2015 MERCEDES-BENZ B-CLASS HATCHBACK key battery

There are several ways to deactivate the alarm:
X To deactivate the alarm with the key: press
the % or& button on the key.
or
X Insert the key into the ignition lock.
or X To deactivate the alarm with KEYLESS-GO:
press the Start/Stop button in the ignition
lock. The key must be in the vehicle.
or
X Lock or unlock the vehicle using KEYLESS-
GO. The key must be outside the vehicle.
If you unlock the vehicle using the emergency
key element, the charge socket flap will not be
unlocked automatically.
Removing the emergency key element X
Push release catch :in the direction of the
arrow and, at the same time, remove emer-
gency key element ;from the key.
Further information about:
R unlocking the driver's door (Y page 80)
R unlocking the luggage compartment
(Y page 81)
R locking the vehicle (Y page 80)
Inserting the emergency key element X
Push emergency key element ;completely
into the key until it engages and release
catch :is back in its basic position. Battery of the key
Important safety notes G
WARNING
Batteries contain toxic and corrosive substan- ces. If batteries are swallowed, it can result in
severe health problems. There is a risk of fatal injury.
Keep batteries out of the reach of children. If
a battery is swallowed, seek medical attention immediately. H
Environmental note Batteries contain pollutants.
It is illegal to dispose of them
with the household rubbish.
They must be collected sep-
arately and disposed of in anenvironmentally responsible
recycling system. Dispose of batteries in an
environmentally responsible
manner. Take discharged
batteries to a qualified spe-
cialist workshop or to a col-
lection point for used batter-
ies.
Mercedes-Benz recommends that you have the
battery replaced at a qualified specialist work-
shop.
Checking the battery X
Press the &or% button.
The battery is working properly if battery
check lamp :lights up briefly. 74
KeyOpening and closing

The battery is discharged if battery check
lamp :does not light up briefly.
X Replace the battery (Y page 75).
i If the key battery is checked within the sig-
nal reception range of the vehicle, pressing
the & or% button:
R locks or
R unlocks the vehicle
i You can obtain a battery from any qualified
specialist workshop.
Replacing the battery You require a CR 2025 3 V cell battery.
X Take the emergency key element out of the
key (Y page 73). X
Press emergency key element ;into the
opening in the key in the direction of the arrow
until battery tray cover :opens. When doing
so, do not hold cover :shut.
X Remove battery tray cover :.X
Repeatedly tap the key against your palm until
battery =falls out.
X Insert the new battery with the positive ter-
minal facing upwards. Use a lint-free cloth to
do so. X
Make sure that the surface of the battery is
free of lint, grease and other contamination.
X Insert the front tabs of battery tray cover :
and then press to close it.
X Insert emergency key element into the key
(Y page 74).
X Check the function of all key buttons on the
vehicle. Key
75Opening and closing Z

Problems with the key
Problem
Possible causes/consequences and
M
MSolutions You cannot lock or
unlock the vehicle using
the key. The key battery is discharged or nearly discharged.
X Vehicles without KEYLESS-GO or KEYLESS-GO start function:
try again to lock/unlock the vehicle using the remote control func-
tion of the key. Point the tip of the key at the driver's door handle
from close range and press the %or& button.
If this does not work:
X Check the key battery (Y page 74) and replace it if necessary
(Y page 75).
X Lock (Y page 80) or unlock (Y page 80) the vehicle using the
emergency key element. There is interference from a powerful source of radio waves.
X Vehicles without KEYLESS-GO or KEYLESS-GO start function:
try again to lock/unlock the vehicle using the remote control func-
tion of the key. Point the tip of the key at the driver's door handle
from close range and press the %or& button.
If this does not work:
X Lock (Y page 80) or unlock (Y page 80) the vehicle using the
emergency key element. The key is faulty.
X Lock (Y page 80) or unlock (Y page 80) the vehicle using the
emergency key element.
X Have the key checked at a qualified specialist workshop. You can no longer lock or
unlock the vehicle using
KEYLESS-GO. The key battery is discharged or nearly discharged.
X Check the key battery (Y page 74) and replace it if necessary
(Y page 75).
If this does not work: X Lock (Y page 80) or unlock (Y page 80) the vehicle using the
emergency key element. There is interference from a powerful source of radio waves.
X Lock (Y page 80) or unlock (Y page 80) the vehicle using the
emergency key element. 76
KeyOpening and closing

