engine MERCEDES-BENZ A CLASS 2012 Repair Manual

Problems with the transmission
Problem Possible causes/consequences and
M SolutionsThe transmission has
problems shifting gear. The transmission is losing oil.
X
Have the transmission checked at a qualified specialist work-
shop immediately. The acceleration ability
is deteriorating.
The transmission no
longer shifts into all of
the gears.
Reverse gear can no
longer be engaged. The transmission is in emergency mode.
X
Stop.
X Shift the transmission to position P.
X Switch off the engine.
X Wait at least 10seconds before restarting the engine.
X Shift the transmission to position D.
X Have the transmission checked at a qualified specialist work-
shop immediately. Refuelling
Important safety notes
G
WARNING
Fuel is highly flammable. If you handle fuel
incorrectly, there is a risk of fire and explo-
sion.
You must avoid fire, naked flames, creating
sparks and smoking. Switch off the engine
and,
if applicable, the auxiliary heating before
refuelling. G
WARNING
Fuels are poisonous and hazardous to health.
There is a danger of injury.
Do

not swallow fuel or let it come into contact
with skin, eyes or clothing. Do not inhale fuel
vapours. Keep fuels out of the reach of chil-
dren.
If you or others come into contact with fuel,
observe the following:
R Wash the fuel off any affected areas of skin
with water and soap immediately.
R If you get fuel in your eyes, rinse them thor-
oughly with clean water immediately. Seek
immediate medical attention. R
If fuel is swallowed, seek immediate medi-
cal attention. Do not induce vomiting.
R Change any clothing that has come into
contact with fuel immediately. G
WARNING
Electrostatic charge can cause sparks and
thereby ignite fuel vapours. There is a risk of
fire and explosion.
Always

touch the vehicle body before opening
the fuel filler flap or touching the fuel pump
nozzle. This discharges any electrostatic
charge that may have built up. G
WARNING
Vehicles with a diesel engine:
If you mix diesel fuel with petrol, the flash
point

of this fuel mixture is lower than that of
pure diesel fuel. When the engine is running,
components in the exhaust system may over-
heat unnoticed. There is a risk of fire.
Never refuel with petrol. Never add petrol to
diesel fuel.
! Do not use petrol to refuel vehicles with a
diesel engine. Do not use diesel to refuel
vehicles with a petrol engine. Do not switch Refuelling
159
Driving and parking Z

on the ignition if you accidentally refuel
with
the wrong fuel. Otherwise, the fuel will
enter the fuel system. Even small amounts
of the wrong fuel could result in damage to
the fuel system and the engine. The repair
costs are high. Notify a qualified specialist
workshop and have the fuel tank and fuel
lines drained completely.
! Overfilling the fuel tank could damage the
fuel system.
! Take care not to spill any fuel on painted
surfaces. You could otherwise damage the
paintwork.
! Use a filter when adding fuel from a fuel
can. The fuel lines and/or the diesel injec-
tion system could otherwise be blocked by
particles from the fuel can.
Do not get into the vehicle again during the
refuelling process. Otherwise, electrostatic
charge could build up again.
If you overfill the fuel tank, some fuel may
spray out when you remove the fuel pump
nozzle.
For further information on fuel and fuel quality
(Y page 339). Refuelling
Opening/closing the fuel filler flap :
To open the fuel filler flap
; Tyre pressure table
= To insert the fuel filler cap
? Fuel type to be refuelled The fuel filler flap is unlocked or locked auto-
matically
when you open or close the vehicle
with the key.
The position of the fuel filler cap is displayed
æ in the instrument cluster. The arrow
next to the filling pump indicates the side of
the vehicle.
Opening X
Switch off the engine.
X Remove the key from the ignition lock.
X Press the fuel filler flap in the direction of
arrow :.
The fuel filler flap swings up.
X Turn the fuel filler flap anti-clockwise and
remove it.
X Insert the fuel filler cap into holder on the
inside of fuel filler flap =.
X Completely insert the filler neck of the fuel
pump nozzle into the tank, hook in place
and refuel.
X Only fill the tank until the pump nozzle
switches off.
i Do not add any more fuel after the pump
stops filling for the first time. Otherwise,
fuel may leak out.
Closing X
Replace the cap on the filler neck and turn
clockwise until it engages audibly.
X Close the fuel filler flap.
i Close
the fuel filler flap before locking the
vehicle. 160
Refuelling
Driving and parking

