ignition MERCEDES-BENZ A-CLASS HATCHBACK 2012 User Guide

Problems with automatic child seat recognition
Problem
Possible causes/consequences and
M
MSolutions The
45 indica-
tor lamp on the centre
console is lit. A special Mercedes-Benz child restraint system with a trans-
ponder for automatic child seat recognition has been fitted to the
front-passenger seat. The front-passenger front airbag has there- fore been disabled as desired. G
WARNING
There is no child restraint system fitted to the front-passenger
seat. Automatic child seat recognition is malfunctioning.
It is also possible that the 6SRS warning lamp lights up and/
or the 45 PASSENGER AIRBAG OFF indicator lamp does
not light up briefly when you switch the ignition on.
There is a risk of injury.
X Remove electronic equipment from the front-passenger seat,
e.g.:
R Laptop
R Mobile phone
R Cards with transponders, such as ski passes or access cards
If the 45 indicator lamp remains lit:
X Visit a qualified specialist workshop. Suitable positioning of the child restraint systems
Key to the letters used in the table:
XS
eat which is unsuitable for children in this weight category.
US uitable for child restraint systems in the "Universal" category that are approved for use
in this weight category.
UF Suitable for forward-facing child restraint systems that belong to the "Universal" category and are approved for use in this weight category.
LS uitable for child restraint systems as recommended, see the following table of "Recom-
mended child restraint systems" (Y page 58).56
Children in the vehicleSafety

ally, further driving safety systems are deac-
tivated. There is an increased danger of skid- ding and accidents.
Drive on carefully. Have ABS checked imme-
diately at a qualified specialist workshop.
If ABS is malfunctioning, other systems,
including driving safety systems, will also
become inoperative. Observe the information on the ABS warning lamp (Y page 258) and
display messages which may be shown in the
instrument cluster (Y page 230).
ABS regulates brake pressure in such a way
that the wheels do not lock when you brake.
This allows you to continue steering the vehi-
cle when braking.
ABS works from a speed of about 8 km/h
upwards, regardless of road-surface condi-
tions. ABS works on slippery surfaces, even
when you only brake gently.
The ! ABS warning lamp in the instrument
cluster lights up when the ignition is switched on. It goes out when the engine is running.
Braking X
If ABS intervenes: continue to depress the
brake pedal with force until the braking sit- uation is over.
X To make a full brake application:
depress the brake pedal with full force.
If ABS intervenes when braking, you will feel a
pulsing in the brake pedal.
The pulsating brake pedal can be an indica-
tion of hazardous road conditions, and func-
tions as a reminder to take extra care while
driving. BAS (Brake Assist)
i Observe the "Important safety notes" sec-
tion (Y page 61). G
WARNING
If BAS is malfunctioning, the braking distance
in an emergency braking situation is
increased. There is a risk of accident.
In an emergency braking situation, depress
the brake pedal with full force. ABS prevents
the wheels from locking.
BAS operates in emergency braking situa-
tions. If you depress the brake pedal quickly,
BAS automatically boosts the braking force,
thus shortening the stopping distance.
The brakes will function as usual once you
release the brake pedal. BAS is deactivated. COLLISION PREVENTION ASSIST
General notes COLLISION PREVENTION ASSIST consists of
the adaptive Brake Assist and the distance
warning signal, which are described in the
following.
Distance warning function Important safety notes
i Observe the "Important safety notes" sec-
tion for driving safety systems (Y page 61). G
WARNING
The distance warning function does not react:
R to people or animals
R to oncoming vehicles
R to crossing traffic
R when cornering
Thus, the distance warning function cannot
provide a warning in all critical situations.
There is a risk of an accident.
Always pay careful attention to the traffic sit-
uation and be ready to brake. G
WARNING
The distance warning function cannot always
clearly identify objects and complex traffic
situations. 62
Driving safety systemsSafety

