNING
If persons (particularly children) are exposed
to heat or cold for a prolonged period, there
is

a risk of serious or even fatal injuries. Never
leave persons (particularly children) unatten-
ded in the vehicle. G
WARNING
If you attach heavy or large objects to the key,
the
key could be unintentionally turned in the
ignition lock. This could cause the engine to
be switched off. There is a risk of an accident.
Do not attach any heavy or large objects to
the key. Remove any bulky keyrings before
inserting the key into the ignition lock.
! Keep the key away from strong magnetic
fields. Otherwise, the remote control func-
tion could be affected.
Strong magnetic fields can occur in the
vicinity of powerful electrical installations.
Do not keep the key:
R with electronic devices, e.g. a mobile
phone or another key
R with metallic objects, e.g. coins or metal
film
R inside metallic objects, e.g. a metal case
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 with the key,
then the double lock function is activated as
standard. You can deactivate the double lock
function by deactivating the interior motion
sensor (Y page 70). The doors can then be
opened from the inside after the vehicle has
been locked from the outside. The anti-theft
alarm system is triggered if the door is
opened from the inside. Switch off the alarm
(Y page 69). 74
Key
Opening and closing

Key functions
:
& To lock the vehicle
; % To unlock the vehicle
X To unlock centrally: press button ;.
If you do not open the vehicle within approx-
imately 40 seconds of unlocking:
R the vehicle is locked again.
R the anti-theft system is primed again.
X To lock centrally: press button :.
The key centrally locks/unlocks:
R the doors
R the tailgate
R the fuel filler flap
When unlocking, the turn signals flash once.
When locking, they flash three times.
i When

it is dark, the surround lighting also
comes on if it is activated in the on-board
computer (Y page 222).
i You can also set an audible signal to con-
firm that the vehicle has been locked. The
audible signal can be activated and deacti-
vated using the on-board computer
(Y page 223). 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 on your own.
X To change the setting: press and hold
down the % and & buttons simulta-
neously

for approximately six seconds until
battery check lamp (Y page 76) flashes
twice.
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.
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 76). Emergency key element
General notes If the vehicle can no longer be unlocked with
the key, 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
(Y page 69).
There are several ways to turn off the alarm:
X
Press the % or &
button on the key.
or
X Insert the key into the ignition lock. Key
75
Opening and closing Z

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. 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 an environmentally 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.
Mercedes-Benz recommends that you have
the
batteries replaced at a qualified specialist
workshop.
Checking the battery X
Press the & or % button.
The battery is working properly if battery
check lamp : lights up briefly.
The battery is discharged if battery check
lamp : does not light up briefly.
X Replace the battery ( Y page 76).
i If the key battery is checked within the
signal
reception range of the vehicle, press-
ing the & or % button:
R locks or
R unlocks the vehicle
i You can obtain a battery from any quali-
fied specialist workshop.
Replacing the battery You require a CR 2025 3 V cell battery.76
Key
Opening and closing

Problems with the key
Problem Possible causes/consequences and
M SolutionsYou cannot lock or
unlock the vehicle
using the key. The key battery is discharged or nearly discharged.
X
Try again to lock/unlock the vehicle using the remote control
function of the key. Point the tip of the key at the driver's door
handle from close range and press the % / & button.
If this does not work:
X Check the key battery and replace it if necessary ( Y page 76).
X Lock ( Y page 81) or unlock ( Y page 81) the vehicle using
the emergency key element. There is interference from a powerful source of radio waves.
X
Try again to lock/unlock the vehicle using the remote control
function of the key. Point the tip of the key at the driver's door
handle from close range and press the % / & button.The key is faulty.
X
Lock ( Y page 81) or unlock ( Y page 81) the vehicle using
the emergency key element.
X Have the key checked at a qualified specialist workshop. 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.78
KeyOpening and closing

Problem Possible causes/consequences and
M SolutionsThe 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 304).
or
X Jump-start the vehicle (Y page 308).
or
X Consult a qualified specialist workshop. The engine cannot be
started using the key. The steering lock is mechanically blocked.
X
Remove the key and reinsert it into the ignition lock. While doing
this, turn the steering wheel in both directions. Doors
Important safety notes
G
WARNING
If children are left unsupervised in the vehicle,
they could:
R open the doors, thus endangering other
people or road users.
R get out and disrupt traffic.
R operate the vehicle's equipment.
Additionally, children could set the vehicle in
motion if, for example, they:
R release the parking brake.
R shift the automatic transmission out of
parking position P.
R shift the 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 or animals unattended in the vehicle.
Always keep the key out of reach of children. G
WARNING
If persons (particularly children) are exposed
to heat or cold for a prolonged period, there
is

a risk of serious or even fatal injuries. Never
leave persons (particularly children) unatten-
ded in the vehicle.
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 with the key,
then the double lock function is activated as
standard. You can deactivate the double lock
function by deactivating the interior motion
sensor (Y page 70). The doors can then be
opened from the inside after the vehicle has
been locked from the outside. The anti-theft Doors
79
Opening and closing Z

alarm system is triggered if the door is
opened from the inside. Switch off the alarm
(Y page 69).
Unlocking and opening the doors
from the inside
X
Pull door handle ;.
If the door is locked, locking knob : pops
up. The door is unlocked and can be
opened.
For all countries except the United King-
dom:
You can open a door from inside the vehicle
even if it has been locked.
If

the vehicle has previously been locked with
the key, opening a door from the inside will
trigger the anti-theft alarm system. Switch off
the alarm ( Y page 69).
You can only open the rear doors from inside
the vehicle if they are not secured by the
child-proof locks (Y page 60).
Only for the United Kingdom: if the vehicle
has been locked with the key, the double lock
function is activated as standard. It is then
not possible to open the doors from inside the
vehicle. Deactivate the interior motion sensor
(Y page 70) before you lock the vehicle with
the key. The doors can then be opened from
the inside after the vehicle has been locked
from the outside. The anti-theft alarm system
is triggered if the door is opened from the
inside. Switch off the alarm (Y page 69). Centrally locking and unlocking the
vehicle from the inside
You can centrally lock or unlock the vehicle
from

the inside. This can be useful if you wish
to lock the vehicle before pulling away, for
example. X
To unlock: press button :.
X To lock: press button ;.
If all the doors and the tailgate are 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.
For all countries except the United King-
dom: you can open a door from inside the
vehicle even if it has been locked.
If the vehicle has previously been locked with
the key, opening a door from the inside will
trigger the anti-theft alarm system. Switch off
the alarm ( Y page 69).
Only for the United Kingdom: if the vehicle
has been locked with the key, the double lock
function is activated as standard. It is then
not possible to open the doors from inside the
vehicle. Deactivate the interior motion sensor
(Y page 70) before you lock the vehicle with
the key. The doors can then be opened from
the inside after the vehicle has been locked
from the outside. The anti-theft alarm system
is triggered if the door is opened from the
inside. Switch off the alarm (Y page 69). 80
Doors
Opening and closing