Problem
Possible causes/consequences and
M
MSolutions There is a fault with KEYLESS-GO.
X Lock/unlock the vehicle using the remote control function of the
key.
X Have the vehicle and key checked at a qualified specialist work-
shop.
If the vehicle can also not be locked/unlocked using the remote con-
trol function:
X Lock (Y page 80) or unlock (Y page 80) the vehicle using the
emergency key element.
X Have the vehicle and key checked at a qualified specialist work-
shop. The drive system cannot
be started using the key. the on-board voltage is too low
X Switch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the drive system again.
If this does not work: X Check the 12 V battery and charge it if necessary (Y page 256).
or
X Check the high-voltage battery and charge it if necessary
(Y page 135).
or
X Jump-start the vehicle (Y page 258).
or
X Consult a qualified specialist workshop. The drive system cannot
be started using the
Start/Stop button. The
key is in the vehicle. The vehicle is locked.
X Unlock the vehicle and try to start the vehicle again. The key battery is discharged or nearly discharged.
X Check the key battery (Y page 74) and replace it if necessary
(Y page 75).
If this does not work: X Start your vehicle with the key in the ignition lock. There is interference from a powerful source of radio waves.
X Start your vehicle with the key in the ignition lock. You have lost a key. X
Have the key deactivated at a qualified specialist workshop.
X Report the loss immediately to the vehicle insurers.
X If necessary, have the locks changed as well. You have lost the emer-
gency key element. X
Report the loss immediately to the vehicle insurers.
X If necessary, have the locks changed as well. Key
77Opening and closing Z

The system automatically switches from level
2
to level 1after approximately ten minutes.
The system automatically switches off approx-
imately 20 minutes after it is set to level 1.
X Turn the key to position 1or 2in the ignition
lock (Y page 126).
X To switch on: press button:repeatedly
until the desired heating level is set.
X To switch off: press button:repeatedly
until all the indicator lamps go out.
i If the battery voltage is too low, the seat
heating may switch off. Seats
91Seats, steering wheel and mirrors Z

Problems with the seat heating
Problem
Possible causes/consequences and
M
MSolutions The seat heating has
switched off prematurely
or cannot be switched
on. The on-board voltage is too low because too many electrical consum-
ers are switched on.
X Switch off electrical consumers that you do not need, such as the
rear window heating or interior lighting.
Once the battery is sufficiently charged, the seat heating will switch
back on automatically. Steering wheel
Important safety notes
G
WARNING
You could lose control of your vehicle if you do the following while driving:
R adjust the driver's seat, head restraint,
steering wheel or mirrors
R fasten the seat belt
There is a risk of an accident.
Adjust the driver's seat, head restraint, steer-
ing wheel and mirror and fasten your seat belt before starting the vehicle's drive system. G
WARNING
Children could become trapped by the steer-
ing wheel if they adjust it. There is a risk of
injury.
When leaving the vehicle, always take the key with you and lock the vehicle. Never leave
children unattended in the vehicle. Adjusting the steering wheel
G
WARNING
The steering wheel may move unexpectedly if you adjust it while driving. This could cause
you to lose control of the vehicle. There is a
risk of an accident.
Make sure that the steering wheel is locked
before driving off. Never unlock the steering
wheel when the vehicle is in motion. :
Release lever
; Adjusts the steering wheel height
= Adjusts the steering wheel position (fore-
and-aft adjustment)
X Push release lever :down completely.
The steering column is unlocked.
X Adjust the steering wheel to the desired posi-
tion.
X Push release lever :up as far as it will go.
The steering column is locked.
X Check if the steering column is locked. When
doing so, try to push the steering wheel up or down or try to move it in the fore-and-aft
direction. 92
Steering wheelSeats, steering wheel and mirrors

