engine MERCEDES-BENZ B-CLASS 2012 Service Manual

Do not switch off the ignition while driving.
G
WARNING
If the parking brake has not been fully
released when driving,
the parking brake can:
R overheat and cause a fire
R lose its hold function.
There is a risk of fire and an accident. Release
the parking brake fully before driving off.
! Warm up the engine quickly. Do not use
the engine's full performance until it has
reached operating temperature.
Only shift the automatic transmission to
the desired drive position when the vehicle
is stationary.
Where possible, avoid spinning the drive
wheels when pulling away on slippery
roads. You could otherwise damage the
drive train. Key positions
g
To remove the SmartKey
(shift the transmission to position P)
1 Power supply for some consumers, such
as the windshield wipers
2 Ignition (power supply for all consumers)
and drive position
3 To start the engine
i The SmartKey can be turned in the
ignition lock even if it is not the correct
SmartKey for the

vehicle. The ignition is not
switched on. The engine cannot be started. Starting the engine
Important safety notes 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. G
WARNING
Flammable materials introduced through
environmental influence or by animals can
ignite if in

contact with the exhaust system or
parts of the engine that heat up. There is a risk
of fire.
Carry out regular checks to make sure that
there are no flammable foreign materials in
the engine compartment or in the exhaust
system.
! Do not depress the accelerator pedal
when starting the engine.
i During a cold start, the engine runs at
higher speeds to enable the catalytic
converter to reach its operating
temperature. The sound of the engine may
change during this time.
Automatic transmission X
Shift the transmission to position P.
Transmission position display
P

is shown in
the multifunction display.
i When the transmission is in position N,
you can also

start the engine with the brake
pedal depressed.
Starting procedure X
Turn the SmartKey to position 3 in the
ignition lock (

Y page 135) and release it as
soon as the engine is running. Driving
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Pulling away
Automatic transmission i
It is only
possible to shift the transmission
from position P to the desired position if
you depress the brake pedal. Only then can
the parking lock be deactivated. If you do
not depress the brake pedal, the DIRECT
SELECT lever can still be moved but the
parking lock remains engaged.
i If the transmission oil temperature is
below Ò4 ‡ (Ò20 † ), you can only shift from
position P when the engine is running.
X Depress the brake pedal and keep it
depressed.
X Shift the transmission to position D or R.
X Release the brake pedal.
X Carefully depress the accelerator pedal.
The electric parking brake (Y page 150) is
automatically released.
The red ! indicator lamp in the
instrument cluster goes out.
i The vehicle locks

centrally once you have
pulled away. The locking knobs in the doors
drop down.
You can open the doors from the inside at
any time.
You can also deactivate the automatic
locking feature (Y page 198).
i Upshifts take place at higher engine
speeds after a cold start. This helps the
catalytic converter to reach its operating
temperature more quickly.
Hill start assist G
WARNING
After a short time, hill start assist will no
longer brake your vehicle and it could roll
away. There is

a risk of an accident and injury.
Therefore, quickly move your foot from the
brake pedal to the accelerator pedal. Never
leave the vehicle when it is held by hill start
assist. Hill start assist helps you when pulling away
forwards or in reverse on an uphill gradient.
It holds the vehicle for a short time after you
have removed
your

foot from the brake pedal.
This gives you enough time to move your foot
from the brake pedal to the accelerator pedal
and to depress it before the vehicle begins to
roll.
X Remove your foot from the brake pedal.
The vehicle is

then held for about a second.
X Pull away.
Hill start assist will not function if:
R you are pulling away on a level road or on
a downhill gradient.
R the transmission is in position N.
R the electric parking brake is applied.
R ESP ®
is malfunctioning.
Further information on holding the vehicle
stationary on uphill gradients ( Y page 143). ECO start/stop function
Important safety notes G
WARNING
If the engine is switched off automatically and
you exit the vehicle, the engine is restarted
automatically. The vehicle

may begin moving.
There is a risk of accident and injury.
If you wish to exit the vehicle, always turn off
the ignition and secure the vehicle against
rolling away.
General notes If the
¤ symbol is shown in the
multifunction display, the ECO start/stop
function switches the engine off
automatically when the vehicle stops.
The engine starts automatically when the
driver wants to pull away again. The ECO
start/stop function thereby helps you to
reduce the fuel consumption and emissions
of your vehicle. 136
Driving
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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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again as soon as the
¤ symbol
reappears in the multifunction display.
Deactivating/activating the ECO start/
stop function ECO button
X
To switch off: press button :.
Indicator lamp ; on button : and the
¤ symbol
in
the multifunction display go
out.
X To switch on: press button :.
Indicator lamp ; lights up.
If all conditions for automatic engine
switch-off ( Y page 137) are fulfilled, the
¤ symbol is

shown in the multifunction
display.
If not all conditions for automatic engine
switch-off ( Y page 137) are fulfilled the
¤ symbol is not shown in the
multifunction display. If this is the case, the
ECO start/stop function is not available.
i If indicator lamp ;

