2012 MERCEDES-BENZ B-CLASS battery

The stop/start function is automatically
activated each
time
you start the engine with
the SmartKey.
If the ECO start/stop function has been
manually deactivated ( Y page 138) or a
malfunction has caused the system to be
deactivated, the ¤ symbol is not
displayed.
Automatic engine switch-off General notes
The ECO start/stop function is operational
and the ¤ symbol is displayed in the
multifunction display, if:
R
the indicator lamp in the ECO button is lit
green.
R the outside temperature is within the
comfort range.
R the engine is at normal operating
temperature.
R the set temperature

for the vehicle interior
has been reached.
R the battery is sufficiently charged.
R the system detects that the windshield is
not fogged up when the air-conditioning
system is switched on.
R the hood is closed.
R the driver's door is closed and the driver's
seat belt is fastened.
If conditions for automatic engine switch-off
have not been fulfilled, the ¤ symbol will
not be shown.
i All of the vehicle's systems remain active
when the engine has been stopped
automatically.
i The engine can be switched off
automatically a maximum of four times
(first stop and three subsequent stops) in
succession. Automatic engine switch-off is
possible again once the ECO symbol
appears in the multifunction display. Vehicles with automatic transmission
If the vehicle is braked to a standstill in
D or
N, the ECO start/stop function switches off
the engine automatically.
i The HOLD function

can be activated if the
engine has been switched off
automatically. It is then not necessary to
continue applying the brakes during the
automatic stop phase. When you depress
the accelerator pedal, the engine starts
automatically and the braking effect of the
HOLD function is deactivated.
Automatic engine start General notes
The engine starts automatically if:
R
you switch off

the ECO start/stop function
by pressing the ECO button.
R you engage reverse gear R.
R the vehicle starts to roll.
R the brake system requires this.
R the temperature in the vehicle interior
deviates from the set range.
R the system detects moisture on the
windshield when the air-conditioning
system is switched on.
R the condition of charge of the battery is too
low.
R the driver's seat belt is removed or the
driver's door is opened.
Vehicles with automatic transmission
The engine is started automatically if you:
R release the brake pedal when HOLD is not
activated and the transmission is in
position D or N.
R depress the accelerator pedal.
R move the transmission out of position P.
i Shifting the transmission to position P
does not start the engine.
i If you shift the transmission from R to D,
the ECO start/stop function is available Driving
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Problems with the engine
Problem Possible causes/consequences and
M SolutionsThe engine does not
start. The HOLD function or DISTRONIC PLUS is activated.
X
Deactivate the HOLD function (Y page 167) or DISTRONIC
PLUS (Y page 159).
X Try to start the engine again. The engine does not
start.
The starter
motor
can be heard. R
There is a malfunction in the engine electronics.
R There is a malfunction in the fuel supply.
X Turn the SmartKey back to position 0
in the

ignition lock before
attempting to start the engine again.
X Try to start the engine again (Y page 135). Avoid excessively
long and frequent

attempts to start the engine as these will drain
the battery.
If the engine does not start after several attempts:
X Consult a qualified specialist workshop. The engine does not
start. You cannot hear
the starter motor. The on-board voltage is too low because the battery is too weak
or discharged.
X
Jump-start the vehicle (Y page 289).
If the engine does not start despite attempts to jump-start it:
X Consult a qualified specialist workshop, e.g. an authorized
Mercedes-Benz Center. The starter motor was exposed to a thermal load that was too high.
X
Allow the starter motor to cool down for approximately two
minutes.
X Try to start the engine again.
If the engine still does not start:
X Consult a qualified specialist workshop. Driving
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Problems with fuel and the 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 SmartKey to position 0
in the
ignition lock immediately
and remove it (Y page 135).
X Do not restart the engine under any circumstances.
X Consult a qualified specialist workshop. The fuel filler flap
cannot be opened. The fuel filler flap is not unlocked.
or
The SmartKey battery is discharged.
X
Unlock the vehicle (Y page 68).
or
X Unlock the vehicle using the mechanical key ( Y page 69).The fuel filler flap is unlocked, but the opening mechanism is
jammed.
X
Consult a qualified specialist workshop. Parking
Important safety notes
G
WARNING
If flammable materials such as leaves, grass
or twigs are

