2012 MERCEDES-BENZ A-CLASS HATCHBACK ECU

Tyres
Display messages
Possible causes/consequences and
M
MSolutions Tyre pressure
Tyre pressure
Check tyres Check tyres The tyre pressure loss warning system has detected a significant
loss in pressure.
A warning tone also sounds.
G WARNING
With tyre pressures which are too low, there is a risk of the fol-
lowing hazards: R the tyres may burst, especially as the load and vehicle speed
increase.
R the tyres may wear excessively and/or unevenly, which may
greatly impair tyre traction.
R the driving characteristics, as well as steering and braking, may
be greatly impaired.
There is a risk of an accident.
X Stop the vehicle without making any sudden steering or braking
manoeuvres. Pay attention to the traffic conditions as you do so.
X Secure the vehicle against rolling away (Y page 162).
X Check the tyres and, if necessary, follow the instructions for a
flat tyre (Y page 300).
X Check the tyre pressures and, if necessary, correct the tyre
pressure.
X Restart the tyre pressure loss warning system when the tyre
pressure is correct (Y page 323).Check tyre pres‐ Check tyre pres‐
sures sures
then restart Run then restart Run
Flat Indicator Flat Indicator The tyre pressure loss warning system generated a display mes-
sage and has not been restarted since.
X Set the correct tyre pressure in all four tyres.
X Restart the tyre pressure loss warning system (Y page 323).Run Run
Flat
Flat Indicator
Indicator
inoperative
inoperative The tyre pressure loss warning system is faulty.
X Visit a qualified specialist workshop. Display
messages
251On-board computer and displays Z

Vehicle
Display messages
Possible causes/consequences and
M
MSolutions To start engine,
To start engine,
shift to either P shift to either P
or N or N You have attempted to start the engine with the transmission in
position Ror D.
X Shift the transmission to position Por N. Auxiliary battery
Auxiliary battery
malfunction malfunction The auxiliary battery for the automatic transmission is no longer
being charged.
X Visit a qualified specialist workshop at the next opportunity.
X Until then, set the automatic transmission to position Pbefore
you switch off the engine.
X Before leaving the vehicle, apply the electric parking brake. Depress brake to
Depress brake to
start engine start engine You have attempted to start the engine with the transmission in
position Nwithout depressing the brake pedal.
X Depress the brake pedal. To shift out of P
To shift out of P
or N or N
depress brake and depress brake and
start engine start engine You have attempted to shift the transmission to position
Ror D
without starting the engine.
X Start the engine.
X Depress the brake pedal.
i It is only possible to shift the transmission from position
Pto
the desired position if you depress the brake pedal. Only then
can the parking lock be deactivated. If you do not depress the
brake pedal, the DIRECT SELECT lever can still be moved but the parking lock remains engaged.
i At transmission fluid temperatures below
Ò20 † you can only
shift out of position Pinto another transmission position when
the engine is running. Apply brake to Apply brake to
deselect Park (P) deselect Park (P)
position position You have attempted to move the transmission selector lever to
position
R,Nor Dwithout depressing the brake pedal.
X Depress the brake pedal. Risk of vehicle Risk of vehicle
rolling rolling
Transmission not Transmission not
in P in P The driver's door is open and the transmission is in position
R,N or
D.
A warning tone also sounds. X Shift the transmission to position P.
X Secure the vehicle against rolling away (Y page 162).252
Display messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions Without changing
Without changing
gear, gear,
consult workshop consult workshop You cannot change the transmission position due to a malfunction.
A warning tone also sounds.
If transmission position Dis selected:
X Drive to a qualified specialist workshop without shifting the
transmission from position D.
If transmission position R,Nor Pis selected:
X Consult a qualified specialist workshop. Only select Park Only select Park
(P) when (P) when
vehicle vehicle
is
isstation‐
station‐
ary
ary The vehicle is moving.
X
Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Shift the transmission to position P.Reversing not Reversing not
poss. poss.
Consult
Consult work‐
work‐
shop
shop The automatic transmission is malfunctioning. You cannot drive in
reverse.
X Visit a qualified specialist workshop. Transmission Mal‐
Transmission Mal‐
function function The automatic transmission is malfunctioning.
X Visit a qualified specialist workshop. Transmission mal‐
Transmission mal‐
function Stop function Stop The automatic transmission is malfunctioning.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 162).
X Consult a qualified specialist workshop. Stop
Stop
vehicle
vehicle Shift
Shift
to P Leave engine
to P Leave engine
running running The automatic transmission has overheated.
X Drive on carefully.
If the display message disappears, the automatic transmission
is available again.
If the display message continues to be displayed:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 162).
X Wait until the automatic transmission has cooled off and the
display message goes out. Display
messages
253On-board computer and displays Z