Problems with the fuel and fuel tank
Problem Possible causes/consequences and
M SolutionsFuel is leaking from the
vehicle. The fuel line or the fuel tank is faulty.
G WARNING
Risk of explosion or fire.
X Turn the key to position 0 in the ignition lock and remove it
immediately
(Y page 143).
X Do not restart the engine under any circumstances.
X Consult a qualified specialist workshop. The engine does not
start. The fuel tank of a vehicle with a diesel engine has been run com-
pletely dry.
X
Refuel the vehicle with at least 5 litres of diesel.
X Turn the ignition on for approximately ten seconds
(Y page 143).
X Start the engine continuously for a maximum of ten seconds
until it runs smoothly.
or
X Start the engine using the touch-start function. To do this, turn
the key to position 3 in the ignition lock and then release it
immediately

(Y page 143).
If the engine does not start:
X Turn the ignition on again a maximum of ten seconds
(Y page 143).
X Start the engine again continuously for a maximum of ten sec-
onds until it runs smoothly.
or
X Start the engine again via the touch-start function.
If the engine does not start after three attempts:
X Consult a qualified specialist workshop. Refuelling
161
Driving and parking Z

Problem Possible causes/consequences and
M SolutionsThe fuel filler flap can-
not be opened. The fuel filler flap is not unlocked.
or
The key battery is discharged.
X
Unlock the vehicle (Y page 75).
or
X Unlock the vehicle using the emergency key element
(Y page 75). The fuel filler flap is unlocked, but the opening mechanism is jam-
med.
X
Consult a qualified specialist workshop. Parking
Important safety notes
G
WARNING
Flammable material such as leaves, grass or
twigs may ignite if they come into contact with
hot parts of the exhaust system or exhaust
gas flow. There is a risk of fire.
Park the vehicle so that no flammable mate-
rial can come into contact with hot vehicle
components. In particular, do not park on dry
grassland or harvested grain fields. G
WARNING
If you leave children unattended in the vehi-
cle, they may be able to set the vehicle in
motion if, for example, they:
R release the parking brake
R shift

the automatic transmission out of park
position P or shift manual transmission into
neutral
R start the engine
In addition, they may operate vehicle equip-
ment and become trapped. 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 unattended in the vehicle. !
Always secure the vehicle correctly
against

rolling away. Otherwise, the vehicle
or its drivetrain could be damaged.
To ensure that the vehicle is secured against
rolling away unintentionally:
R the electric parking brake must be applied.
R on vehicles with manual transmission,
engage first gear or reverse gear.
R on vehicles with automatic transmission,
the transmission must be in position P and
the transmission position display must
show P in the multifunction display.
R the key must be removed from the ignition
lock.
R on uphill or downhill gradients, the front
wheels must be turned towards the kerb. Switching off the engine
Important safety notes G
WARNING
The automatic transmission switches to neu-
tral
position N when you switch off the engine.
The vehicle may roll away. There is a risk of
an accident.
After switching off the engine, always switch
to parking position P. Prevent the parked vehi-162
Parking
Driving and parking

cle from rolling away by applying the parking
brake.
Vehicles with manual transmission X
Shift to either first gear or reverse gear R.
X Turn the key to position 0 in the ignition
lock and remove it.
The immobiliser is activated.
X Apply the electric parking brake.
Vehicles with automatic transmission All vehicles (except AMG vehicles)
X
Apply the electric parking brake.
X Shift the transmission to position P.Selector lever in AMG vehicles
AMG vehicles:
X
Apply the electric parking brake.
X Press P button :.
X Turn the key to position 0 in the ignition
lock and remove it.
The immobiliser is activated.
i If you switch the engine off with the trans-
mission in position R or D, the automatic
transmission shifts to N automatically.
If you then open one of the front doors or
remove the key from the ignition, the auto-
matic transmission shifts to P.
If you shift the automatic transmission to
N before switching off the engine, the auto-
matic transmission remains in N even if a
door is opened. Electric parking brake
General notes G
WARNING
If you leave children unattended in the vehi-
cle, they could set the vehicle in motion by,
for example:
R releasing the parking brake
R shifting an automatic transmission out of
parking position P
R shifting

a manual transmission into neutral
R starting the engine
They could also operate vehicle equipment.
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 unattended in the vehicle. i
The electric parking brake carries out a
function check at regular intervals when
the engine is switched off. Noises that
occur are normal.
Engaging/releasing manually Engaging
X
Push handle :.
When
the electric parking brake is applied,
the ! red indicator lamp lights up in the
instrument cluster.
i The electric parking brake can also be
applied when the key is removed. Parking
163
Driving and parking Z

