2012 MERCEDES-BENZ B-CLASS coolant

!
A display message
is shown if the coolant
temperature is too high.
If the coolant temperature is over
248 ‡(120 †), do not continue driving. The
engine will otherwise be damaged.
The coolant temperature gage is in the
instrument cluster on the right-hand side.
Under normal operating conditions and with
the specified coolant level, the coolant
temperature may rise to 248 ‡ (120 †). Tachometer
! Do not drive in the overrevving range, as
this could damage the engine.
The red band

in the tachometer indicates the
engine's overrevving range.
The fuel supply is interrupted to protect the
engine when the red band is reached. Outside temperature display
You should pay special attention to road
conditions when temperatures are around
freezing point.
The outside temperature display is in the
multifunction display.
Changes in the outside temperature are
displayed after a short delay. Speedometer with segments
The segments in the speedometer indicate
which speed range is available.
R Cruise control activated ( Y page 157):
The segments light up from the stored
speed to the maximum speed.
R DISTRONIC PLUS activated (Y page 159):
One or two segments in the set speed
range light up.
R DISTRONIC PLUS detects

a vehicle in front:The segments between the speed of the
vehicle in front and the stored speed light
up. Operating the on-board computer
Overview :
Multifunction display
; Switches on the Voice Control System;
see the separate operating instructions
= Right control panel
? Left control panel
A Back button
X To activate the on-board computer: turn
the SmartKey to position 1 in the ignition
lock.
You

can control the multifunction display and
the settings in the on-board computer using
the buttons on the multifunction steering
wheel. Displays and operation
187
On-board computer and displays Z
ProCarManuals.com

Display messages Possible causes/consequences and
M Solutionsb
Switch Off Lights The lights are still switched on when you leave the vehicle. A
warning tone also sounds.
X
Turn the light switch to Ã. Adaptive Highbeam
Assist Inoperative Adaptive Highbeam Assist is faulty.
X
Visit a qualified specialist workshop. Adaptive Highbeam
Assist Currently
Unavailable See
Operator's Manual Adaptive Highbeam Assist is deactivated and temporarily
inoperative. Possible causes are:
R
the windshield in the camera's field of vision is dirty.
R visibility is impaired due to heavy rain, snow or fog.
X Clean the windshield.
If the system detects that the camera is fully operational again,
the Adaptive Highbeam Assist Now Available message is
displayed.
Adaptive Highbeam Assist is operational again. Engine
Display messages Possible causes/consequences and
M Solutions+
Check Coolant
Level See
Operator's Manual The coolant level is too low.
!
Avoid making long
journeys with too little coolant in the engine
cooling system. The engine will otherwise be damaged.
X Add coolant, observing the warning notes before doing so
(Y page 269).
X If coolant needs to be added more often than usual, have the
engine coolant system checked at a qualified specialist
workshop. ? The fan motor is faulty.
X
At coolant temperatures below 248 ‡ (120 †), drive to the
nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic.212
Display messages
On-board computer and displays
ProCarManuals.com

Display messages Possible causes/consequences and
M Solutions?
Coolant Too Hot
Stop Vehicle Turn
Engine Off The coolant is too hot.
A warning tone also sounds.
G WARNING
Do not drive when your engine is overheated. This can cause some
fluids which may have leaked into the engine compartment to
catch fire.
Steam from the overheated engine can also cause serious burns
which can occur just by opening the hood.
There is a risk of injury.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Y page 149).
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 snow, slush or ice.
X Do not start the engine again until the display message goes out
and the coolant temperature is below 248 ‡ (120 †).
Otherwise, the engine could 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 248 ‡ (120 †). # The battery is not being charged.
A warning tone also sounds.
Possible causes are:
R
a defective alternator
R a torn poly-V-belt
R a malfunction in the electronics
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Open the hood.
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 not damaged:
X Visit a qualified specialist workshop immediately. Display messages
213
On-board computer and displays Z
ProCarManuals.com

Engine
Problem Possible causes/consequences and
M Solutions;
The yellow Check
Engine warning lamp
lights up while the
engine is running.
There may be a malfunction, for example:
R
in the engine management
R in the fuel injection system
R in the exhaust system
R in the ignition system
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.
i In some states, you must immediately visit a qualified
specialist workshop as
soon as the yellow Check Engine warning
lamp lights up. This depends on the locally applicable legal
requirements. If in doubt, check whether such legal regulations
apply in the state in which you are currently driving. æ
The yellow reserve fuel
warning lamp lights up
while the engine is
running.
The fuel level has dropped into the reserve range.
X
Refuel at the nearest gas station. æ
The yellow reserve fuel
warning lamp flashes
while the engine is
running.
The fuel system pressure is too low. The fuel filler cap is not closed
correctly or the fuel system is leaking.
X
Check that the fuel filler cap is correctly closed.
X If the fuel filler cap is not correctly closed:
close the

fuel filler
cap.
X If the fuel filler cap is closed: visit a qualified specialist
workshop. ?
The red coolant
warning lamp lights up
while the engine is
running and
the

coolant
temperature gage is at
the start of the scale. The temperature sensor for the coolant temperature gage is
defective.
The coolant
temperature
is no longer being monitored. There is a
risk of engine damage if the coolant temperature is too high.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to

road and traffic conditions. Do not continue
driving under any circumstances.
X Secure the vehicle against rolling away ( Y page 149).
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
231
On-board computer and displays Z
ProCarManuals.com