Warning and indicator lamps in the instrument cluster
Seat belts
Problem
Possible causes/consequences and
M
MSolutions ü
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
257On-board computer and displays Z

Safety systems
Problem
Possible causes/consequences and
M
MSolutions J
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 clusterOn-board computer and displays

Engine
Problem
Possible causes/consequences and
M
MSolutions ;
The yellow engine diag-
nostics warning lamp
lights up while the
engine is running. There may be a fault, for example:
R in the engine management
R in the fuel injection system
R in the exhaust system
R in the ignition system (for vehicles with petrol engines)
R in the fuel system
The emission limit values may be exceeded and the engine may be running in emergency mode.
X Have the vehicle checked as soon as possible at a qualified
specialist workshop. Vehicles with a diesel engine: the fuel tank has been run dry
(Y
page 161).
X Start the engine three to four times after refuelling.
If the yellow engine diagnostics warning lamp goes out, emer-
gency running mode is cancelled. The vehicle need not be
checked. æ
The yellow reserve fuel
warning lamp lights up
while the engine is run-
ning.
The fuel level has dropped into the reserve range.
Operation of the auxiliary heating is deactivated when the fuel level drops into the reserve range.
X Refuel at the nearest filling station. ?
The red coolant warn-
ing lamp lights up while
the engine is running
and the coolant tem-
perature gauge is at the start of the scale. The temperature sensor for the coolant temperature gauge is
faulty.
The coolant temperature is no longer being monitored. There is a risk of engine damage if the coolant temperature is too high.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine. Do not continue driving
under any circumstances.
X Secure the vehicle against rolling away (Y page 162).
X Consult a qualified specialist workshop. 264
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Problem
Possible causes/consequences and
M
MSolutions ?
The red coolant warn-
ing lamp comes on
while the engine is run-
ning.
The coolant level is too low.
If the coolant level is correct, the airflow to the engine radiator may
be blocked or the electric engine radiator fan may be malfunc-
tioning.
The coolant is too hot and the engine is no longer being cooled
sufficiently.
X Observe the additional display messages in the multifunction
display.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Secure the vehicle against rolling away (Y page 162).
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and top up the coolant (Y page 288).
Observe the warning notes as you do so.
X If you have to top up the coolant frequently, have the engine
cooling system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by frozen slush.
X Do not start the engine again until the coolant temperature is
below 120 †. The engine may otherwise be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in
mountainous terrain and stop-start traffic. ?
The red coolant warn-
ing lamp comes on
while the engine is run-
ning. A warning tone
also sounds.
The coolant temperature has exceeded 120 †. The airflow to the
engine radiator may be blocked or the coolant level may be too
low.
G WARNING
The engine is not being cooled sufficiently and may be damaged.
Never drive with an overheated engine. Driving when your engine is overheated can cause some fluids which may have leaked into
the engine compartment to catch fire.
Steam from an overheated engine can cause serious burns which
can occur just by opening the bonnet.
This poses a risk of injury.
X Observe the additional display messages in the multifunction
display.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Secure the vehicle against rolling away (Y page 162).Warning and indicator lamps in the instrument cluster
265On-board computer and displays 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). Loading guidelines
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. G
WARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. If the tailgate is open when the engine is running, particu-
larly if the vehicle is moving, exhaust fumes
could enter the passenger compartment.
There is a risk of poisoning.
Turn off the engine before opening the tail-
gate. Never drive with the tailgate open.
The handling characteristics of a laden vehi-
cle are dependent on the distribution of the
load within the vehicle. For this reason, you
should observe the following notes when
transporting a load:
R when transporting a load, never exceed the
maximum permissible gross vehicle weight or the permissible axle loads for the vehicle
(including occupants).
R the luggage compartment is the preferred
place to carry objects.
R position heavy loads as far forwards as pos-
sible and as low down in the luggage com-
partment as possible.
R the load must not protrude above the upper
edge of the seat backrests.
R always place the load against the rear or
front seat backrests. Make sure that the
seat backrests are securely locked into
place.
R always place the load behind unoccupied
seats if possible.
R use the lashing eyelets and the luggage
nets to transport loads and luggage.
R only use lashing eyelets and fastening com-
ponents that are suitable for the weight and size of the load.
R the maximum load capacity of the stowage
well under the luggage compartment floor
is 25 kg.
R secure the load with sufficiently strong and
wear-resistant lashing material. Pad sharp
edges for protection.
i Lashing material is available at any quali-
fied specialist workshop.
! Do not position the load on one part of the
folding luggage compartment floor only.
The maximum load capacity of the folding
luggage compartment floor is 100 kg.
Spread the weight evenly to avoid damag-
ing the luggage compartment floor. Place a
solid board under the load if necessary.
Please note that the load on the luggage
compartment floor will be increased when
the load is lashed down. 268
Loading guidelinesStowing and features