2012 MERCEDES-BENZ B-CLASS o2 sensor

Warning notice on the front-passenger sun visor
Warning symbol for a rearward-facing child
restraint system
Do not use a rearward-facing child restraint
system on a seat that is protected by an air
bag installed in front of it.
Air bag deactivation system on the
front-passenger seat
G
WARNING
If the 4 PASSENGER AIRBAG OFF
indicator lamp does not light up when the
child restraint system is installed, the front-
passenger air bag has not been disabled. If
the front-passenger air
bag deploys, the child
could be seriously or even fatally injured.
Proceed as follows:
R do not use a rearward-facing child restraint
system on the front-passenger seat.
R install a rearward-facing child restraint
system on a suitable rear seat.
or R
only use a forward-facing child restraint
system on the front-passenger seat and
move the front-passenger seat to the
rearmost position.
R have the air bag deactivation system
checked at a

qualified specialist workshop.
To ensure that the air bag deactivation system
on the front-passenger seat functions/
communicates correctly, never place objects,
e.g. a cushion, under the child restraint
system. The entire base of the child restraint
system must always rest on the seat cushion.
An incorrectly installed child restraint system
cannot perform its intended protective
function in the event of an accident, and could
lead to injuries. G
WARNING
Do not place electronic devices on the front-
passenger seat, e.g.:
R laptops, when switched on
R mobile phones
R cards with transponders,

e.g. ski passes or
access cards
Signals from electronic equipment can cause
interference in the sensor system of the air
bag deactivation system. This can lead to a
system malfunction. This may cause the
4 PASSENGER AIR BAG OFF indicator
lamp to light up even if no child seat with a
transponder for an air bag deactivation
system is installed. The front-passenger air
bag would not then deploy during an accident.
It is also possible that the 6 SRS warning
lamp lights up and/or the 4 PASSENGER
AIR BAG OFF indicator lamp does not light up
briefly when you turn the key in the ignition
lock to position 2. Children in the vehicle
53
Safety Z
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If the front-passenger seat of your vehicle
does not
have
an air bag deactivation system,
this is indicated by a special sticker. The
sticker is affixed to the side of the dashboard
on the front-passenger side. The sticker is
visible when you open the front-passenger
door.
Vehicles without an air bag deactivation
system on the front-passenger seat: if you
turn the SmartKey to position 2 in the ignition
lock, the 45 indicator lamp lights up
briefly but has no function. It does not
indicate that there is an air bag deactivation
system on the front-passenger seat. The sensor system for the air bag deactivation
system detects
whether

a special Mercedes-
Benz child seat with a transponder for the air
bag deactivation system has been installed.
In this case, 45 indicator lamp :
lights up. The front-passenger front air bag is
deactivated: i
If the front-passenger front air bag is
disabled by the air bag deactivation
system, the following remain enabled on
the front-passenger side:
R the side impact air bag
R the window curtain air bag
R the Emergency Tensioning Device
LATCH-type (ISOFIX) child

seat anchors
in the rear G
WARNING
Children that are too large for a child restraint
must travel in seats using normal seat belts.
Position the shoulder belt across the chest
and shoulder, not the face or neck.
A booster seat may be necessary to achieve
proper seat belt positioning for children over
41 lbs (18 kg

) until they reach a height where
a normal shoulder/lap belt fit properly
without a booster.
Install the child seat according to
manufacturer's instructions.
The child seat must be firmly attached to both
anchors.
An incorrectly installed child restraint system
could come loose during an accident and
seriously or even fatally injure the child.
Damaged or impact damaged child seats or
child seat mountings must be replaced.
! When installing the LATCH-type (ISOFIX)
child restraint system, make sure that the
seat belt for the center seat does not get
trapped. Otherwise, the seat belt could be
damaged. 54
Children in the vehicle
Safety
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Due to the nature of the system, particularly
complicated driving
conditions
may cause the
system to display unnecessary warnings.
With the help of the radar sensor system, the
distance warning function can detect
obstacles that are in the path of your vehicle
for an extended period of time.
At speeds up to 40 mph (70 km/h), the
distance warning function may also detect
stationary obstacles, for example stopped or
parked vehicles.
If you approach an obstacle and the distance
warning function detects a risk of a collision,
the system will initially alert you both visually
and acoustically.
In particular, the detection of obstacles can
be impaired if:
R dirt on the sensors or anything else
covering the sensors
R snow or heavy rain
R interference by other radar sources
R there are strong radar reflections, for
example in parking garages
R a narrow vehicle traveling in front, e.g. a
motorbike
R a vehicle traveling in front on a different line
relative to the center of your vehicle
Following damage to the front end of the
vehicle, have the configuration and operation
of the radar sensor checked at a qualified
specialist workshop. This also applies to
collisions at low speeds where there is no
visible damage to the front of the vehicle.
Adaptive Brake Assist i
Observe the "Important safety notes"
section for driving safety systems
(Y page 59). G
WARNING
Adaptive Brake Assist cannot always clearly
identify objects and complex traffic
situations. In these cases, Adaptive Brake
Assist may not