is off, the ECO start/
stop function has been deactivated
manually or as the result of a malfunction.
The engine will then not be switched off
automatically when the vehicle stops. 138
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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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Problem Possible causes/consequences and
M SolutionsThe engine is not
running smoothly and
is misfiring. There is a malfunction in the engine electronics or in a mechanical
component of the engine management system.
X
Only depress the accelerator pedal slightly.
X Have the cause rectified immediately at a qualified specialist
workshop.
Otherwise, non-combusted fuel may get into the catalytic
converter and damage it. The coolant
temperature display is
showing more than
248 ‡
(120 †). The
coolant warning lamp
may also be lit and a
warning tone may
sound. The coolant level is too low. The coolant is too hot and the engine
is no longer being cooled sufficiently.
X
Stop as soon as possible and allow the engine and the coolant
to cool down.
X Check the coolant level (Y page 269). Observe the warning
notes as you do so and add coolant if necessary. Automatic transmission
Important safety notes
G
WARNING
If the engine speed is above the idling speed
and you engage transmission position D or
R, the vehicle
could pull away suddenly. There
is a risk of an accident.
When engaging transmission position D or R,
always firmly depress the brake pedal and do
not simultaneously accelerate. G
WARNING
The automatic transmission switches to
neutral position N when you switch off the
engine. The vehicle may roll away. There is a
risk of an accident.
After switching off the engine, always switch
to parking position P. Prevent the parked
vehicle from rolling away by applying the
parking brake. DIRECT SELECT lever
Overview of transmission positions The DIRECT SELECT lever is on the right of the
steering column.
j
Park position with parking lock
k Reverse gear
i Neutral
h Drive
i The DIRECT SELECT lever always returns
to its original position. The current
transmission position
P, R

, N or D appears
in the transmission position display
(Y page 141) in the multifunction display. 140
Automatic transmission
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Transmission position and drive
program display
The current transmission position and drive
program appear in the multifunction display.
:
Transmission position display
; Drive program display
i The arrows in the transmission position
display show how and into which
transmission positions you can change
using the DIRECT SELECT lever.
! If the
transmission
position display in the
multifunction display is not working, you
should pull away carefully to check whether
the desired transmission position is
engaged. Ideally, you should select
transmission position D and drive program
E or S.
Engaging park position P X
Push the DIRECT SELECT lever in the
direction of arrow P.
Transmission position display P

is shown in
the multifunction display.
i When you engage park position P, make
sure that the

transmission position display
shows P in the multifunction display.
i You can only engage park position P when
the vehicle is stationary.
i The automatic transmission shifts into
park position P automatically:
R if you open the driver's door while the
vehicle is stationary in transmission
position D or R
R if you open the door while traveling at
very low speeds in transmission position
D or R In addition, a warning tone sounds and a
display message is shown.
i Depressing the brake and pushing the
DIRECT SELECT lever up or down
disengages the parking lock. The
transmission is in N neutral.
At transmission fluid temperatures below
Ò4 ‡ (Ò 20

†), you can only shift out of park
position P into another transmission
position when the engine is running.
In order to shift from park position P
directly into R or D:
R depress the brake pedal and
R push the DIRECT SELECT lever up or
down past the first point of resistance
! If the engine speed is too high or the
vehicle is moving, do not shift the
automatic transmission directly from D to
R, from R to D or directly to P. The
automatic transmission could otherwise be
damaged.
Engaging reverse gear R !
Only shift the automatic transmission to
R when the vehicle is stationary.
i The ECO start/stop function is not
available when reverse gear is engaged.
Further information on

the ECO start/stop
function ( Y page 136).
X When the vehicle is stationary, depress the
brake pedal.
X Push the DIRECT SELECT lever up past the
first point of resistance.
Shifting to neutral N X
When the vehicle is stationary, depress the
brake pedal.
X Push the DIRECT SELECT lever up or down
to the first point of resistance.
If the engine has been switched off, the
automatic transmission automatically shifts
to N. Automatic transmission
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Remaining in neutral N
If the automatic transmission is to remain in
neutral N, e.g. for washing the vehicle in car
washes with
a
towing device, please observe
the following instructions: G
WARNING
If children are left unsupervised in the vehicle,
they could:
R open the doors, thus endangering other
people or road users.
R get out and disrupt traffic.
R operate the vehicle's equipment.
Additionally, children could set the vehicle in
motion if, for example, they:
R release the parking brake.
R shift the automatic transmission out of
parking position P.
R starting the engine.
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 or animals unattended in the
vehicle. Always keep the SmartKey out of
reach of children.
R Make sure that the ignition is switched on.
R When the vehicle is stationary, depress the
brake pedal and keep it depressed.
R Shift to neutral N.
R Release the brake pedal.
R If the electric parking brake is engaged,
release it.
R Switch off the ignition and leave the
SmartKey in the ignition lock.
Engaging drive position D X
When the vehicle is stationary, depress the
brake pedal.
X Push the DIRECT SELECT lever down past
the first point of resistance. Transmission positions
B
Park position
Do not shift the transmission into
position P unless the vehicle is
stationary (
Y page 149). The
parking lock should