Folding the exterior mirrors in/out elec-
trically X
Turn the key to position 1or 2in the ignition
lock (Y page 126).
X Briefly press button :.
Both exterior mirrors fold in or out.
i Make sure that the exterior mirrors are
always folded out fully while driving. They
could otherwise vibrate.
i If you are driving faster than 47 km/h, you
can no longer fold in the exterior mirrors.
Resetting the exterior mirrors If the battery has been disconnected or com-
pletely discharged, the exterior mirrors must be
reset. The exterior mirrors will otherwise not
fold in when you select the "Fold in mirrors whenlocking" function in the on-board computer
(Y page 188).
X Turn the key to position 1in the ignition lock
(Y page 126).
X Briefly press button :.
Folding the exterior mirrors in/out
automatically If the "Fold in mirrors when locking" function is
activated in the on-board computer
(Y page 188):
R the exterior mirrors fold in automatically as
soon as you lock the vehicle from the outside
R the exterior mirrors fold out again automati-
cally as soon as you unlock the vehicle and
then open the driver's or front-passenger
door
i If the exterior mirrors have been folded in
manually, they do not fold out. Exterior mirror pushed out of position If an exterior mirror has been pushed out of
position (forwards or backwards), proceed as
follows:
X Vehicles without electrically folding exte-
rior mirrors: manually move the exterior mir-
ror into the correct position.
X Vehicles with electrically folding exterior
mirrors: press and hold the mirror-folding
button (Y page 94) until you hear a click and
the mirror audibly engages into position.
The mirror housing is engaged again and you can adjust the exterior mirrors as usual
(Y page 93). Automatic anti-dazzle mirrors
G
WARNING
Electrolyte may escape if the glass of an auto- matic anti-dazzle mirror breaks. Electrolyte is
harmful and causes irritation. It must not
come into contact with your skin, eyes, res-
piratory organs or clothing or be swallowed.
There is a risk of injury.
If you come into contact with electrolyte,
observe the following:
R immediately rinse off electrolyte from your
skin with water.
R immediately and thoroughly rinse electro-
lyte out of eyes using clean water.
R if electrolyte is swallowed, immediately
rinse out your mouth thoroughly. Do not
induce vomiting.
R if electrolyte comes into contact with skin
or eyes or is swallowed, seek medical atten-
tion immediately.
R immediately change out of clothing that has
been in contact with electrolyte.
R if an allergic reaction occurs, seek medical
attention immediately.
The "Automatic anti-dazzle mirrors" function is
only available if the vehicle is equipped with the
"Mirror package". 94
MirrorsSeats, steering wheel and
mirrors

The exterior lighting (except the side lamps/
parking lamps) switches off automatically if you:
R remove the key from the ignition lock
R open the driver's door with the key in posi-
tion 0in the ignition lock.
Automatic headlamp mode à is the preferred light switch setting. The
light setting is automatically selected according to the brightness of the ambient light (excep-
tion: poor visibility due to weather conditions
such as fog, snow or spray):
R key in position 1in the ignition lock: the side
lamps are switched on or off automatically
depending on the brightness of the ambient
light
R with the drive system running: if you have
switched on the daytime driving lights func-
tion in the on-board computer, the daytime
driving lights or the side lamps and dipped-
beam headlamps are switched on or off auto-
matically depending on the brightness of the
ambient light
X To switch on the automatic headlamps:
turn the light switch to the
Ãposition. G
WARNING
When the light switch is set to Ã, the
dipped-beam headlamps may not be switched on automatically if there is fog, snow or othercauses of poor visibility due to the weather
conditions such as spray. There is a risk of an
accident.
In such situations, turn the light switch to
L.
The automatic headlamp feature is only an aid.
The driver is responsible for the vehicle lighting at all times.
The daytime driving lights improve the detecta-
bility of your vehicle during the day. To do this,
the daytime driving lights function must be
switched on via the on-board computer
(Y page 186).
When the side lamps and dipped-beam head-
lamps are switched on, the green T(side
lamps) and L(dipped-beam headlamps)
indicator lamps in the instrument cluster light
up. Dipped-beam headlamps
When the ignition is switched on and the light
switch is in the Lposition, the side lamps
and dipped-beam headlamps are switched on
even if the light sensor does not sense dark
ambient light conditions. This is advantageous
when there is fog or rain.
X To switch on the dipped-beam headlamps:
turn the key to position 2in the ignition lock
or start the drive system.
X Turn the light switch to L.
The green Lindicator lamp in the instru-
ment cluster lights up.
Rear foglamp The rear foglamp improves the visibility of your
vehicle in heavy fog for the following traffic.
Please observe the country-specific laws on the
use of rear foglamps.
X To switch on the rear foglamp: turn the key
to position 2in the ignition lock or start the
drive system.
X Turn the light switch to LorÃ.
X Press the Rbutton.
The yellow Rindicator lamp in the instru-
ment cluster lights up.
X To switch off the rear foglamp: press the
R button.
The yellow Rindicator lamp in the instru-
ment cluster goes out.
Side lamps
! If the battery charge level is very low, the
side lamps or parking lamps are switched off automatically in order to preserve energy to
start the drive system. Always park your vehi-
cle safely in a place that is adequately lit in
accordance with legal stipulations. Avoid
using the side lamps Tfor periods of sev-
eral hours. Where possible, switch the right-
hand X or left-hand Wparking lamp on.
X To switch on: turn the light switch to T.
The green Tindicator lamp in the instru-
ment cluster lights up.
Parking lamps Switching on the parking lamps ensures that the
corresponding side of the vehicle is illuminated. 98
Exterior lightingLights and windscreen wipers