intervene. There is a risk of an
accident. Always pay careful attention to the traffic
situation and be ready to brake.
G
WARNING
Adaptive Brake Assist does not react:
R to people or animals
R to oncoming vehicles
R to crossing traffic
R to stationary obstacles
R when cornering
As a result, Adaptive Brake Assist may not
intervene in all critical conditions. There is a
risk of an accident.
Always pay careful attention to the traffic
situation and be ready to brake.
Adaptive Brake Assist provides braking
assistance in hazardous situations at speeds
greater than 20 mph (30 km/h ) and uses
radar sensor technology to assess the traffic
situation.
With the help of a sensor system, adaptive
Brake Assist

can detect obstacles that are in
the path of your vehicle for an extended
period of time.
Should you approach an obstacle and
Adaptive Brake Assist has detected a risk of
collision, Adaptive Brake Assist calculates the
braking force necessary to avoid a rear-end
collision. Should you apply the brakes
vigorously, Adaptive Brake Assist will
automatically increase the braking force to a
level suitable for the traffic conditions.
X Keep the brake pedal depressed until the
emergency braking situation is over.
ABS prevents the wheels from locking.
The brakes will work normally again if:
R you release the brake pedal.
R there is no

longer any danger of a rear-end
collision.
R no obstacle is detected in front of your
vehicle.
Adaptive Brake Assist is then deactivated. Driving safety systems
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Safety Z
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Up to vehicle speeds of around 155 mph
(250 km/h
),
adaptive Brake Assist is capable
of reacting to moving objects that have
already been recognized as such at least once
over the period of observation. Adaptive
Brake Assist does not react to stationary
obstacles.
If Adaptive Brake Assist is not available due
to a malfunction in the radar sensor system,
the brake system remains available with full
brake boosting effect and BAS.
In particular, the detection of obstacles can
be impaired if there is:
R dirt on the sensors or anything else
covering the sensors
R snow or heavy rain
R interference by other radar sources
R there are strong radar reflections, for
example in parking garages
R a narrow vehicle traveling in front, e.g. a
motorbike
R a vehicle traveling in front on a different line
relative to the center of your vehicle
Following damage to the front end of the
vehicle, have the configuration and operation
of the radar sensor checked at a qualified
specialist workshop. This also applies to
collisions at low speeds where there is no
visible damage to the front of the vehicle. Adaptive brake lights
If you brake sharply from a speed of more
than 50 km/h

or if braking is assisted by BAS
or Adaptive Brake Assist, the brake lamps
flash rapidly. In this way, traffic traveling
behind you is warned in an even more
noticeable manner.
If you brake sharply to a standstill from a
speed of more than 70 km/h, the hazard
warning lamps are activated automatically. If
the brakes are applied again, the brake lamps
light up continuously. The hazard warning
lamps switch off automatically if you travel
faster than 10 km/h. You can also switch off the hazard warning lamps using the hazard
warning button (Y page 101).
i
Adaptive brake lamps

are only available in
certain countries. ESP
®
(Electronic Stability Program)
General notes i
Observe the "Important safety notes"
section ( Y page 59).
ESP ®
monitors driving stability and traction,
i.e. power transmission