exposed to prolonged contact to
parts of the exhaust system that heat up, they
could ignite. There is a risk of fire.
Park the vehicle so that no flammable
materials come into contact with parts of the
vehicle which are hot. Take particular care not
to park on dry grassland or harvested grain
fields. G
WARNING
If you leave children unsupervised in the
vehicle, they could set it in motion by, for
example:
R releasing the parking brake
R shifting the automatic transmission out of
the parking position P
R starting the engine.
They could also operate the vehicle's
equipment. There is

a risk of an accident and
injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children unsupervised in the vehicle.
! Always secure the vehicle correctly
against rolling away. Otherwise, the vehicle
or its drivetrain could be damaged. Parking
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Parking the vehicle for a long period
If you leave
the vehicle parked for longer than
four weeks, the battery may be damaged by
exhaustive discharging.
If you leave the vehicle parked for longer than
six weeks, the vehicle may suffer damage 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
workshop. Driving tips
General notes
Important safety 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. G
WARNING
If you operate mobile communication
equipment while driving, you will be
distracted from traffic conditions. You could
also lose control

of the vehicle. There is a risk
of an accident.
Only operate this equipment when the vehicle
is stationary.
Observe the legal requirements for the
country in which you are driving. Some
jurisdictions prohibit the driver from using a
mobile phone while driving a vehicle.
If you make a call while driving, always use
hands-free mode. Only operate the telephone
when the traffic situation permits. If you are unsure, pull over to a safe location and stop
before operating the telephone.
Bear in mind that at a speed of only 30 mph
(approximately
50 km/h), the vehicle covers
a distance of 44 feet (approximately

14 m)
per second.
Drive sensibly – save fuel Observe the following tips to save fuel:
R
The tires should always be inflated to the
recommended tire pressure.
R Remove unnecessary loads.
R Remove roof racks when they are not
needed.
R Warm up the

engine at low engine speeds.
R Avoid frequent acceleration or braking.
R Have all maintenance work carried out as
indicated by the service intervals in the
Maintenance Booklet or by the service
interval display.
Fuel consumption also increases when
driving in cold weather, in stop-start traffic
and in hilly terrain.
Drinking and driving G
WARNING
Drinking and driving and/or taking drugs and
driving are very dangerous combinations.
Even a small amount of alcohol or drugs can
affect your reflexes, perceptions and
judgment.
The possibility of a serious or even fatal
accident are greatly

increased when you drink
or take drugs and drive.
Do not drink or take drugs and drive or allow
anyone to drive who has been drinking or
taking drugs.
Emission control G
WARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Inhaling
these exhaust gases

leads to poisoning. There152
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vehicle occupant or from outside the
vehicle.
R the electrical system in the engine
compartment, the battery
or the fuses have
been tampered with.
R the battery is disconnected.
R the accelerator pedal has been depressed,
e.g. by a vehicle occupant.
There is a risk of an accident.
If you wish to exit the vehicle, always turn off
DISTRONIC PLUS and secure the vehicle
against rolling away.
Deactivating DISTRONIC PLUS
(Y page 165).
If DISTRONIC PLUS detects that the vehicle
in front is stopping, it brakes your vehicle until
it is stationary.
Once your vehicle is stationary, it remains
stationary and you do not need to depress the
brake.
i After a time, the electric parking brake
secures the vehicle and relieves the service
brake.
i Depending on the specified minimum
distance, your vehicle will come to a
standstill at a sufficient distance behind the
vehicle in front. The specified minimum
distance is set using the control on the
cruise control lever.
The electric parking brake automatically
secures the vehicle if DISTRONIC PLUS is
activated and:
R the driver's door is open and the driver's
seat belt is unfastened.
R the engine is switched off, unless it is
automatically switched off by the ECO
start/stop function.
R a system malfunction occurs.
R the power supply is not sufficient.
If a malfunction occurs, then the transmission
may be shifted into position P automatically.Storing the current speed or calling up the
last stored speed G
WARNING
If you call up the stored speed and it differs
from the current speed, the vehicle
accelerates or decelerates.