Releasing
X
Pull handle :.
The red ! indicator lamp in the instru-
ment cluster goes out.
i You can only release the electric parking
brake when the key is in position 1 or 2 in
the ignition lock.
Applying automatically The electric parking brake is applied auto-
matically:
R
if DISTRONIC PLUS brings the vehicle to a
standstill (vehicles with automatic trans-
mission) or
R if
the HOLD function is keeping the vehicle
stationary.
In addition, at least one of the following con-
ditions must be fulfilled:
R the engine is switched off
R the driver's door is open and the seat belt
is not fastened
R there is a system malfunction
R the power supply is insufficient
R the vehicle is stationary for a lengthy
period.
The red ! indicator lamp in the instrument
cluster lights up.
i The electric parking brake is not automat-
ically applied if the engine is switched off
by the ECO start/stop function.
Releasing automatically i
The electric parking brake can only be
released automatically in vehicles with
automatic transmission.
The electric parking brake of your vehicle is
released

automatically when all of the follow-
ing conditions are fulfilled:
R the engine is running.
R the transmission is in position D or R.
R the seat belt is fastened.
R you depress the accelerator pedal. If the transmission is in position
R,
the tailgate
must be closed.
If your seat belt is not fastened, the following
conditions must be fulfilled to automatically
release the electric parking brake:
R the driver's door is closed.
R you have shifted out of transmission posi-
tion P or you have previously driven faster
than 3 km/h.
Emergency braking The vehicle can also be braked during an
emergency using the electric parking brake.
X
While driving, push handle :
of the electric
parking brake ( Y page 163).
i The vehicle is braked for as long as han-
dle : of the electric parking brake
pressed. The longer the electric parking
brake handle : is depressed, the greater
the braking force.
During braking:
R a warning tone sounds
R the Release parking brake message
appears
R the red ! indicator lamp in the instru-
ment cluster flashes
When

the vehicle has been braked to a stand-
still, the electric parking brake is engaged. Parking up the vehicle
If you leave the vehicle parked up for longer
than

four weeks, the battery may be damaged
by exhaustive discharging.
If you leave the vehicle parked up for longer
than six weeks, the vehicle may suffer dam-
age as a result of lack of use.
X Visit a qualified specialist workshop and
seek advice.
i You can obtain information about trickle
chargers from a qualified specialist work-
shop. 164
Parking
Driving and parking

Driving tips
General notes
G
WARNING
If you switch off the ignition while driving,
safety-relevant functions are only available
with
limitations, or not at all. This could affect,
for example, the power steering and the brake
boosting effect. You will require considerably
more effort to steer and brake. There is a risk
of an accident.
Do not switch off the ignition while driving. ECO display
The ECO display provides feedback on how
economical your driving characteristics are.
The ECO display assists you in achieving the
most economical driving style for the selec-
ted settings and prevailing conditions. Con-
sumption can be significantly influenced by
your driving style. Example: ECO display
The ECO display consists of three bars:
R
Acceleration
R Constant
R Coasting
The

percentage count is the mean value of the
three bar values. The three bars and the mean
value begin at the value of 50%. A higher per-
centage count indicates a more economical
driving style.
The ECO display does not indicate the actual
fuel consumption and a fixed percentage
count in the ECO display does not indicate a
fixed consumption figure. In addition to driving style, the consumption
is affected by many other factors, such as:
R
load
R tyre pressure
R cold start
R choice of route
R the use of electrical consumers
These