between the tires and
the road surface.
If ESP ®
detects that the vehicle is deviating
from the direction desired by the driver, one
or more wheels are braked to stabilize the
vehicle. The engine output is also modified to
keep the vehicle on the desired course within
physical limits. ESP ®
assists the driver when
pulling away on wet or slippery roads. ESP ®
can also stabilize the vehicle during braking.
ETS (Electronic Traction System) i
Observe the "Important safety notes"
section for driving safety systems
(Y page 59).
ETS traction control is part of ESP ®
.
ETS brakes the drive wheels individually if
they spin. This enables you to pull away and
accelerate on slippery surfaces, for example
if the road surface is slippery on one side.
ETS remains active when you deactivate
ESP ®
.
Important safety notes G
WARNING
If ESP ®
is malfunctioning, ESP ®
is unable to
stabilize the vehicle. Additionally, further
driving safety systems are deactivated. This
increases the risk

of skidding and an accident.
Drive on carefully. Have ESP ®
checked at a
qualified specialist workshop. 62
Driving safety systems
Safety
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defroster is switched on and the outside
temperature is
low.
Mirror heating lasts up to
10 minutes.
i You can also heat up the exterior mirrors
manually by switching on the rear window
defroster.
Folding the exterior mirrors in or out
electrically X
Make sure that the SmartKey is in position
1 or 2 in the ignition lock.
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
30 mph (47 km/h ), you can no longer fold
in the exterior mirrors.
Setting the exterior mirrors If the battery has been disconnected or
completely discharged, the exterior mirrors
must be reset. The exterior mirrors will
otherwise not fold in when you select the
"Fold in
mirrors

when locking" function in the
on-board computer (Y page 199).
X Make sure that the SmartKey is in
position 1 in the ignition lock.
X Briefly press button :. Folding the exterior mirrors in or out
automatically If the "Fold in mirrors when locking" function
is activated in the on-board computer
(Y page 199):
R
the exterior mirrors

fold in automatically as
soon as you lock the vehicle from the
outside.
R the exterior mirrors fold out again
automatically 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, proceed as follows:
X
Vehicles without electrically folding
exterior mirrors:
move

the exterior mirror
into the correct position manually.
X Vehicles with electrically folding
exterior mirrors: press and hold mirror-
folding button ( Y page

93) until you hear a
click and then the mirrors engage in
position.
The mirror housing is engaged again and
you can adjust the exterior mirrors as usual
(Y page 92). Automatic anti-glare mirrors
The "Automatic anti-glare

mirrors" function is
only available if the vehicle is equipped with
the "Mirrors package".
The rear-view mirror and the exterior mirror
on the driver's side automatically go into anti-
glare mode if:
R the ignition is switched on and
R incident light from headlamps strikes the
sensor in the rear-view mirror.
The mirrors do not go into anti-glare mode if
reverse gear is engaged or the interior lighting
is switched on. Mirrors
93
Seats, steering wheel and mirrors Z
ProCarManuals.com

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).Exterior lighting
General notes
For reasons of safety, Mercedes-Benz
recommends that you drive with the lights
switched on even

during the daytime. In some
countries, operation of the headlamps varies
due to legal requirements and self-imposed
obligations. Driving abroad
Conversion to symmetrical low beam Switch the headlamps to symmetrical low
beam in countries in which traffic drives on
the opposite
side

of the road from the country
where the vehicle is registered. This prevents
glare to oncoming traffic. When using
symmetrical lights, the edge of the road is not
lit as widely and as far ahead as normal.
Have the headlamps converted at a qualified
specialist workshop as close to the border as
possible before driving in these countries.
Conversion to asymmetrical low beam
after returning Have the headlamps converted back to
asymmetrical low-beam headlamps at a
qualified specialist workshop as soon as
possible after crossing the border again. Setting the exterior lighting
Setting options Exterior lighting can be set using:
R
the light switch
R the combination switch ( Y page 100)
R the on-board computer (Y page 197)
Light switch Operation
1W
Left-hand standing lamps
2X Right-hand standing lamps
3T Parking lamps, license plate and
instrument cluster lighting
4Ã Automatic headlamp mode,
controlled by the light sensor
5L Low-beam/high-beam headlamps
BR Rear fog lamp
CN Fog lamp (only vehicles with front fog
lamps)
If you hear a warning tone when you leave the
vehicle, the lights may still be switched on.
X Turn the light switch to Ã.
The exterior lighting (except the parking/
standing lamps) switches off automatically if
you:
R remove the
SmartKey

