check engine MERCEDES-BENZ A-CLASS HATCHBACK 2012 Owner's Guide

Problem
Possible causes/consequences and
M
MSolutions !
The red indicator lamp
for the electric parking
brake flashes or is lit
and/or the yellow
warning lamp for the
electric parking brake
is lit. X
Observe the additional display messages in the multifunction
display. 6
The red SRS warning
lamp is lit while the
engine is running.
There is a malfunction in the SRS (Supplemental Restraint Sys-
tem).
G WARNING
The airbags or belt tensioners may either be triggered uninten-
tionally or, in the event of an accident, may not be triggered.
This poses an increased risk of injury. X Drive on carefully.
X Have SRS checked at a qualified specialist workshop immedi-
ately.
For further information about the Supplemental Restraint System, see (Y page 41). Warning and indicator lamps in the instrument cluster
263On-board computer and displays Z

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

Problem
Possible causes/consequences and
M
MSolutions 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 If the coolant temperature is below 120 †, you can continue
driving 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. Driving systems
Problem
Possible causes/consequences and
M MSolutions ·
The red distance warn-
ing lamp lights up while
the vehicle is in motion. The distance to the vehicle in front is too small for the speed
selected.
X Increase the distance. ·
The red distance warn-
ing lamp lights up while
the vehicle is in motion. A warning tone also
sounds. You are approaching a vehicle or a stationary obstacle in your line
of travel at too high a speed.
X Be prepared to brake immediately.
X Pay careful attention to the traffic situation. You may have to
brake or take evasive action. 266
Warning and indicator lamps in the instrument clusterOn-board computer and displays

X
Pull support strut ?out of bracket A.
X Lift up support strut ?and insert it into
yellow retaining clip =.
Closing the bonnet X
Raise the bonnet slightly and, at the same
time, remove support strut ?from yellow
retaining clip =.
X Swing support strut ?down and press it
into bracket Auntil it engages.
X Lower the bonnet and let it fall from a
height of approximately 20 cm.
X Check that the bonnet has engaged prop-
erly.
If the bonnet can be raised slightly, it is not
properly engaged. Do not press the bonnet closed. Open the bonnet again and close it
with a little more force. Engine oil
General notes Depending on your driving style, the vehicle
consumes up to 0.8
lof oil per 1,000 km. The
oil consumption may be higher than this when the vehicle is new or if you frequently drive at
high engine speeds.
Depending on the engine, the oil dipstick may be installed at a different location. When checking the oil level:
R park the vehicle on a level surface.
R the engine should be switched off for
approximately five minutes if the engine is
at normal operating temperature.
R if the engine is not at normal operating
temperature, e.g. if the engine was only
started briefly: wait about 30 minutes
before carrying out the measurement. 286
Engine compartmentMaintenance and care

Checking the oil level using the oil dip-
stick Example: vehicles with a petrol engine
Vehicles with a diesel engine (apart from the A 180
CDI BlueEFFICIENCY model with manual transmis-
sion) A 180 CDI BlueEFFICIENCY, manual transmission
X All models apart from the A 180 CDI
BlueEFFICIENCY model with manual
transmission: pull out oil dipstick :.
X A 180 CDI BlueEFFICIENCY model with
manual transmission: undo the oil filler
cap and pull it out together with integrated
oil dipstick :. X
Wipe off oil dipstick :.
X Slowly slide oil dipstick :into the guide
tube to the stop, and take it out again.
If the level is between MIN mark =and
MAX mark ;, the oil level is correct.
X If the oil level has dropped to MIN mark =
or below, top up with 1.0 litre of engine oil.
Adding engine oil G
WARNING
If engine oil comes into contact with hot com- ponents in the engine compartment, it may
ignite. There is a risk of fire and injury.
Make sure that engine oil does not spill out
over the filler neck. Allow the engine to cool
down and thoroughly clean the components
that have come into contact with engine oil
before you start the engine. H
Environmental note
When topping up the oil, take care not to spill
any. If oil enters the soil or waterways, it is
harmful to the environment.
! Only use engine oils and oil filters that
have been approved for vehicles with a ser-
vice system. You can obtain a list of the
engine oils and oil filters tested and
approved in accordance with the
Mercedes-Benz Specifications for Service
Products at any Mercedes-Benz Service
Centre.
Damage to the engine or exhaust system is caused by the following:
R using engine oils and oil filters that have
not been specifically approved for the
service system
R changing the engine oil and oil filter after
missing the change interval required by
the service system
R using engine oil additives
! Do not add too much oil. Topping up with
too much engine oil can result in damage to
the engine or to the catalytic converter.
Have excess engine oil siphoned off. Engine compartment
287Maintenance and care Z

