warning lights MERCEDES-BENZ B-CLASS HATCHBACK 2015 Workshop Manual

Safety
Seat belts Problem
Possible causes/consequences and
M
MSolutions ü
Only for certain coun-
tries: the red seat belt
warning lamp lights up
for 6 seconds after the
drive system starts.
The seat belt warning lamp reminds the driver and front passenger to
fasten their seat belts.
X Fasten your seat belt (Y page 37).ü
Only for certain coun-
tries: the red seat belt
warning lamp lights up
after the drive system
starts. In addition, a
warning tone sounds for
up to 6 seconds.
The driver's seat belt is not fastened.
X Fasten your seat belt (Y page 37).
The warning tone ceases. ü
The red seat belt warning
lamp lights up after the
drive system starts, as
soon as the driver's or
the front-passenger door is closed. The driver or passenger has not fastened their seat belt.
X Fasten your seat belt (Y page 37).
The warning lamp goes out. There are objects on the front-passenger seat.
X Remove the objects from the front-passenger seat and stow them in
a secure place.
The warning lamp goes out. ü
The red seat belt warning
lamp flashes and an
intermittent audible
warning sounds. The driver or passenger has not fastened their seat belt. At the same
time, you are driving faster than 25 km/h or have briefly driven faster
than 25 km/h.
X Fasten your seat belt (Y page 37).
The warning lamp goes out and the intermittent warning tone
ceases. There are objects on the front-passenger seat. At the same time, you
are driving faster than 25 km/h or have briefly driven faster than
25 km/h.
X Remove the objects from the front-passenger seat and stow them in
a secure place.
The warning lamp goes out and the intermittent warning tone
ceases. 214
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Problem
Possible causes/consequences and
M
MSolutions J
The red brake system
warning lamp is lit while
the drive system is run-
ning. A warning tone also
sounds. There is insufficient brake fluid in the brake fluid reservoir.
G WARNING
Braking efficiency may be impaired.
There is a risk of an accident.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.
X Safeguard the vehicle against rolling away (Y page 145).
X Do not top up the brake fluid. Topping up will not rectify the fault.
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction dis-
play. !֌J
The yellow ABS, ESP
®
,
ESP ®
OFF and brakes
warning lamps are lit
while the drive system is running. ABS (Anti-lock Braking System) has been deactivated due to a fault.
Therefore, BAS (Brake Assist), COLLISION PREVENTION ASSIST
PLUS, ESP ®
(Electronic Stability Program), RBS, PRE ‑SAFE®
, the
HOLD function, hill start assist and the adaptive brake lights, for
example, are also deactivated.
ATTENTION ASSIST is deactivated.
G WARNING
The braking performance of the electric motor using recuperative
braking may be either reduced or not effective. If you do not make an
additional effort to apply the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative brak-
ing effect by applying the brake yourself.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you brake
hard, for example.
The steerability and braking characteristics may be severely affected. The braking distance may increase in an emergency braking situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction dis-
play.
X Drive on carefully.
X Consult a qualified specialist workshop immediately.
If the ABS control unit is malfunctioning, other systems may also not
be available, e.g. the navigation system. 216
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Problem
Possible causes/consequences and
M
MSolutions !֌J
The yellow ABS, ESP
®
,
ESP ®
OFF and brakes
warning lamps are lit
while the drive system is running. ABS is temporarily unavailable. Therefore, BAS, RBS, COLLISION PRE-
VENTION ASSIST PLUS, ESP ®
, EBD (electronic brake force distribu-
tion), PRE‑SAFE ®
, the HOLD function, hill start assist and the adaptive
brake lights, for example, are also deactivated.
Possible causes:
R Self-diagnosis is not yet complete
R The on-board voltage may be insufficient.
ATTENTION ASSIST is deactivated.
G WARNING
The braking performance of the electric motor using recuperative
braking may be either reduced or not effective. If you do not make an
additional effort to apply the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative brak-
ing effect by applying the brake yourself.
The brake system continues to function normally, but without the
functions listed above. The front and rear wheels could therefore lock, for example, if you brake hard.
The steerability and braking characteristics may be severely affected.The braking distance may increase in an emergency braking situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is a risk of an accident.
X Carefully drive on a suitable stretch of road making slight steering
movements at a speed above 20 km/h.
The functions mentioned above are available again when the warn-
ing lamp goes out.
If the warning lamp is still on: X Observe the additional display messages in the multifunction dis-
play.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. Warning and indicator lamps in the instrument cluster
217On-board computer and displays Z

