2012 MERCEDES-BENZ B-CLASS warning

i
If the power supply has been interrupted,
e.g. if you reconnect the battery, you will
have to:
R set the clock (audio system/COMAND,
see the
separate operating instructions).
R reset the function for folding the exterior
mirrors in/out automatically, by folding
the mirrors out once ( Y page 93).Charging the battery
G
WARNING
During charging and jump-starting, explosive
gases can escape

from the battery. There is a
risk of an explosion.
Particularly avoid fire, open flames, creating
sparks and smoking. Ensure there is sufficient
ventilation while charging and jump-starting.
Do not lean over a battery. 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. G
WARNING
A discharged battery can freeze at
temperatures below freezing point. When
jump-starting the vehicle or charging the
battery, gases can escape from the battery.
There is a risk of an explosion.
Allow the frozen battery to thaw out before
charging it or jump-starting.
! Only use battery chargers with a
maximum charging voltage of 14.8 V.
! Only charge the battery using the jump-
starting connection point.
The jump-starting connection point is in the
engine compartment (Y

page 289). X
Open the hood (Y page 266).
X Connect the battery charger to the positive
terminal and ground point in the same
order as when connecting the donor
battery in the jump-starting procedure
(Y page 289).
If, at low temperatures, the indicator lamps/
warning lamps in the instrument cluster do
not light up, it is highly likely that the
discharged battery has frozen. In this case
you may neither jump-start the vehicle nor
charge the battery. The service life of a
thawed-out battery may be shorter. The
starting characteristics can be impaired,
particularly at low temperatures. Have the
thawed-out battery checked at a qualified
specialist workshop.
Only charge the installed battery with a
battery charger which has been tested and
approved by Mercedes-Benz. An accessory
battery charge unit specially adapted for
Mercedes-Benz vehicles and tested and
approved by Mercedes-Benz is available. It
permits the charging of the battery in its
installed position. Contact an authorized
Mercedes-Benz Center for further
information and availability.

Read the battery
charger's operating instructions before
charging the battery. 288
Battery (vehicle)
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Jump-starting
For the jump-starting
procedure, use only the jump-starting connection point, consisting of a
positive terminal and an earth point, in the engine compartment. 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. G
WARNING
During charging and jump-starting, explosive gases can escape from the battery. There is a risk
of an explosion.
Particularly avoid fire, open flames, creating sparks and smoking. Ensure there is sufficient
ventilation while charging and jump-starting. Do not lean over a battery. G
WARNING
During the charging process, a battery produces 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 contact with
vehicle parts.
R Never place metal objects or tools on a battery.
R It is important

that you observe the described 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 disconnecting
the jumper cables.
R Never connect or disconnect the battery terminals while the engine is running. G
WARNING
A discharged battery can freeze at temperatures below freezing point. When jump-starting the
vehicle or charging

the battery, gases can escape from the battery. There is a risk of an explosion.
Allow the frozen battery to thaw out before charging it or jump-starting. G
WARNING
Non-combusted fuel can collect in the exhaust system and ignite. There is a risk of fire. Avoid
repeated and lengthy starting attempts.
! Avoid repeated and

lengthy starting attempts. Otherwise, the catalytic converter could be
damaged by the non-combusted fuel.
If, at low temperatures, the indicator lamps/warning lamps in the instrument cluster do not
light up, it is highly likely that the discharged battery has frozen. In this case you may neither
jump-start the vehicle nor charge the battery. The service life of a thawed-out battery may be Jump-starting
289
Breakdown assistance Z
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Position number
B identifies the charged battery of the other vehicle or an equivalent jump-
starting device.
X Press together cover : of positive clamp ; and slide it back.
X Connect positive terminal ; on your vehicle to positive terminal = of donor battery B
using the jumper cable, beginning with your own battery.
X Start the engine of the donor vehicle and run it at idling speed.
X Connect negative terminal ? of
donor
battery B to ground point A of your vehicle using
the jumper cable, connecting the jumper cable to donor battery B first.
X Start the engine.
X Before disconnecting the jumper cables, let the engine run for several minutes.
X First, remove the jumper cables from earth point A and negative terminal ?, then from
positive clamp ; and positive terminal =. Begin each time at the contacts on your own
vehicle first.
X Close cover : of positive terminal ; after removing the jumper cables.
X Have the battery checked at a qualified specialist workshop.
i Jump-starting is not considered to be a normal operating condition.
i Jumper cables and further information regarding jump-starting can be obtained at any
qualified specialist workshop. Towing and tow-starting
Important safety notes
G
WARNING
Functions relevant to safety are restricted or
no longer available if:
R the engine is not running.
R the brake system or the power steering is
malfunctioning.
R there is a