from the ignition lock
R open the driver's door with the SmartKey
in position 0.98
Exterior lighting
Lights and windshield wipers
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Automatic headlamp mode
G
WARNING
When the light switch is set to Ã,
the low-
beam headlamps may not be switched on
automatically if there is fog, snow or other
causes 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's
lighting at all times.
à is the favored light switch setting. The
light setting is automatically selected
according to the brightness of the ambient
light (exception: poor visibility due to weather
conditions such as fog, snow or spray):
R SmartKey in position 1 in the ignition lock:
the parking lamps are switched on or off
automatically depending on the brightness
of the ambient light.
R With the engine running: if you have
activated the daytime running lamps
function via the on-board computer, the
daytime running lamps or the low-beam
headlamps and parking lamps are switched
on or off automatically depending on the
brightness of the ambient light.
X To switch on automatic headlamp
mode: turn the light switch to Ã.
The daytime running lamps improve the
visibility of your vehicle during the day. The
daytime running lamps

function is required by
law in Canada.
When the engine is running and the vehicle is
stationary: if you move the selector lever from
a drive position to P, the daytime running
lamps/low-beam headlamps go out after
three minutes.
When the engine is running, the vehicle is
stationary and in high ambient light: if you
turn the light switch to T, you turn on the
daytime running lamps and parking lamps. If the engine is running and you turn the light
switch to L, the manual settings take
precedence over the daytime running lamps.
Low-beam headlamps
Even if the light sensor does not detect that
it is dark, the parking lamps and low-beam
headlamps switch on when the ignition is
switched
on and

the light switch is set to the
L position. This is a particularly useful
function in the event of rain and fog.
X To switch on the low-beam headlamps:
turn the SmartKey in the ignition lock to
position 2 or start the engine.
X Turn the light switch to L.
The green L indicator lamp in the
instrument cluster lights up.
Front fog lamps
In conditions where visibility is poor due to
fog, snow or rain, the fog lamps improve
visibility as well as making it easier for other
road users to see you. They can be operated
together with the parking lamps or together
with the parking lamps and low-beam
headlamps.
X To switch on the front fog lamps: turn
the SmartKey in

the ignition lock to position
2 or start the engine.
X Turn the light switch to L or Ã.
X Press the N button.
The green N indicator lamp in the
instrument cluster lights up.
X To switch off the front fog lamps: press
the N button.
The green N indicator lamp in the
instrument cluster goes out.
Only vehicles with front fog lamps are
equipped with the "fog lamp" function;
information on the fog lamp function for
vehicles with Intelligent Light System
(Y page 102). Exterior lighting
99Lights and windshield wipers Z
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Active:
R
if you are driving at speeds below 25 mph
(40 km/h )
and switch on the turn signal or
turn the steering wheel.
R if you are driving at speeds between
25 mph (40 km/h) and 45 mph (70 km/h)
and turn the steering wheel.
Not active: if you are driving at speeds above
25 mph (40 km/h) or switch off the turn
signal or turn the steering wheel to the
straight-ahead position.
The cornering lamp may remain lit for a short
time, but is automatically switched off after
no more than three minutes. Extended range fog lamps
The extended range fog lamps reduce the
glare experienced by the driver and improve
the illumination of the edge of the road.
Active:
if you are driving at speeds below
40 mph (70

km/h) and you switch on the rear
fog lamp.
Not active: if, following activation, you are
driving at speeds above 60 mph (100 km/h)
or if you switch off the rear fog lamp. Adaptive Highbeam Assist
G
WARNING
Adaptive Highbeam Assist does not recognize
road users:
R who have no lights, e.g. pedestrians
R who have poor lighting, e.g. cyclists
R whose lighting is blocked, e.g. by a barrier
In very rare

cases, Adaptive Highbeam Assist
may fail to recognize other road users that
have lights, or may recognize them too late.
In this or similar situations, the automatic
high-beam headlamps will not be deactivated
or activated regardless. There is a risk of an
accident.
Always carefully observe the traffic conditions
and switch off the high-beam headlamps in
good time.
You can use this function to set the
headlamps to change between low beam and
high beam automatically. The system
recognizes vehicles with their lights on, either
approaching from the opposite direction or
traveling in front of your vehicle, and
consequently switches the headlamps from
high beam to low beam.
The system automatically adapts the low-
beam headlamp range depending on the
distance to the other vehicle. Once the
system no longer detects any other vehicles,
it reactivates the high-beam headlamps.
The system's optical sensor is located behind
the windshield near the overhead control
panel. 102
Exterior lighting
Lights and windshield wipers
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