Problem
Possible causes/consequences and
M
MSolutions !֌J
The yellow ABS, ESP
®
,
ESP ®
OFF and brakes
warning lamps are lit
while the drive system is running. EBD is faulty. Therefore, ABS, BAS, COLLISION PREVENTION ASSIST
PLUS, ESP ®
, RBS, PRE ‑SAFE®
, the HOLD function, hill start assist and
the adaptive brake lights, for example, are not available either.
ATTENTION ASSIST is deactivated.
G WARNING
The braking performance of the electric motor using recuperative
braking may be either reduced or not effective. If you do not make an
additional effort to apply the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative brak-
ing effect by applying the brake yourself.
The brake system continues to function normally, but without the
functions listed above. The front and rear wheels could therefore lock, for example, if you brake hard.
The steerability and braking characteristics may be severely affected.The braking distance may increase in an emergency braking situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction dis-
play.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. !֌J
The red brake system
warning lamp and the
yellow ABS, ESP
®
and
ESP ®
OFF warning lamps
are lit while the drive sys-
tem is running. ABS and ESP
®
are malfunctioning. Therefore, BAS, RBS, COLLISION
PREVENTION ASSIST PLUS, EBD, PRE ‑SAFE®
, the HOLD function, hill-
start assist and the adaptive brake lights, for example, are not avail-
able either.
ATTENTION ASSIST is deactivated.
G WARNING
The braking performance of the electric motor using recuperative
braking may be either reduced or not effective. If you do not make an
additional effort to apply the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative brak-
ing effect by applying the brake yourself.
The brake system continues to function normally, but without the
functions listed above. The front and rear wheels could therefore lock, for example, if you brake hard.
The steerability and braking characteristics may be severely affected.The braking distance may increase in an emergency braking situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction dis-
play.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. 218
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Problem
Possible causes/consequences and
M
MSolutions ֌J
The yellow ESP
®
, ESP ®
OFF and brakes warning
lamps are lit while the
drive system is running. ESP
®
, RBS, BAS, COLLISION PREVENTION ASSIST PLUS, PRE‑SAFE ®
,
the HOLD function, hill start assist and the adaptive brake lights are
not available due to a malfunction.
ATTENTION ASSIST is deactivated.
G WARNING
The braking performance of the electric motor using recuperative
braking may be either reduced or not effective. If you do not make an
additional effort to apply the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative brak-
ing effect by applying the brake yourself.
The brake system continues to function normally, but without the
functions listed above.
The braking distance may thus increase in an emergency braking sit-
uation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction dis-
play.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. 220
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Problem
Possible causes/consequences and
M
MSolutions ֌J
The yellow ESP
®
, ESP ®
OFF and brakes warning
lamps are lit while the
drive system is running. ESP
®
, BAS, PRE‑SAFE ®
, the HOLD function and hill start assist are
temporarily unavailable.
The adaptive brake lights and COLLISION PREVENTION ASSIST PLUS
may also have failed.
ATTENTION ASSIST is deactivated.
Self-diagnosis is not yet complete
G WARNING
The braking performance of the electric motor using recuperative
braking may be either reduced or not effective. If you do not make an
additional effort to apply the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative brak-
ing effect by applying the brake yourself.
The brake system continues to function normally, but without the
functions listed above.
The braking distance may thus increase in an emergency braking sit-
uation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Carefully drive on a suitable stretch of road, making slight steering
movements at a speed above 20 km/h.
The functions mentioned above are available again when the warn- ing lamp goes out.
If the warning lamp is still on: X Observe the additional display messages in the multifunction dis-
play.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. Warning and indicator lamps in the instrument cluster
221On-board computer and displays Z