Example: engine oil filler cap
X Turn cap :anti-clockwise and remove it.
X Top up the engine oil.
If the oil level is at or below the MIN mark on
the oil dipstick, top up with 1.0 litre of
engine oil.
X Replace cap :on the filler neck and turn
clockwise.
Make sure that the cap locks securely into
place.
X Check the oil level again with the oil dip-
stick (Y page 287).
For further information on engine oil, see
(Y page 343). Checking and adding other service
products
Checking the coolant level G
WARNING
The engine cooling system is under pressure, particularly if the engine is warm. You could
be scalded by hot coolant spraying out when
opening the cap. There is a danger of injury.
Allow the engine to cool before opening the
cap. Wear gloves and protective eyewear
when opening. Slowly turn the cap half a turn
to allow pressure to escape.
! The coolant level must only be checked
and corrected when the engine has cooled
down (coolant temperature under 40 †).
Checking the coolant level when the cool-
ant temperature is over 40 † can lead to damage to the engine or engine cooling
system.
Example
X Park the vehicle on a level surface.
Only check the coolant level if the vehicle is
on a level surface and the engine has
cooled down.
X Turn the key to position 2in the ignition
lock (Y page 143).
X Check the coolant temperature display in
the instrument cluster.
The coolant temperature must be below
40 †.
X Turn the key to position 0(Y page 143) in
the ignition lock.
X Slowly turn cap :half a turn anti-clock-
wise to allow excess pressure to escape.
X Turn cap :further anti-clockwise and
remove it.
If the coolant is at the level of marker bar =
in the filler neck when cold, there is enough coolant in coolant expansion tank ;.
X If necessary, top up with coolant that has
been tested and approved by Mercedes-
Benz.
X Replace cap :and turn it clockwise as far
as it will go.
For further information on coolant, see
(Y page 344). 288
Engine compartmentMaintenance and care

Displaying service messages
X
Switch the ignition on.
X Using =or;, select the Service
Service
menu.
X Press 9or: to select the ASSYST
ASSYST
PLUS
PLUS submenu and press ato confirm.
The service due date appears in the multi-
function display.
Information about Service Resetting the ASSYST PLUS service inter-
val display
! If the ASSYST PLUS service interval dis-
play has been inadvertently reset, this set-
ting can be corrected at a qualified special-
ist workshop.
Have service work carried out as described in the Service Booklet. This may otherwise
lead to increased wear and damage to the
major assemblies or the vehicle.
A qualified specialist workshop, e.g. a
Mercedes-Benz Service Centre, will reset the ASSYST PLUS service interval display after
the service work has been carried out. You
can also obtain further information on main-
tenance work, for example.
Special service requirements
The prescribed service interval is based on
normal operation of the vehicle. Service work
will need to be performed more often if the
vehicle is operated under arduous conditions or increased loads, for example:
R regular city driving with frequent intermedi-
ate stops
R if the vehicle is primarily used to travel
short distances
R for frequent operation in mountainous ter-
rain or on poor road surfaces
R if the engine is often left idling for long peri-
ods
In these or similar operating conditions, have
the air filter, engine oil and oil filter, for exam- ple, changed more frequently. The tyres must be checked more frequently if the vehicle is
operated under increased loads. Further
information can be obtained at a qualified
specialist workshop, e.g. a Mercedes-Benz
Service Centre.
Driving abroad
An extensive Mercedes-Benz Service network is also available in other countries. The Ser-
vice Hotline's current telephone numbers for
use when you are abroad are to be found in
the "Mercedes-Benz Service24h" section of
the Service Booklet. Care
General notes
H
Environmental note
Dispose of empty packaging and cleaning
cloths in an environmentally responsible man- ner.
! For cleaning your vehicle, do not use any
of the following:
R dry, rough or hard cloths
R abrasive cleaning agents
R solvents
R cleaning agents containing solvents
Do not scrub.
Do not touch the surfaces or protective
films with hard objects, e.g. a ring or ice
scraper. You could otherwise scratch or
damage the surfaces and protective film.
! Do not park up the vehicle for an extended
period straight after cleaning it, particularly after having cleaned the wheels with wheel
cleaner. Wheel cleaners could cause
increased corrosion of the brake discs and
brake pads/linings. For this reason, you
should drive for a few minutes after clean-
ing. Braking heats the brake discs and the
brake pads/linings, thus drying them. The
vehicle can then be parked up. 290
CareMaintenance and care