not be used as
a brake when parking. Always
apply the electronic parking brake
in addition to the parking lock in
order to secure the vehicle.
If the vehicle electronics are
malfunctioning, the transmission
may be locked in position P.
Have the vehicle electronics
checked immediately at a qualified
specialist workshop. C
Reverse gear
Only shift the transmission to
R
when the vehicle is stationary. A
Neutral
No power is transmitted from the
engine to the drive wheels.
Releasing the
brakes

will allow you
to move the vehicle freely, e.g. to
push it or tow it.
If ESP ®
is deactivated or faulty:
only shift the transmission to
position N if the vehicle is in danger
of skidding, e.g. on icy roads.
When you switch off the engine, the
automatic transmission
automatically shifts into neutral N. 7
Drive
The automatic transmission
changes gear automatically. All
forward gears are available.142
Automatic transmission
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Changing gear
The automatic transmission shifts to the
individual gears automatically when it is in
transmission position D. This automatic
gearshifting behavior is determined by:
R the selected drive program ( Y page 143)
R the position of the accelerator pedal
R the road speed Driving tips
Holding the vehicle stationary on uphill
gradients G
WARNING
If the clutch overheats, the electronic
management system is automatically
deactivated. This interrupts the power
transmission. The vehicle may, for example,
roll backwards on

gradients. There is a risk of
an accident.
Never hold the vehicle stationary on uphill
gradients by depressing the accelerator.
The clutch may overheat if you hold the
vehicle stationary on uphill gradients by
depressing the accelerator pedal. If the clutch
overheats, a warning tone sounds. The Stop
Vehicle Shift to P Leave Engine
Running display message appears in the
multifunction display. You will only be able to
continue your journey once the clutch has
cooled down and the display message in the
multifunction display has disappeared.
Never hold the vehicle stationary on uphill
gradients by depressing the accelerator.
Instead, only ever hold the vehicle stationary
on uphill gradients by:
R depressing the brake pedal
R activating the HOLD function
R engaging the electric parking brake Kickdown Use kickdown for maximum acceleration:
X
Depress the accelerator pedal beyond the
pressure point.
The automatic transmission shifts to a
lower gear depending

on the engine speed.
X Ease off the accelerator pedal once the
desired speed is reached.
The automatic transmission

shifts back up.
Rocking the vehicle free Shifting the transmission repeatedly between
gears
D and R may help to free the vehicle if
it has become stuck in slush or snow. The
vehicle's engine management system limits
the speed to a maximum of 5 mph (9 km/h)
when shifting back and forth. To shift back
and forth between transmission positions D
and R, move the selector lever up and down
beyond the pressure point. Program selector button
General notes The program selector button allows you to
choose between drive programs with
different driving characteristics.
Example: program selector button Automatic transmission
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E Economy Comfortable, economical
driving
S Sport Sporty driving style
M Manual Manual gear shifting
Only change from automatic drive program
E or S to manual drive program
M when the
vehicle is stationary.
X Press program selector button :
repeatedly until the letter for the desired
gearshift program appears in the
multifunction display.
i The automatic transmission shifts to
automatic drive program E each time the
engine is started.
i For further information on the automatic
drive program, see ( Y page 144). Steering wheel paddle shifters
:
Left steering wheel paddle shifter (shifts
down)
; Right steering wheel paddle shifter (shifts
up)
In drive program M, you can change gear
yourself using the steering wheel paddle
shifters.
If you pull the left or right steering wheel
paddle shifter when in automatic drive
program E or S, the automatic transmission
shifts into drive
program M for a limited time.
Depending on which paddle shifter is pulled, the automatic transmission immediately
shifts into the next gear down or up.
i
You can only change gear with the
steering wheel paddle shifters when the
transmission is in position D.
i For further information on the manual
drive program, see ( Y page 144). Automatic drive program
Drive program E is characterized by the
following:
R comfort-oriented engine settings
R optimal fuel consumption resulting from
the automatic transmission shifting up
sooner
R the vehicle pulling away more gently in
forward and reverse gears, unless the
accelerator pedal is depressed fully
R increased sensitivity. This

improves driving
stability on slippery road surfaces, for
example
R the automatic transmission shifting up
sooner. This results in the vehicle being
driven at lower engine speeds and the
wheels being less likely to spin
Drive program S is characterized by the
following:
R sporty engine settings
R the automatic transmission shifting up
later
R the fuel consumption possibly being higher
as a result of the later automatic
transmission shift points Manual drive program
Introduction In manual drive program
M, you can change
gear yourself by using the steering wheel
paddle shifters. For this, the transmission
must be in position D. The gear currently 144
Automatic transmission
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