malfunction in the voltage supply
or the vehicle's electrical system.
If your vehicle is being towed, much more
force may be necessary to steer or brake.
There is a risk of an accident.
In such cases, use a tow bar. Before towing,
make sure that the steering moves freely. G
WARNING
If the weight of the vehicle to be towed or tow-
started is greater than the permissible gross
weight of your vehicle:
R the towing eye could detach itself
R the vehicle/trailer combination could
rollover.
There is a risk of an accident.
When towing or tow-starting another vehicle,
its weight should not be greater than the
permissible gross weight of your vehicle.
Information on your vehicle's gross vehicle
weight rating can be found on the vehicle
identification plate ( Y page 328). G
WARNING
The vehicle is braked if the HOLD function is
activated. Therefore, deactivate HOLD if the
vehicle is to be towed. Towing and tow-starting
291
Breakdown assistance Z
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Towing the vehicle with the front axle
raised
! The ignition must be switched off if the
vehicle is being towed with the front axle
raised. Otherwise, ESP®

may intervene and
damage the brake system.
X Turn the SmartKey to position 2 in the
ignition lock.
X When the vehicle is stationary, depress the
brake pedal and keep it depressed.
X Shift the automatic transmission to
position P.
X Release the brake pedal.
X Release the electric parking brake.
X Deactivate automatic locking
(Y page 198).
X Switch on the hazard warning lamps
(Y page 101).
X Turn the SmartKey to position 0 in the
ignition lock and

leave the SmartKey in the
ignition lock.
When towing your vehicle with the front axle
raised, it is important that you observe the
safety instructions ( Y page 291).Towing a vehicle with both axles on
the ground
G
WARNING
The power assistance for the steering and the
brake force booster do not work when the
engine is not running. You will then need
much more effort to brake and steer the
vehicle. Adapt your style of driving
accordingly.
i In order to signal a change of direction
when towing with

the hazard warning lamps
switched on, use the combination switch as
usual. In this case, only the turn signals for
the desired direction flash. When you reset
the combination switch, the hazard
warning lamps start flashing again. The automatic transmission automatically
shifts
to position P

when you open the driver's
or front-passenger door or when you remove
the SmartKey from the ignition lock. In order
to ensure that the automatic transmission
stays in position N when towing the vehicle,
you must observe the following points:
X Make sure that the vehicle is stationary.
X Turn the SmartKey to position 2 in the
ignition lock.
X Depress and hold the brake pedal.
X Shift the automatic transmission to
position N.
X Leave the SmartKey in position 2 in the
ignition lock.
X Release the brake pedal.
X Release the electric parking brake.
X Switch on the hazard warning lamps
(Y page 101).
It is important that you observe the safety
instructions when towing away your vehicle
(Y page 291). Transporting the vehicle
! Only lash the

vehicle down by the wheels
or wheel rims, not by parts of the vehicle
such as axle or steering components.
Otherwise, the vehicle could be damaged.
X Turn the SmartKey to position 2 in the
ignition lock.
X Shift the transmission to position N.
As soon as the vehicle is loaded:
X Prevent the vehicle from rolling away by
applying the electric parking brake.
X Shift the transmission to position P.
X Turn the SmartKey to position 0 in the
ignition lock and remove it.
X Secure the vehicle.
The towing eye can be used to pull the vehicle
onto a trailer or transporter for transporting
purposes. Towing and tow-starting
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Breakdown assistance Z
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Tow-starting (emergency engine
starting)
! Vehicles with automatic transmission
must not be tow-started. You could
otherwise damage the automatic
transmission.
When tow-starting, it is important that you
observe the safety
instructions (Y page 291).Fuses
Important safety notes
G
WARNING
If you manipulate or bridge a faulty fuse or if
you replace it with a fuse with a higher
amperage, the electric cables could be
overloaded. This could result in a fire. There
is a risk of an accident and injury.
Always replace faulty

