2012 MERCEDES-BENZ A CLASS coolant temperature

Display messages Possible causes/consequences and
M Solutions?
Coolant Stop vehi‐
cle Switch engine
off The coolant is too hot.
A warning tone also sounds.
G WARNING
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.
There is a risk of injury.
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 Wait until the engine has cooled down.
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 display message goes out
and the coolant temperature is below

120 †. The engine may
otherwise be damaged.
X Pay attention to the coolant temperature display.
X If the temperature increases again, visit a qualified specialist
workshop immediately.
Under normal operating conditions and with the specified coolant
level, the coolant temperature may rise to
120 †.# The battery is not being charged.
A warning tone also sounds.
Possible causes:
R
faulty alternator
R torn poly-V-belt
R a malfunction in the electronics
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Open the bonnet.
X Check whether the poly-V-belt is torn.
If the poly-V-belt is torn:
! Do

not continue driving. The engine could otherwise overheat.
X Consult a qualified specialist workshop.
If the poly-V-belt is OK:
X Visit a qualified specialist workshop immediately.244
Display messages
On-board computer and displays

Engine
Problem Possible causes/consequences and
M Solutions;
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 cluster
On-board computer and displays

Problem Possible causes/consequences and
M Solutions?
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 mal-
functioning.
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
265
On-board computer and displays Z

Problem Possible causes/consequences and
M SolutionsX
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 Solutions·
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 cluster
On-board computer and displays

to the engine or to the catalytic converter.
Have excess engine oil siphoned off.
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 2 in 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 compartment
Maintenance and care

Model Replacement
amount A 180 BlueEFFICIENCY
A 200 BlueEFFICIENCY
5.8 l
A 250 BlueEFFICIENCY
5.6 l
A 180 CDI BlueEFFI-
CIENCY, manual trans-
mission
4.5 l
A 180 CDI BlueEFFI-
CIENCY, automatic
transmission
A 200 CDI BlueEFFI-
CIENCY
A 220 CDI BlueEFFI-
CIENCY
7.0 l
A 45 AMG 4MATIC
5.5 l
Additives
!
Do not use any additives with the engine
oil. This could damage the engine.
Engine oil viscosity Viscosity describes the flow characteristics
of
a fluid. If an engine oil has a high viscosity
rating, it flows slowly; the lower the viscosity,
the faster it flows.
Engine oil selection is based on the respective
outside temperatures and in accordance with
the SAE classification (viscosity). The table
shows you which SAE classifications are to be
used. The low-temperature properties of engine oils can be significantly impaired dur-
ing operation due to, for example, ageing or
soot and fuel accretion. It is therefore
strongly

recommended to observe regular oil
changes using an approved engine oil with the
appropriate SAE classification. Brake fluid
G
WARNING
The brake fluid continuously absorbs mois-
ture from the air. This results in the boiling
point

of the brake fluid lowering. If the boiling
point of the brake fluid is too low, vapour
pockets may form when the brakes are sub-
jected to a heavy load. This would impair brak-
ing efficiency. There is a risk of an accident.
Have the brake fluid renewed at the prescri-
bed intervals.
When handling brake fluid, observe the
important safety notes on service products
(Y page 338).
The brake fluid change intervals can be found
in the Service Booklet.
Only use brake fluid approved by Mercedes-
Benz according to MB Approval 331.0.
Information about approved brake fluid can
be obtained at any qualified specialist work-
shop or on the Internet at:
http://bevo.mercedes-benz.com.
i Have the brake fluid regularly replaced at
a qualified specialist workshop. Coolant
Important safety notes G
WARNING
If antifreeze comes into contact with hot com-
ponents in the engine compartment, it may
ignite. There is a risk of fire and injury.
Let the engine cool down before you top up
the antifreeze. Make sure that antifreeze is
not spilled next to the filler neck. Thoroughly 344
Service products and capacities
Technical data

clean the antifreeze from components before
starting the engine.
! Only
add coolant that has been premixed
with the desired antifreeze protection. You
could otherwise damage the engine.
Further information on coolants can be
found in the Mercedes-Benz Specifications
for Service Products, MB Specifications for
Service Products 310.1, e.g. on the Inter-
net at http://bevo.mercedes-benz.com.
Or contact a qualified specialist workshop.
! Always use a suitable coolant mixture,
even in countries where high temperatures
prevail.
Otherwise, the engine cooling system is not
sufficiently protected from corrosion and
overheating.
! The engine cooling system is filled with
coolant, which must be renewed after
15 years or after 250,000 kilometres at the
latest.
When handling coolant, observe the impor-
tant safety notes on service products
(Y page 338).
The coolant is a mixture of water and anti-
freeze/corrosion inhibitor. It performs the
following tasks:
R anti-corrosion protection
R antifreeze protection
R raising the boiling point
If antifreeze/corrosion inhibitor is present in
the correct concentration, the boiling point of
the coolant during operation will be approx-
imately 130 †.
The antifreeze/corrosion inhibitor concentra-
tion in the engine cooling system should:
R be at least 50%. This will protect the engine
cooling system against freezing down to
approximately -37 †.
R not exceed 55% (antifreeze protection
down to -45 †). Heat will otherwise not be
dissipated as effectively. If the vehicle has lost coolant, top it up with
equal amounts of water and antifreeze/cor-
rosion inhibitor.
Mercedes-Benz recommends an antifreeze/
corrosion inhibitor concentrate in accord-
ance
with MB Specifications for Service Prod-
ucts 310.1.
The coolant is checked at every maintenance
interval at a qualified specialist workshop.
i When the vehicle is first delivered, it is fil-
led with a coolant mixture that ensures
adequate antifreeze and corrosion protec-
tion. Windscreen washer system and head-
lamp cleaning system
Important safety notes G
WARNING
Windscreen washer concentrate is highly
flammable. If it comes into contact with hot
engine components or the exhaust system it
could ignite. There is a risk of fire and injury.
Make sure that no windscreen washer con-
centrate is spilled next to the filler neck.
! Only use washer fluid that is suitable for
plastic lamp lenses, e.g. MB SummerFit or
MB WinterFit. Unsuitable washer fluid
could damage the plastic lenses of the
headlamps.
! Do

not use distilled or de-ionised water in
the washer fluid reservoir. Otherwise, the
level sensor may be damaged.
! Only the washer fluids SummerFit and
WinterFit can be mixed. Otherwise, the
spraying nozzles could become blocked.
When handling washer fluid, observe the
important safety notes on service products
(Y page 338). Service products and capacities
345
Technical data Z