2012 MERCEDES-BENZ B-CLASS engine

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
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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
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Useful information
i This Operator's Manual describes all
models and all standard and optional
equipment of your vehicle available at the
time of publication of the Operator's
Manual. Country-specific differences are
possible. Please note
that your vehicle may
not be equipped with all features
described. This also applies to safety-
related systems and functions.
i Read the information on qualified
specialist 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,
particularly in the event of sudden braking or
a sudden change in direction.
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,
particularly 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
tailgate. Never drive with the tailgate open.
The handling characteristics of a laden
vehicle 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 Never exceed the maximum permissible
gross vehicle weight or the gross axle weight rating of the vehicle (including
occupants). The
values

are specified on the
vehicle identification plate on the B-pillar of
the driver's door.
R The cargo compartment is the preferred
place to carry objects.
R Position heavy loads as far forwards as
possible and as low down in the cargo
compartment 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 cargo tie down rings and the parcel
nets to transport loads and luggage.
R Use cargo tie-down rings and fastening
materials appropriate for the weight and
size of the load.
R Hook in the cargo net when loading.
R The maximum load capacity of the stowage
well under the cargo compartment floor is
55 lbs (25 kg).
R Secure the load with sufficiently strong and
wear-resistant tie-downs. pad sharp edges
for protection.
! Do not position the load on one part of the
folding cargo compartment floor only. The
maximum load capacity of the folding cargo
compartment floor is 220 lbs (100 kg).
Distribute the weight evenly to avoid
damaging the cargo compartment floor.
Place a solid board under the load if
necessary. Please note that the load on the
cargo compartment floor will be increased
when the load is lashed down. 236
Loading guidelines
Stowage and features
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i
If you remove the ashtray insert, you can
use the resulting compartment for
stowage.
Rear-compartment ashtray X
To open: pull cover = out by its top edge.
X To remove: pull insert ; by recess : in
the direction of arrow ? until it audibly
releases.
X Lift insert ; up and out.
X To install the insert: place
insert ;
from
above into the holder and press down until
it engages. Cigarette lighter
G
WARNING
You can burn yourself if you touch the hot
heating element or

the socket of the cigarette
lighter.
In addition, flammable materials can ignite if:
R the hot cigarette lighter falls
R a child holds the hot cigarette lighter to
objects, for example
There is a risk of fire and injury.
Always hold the cigarette lighter by the knob.
Always make sure that the cigarette lighter is
out of reach of children. Never leave children
unsupervised in the vehicle.
Your attention must always be focused on the
traffic conditions. Only use the cigarette lighter when road and traffic conditions
permit.
Example: vehicles with a cover over the stowage
compartment
X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To open: push the lower section of
cover :.
The stowage compartment opens.
X Press in cigarette lighter ;.
Cigarette lighter ; will pop out
automatically when the heating element is
red-hot. 12 V sockets
Points to observe before use X
Turn the SmartKey to position 1 in the
ignition lock (Y page 135).
The sockets can be used for accessories with
a maximum draw of 180 W (15 A).
Accessories include such items as lamps or
chargers for mobile phones.
If you use the sockets for long periods when
the engine is switched off, the battery may
discharge.
i An emergency cut-out ensures that the
on-board voltage does not drop too low. If
the on-board voltage is too low, the power
to the sockets is automatically cut. This
ensures that there is sufficient power to
start the engine. 250
Features
Stowage and features
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simultaneously. Different settings are
possible for each area.
USA only: these settings can be called up
under "Owners Online" at http://
www.mbusa.com.
Alternatively, you can trigger an MB Info call
and inform the customer service
representative that you wish to activate geo
fencing.
Currently inactive areas can be activated by
SMS.
Triggering the vehicle alarm
With this function, you can trigger the
vehicle's panic alarm via SMS. An alarm
sounds and the exterior lighting flashes.
Depending on the setting, the panic alarm
lasts five or ten seconds. Afterwards, the
alarm switches off.
Garage door opener
Important safety notes G
WARNING
When you operate or program the garage door
with the integrated garage door opener,
persons in the range of movement of the
garage door can
become trapped or struck by
the garage door. There is a risk of injury.
When using the integrated garage door
opener, always make sure that nobody is
within the range of movement of the garage
door. G
WARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Inhaling
these exhaust gases