fuses with the specified
new fuses having the correct amperage.
! Only use fuses that have been approved
for Mercedes-Benz vehicles and which
have the correct fuse rating for the system
concerned. Only use fuses marked with an
"S". Otherwise, components or systems
could be damaged.
The fuses in your vehicle serve to close down
faulty circuits. If a fuse blows, all the
components on the circuit and their functions
stop operating.
Blown fuses must be replaced with fuses of
the same rating, which you can recognize by
the color and value. The fuse ratings are listed
in the fuse allocation chart.
If a newly inserted fuse also blows, have the
cause traced and rectified at a qualified
specialist workshop, e.g. an authorized
Mercedes-Benz Center. Before changing a fuse
X Secure the vehicle against rolling away
(Y page 149).
X Switch off all electrical consumers.
X Turn the SmartKey to position 0 in the
ignition lock and remove it (Y page 135).
All indicator lamps

in the instrument cluster
must be off.
The fuses are located in various fuse boxes:
R Fuse box in

the engine compartment on the
left-hand side of the vehicle, when viewed
in the direction of travel
R Fuse box in the front-passenger footwell
The fuse allocation chart is on the fuse box in
the front-passenger footwell ( Y page 295). Fuse box in the engine compartment
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.
! Make sure that

no moisture can enter the
fuse box when the cover is open.
! When closing the cover, make sure that it
is lying correctly on the fuse box. Moisture
seeping in or dirt could otherwise impair
the operation of the fuses. 294
Fuses
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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).Important safety notes
G
WARNING
If wheels and tires of the wrong size are used,
the wheel brakes or suspension components
may be damaged. There is a risk of an
accident.
Always replace wheels and tires with those
that fulfill the specifications of the original
part.
When replacing wheels,

make sure to use the
correct:
R designation
R model
When replacing tires, make sure to use the
correct:
R designation
R manufacturer
R model G
WARNING
A flat tire severely impairs the driving,
steering and braking characteristics of the
vehicle. There is a risk of accident.
Tires without run-flat characteristics:
R do not drive with a flat tire.
R immediately replace the flat tire with your
emergency spare wheel or spare wheel, or
consult a qualified specialist workshop. Tires with run-flat characteristics:
R
pay attention to the information and
warning notices on

MOExtended tires (tires
with run-flat characteristics).
Accessories that are not approved for your
vehicle by Mercedes-Benz or are not being
used correctly can impair the operating
safety.
Before purchasing and using non-approved
accessories, visit a qualified specialist
workshop and inquire about:
R suitability
R legal stipulations
R factory recommendations
Information on dimensions and types of
wheels and tires for your vehicle can be found
(Y page 323).
Information on air pressure for the tires on
your vehicle can be found:
R on the vehicle's Tire and Loading
Information placard on the B-pillar
R on the tire pressure label on the fuel filler
flap
R under "Tire pressure"
i Further information on wheels and tires
can be obtained at any qualified specialist
workshop. Operation
Information on driving
R If the vehicle is heavily loaded, check the
tire pressures and correct them if
necessary.
R While driving, pay attention to vibrations,
noises and unusual handling
characteristics, e.g. pulling to one side.
This may indicate that the wheels or tires
are damaged. If you suspect that a tire is
defective, reduce your speed immediately.
Stop the vehicle as soon as possible to
check the wheels and tires for damage.
Hidden tire damage could also be causing298
Operation
Wheels and tires
ProCarManuals.com

the unusual handling characteristics. If you
find no signs of damage, have the wheels
and tires checked at a qualified specialist
workshop.
R When parking your
vehicle, make sure that
the tires do not get deformed by the curb
or other obstacles. If it is necessary to drive
over curbs, speed humps or similar
elevations, try to do so slowly and at an
obtuse angle. Otherwise, the tires,
particularly the sidewalls, may be
damaged. Regular checking of wheels and tires
G
WARNING
Damaged tires can cause tire inflation
pressure loss. As a result, you could lose
control of your vehicle. There is a risk of
accident.
Check the tires regularly for signs of damage
and replace any damaged tires immediately.
Regularly check the wheels and tires of your
vehicle for damage

