2012 MERCEDES-BENZ A CLASS Owners Manual

Display messages Possible causes/consequences and
M Solutionsj
Check trailer
hitch lock The trailer tow hitch is not correctly engaged.
A warning tone also sounds.
X
Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Apply the electric parking brake.
X Engage the trailer coupling's ball coupling in the end position
(Y page 203).
Otherwise, the trailer may detach itself. Ð
Power
steering mal‐
function See Own‐
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. &
inoperative Bat‐
tery low You have attempted to switch on the auxiliary heating or to acti-
vate

a departure time using the on-board computer after operating
the auxiliary heating twice.
X Let the engine run for 10 seconds.
The auxiliary heating is operational again. The on-board voltage is too low. The auxiliary heating has switched
itself off or cannot be switched on

(Y page 134).
X Drive for a longer distance.
The

battery is being charged. The auxiliary heating is operational
again as soon as the on-board electrical system voltage is suf-
ficient. &
inoperative

Refuel
vehicle There is too little fuel in the fuel tank. The auxiliary heating cannot
be switched on (
Y page 134).
X Refuel at the nearest filling station. Display messages
255
On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutions&
inoperative See
Owner's Man. The auxiliary heating has a temporary malfunction or is 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 heat-
ing, waiting several minutes between each attempt
(Y page 134).
X If the auxiliary heating does not switch on, consult a qualified
specialist workshop. Telephone No
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. ¥
Top

up washer fluid The washer fluid level in the washer fluid reservoir has dropped
below the minimum.
i
If, during the winter months, you do not add antifreeze to the
washer
fluid, it may freeze in the washer fluid container. In this
case, the Top up washer fluid display message may appear
in the multifunction display.
X Top up the washer fluid ( Y page 289).Wiper malfunction‐
ing The windscreen wipers are defective.
X
Visit a qualified specialist workshop. Hazard warning
lamps malfunction‐
ing The hazard warning lamps are faulty.
X
Visit a qualified specialist workshop. Key
Display messages Possible causes/consequences and
M Solutions+
Key does not
belong to vehicle You have put the wrong key in the ignition lock.
X
Use the correct key. +
Replace key The key needs to be replaced.
X
Visit a qualified specialist workshop.256
Display messages
On-board computer and displays

Warning and indicator lamps in the instrument cluster
Seat belts
Problem Possible causes/consequences and
M Solutionsü
Only for certain coun-
tries: the red seat belt
warning lamp lights up
for six seconds after
the engine starts.
The seat belt warning lamp reminds the driver and front passenger
to fasten their seat belts.
X
Fasten your seat belt ( Y page 46).ü
Only for certain coun-
tries: the red seat belt
warning lamp lights up
after the engine starts.
In addition, a warning
tone sounds for up to
six seconds.
The driver's seat belt is not fastened.
X
Fasten your seat belt ( Y page 46).
The warning tone ceases. ü
The red seat belt warn-
ing lamp lights up after
the engine starts, as
soon as the driver's or
the front-passenger
door is closed.
The driver or front passenger has not fastened their seat belt.
X
Fasten your seat belt ( Y page 46).
The warning lamp goes out. There are objects on the front-passenger seat.
X
Remove the objects from the front-passenger seat and stow
them in a secure place.
The warning lamp goes out. ü
The red seat belt warn-
ing
lamp flashes and an
intermittent audible
warning sounds. The driver or front passenger has not fastened their seat belt. At
the
same time, you are driving faster than 25 km/h or have briefly
driven faster than 25 km/h.
X Fasten your seat belt ( Y page 46).
The warning lamp goes out and the intermittent warning tone
ceases. There are objects on the front-passenger seat. At the same time,
you are driving faster than 25 km/h or have briefly driven faster
than 25 km/h

.
X Remove the objects from the front-passenger seat and stow
them in a secure place.
The warning lamp goes out and the intermittent warning tone
ceases. Warning and indicator lamps in the instrument cluster
257
On-board computer and displays Z

Safety systems
Problem Possible causes/consequences and
M SolutionsJ
The red brake system
warning
lamp is lit while
the engine is running. A
warning tone also
sounds. There is insufficient brake fluid in the brake fluid reservoir.
G WARNING
The braking efficiency may be impaired.
There is a risk of an accident.
X Pull over and stop the vehicle safely as soon as possible, paying
attention

to road and traffic conditions. Do not continue driving
under any circumstances.
X Secure the vehicle against rolling away ( Y page 162).
X Do not top up the brake fluid. Topping up will not rectify the
fault.
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction
display. !
The

yellow ABS warning
lamp is lit while the
engine is running. ABS (Anti-lock Brake System) has been deactivated due to a fault.
BAS
(Brake Assist), COLLISION PREVENTION ASSIST, ESP ®
(Elec-
tronic Stability Program), PRE-SAFE ®
, the HOLD function, hill start
assist, the adaptive brake lights and ESP ®
trailer stabilisation are
also therefore deactivated, for example.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
The

steerability and braking characteristics may be severely affec-
ted. The braking distance may increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop.
If the ABS control unit is faulty, there is also a possibility that other
systems, such as the navigation system or the automatic trans-
mission, will be unavailable. 258
Warning and indicator lamps in the instrument cluster
On-board computer and displays