leads to poisoning. There
is a risk of fatal injury. Therefore never leave
the engine running in enclosed spaces
without sufficient ventilation.
The HomeLink ®
garage door opener
integrated in the rear-view mirror allows you to operate up to three different door and gate
systems.
Only operate garage doors using the
integrated garage door opener if:
R
they are equipped with a safety stop and
reverse feature, and
R they conform to the current U.S. safety
standards.
When programming a garage door opener,
park vehicle outside the garage.
i Certain garage door drives are
incompatible with the integrated garage
door opener. If you have difficulty
programming the integrated garage door
opener, contact an authorized Mercedes-
Benz Center.
Alternatively, you can call the following
telephone assistance services:
R USA: Mercedes-Benz Customer
Assistance Center at
1-800-FOR-MERCedes
R Canada: Customer Service at
1-800-387-0100
R HomeLink ®
hotline 1-800-355-3515
(free of charge)
More information on HomeLink ®
and/or
compatible products is also available
online at http://www.homelink.com.
i Notes on the declaration of conformity
( Y

page 23).
Programming Programming buttons
Observe the "Important safety notes"
(Y page 260).260
Features
Stowage and features
ProCarManuals.com

Useful information ............................
266
Engine compartment ........................ 266
Maintenance ...................................... 270
Care .................................................... 271 265Maintenance and care
ProCarManuals.com

Useful information
i This Operator's Manual describes all
models and all standard and optional
equipment of your vehicle available at the
time of publication of the Operator's
Manual. Country-specific differences are
possible. Please note
that your vehicle may
not be equipped with all features
described. This also applies to safety-
related systems and functions.
i Read the information on qualified
specialist workshops: ( Y page 24).Engine compartment
Hood
Important safety notes G
WARNING
If the hood is unlatched, it may open up when
the vehicle is in motion and block your view.
There is a risk of an accident.
Never unlatch the hood while driving. G
WARNING
When opening and closing the hood, it may
suddenly fall into

the closed position. There is
a risk of injury to persons within range of
movement of the hood.
Open and close the hood only when no one is
within its range of movement. G
WARNING
Certain components in the engine
compartment, such as the engine, radiator
and parts of

the exhaust system, can become
very hot. Working in the engine compartment
poses a risk of injury.
Where possible, let the engine cool down and
touch only the components described in the
following. G
WARNING
Opening the hood when the engine is
overheated or when there is a fire in the
engine compartment could

expose you to hot
gases or other service products. There is a
risk of injury.
Let an overheated engine cool down before
opening the hood. If there is a fire in the
engine compartment, keep the hood closed
and contact the fire department. G
WARNING
The engine compartment contains moving
components. Certain components, such as
the radiator fan, may continue to run or start
again suddenly when

the ignition is off. There
is a risk of injury.
If you need to do any work inside the engine
compartment,
R switch off the ignition
R never reach into the area where there is a
risk of danger from moving components,
such as the fan rotation area
R keep clothing away from moving parts G
WARNING
The ignition system and the fuel injection
system work under

high voltage. If you touch
components which are under voltage, you
could get an electric shock. There is a risk of
injury.
Never touch components of the ignition
system or fuel injection system when the
ignition is switched on.
Opening the hood G
WARNING
When the hood is open and the windshield
wipers are set in motion, you can be injured
by the wiper linkage. There is a risk of injury.
Always switch off the windshield wipers and
the ignition before opening the hood. 266
Engine compartment
Maintenance and care
ProCarManuals.com

!
Make sure that
the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield
wipers or the hood. X
Make sure that the windshield wipers are
switched off.
X Pull release lever : on the hood.
The hood is released. X
Reach into the gap between the hood and
the radiator trim and press hood catch
lever ; to the left.
X Raise the hood. X
Pull support strut ? out of bracket A.
X Lift up support strut ? and insert it into
yellow retaining clip =.
Closing the hood X
Raise the hood slightly and, at the same
time, remove support strut ? from yellow
retaining clip =.
X Swing support strut ? down and press it
into bracket A until it engages.
X Lower the hood and let it fall from a height
of approximately 8 in (20 cm).
X Check that

the hood has engaged properly.
If the hood can be raised slightly, it is not
properly engaged. Do not press the hood
closed. Open the hood again and close it
with a little more force. Engine oil
General notes Depending on the driving style, the vehicle
consumes up to 0.9 US qt (0.8 liters) of oil
over a

distance of 600 miles (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 in 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. Engine compartment
267
Maintenance and care Z
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