If you do not know
the stored speed, the vehicle could accelerate
or brake unexpectedly. There is a risk of an
accident.
Pay attention to the road and traffic
conditions before calling up the stored speed.
If you do not know the stored speed, store the
desired speed again.
X Briefly pull the cruise control lever
(Y page 161) towards you.
X Remove your foot from the accelerator
pedal.
DISTRONIC PLUS is activated. The first
time it is activated, the current speed is
stored. Otherwise, it

sets the vehicle cruise
speed to the previously stored value.
Setting a speed Keep in mind that it may take a brief moment
until the
vehicle

has accelerated or braked to
the speed set. :
To store the current speed or a higher
speed
; To store the current speed or a lower
speed164
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Other vehicles changing lanes
DISTRONIC PLUS has not detected the
vehicle cutting in yet. The distance to this
vehicle will be too short.
Narrow vehicles
DISTRONIC PLUS has not yet detected the
vehicle in front on the edge of the road,
because of its narrow width. The distance to
the vehicle in front will be too short.
Obstructions and stationary vehicles
DISTRONIC PLUS does not brake for
obstacles or stationary vehicles. If, for example, the detected vehicle turns a corner
and reveals
an
obstacle or stationary vehicle,
DISTRONIC PLUS will not brake for these.
Crossing vehicles DISTRONIC PLUS may detect vehicles that
are crossing
your

lane by mistake. Activating
DISTRONIC PLUS at traffic lights with
crossing traffic, for example, could cause
your vehicle to pull away unintentionally. HOLD function
Important safety notes G
WARNING
When leaving the vehicle, it can still roll away
despite being braked

by the HOLD function if:
R there is a malfunction in the system or in
the voltage supply.
R the HOLD function has been deactivated by
pressing the accelerator pedal or the brake
pedal, e.g. by a vehicle occupant.
R the electrical system in the engine
compartment, the battery or the fuses have
been tampered with.
R the battery is disconnected
There is a risk of an accident.
If you wish to exit the vehicle, always turn off
the HOLD function and secure the vehicle
against rolling away. Driving systems
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Display messages Possible causes/consequences and
M SolutionsThe yellow
! warning lamp lights up. If you manually apply or
release the electric parking brake, the red F (USA
only)/! (Canada only) indicator lamp flashes.
The electric parking brake is malfunctioning. It is not possible to
apply the electric parking brake manually.
X Shift the transmission to P.
X Visit a qualified specialist workshop. F(USA
only)!(Canada
only)
Parking Brake
Inoperative The yellow
! warning lamp lights up. The red F (USA
only)/! (Canada only) indicator lamp flashes for about ten
seconds after the electric parking brake has been applied or
released. It then goes out or remains lit.
The electric parking brake is malfunctioning, e.g. because of
overvoltage or undervoltage.
X Remove the cause for the overvoltage or undervoltage, e.g. by
charging the battery or restarting the engine.
X Engage or release the electric parking brake.
If it remains impossible to apply or release the electric parking
brake:
X Switch off the ignition and turn it back on.
X Engage or release the electric parking brake.
If the electric parking brake still cannot be released:
X Consult a qualified specialist workshop. The display message is only shown while the vehicle is in motion.
The yellow
! warning lamp lights up and the red F (USA
only)/ ! (Canada only) indicator lamp flashes.
It is not possible to apply the electric parking brake manually.
X Shift the transmission to P.
X Visit a qualified specialist workshop. F(USA
only)!(Canada
only)
Turn On the
Ignition to
Release the
Parking Brake The red
F (USA
only)/ ! (Canada only) indicator lamp lights
up.
You attempted to release the electric parking brake while the
ignition was switched off.
X Turn the SmartKey to position 1 in the ignition lock.206
Display messages
On-board computer and displays
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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
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