or adaptive Brake Assist, the brake lamps
flash rapidly. In this way, traffic travelling
behind you is warned in an even more notice-
able manner.
If you brake sharply from a speed of more
than 70 km/ht o a standstill, the hazard warn-
ing lamps are activated automatically. If the
brakes are applied again, the brake lamps
light up continuously. The hazard warning
lamps switch off automatically if you travel
faster than 10 km/h. You can also switch off
the hazard warning lamps using the hazard
warning switch button (Y page 108).
i Adaptive brake lamps are only available in
certain countries. ESP
®
(Electronic Stability Program)
General notes i
Observe the "Important safety notes" sec-
tion (Y page 61).
ESP ®
monitors driving stability and traction,
i.e. power transmission between the tyres
and the road surface.
If ESP ®
detects that the vehicle is deviating
from the direction desired by the driver, one
or more wheels are braked to stabilise the
vehicle. The engine output is also modified to keep the vehicle on the desired course within
physical limits. ESP ®
assists the driver when
pulling away on wet or slippery roads. ESP ®
can also stabilise the vehicle during braking.
ETS/4ETS (Electronic Traction System) i
Observe the "Important safety notes" sec-
tion (Y page 61).
ETS/4ETS traction control is part of ESP ®
.
ETS brakes the drive wheels individually if
they spin. This enables you to pull away and
accelerate on slippery surfaces, for example
if the road surface is slippery on one side. In
addition, more drive torque is transferred to
the wheel or wheels with traction. ETS remains active when you deactivate
ESP
®
.
Important safety notes G
WARNING
If ESP ®
is malfunctioning, ESP ®
is unable to
stabilise the vehicle. In addition, other driving
safety systems are switched off. This increa-
ses the risk of skidding and an accident.
Drive on carefully. Have ESP ®
checked at a
qualified specialist workshop.
! When testing the electric parking brake
on a braking dynamometer, switch off the
ignition. Application of the brakes by ESP ®
may otherwise destroy the brake system.
! Vehicles with 4MATIC: switch off the igni-
tion when the electric parking brake is
being tested using a dynamometer.
Application of the brakes by ESP ®
may oth-
erwise destroy the brake system.
! Vehicles with 4MATIC: function or per-
formance tests may only be carried out on
a 2-axle dynamometer. Before operating
the vehicle on such a dynamometer, please
consult a qualified specialist workshop.
You could otherwise damage the drive train
or the brake system.
! Do not tow vehicles with 4MATIC with the
front or rear axle raised.
Vehicles without 4MATIC: when towing your
vehicle with the front axle raised, it is impor-
tant that you observe the notes on
ESP ®
(Y page 312).
Vehicles with 4MATIC: when towing your
vehicle with both axles on the ground, it is
important that you observe the notes on
ESP ®
(Y page 312).
ESP ®
is deactivated if the åESP®
OFF
warning lamp in the instrument cluster lights up continuously when the engine is running. Driving safety systems
65Safety Z

Observe information regarding indicator and
warning lamps (Y page 258) as well as dis-
play messages (Y page 232).
EBD monitors and controls the brake pres-
sure on the rear wheels to improve driving
stability while braking. ADAPTIVE BRAKE
ADAPTIVE BRAKE enhances braking safety
and offers increased braking comfort. In addi-
tion to the braking function, ADAPTIVE BRAKE
also has the HOLD function (Y page 180) and
hill start assist (Y page 145). For further
information, see Driving tips (Y page 166).STEER CONTROL
STEER CONTROL helps you by transmitting a noticeable steering force to the steering
wheel in the direction required for vehicle
stabilisation.
This steering support is provided in particular
if:
R both right wheels or both left wheels are on
a wet or slippery road surface when you
brake
R the vehicle starts to skid.
If there is an ESP ®
malfunction, you will not
receive any steering support from STEER
CONTROL. Power steering will, however, con-
tinue to function. Anti-theft systems
Immobiliser
The immobiliser prevents your vehicle from
being started without the correct key.
X To activate: remove the key from the igni-
tion lock.
X To deactivate: switch on the ignition.
When leaving the vehicle, always take the key
with you and lock the vehicle. The engine can be started by anyone with a valid key that is
left inside the vehicle.
i The immobiliser is always deactivated
when you start the engine. ATA (Anti-Theft Alarm system)
X
To prime: lock the vehicle with the key.
Indicator lamp :flashes. The alarm sys-
tem is primed after approximately
15 seconds.
X To deactivate: unlock the vehicle with the
key.
or X Insert the key into the ignition 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. Anti-theft systems
69Safety Z

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.
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. 70
Anti-theft systemsSafety

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 syste
ms
71Safety 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 insert-
ing 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
KeyOpening 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
75Opening 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
KeyOpening and closing

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 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
79Opening and closing Z