Flat tyre
Preparing the vehicle
Your vehicle may be equipped with: R MOExtended tyres (tyres with run-flat char-
acteristics) (Y page 300)
Vehicle preparation is not necessary on
vehicles with MOExtended tyres.
R a TIREFIT kit (Y page 299)
R an emergency spare wheel (only for certain
countries)
Information on changing/fitting a wheel
(Y page 325).
X Stop the vehicle as far away as possible
from traffic on solid, non-slippery and level
ground.
X Switch on the hazard warning lamps.
X Secure the vehicle against rolling away
(Y page 162).
X If possible, bring the front wheels into the
straight-ahead position.
X Switch off the engine.
X Remove the key from the ignition lock.
X All occupants must get out of the vehicle.
Make sure that they are not endangered as they do so.
X Make sure that no one is near the danger
area while a wheel is being changed. Any-
one who is not directly assisting in the
wheel change should, for example, stand
behind the barrier.
X Get out of the vehicle. Pay attention to traf-
fic conditions when doing so.
X Close the driver's door.
X Place the warning triangle a suitable dis-
tance away (Y page 298). Observe legal
requirements.
i Vehicles with MOExtended tyres are not
equipped with a TIREFIT kit at the factory. It
is therefore recommended that you addi-
tionally equip your vehicle with a TIREFIT kit if you fit tyres that do not feature run-flat
characteristics, e.g. winter tyres. A TIREFIT kit can be obtained from a qualified spe-
cialist workshop. MOExtended tyres (tyres with run-flat
characteristics)
General notes With MOExtended tyres (tyres with run-flat
characteristics), you can continue to drive
your vehicle even if there is a total loss of
pressure in one or more tyres. The affected
tyre must not show any clearly visible dam-
age.
You can recognise MOExtended tyres by the
MOExtended marking which appears on the
tyre wall. You will find this marking next to the
tyre size designation, the load-bearing capa-
city and the speed index.
MOExtended tyres may only be used in con-
junction with an active tyre pressure loss
warning system.
If the pressure loss warning message
appears in the multifunction display:
R Observe the instructions in the display
messages (Y page 251).
R Check the tyre for damage.
R If driving on, observe the following notes.
The maximum driving distance is approx-
imately 80 km when the vehicle is partially
laden and approximately 30 km when the
vehicle is fully laden.
In addition to the vehicle load, the driving dis-
tance possible depends upon:
R speed
R road condition
R outside temperature
The driving distance possible in run-flat mode may be reduced by extreme driving condi-
tions/manoeuvres, or it can be increased
through a moderate style of driving.
The maximum permissible distance which
can be driven in run-flat mode is counted from
the moment the tyre pressure loss warning
appears in the multifunction display. 300
Flat tyreBreakdown assistance

The highly flammable gas mixture is formed
when charging the battery or jump-starting
the vehicle.
Always make sure that neither you nor the
battery is electrostatically charged. Electro-
static charge is caused, for example, by:
R wearing synthetic clothing
R the friction of clothing on the seat
R pulling or sliding the battery over carpets or
other synthetic materials
R rubbing the battery with a cloth G
WARNING
During the charging process, a battery produ- ces hydrogen gas. If a short circuit occurs or
sparks are created, the hydrogen gas can
ignite. There is a risk of an explosion.
R Make sure that the positive terminal of a
connected battery does not come into con- tact with vehicle parts.
R Never place metal objects or tools on a bat-
tery.
R It is important that you observe the descri-
bed order of the battery terminals when
connecting and disconnecting a battery.
R When jump-starting, make sure that the
battery poles with identical polarity are
connected.
R It is particularly important to observe the
described order when connecting and dis-
connecting the jump leads.
R Never connect or disconnect the battery
terminals while the engine is running. G
WARNING
Battery acid is caustic. There is a risk of injury. Avoid contact with the skin, eyes or clothing.
Do not inhale any battery gases. Do not lean
over the battery. Keep children away from
batteries. Wash battery acid immediately with water and seek medical attention. 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 anenvironmentally 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.
! Have the battery checked regularly at a
qualified specialist workshop.
Observe the service intervals in the Service
Booklet or contact a qualified specialist
workshop for more information.
! Always have work on the battery carried
out at a qualified specialist workshop.
Should it, in exceptional circumstances, be
absolutely necessary to disconnect the bat-
tery yourself, please observe the following:
R switch off the engine and remove the
key. Check that all the indicator lamps in the instrument cluster are off. Otherwise,
you may damage electronic components such as the alternator, for example.
R first, disconnect the negative terminal
clamp, followed by the positive terminal
clamp. Never swap the terminal clamps.
The vehicle electronics may otherwise be
damaged.
R on vehicles with automatic transmission,
the transmission is locked in position P
after disconnecting the battery. The vehi-
cle is secured against rolling away. You
can then no longer move the vehicle.
The battery and the cover of the positive
terminal clamp must be fitted securely dur- ing operation. Battery (vehicle)
305Breakdown assistance Z