factors are not included in the ECO dis-
play.
The evaluation of your driving style takes the
following three categories into consideration:
R Acceleration (evaluation of all accelera-
tion processes):
-The bar fills up: moderate acceleration,
especially at higher speeds
- The bar empties: sporty acceleration
R Constant (assessment of driving behav-
iour at all times):
-The bar fills up: constant speed and
avoidance of unnecessary acceleration
and deceleration
- The bar empties: fluctuations in speed
R Coasting (assessment of all deceleration
processes):
-The bar fills up: anticipatory driving,
keeping your distance and early release
of the accelerator. The vehicle can coast
without use of the brakes
- The bar empties: frequent braking
i An economical driving style involves driv-
ing at a moderate engine speed.
To achieve a higher value in the categories
Acceleration and Constant:
R observe the gearshift recommendation.
R drive the vehicle in drive program E (vehi-
cles with automatic transmission).
i On long journeys at a constant speed, e.g.
on the motorway, only the bar for Con‐
stant will change.
i The ECO display summarises the driving
characteristics from the start of the journey
to its completion. Therefore, there are Driving tips
165
Driving and parking Z

dynamic changes in the bars at the start of
a
journey. During a prolonged driving time,
these changes are smaller. For more
dynamic changes, perform a manual reset.
For further information on the ECO display,
see ( Y page 212). Braking
Important safety notes G
WARNING
If you shift down on a slippery road surface in
an attempt to increase the engine's braking
effect, the drive wheels could lose their grip.
This

increases the risk of skidding and having
an accident.
Do not shift down for additional engine brak-
ing on a slippery road surface.
Downhill gradients Change into a lower gear in good time on long
and

steep downhill gradients. Take particular
note of this when driving a laden vehicle and
when towing a trailer. For vehicles with auto-
matic transmission, you need to have selec-
ted manual drive program M(Y page 156).
i This also applies if you have activated
cruise control, SPEEDTRONIC or DIS-
TRONIC PLUS.
This will use the braking effect of the engine,
so less braking will be required to prevent the
vehicle from gaining speed. This relieves the
load on the brake system and prevents the
brakes from overheating and wearing too
quickly.
i Briefly depressing the accelerator pedal
on downhill gradients while the manual
drive program M is temporarily activated
(vehicles with automatic transmission): the
automatic transmission may switch back to
the last active automatic drive program E
or S. The automatic transmission may shift to a higher gear. This can reduce the
engine's braking effect.
Heavy and light loads G
WARNING
The braking system can overheat if you leave
your foot on the brake pedal while driving.
This

increases the braking distance and could
even cause the braking system to fail. There
is a risk of an accident.
Never use the brake pedal as a footrest. Do
not simultaneously depress both the brake
pedal and the accelerator pedal while driving.
! Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
If heavy demands are made on the brakes, do
not park the vehicle immediately. Drive on for
a short while. This allows the airflow to cool
the brakes more quickly.
If the brakes have been used only moderately,
you should occasionally test their effective-
ness. To do this, brake more firmly from a
higher speed, paying attention to traffic con-
ditions. This improves the grip of the brakes.
Wet road surfaces If you have driven for a long time in heavy rain
without

braking, there may be a delayed reac-
tion from the brakes when braking for the first
time. This may also occur after a car wash or
after driving through deep water.
You have to depress the brake pedal more
firmly. Maintain a greater distance from the
vehicle in front.
After driving on a wet road or having the vehi-
cle washed, brake firmly while paying atten-
tion to the traffic conditions. This will warm
up the brake discs, thereby drying them more
quickly and protecting them against corro-
sion. 166
Driving tips
Driving and parking

Limited braking performance on salt-
treated roads
If you drive on salted roads, a layer of salt
residue may form on the brake discs and
brake pads. This can result in a significantly
longer braking distance.
R
Brake
occasionally to remove any possible
salt residue. Make sure that you do not
endanger other road users when doing so.
R Carefully depress the brake pedal and the
beginning and end of a journey.
R Maintain a greater distance to the vehicle
ahead.
New brake pads/linings New and replaced brake pads and discs only
reach

their optimum braking effect after sev-
eral hundred kilometres of driving. Compen-
sate for this by applying greater force to the
brake pedal.
For safety reasons, Mercedes-Benz recom-
mends that you only have brake pads/linings
fitted to your vehicle which have been
approved for Mercedes-Benz vehicles or
which correspond to an equivalent quality
standard. Brake pads/linings which have not
been approved for Mercedes-Benz vehicles or
which are not of an equivalent quality could
affect your vehicle's operating safety. Driving on wet roads
Aquaplaning If water has accumulated to a certain depth
on

