key MERCEDES-BENZ B-CLASS 2012 Workshop Manual

setting in small increments. Start at 72 ‡
(22 †).
Setting the air distribution
Automatic climate control Air distribution settings
¯
Directs air through the defroster vents
P Directs air through the center and side
air vents
O Directs air through the footwell air
vents
i You can also activate several air
distribution settings simultaneously. To do
this, press multiple
air distribution buttons.
The air is then directed through various
vents.
Setting the air distribution
X Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X Press one or more of the P, O,
¯ buttons.
The corresponding indicator

lamp lights up
briefly.
Dual-zone automatic climate control Air distribution settings
¯
Directs air through the defroster vents
P Directs air through the center and side
air vents
O Directs air through the footwell air
vents
b Directs air through the defroster,
center and side air vents
a Directs air through the defroster and
footwell vents
i Regardless of the air distribution setting,
airflow is always directed through the side
air vents. The side air vents can only be
closed if the

adjusters are turned clockwise
until they engage. Setting the air distribution
X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X Press the É or Ë button repeatedly
until the desired symbol appears in the
display. Setting the airflow
Automatic climate control X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To increase/reduce: turn control A
clockwise or counter-clockwise
(Y page 119).
Dual-zone automatic climate control X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To increase/reduce: press the K or
I button. Switching the ZONE function on/off
This function is only available with dual-zone
automatic climate control.
X To activate: press the á button.
The indicator lamp

in the á button lights
up.
The temperature setting for the driver's
side is not adopted for the front-passenger
side.
X To deactivate: press the á button.
The indicator lamp

in the á button goes
out.
The temperature setting for the driver's
side is adopted for the front-passenger
side. 126
Operating the climate control systems
Climate control
ProCarManuals.com

Defrosting the windshield
You can use this function to defrost the
windshield or to defrost the inside of the
windshield and the side windows.
i You should only select the "windshield
defrosting" function until the windshield is
clear again.
X Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To activate: press the ¬ button.
The indicator lamp
in the ¬ button lights
up.
The climate control system switches to the
following functions:
R high airflow
R high temperature
R air distribution to the windshield and
front side windows
R air-recirculation mode off
i The "windshield defrosting" function
automatically sets the

blower output to the
optimum defrosting effect. As a result, the
airflow may increase or decrease
automatically after the button is pressed.
i You can adjust the blower output
manually while the "Windshield defrosting"
function is in operation:
R Automatic climate control: turn airflow
control A clockwise or counter-
clockwise (Y page 119).
R Dual-zone automatic climate control:
press the ó or ô button.
X To deactivate: press the ¬ button.
The indicator lamp

in the ¬ button goes
out. The previously selected settings are
restored. Air-recirculation mode remains
deactivated.
or X
Press the à button. 5
The indicator
lamp

in the ¬ button goes
out. Airflow and air distribution are set to
automatic mode.
or
X Automatic climate control: turn
temperature control : clockwise or
counter-clockwise ( Y page 119).
Dual-zone automatic climate control:
turn temperature controls : or E
clockwise or counter-clockwise
(Y page 121). MAX COOL maximum cooling
The MAX COOL function is only available in
vehicles for the USA.
MAX COOL is only operational when the
engine is running.
X To activate: press the Ù button.
The indicator lamp in the button lights up.
X To deactivate: press the Ù button
again.
The indicator lamp

goes out. The previously
selected settings are restored.
When you activate MAX COOL, climate
control switches to the following functions:
R maximum cooling
R maximum airflow
R air-recirculation mode on Defrosting the windows
Windows fogged up on the inside Automatic climate control
X
Activate the ¿ "Cooling with air
dehumidification" function.
X If the windows continue to fog up, activate
the "windshield defrosting" function
(Y page 127).
5 3-zone automatic climate control only. Operating the climate control systems
127Climate control
ProCarManuals.com

i
You should only select this setting until
the windshield is clear again.
Dual-zone automatic climate control
X Activate the ¿ "Cooling with air
dehumidification" function.
X Activate automatic mode Ã.
X If the windows continue to fog up, activate
the "windshield defrosting" function
(Y page 127).
i You should only select this setting until
the windshield is clear again.
Windows fogged up on the outside X
Activate the windshield wipers.
X Set the air distribution to P or O.
i You should only select this setting until
the windshield is clear again. Rear window defroster
Activating/deactivating The rear window defroster has a high current
draw. You should therefore switch it off as
soon as the rear window is clear. Otherwise,
the rear window defroster switches off
automatically after several minutes.
If the battery voltage is too low, the rear
window defroster may switch off.
X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X Press the ¤ button.
The indicator lamp
in the ¤ button lights
up or goes out. 128
Operating the climate control systems
Climate control
ProCarManuals.com