Problem Possible causes/consequences and
M Solutions!
The
yellow ABS warning
lamp is lit while the
engine is running. ABS is temporarily unavailable. Therefore, BAS, COLLISION PRE-
VENTION
ASSIST, ESP ®
, EBD (electronic brake force distribution),
PRE-SAFE ®
, the HOLD function, hill start assist, the adaptive brake
lights and ESP ®
trailer stabilisation, for example, are also deacti-
vated.
Possible causes:
R Self-diagnosis is not yet complete.
R the on-board voltage may be insufficient
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The front and rear wheels could therefore
lock, for example, if you brake hard.
The

steerability and braking characteristics may be severely affec-
ted. The braking distance may increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is a risk of an accident.
X Carefully drive on a suitable stretch of road, making slight steer-
ing movements at a speed above 20 km/h.
The functions mentioned above are available again when the
warning lamp goes out.
If the warning lamp is still on:
X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
259
On-board computer and displays Z

Problem Possible causes/consequences and
M Solutions!
The
yellow ABS warning
lamp is lit while the
engine is running. A
warning tone also
sounds. EBD is faulty. Therefore, ABS, BAS, COLLISION PREVENTION
ASSIST,
ESP®
, PRE-SAFE ®
, the HOLD function, hill start assist, the
adaptive brake lights and ESP ®
trailer stabilisation, for example,
are not available either.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The front and rear wheels could therefore
lock, for example, if you brake hard.
The

steerability and braking characteristics may be severely affec-
ted. The braking distance may increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop. J֌!
The red brake warning
lamp, the yellow ESP
®
and ESP ®
OFF warning
lamps and the yellow
ABS warning lamp are
lit while the engine is
running. ABS and ESP
®
are malfunctioning. Therefore, BAS, COLLISION
PREVENTION ASSIST, EBD, PRE-SAFE ®
, the HOLD function, hill
start assist, the adaptive brake lights and ESP ®
trailer stabilisa-
tion, for example, are not available either.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The front and rear wheels could therefore
lock, for example, if you brake hard.
The

steerability and braking characteristics may be severely affec-
ted. The braking distance may increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop.260
Warning and indicator lamps in the instrument cluster
On-board computer and displays

Problem Possible causes/consequences and
M Solutions÷
The yellow ESP
®
warn-
ing lamp flashes while
the
vehicle is in motion. ESP
®
or traction control has intervened because there is a risk of
skidding or at least one wheel has started to spin.
Cruise control or DISTRONIC PLUS is deactivated.
X Only depress the accelerator pedal as far as necessary when
pulling away.
X Accelerate more gently while the vehicle is in motion.
X Adapt your driving style to suit the road and weather conditions.
X Do not deactivate ESP ®
.
For exceptions, see: ( Y page 65).å
The yellow ESP
®
OFF
warning

lamp is lit while
the engine is running. ESP
®
and ESP ®
trailer stabilisation are deactivated. ESP ®
will not
stabilise the vehicle if it starts to skid or if a wheel starts to spin.
G WARNING
If ESP ®
is deactivated, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Reactivate ESP ®
.
For exceptions, see: ( Y page 65).
X Adapt your driving style to suit the road and weather conditions.
If ESP ®
cannot be activated:
X Have ESP ®
checked at a qualified specialist workshop. M
AMG vehicles only:
The yellow SPORT han-
dling mode warning
lamp is lit while the
engine is running.
SPORT handling mode is activated.
G WARNING
When SPORT handling mode is switched on, ESP ®
is unable to
stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Only switch on SPORT handling mode in certain situations
(Y page 66). Warning and indicator lamps in the instrument cluster
261
On-board computer and displays Z

Problem Possible causes/consequences and
M Solutions֌
The yellow ESP
®
and
ESP ®
OFF warning
lamps are lit while the
engine is running. ESP
®
, BAS, COLLISION PREVENTION ASSIST, PRE-SAFE ®
, the
HOLD function, hill start assist, the adaptive brake lights and
ESP ®
trailer stabilisation are not available due to a malfunction.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the
functions listed above.
The
braking distance may thus increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop. ֌
The yellow ESP
®
and
ESP ®
OFF warning
lamps are lit while the
engine is running. ESP
®
, BAS, PRE-SAFE ®
, the HOLD function, hill start assist and
ESP ®
trailer stabilisation are temporarily unavailable.
The adaptive brake lights and COLLISION PREVENTION ASSIST
may also have failed.
ATTENTION ASSIST is deactivated.
Self-diagnosis is not yet complete.
G WARNING
The brake system continues to function normally, but without the
functions listed above.
The

braking distance may thus increase in an emergency braking
situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Carefully drive on a suitable stretch of road, making slight steer-
ing movements at a speed above 20 km/h.
The functions mentioned above are available again when the
warning lamp goes out.
If the warning lamp is still on:
X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop.262
Warning and indicator lamps in the instrument cluster
On-board computer and displays