the road surface, there is a danger of aqua-
planing occurring, even if:
R you are driving at low speeds
R the tyres have adequate tread depth
For this reason, do not drive in tyre ruts and
brake carefully. Driving on flooded roads !
Bear in mind that vehicles travelling in
front or in the opposite direction create
waves. This may cause the maximum per-
missible water depth to be exceeded.
These notes must be observed under all
circumstances. You could otherwise dam-
age

the engine, the electronics or the trans-
mission.
If you have to drive on stretches of road on
which water has collected, please bear in
mind that:
R the maximum permissible fording depth in
still water is 25 cm
R you should drive no faster than walking
pace Winter driving
General notes G
WARNING
If you shift down on a slippery road surface in
an attempt to increase the engine's braking
effect, the drive wheels could lose their grip.
This

increases the risk of skidding and having
an accident.
Do not shift down for additional engine brak-
ing on a slippery road surface. G
DANGER
If the exhaust pipe is blocked or adequate
ventilation is not possible, poisonous gases
such

as carbon monoxide (CO) may enter the
vehicle. This is the case, e.g. if the vehicle
becomes trapped in snow. There is a risk of
fatal injury.
If you leave the engine or the auxiliary heating
running, make sure the exhaust pipe and area
around the vehicle are clear of snow. To
ensure an adequate supply of fresh air, open
a window on the side of the vehicle that is not
facing into the wind. Driving tips
167
Driving and parking Z

Have your vehicle winterproofed at a qualified
specialist workshop at the onset of winter.
Observe the notes in the "Winter operation"
section (
Y page 320).
Driving with summer tyres Observe the notes in the "Winter operation"
section (
Y page 320).
Slippery road surfaces G
WARNING
If you shift down on a slippery road surface in
an attempt to increase the engine's braking
effect, the drive wheels could lose their grip.
This
increases the risk of skidding and having
an accident.
Do not shift down for additional engine brak-
ing on a slippery road surface.
If the vehicle threatens to skid or cannot be
stopped when moving at low speed:
X Vehicles with manual transmission:
shift to neutral.
X Vehicles with automatic transmission:
shift the transmission to position N.
X Try to bring the vehicle under control by
using corrective steering.
You should drive particularly carefully on slip-
pery road surfaces. Avoid sudden accelera-
tion, steering and braking manoeuvres.
The outside temperature indicator is not
designed to serve as an ice-warning device
and is therefore unsuitable for that purpose.
Changes in the outside temperature are dis-
played after a short delay.
Indicated temperatures just above the freez-
ing point do not guarantee that the road sur-
face is free of ice. The road may still be icy,
especially

in wooded areas or on bridges. You
should pay special attention to road condi-
tions when temperatures are around freezing
point.
i For more information on driving with
snow chains, see ( Y page 321). Driving systems
Cruise control
Important safety notes If you fail to adapt your driving style, cruise
control

can neither reduce the risk of an acci-
dent nor override the laws of physics. Cruise
control cannot take into account road,
weather or traffic conditions. Cruise control
is only an aid. You are responsible for the dis-
tance to the vehicle in front, for vehicle speed,
for braking in good time, and for staying in the
lane.
Do not use cruise control:
R in road and traffic conditions which do not
allow you to maintain a constant speed
(e.g. in heavy traffic or on winding roads).
R on smooth or slippery roads. Braking or
accelerating can cause the drive wheels to
lose traction and the vehicle could then
skid.
R when there is poor visibility, e.g. due to fog,
heavy rain or snow.
If there is a change of drivers, advise the new
driver of the speed stored.
General notes Cruise control maintains a constant road
speed

for you. It brakes automatically in order
to avoid exceeding the set speed. You must
select a lower gear in good time on long and
steep downhill gradients, especially if the
vehicle is laden or towing a trailer. For vehi-
cles with automatic transmission, you need
to have selected manual drive program
M(Y page 156). By doing so, you will make
use of the braking effect of the engine. This
relieves the load on the brake system and
prevents the brakes from overheating and
wearing too quickly.
Use cruise control only if road and traffic con-
ditions make it appropriate to maintain a
steady speed for a prolonged period. You can
store any road speed above 30 km/h. 168
Driving systems
Driving and parking