at least once a month, as
well as after driving off-road or on rough
roads. Damaged wheels can cause a loss of
tire pressure. Pay particular attention to
damage such as:
R cuts in the tires
R punctures
R tears in the tires
R bulges on tires
R deformation or severe corrosion on wheels
Regularly check the tire tread depth and the
condition of the tread across the whole width
of the tire (Y page 299). If necessary, turn
the front wheels to full lock in order to inspect
the inner side of the tire surface.
All wheels must have a valve cap to protect
the valve against dirt and moisture. Do not
mount anything onto the valve other than the
standard valve cap or other valve caps
approved by Mercedes-Benz for your vehicle. Do not use any other valve caps or systems,
e.g. tire pressure monitoring systems.
Regularly check the pressure of all the tires
particularly prior
to

long trips. Adjust the tire
pressure as necessary ( Y page 301).
The service life of tires depends, among other
things, on the following factors:
R Driving style
R Tire pressure
R Distance covered Tire tread
G
WARNING
Insufficient tire tread will reduce tire traction.
The tire is no longer able to dissipate water.
This means that

on wet road surfaces, the risk
of hydroplaning increases, in particular where
speed is not adapted to suit the driving
conditions. There is a risk of accident.
If the tire pressure is too high or too low, tires
may exhibit different levels of wear at
different locations on the tire tread. Thus, you
should regularly check the tread depth and
the condition of the tread across the entire
width of all tires.
Minimum tire tread depth for:
R Summer tires: â in (3 mm)
R M+S tires: ã in (4 mm)
For safety reasons, replace the tires before
the legally prescribed limit for the minimum
tire tread depth is reached. Operation
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Wheels and tires Z
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Bar indicator : for tread wear is integrated
into the tire tread.
Treadwear indicators (TWI) are required by
law. Six indicators are positioned on the tire
tread. They are visible once the tread depth
is approximately
á
in (1.6 mm). If this is the
case, the tire is so worn that it must be
replaced. Selecting, mounting and replacing
tires
R Only mount tires and wheels of the same
type and make.
Exception: it is permissible to mount a
different type or

make in the event of a flat
tire. Observe the "MOExtended tires (tires
with run-flat characteristics" section
(Y page 281).
R Only mount tires of the correct size onto
the wheels.
R After mounting new tires, break in them in
at moderate speeds for the first 60 miles
(100 km), as they only reach their full
performance after this distance.
R Do not drive with tires which have too little
tread depth, as this significantly reduces
the traction on wet roads (hydroplaning).
R Replace the tires after six years at the
latest, regardless of wear. MOExtended tires (tires with run-flat
properties)
With MOExtended tires (tires with run flat
characteristics), you can continue to drive
your vehicle even if there is a total loss of
pressure in one or more tires.
MOExtended tires may only be used in
conjunction with an active tire pressure loss
warning system and only on wheels
specifically tested by Mercedes-Benz.
Notes on driving with MOExtended tires with
a flat tire ( Y page 281). i
Vehicles equipped with

MOExtended tires
are not equipped with a TIREFIT kit at the
factory. It is therefore recommended that
you additionally equip your vehicle with a
TIREFIT kit if you mount tires that do not
feature run-flat properties, e.g. winter tires.
A TIREFIT kit can be obtained from a
qualified specialist workshop. Winter operation
General notes
Have your vehicle

winterproofed at a qualified
specialist workshop at the onset of winter.
Observe the notes in the "Changing a wheel"
section ( Y page 319). Driving with summer tires
At temperatures below

45 ‡ (+7 †), summer
tires lose elasticity and therefore traction and
braking power. Change the tires on your
vehicle to M+S tires. Using summer tires at
very cold temperatures could cause cracks to
form, thereby damaging the tires
permanently. Mercedes-Benz cannot accept
responsibility for this type of damage. M+S tires
G
WARNING
M+S tires with a tire tread depth of less than
ã in (4

mm) are not suitable for use in winter
and do not provide sufficient traction. There
is a risk of an accident.
M+S tires with a tread depth of less than ã
in (4 mm) must be replaced immediately.
At temperatures below 45 ‡ (+7 †), use
winter tires or all-season tires. Both types of
tire are identified by the M+S marking.
Only winter tires bearing the i snowflake
symbol in addition to the M+S marking
provide the best possible grip in wintry road
conditions. Only these tires will allow driving 300
Winter operation
Wheels and tires
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