Problems with the rear window defroster
Problem Possible causes/consequences and
M SolutionsThe rear window
defroster has
deactivated
prematurely or cannot
be activated. The battery has not been sufficiently charged.
X
Switch off any consumers that are not required, e.g. reading
lamps, interior lighting or the seat heating.
When the battery is sufficiently charged, the rear window
defroster can be activated again. Activating/deactivating air-
recirculation mode
If you switch on air-recirculation mode, the
windows can fog up more quickly, in
particular at low temperatures. Only use air-
recirculation mode briefly to prevent the
windows from fogging up.
You can deactivate the flow of fresh air if
unpleasant odors are entering the vehicle
from outside. The air already inside the
vehicle will then be recirculated.
The operation of
air-recirculation mode is the
same for all control panels.
X Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To activate: press the e button.
The indicator lamp

in the e button lights
up.
i Air-recirculation mode is activated
automatically at high outside
temperatures. When air-recirculation

mode
is activated automatically, the indicator
lamp in the e button is not lit.
Outside air is added after about
30 minutes.
X To deactivate: press the e button.
The indicator lamp

in the e button goes
out. i
Air-recirculation mode deactivates
automatically:
R after approximately five minutes at
outside temperatures below
approximately 41 ‡ (5 †)
R after approximately five minutes if the
"Cooling with air dehumidification"
function is deactivated
R after approximately 30 minutes at
outside temperatures above
approximately

41 ‡(5 †) if the "Cooling
with air dehumidification" function is
activated Activating/deactivating the residual
heat function
The residual heat

function is only available in
vehicles for Canada with dual-zone automatic
climate control.
It is possible to make use of the residual heat
of the engine to continue heating the vehicle
for approximately 30 minutes after the engine
has been switched off. The heating time
depends on the temperature that has been
set.
i The blower will run at a low speed
regardless of the airflow setting.
i If you activate the residual heat function
at high temperatures, only the ventilation
will be activated. The blower runs at
medium speed. Operating the climate control systems
129
Climate control
ProCarManuals.com

X
Turn the SmartKey to position 0 in the
ignition lock or remove it ( Y page 135).
X To activate: press the Ì button.
The indicator lamp
in the Ì button lights
up.
X To deactivate: press the Ì button.
The indicator lamp

in the Ì button goes
out.
i Residual heat is deactivated
automatically:
R after approximately 30 minutes
R when the ignition is switched on
R if the battery voltage drops
R when the auxiliary heating is activated Setting the air vents
Important safety notes
G
WARNING
Very hot or very cold air can flow from the air
vents. This could

result in burns or frostbite in
the immediate vicinity of the air vents. There
is a risk of injury.
Make sure that all vehicle occupants always
maintain a sufficient distance to the air
outlets. If necessary, redirect the airflow to
another area of the vehicle interior.
In order to ensure the direct flow of fresh air
through the air vents into the vehicle interior,
please observe the following notes:
R keep the air inlet between the windshield
and the hood free of blockages, such as ice,
snow or leaves.
R never cover the air vents or air intake grilles
in the vehicle interior.
i You can move the adjusters for the air
vents vertically or horizontally to set the
direction of the airflow.
i For optimal climate control in the vehicle,
open the air vents completely and set the
adjusters to the central position. Setting the center air vents
X
To open the center air vent: turn the
adjuster in one of center air vents :
counter-clockwise.
X To close the center air vent: turn the
adjuster in one of center air vents :
clockwise until it engages. Setting the side air vents
:
Side window defroster vent
; Side air vent
X To open a side air vent: turn the adjuster
in side air vent ; counter-clockwise.
X To close a side air vent: turn the
adjuster
in side air vent ; clockwise until it
engages. 130
Setting the air vents
Climate control
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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
135
Driving and parking Z
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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
137
Driving and parking Z
ProCarManuals.com

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
139Driving and parking Z
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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
Driving and parking
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!
Overfilling the fuel
tank could damage the
fuel system.
! Take care not to spill any fuel on painted
surfaces. You could otherwise damage the
paintwork.
! Use a filter when refueling from a fuel can.
Otherwise, the fuel lines and/or injection
system could be blocked by particles from
the fuel can.
Do not get into the vehicle again during the
refueling process. Otherwise, electrostatic
charge could build up again.
If you overfill the fuel tank, fuel could spray
out when the fuel pump nozzle is removed.
For further information on fuel and fuel quality
(Y page 330). Refueling
Opening/closing the fuel filler flap :
To open the fuel filler flap
; Tire pressure table
= To insert the fuel filler cap
? Fuel type to be used
The fuel filler flap is unlocked or locked
automatically when you open or close the
vehicle with the SmartKey.
The position of the fuel filler cap is displayed
æ in
the

instrument cluster. The arrow on
the filling pump indicates the side of the
vehicle. Opening X
Switch the engine off.
X Remove the SmartKey from the ignition
lock.
X Press the fuel filler flap in the direction of
arrow :.
The fuel filler flap swings up.
X Turn the fuel filler flap counter-clockwise
and remove it.
X Insert the fuel filler cap into holder on the
inside of fuel filler flap =.
X Completely insert the filler neck of the fuel
pump nozzle into the tank, hook in place
and refuel.
X Only fill the tank until the pump nozzle
switches off.
i Do not add any more fuel after the pump
stops filling for the first time. Otherwise,
fuel may leak out.
Closing X
Replace the cap on the filler neck and turn
clockwise until it engages audibly.
X Close the fuel filler flap.
i Close the fuel

filler flap before locking the
vehicle.
i If you are driving with the fuel filler cap
open, the 8 reserve fuel warning lamp
flashes. A message appears in the
multifunction display ( Y page 214).
In addition, the ; Check Engine warning
lamp may light up ( Y page 231).
For further information on warning and
indicator lamps in the instrument cluster,
see ( Y page 231).148
Refueling
Driving and parking
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