Problem Possible causes/consequences and
M Solutions?
The red coolant
warning lamp
comes
on
while the engine is
running. 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
malfunctioning.
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 Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Y page 149).
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and add coolant (Y page 269). Observe
the warning notes.
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X Do not start the engine again until the coolant temperature is
under

248 ‡
(120 †). Otherwise, the engine could be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic. ?
The red coolant
warning lamp
comes

on
while the engine is
running. A warning tone
also sounds. The coolant temperature has exceeded 248 ‡ (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.
Do not drive
when your engine is overheated. This can cause some
fluids which may have leaked into the engine compartment to
catch fire.
Vapor from the overheated engine can also cause serious burns
which can occur just by opening the hood.
There is a risk of injury.
X Observe the additional display messages in the multifunction
display.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Y page 149).232
Warning and indicator lamps in the instrument cluster
On-board computer and displays
ProCarManuals.com

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 add coolant (Y page 269). Observe
the warning notes.
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X At
coolant temperatures under 248 ‡ (120 †),
drive to the next
qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic. Driving systems
Problem Possible causes/consequences and
M Solutions·
The red distance
warning 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. Warning and indicator lamps in the instrument cluster
233
On-board computer and displays Z
ProCarManuals.com

Checking and adding other service
products
Checking coolant level G
WARNING
The engine cooling system is pressurized,
particularly when the engine is warm. When
opening the cap,
you could be scalded by hot
coolant spraying out. There is a risk of injury.
Let the engine cool down before opening the
cap. Wear eye and hand protection when
opening the cap. Open the cap slowly half a
turn to allow pressure to escape.
! The coolant may only be checked and
corrected when the engine is cool (coolant
temperature below 104 ‡ (40 †).
Checking the coolant when the coolant
temperature is above 104 ‡ (40 †) may
result in damage to the engine or to the
engine cooling system. Example
X
Park the vehicle on a level surface.
Only check the coolant level when the
vehicle is on

a level surface and the engine
has cooled down.
X Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X Check the coolant temperature display in
the instrument cluster.
The coolant temperature must be below
104 ‡ (40 †).
X Turn the SmartKey to position
0 (

Y page 135) in the ignition lock. X
Slowly turn cap : half a turn counter-
clockwise to allow excess pressure to
escape.
X Turn cap : further counter-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, add 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 333).
Adding washer fluid to the windshield
washer system/headlamp cleaning
system G
WARNING
Windshield 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 windshield washer
concentrate is spilled next to the filler neck. Example
X
To open: pull cap : upwards by the tab.
X Add the premixed washer fluid.
X To close:
press cap :
onto the filler neck
until it engages. Engine compartment
269
Maintenance and care Z
ProCarManuals.com

Cleaning the wheels
!
Do not use
acidic wheel cleaning products
to remove brake dust. This could damage
wheel bolts and brake components.
! Do not park 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
cleaning. Braking heats the brake discs and
the brake pads/linings, thus drying them.
The vehicle can then be parked.
Cleaning the paintwork !
Do not affix:
R stickers
R films
R magnetic plates or similar items
to painted surfaces. You could otherwise
damage the paintwork.
X Remove dirt immediately, where possible,
while avoiding rubbing too hard.
X Soak insect remains with insect remover
and rinse off the treated areas afterwards.
X Soak bird droppings with water and rinse
off the treated areas afterwards.
X Remove coolant, brake fluid, tree resin,
oils, fuels and greases by rubbing gently
with a cloth soaked in petroleum ether or
lighter fluid.
X Use tar remover to remove tar stains.
X Use silicone remover to remove wax.
X Use a suitable touch-up stick, e.g. MB
Touch-Up Stick, to repair slight damage to
the paintwork quickly and provisionally.
The following cannot always be completely
repaired:
R scratches
R corrosive deposits R
areas affected by corrosion
R damage caused by inadequate care
In such cases, visit a qualified specialist
workshop.
If water no

longer forms "beads" on the paint
surface, use the paint care products
recommended and approved by Mercedes-
Benz. This is the case approximately every
three to five months, depending on the
climate conditions and the care product used.
If the dirt has penetrated the paint surface or
if the paintwork has become dull, then the
paintwork should be cleaned. For cleaning,
please use the paint cleaner recommend and
approved by Mercedes Benz.
Do not use these care products in the sun or
on the hood while the hood is hot.
Matte finish care !
Never polish the vehicle or the light alloy
wheels. Polishing causes the finish to
shine.
! The following may cause the paint to
become shiny and thus reduce the matte
effect:
R Vigorous rubbing with unsuitable
materials.
R Frequent use of car washes.
R Washing the vehicle in direct sunlight.
! Never use paint cleaner, buffing or
polishing products, or

gloss preserver, e.g.
wax. These products are only suitable for
high-gloss surfaces. Their use on vehicles
with matte finish leads to considerable
surface damage (shiny, spotted areas).
Always have paintwork repairs carried out
at a qualified specialist workshop.
! Do not use wash programs with a hot wax
treatment under any circumstances.
Observe these notes if your vehicle has a
clear matte finish. This will help you to avoid
damage to the paintwork due to incorrect
treatment. Care
273
Maintenance and care Z
ProCarManuals.com