Problem
Possible causes/consequences and
M
MSolutions !
The red indicator lamp
for the electric parking
brake flashes or is lit
and/or the yellow warn-
ing lamp for the electric
parking brake is lit. X
Observe the additional display messages in the multifunction dis-
play. 6
The red restraint system
warning lamp is lit while
the drive system is run-
ning.
The restraint system is faulty.
G WARNING
The airbags or belt tensioners may either be triggered unintentionally or, in the event of an accident, may not be triggered.
This poses an increased risk of injury.
X Observe the additional display messages in the multifunction dis-
play.
X Drive on carefully.
X Contact a qualified specialist workshop and have the restraint sys-
tem checked.
For further information about the restraint system, see (Y page 34).Drive system
Problem
Possible causes/consequences and
M MSolutions Ý
The yellow battery
charge warning lamp is
on.
The charge level of the high-voltage battery has dropped into the
reserve range.
X
Charge the high-voltage battery. Driving systems
Problem
Possible causes/consequences and
M MSolutions ·
The red distance warning
lamp lights up while the
vehicle is in motion. The distance to the vehicle in front is too small for the speed selected.
X Increase the distance. ·
The red distance warning
lamp lights up while the
vehicle is in motion. A
warning tone also
sounds. You are approaching a vehicle or a stationary obstacle in your line of
travel at too high a speed.
X Be prepared to brake immediately.
X Pay careful attention to the traffic situation. You may have to brake
or take evasive action.
For further information on the distance warning function of COLLI-
SION PREVENTION ASSIST PLUS, see (Y page 62).222
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Washing the vehicle and cleaning the
paintwork
Automatic car wash G
WARNING
Braking efficiency is reduced after the vehicle has been washed. There is a risk of an acci-
dent.
After washing the vehicle, brake carefully
while paying attention to the traffic conditions in order to restore full braking efficiency.
! When the HOLD function is activated, the
vehicle brakes automatically in certain situa-
tions.
To avoid damage to the vehicle, deactivate
the HOLD function in the following or similar
situations:
R when towing away
R in a car wash
! When washing your vehicle in a tow-through
car wash, make sure that the selector lever is in position N, otherwise the vehicle could be
damaged.
! Make sure:
R the side windows are closed completely.
R the blower for the ventilation/heating is
switched off (OFF button is depressed/
airflow control is turned to position 0).
R the windscreen wiper switch is at position
0.
The vehicle could otherwise be damaged.
You can wash the vehicle in an automatic car
wash from the very start.
Wash off excess dirt before cleaning the vehicle
in an automatic car wash.
After using an automatic car wash, wipe off wax
from the windscreen and the wiper blades. This
will prevent smears and reduce wiping noises
caused by residue on the windscreen.
Washing by hand In some countries, washing by hand is only
allowed at specially equipped washing bays.
Observe the legal requirements for each indi-
vidual country. X
Do not use hot water and do not wash the
vehicle in direct sunlight.
X Use a soft sponge to clean.
X Use a mild cleaning agent, such as a car
shampoo approved by Mercedes-Benz.
X Thoroughly hose down the vehicle with a gen-
tle jet of water.
X Do not point the water jet directly towards the
air inlet.
X Use plenty of water and rinse out the sponge
frequently.
X Rinse the vehicle with clean water and dry
thoroughly with a chamois.
X Do not let the cleaning agent dry on the paint-
work.
When using the vehicle in winter, remove all
traces of road salt deposits carefully and as
soon as possible.
High-pressure cleaning equipment G
WARNING
The water jet of circular-jet nozzles (dirt grind- ers) can cause damage not visible from the
outside to tyres or chassis components. Com-
ponents damaged in this way can unexpect-
edly fail. There is a risk of an accident.
Do not use high-pressure cleaners with circu-
lar-jet nozzles to clean the vehicle. Have dam- aged tyres or chassis components replaced
immediately.
! Always maintain a distance of at least 30 cm
between the vehicle and the high-pressure
cleaner nozzle. Information about the correct
distance is available from the equipment
manufacturer.
Move the high-pressure cleaner nozzle
around when cleaning your vehicle.
Do not aim directly at any of the following:
R tyres
R door gaps, roof gaps, joints etc.
R electrical components
R battery
R connectors
R lights
R seals
R trim elements
R ventilation slots Care
243Maintenance and care Z

Removing the towing eye
X
Loosen the towing eye and unscrew it.
X Place the towing eye in the stowage well
under the luggage compartment floor
(Y page 249).
X Vehicles with a TIREFIT kit: replace the tyre
inflation compressor. Towing the vehicle with both axles on
the ground
It is important that you observe the safety
instructions when towing away your vehicle
(Y page 260).
X On vehicles with KEYLESS-GO or the KEY-
LESS-GO start function: you must use the
key instead of the Start/Stop button
(Y page 127).
The transmission automatically shifts to posi-
tion Pwhen you open the driver's or front-
passenger door or when you remove the key
from the ignition lock. In order to ensure that the transmission stays in position Nwhen towing
the vehicle, you must observe the following
points:
X Make sure that the vehicle is stationary.
X Turn the key to position 2in the ignition lock.
X Depress the brake pedal and keep it
depressed.
X Shift the transmission to position N.
X Release the brake pedal.
X Release the electric parking brake.
X Switch on the hazard warning lamps
(Y page 100).
X Leave the key in position 2in the ignition lock.
If the 12 V battery indicator lamp lights up, you
must observe the following points:
X Pull over and safely stop the vehicle as soon
as possible, paying attention to road and traf-
fic conditions.
X Shift the transmission to position P.
X Apply the electric parking brake.
i In order to signal a change of direction when
towing the vehicle with the hazard warning
lamps switched on, use the combination
switch as usual. In this case, only the turn
signals for the desired direction flash. When you reset the combination switch, the hazard
warning lamps start flashing again. Towing the vehicle with the front axle
raised
When towing your vehicle with the front axle
raised, it is important that you observe the
safety instructions (Y page 260).
! The ignition must be switched off if you are
towing the vehicle with the front axle raised.
Intervention by ESP ®
could otherwise dam-
age the brake system.
X On vehicles with KEYLESS-GO or the KEY-
LESS-GO start function: you must use the
key instead of the Start/Stop button
(Y page 127).
X Make sure that the vehicle is stationary.
X Turn the key to position 2in the ignition lock.
X When the vehicle is stationary, depress the
brake pedal and keep it depressed.
X Shift the transmission to position P.
X Release the brake pedal.
X Release the electric parking brake.
X Deactivate tow-away protection (Y page 68).
X Deactivate automatic locking (Y page 187).
X Switch on the hazard warning lamps
(Y page 100).
X Turn the key in the ignition lock to position 0
and leave the key in the ignition lock. Towing the vehicle away with the rear
axle raised
When towing your vehicle away with the rear
axle raised, it is important that you observe the safety instructions (Y page 260).
! The ignition must be switched off if you are
towing the vehicle with the rear axle raised.
Intervention by ESP ®
could otherwise dam-
age the brake system. 262
RecoveryBreakdown assistance

Important safety notes
It is the driver's responsibility to set the tyre
pressure to the recommended cold tyre pres-
sure suitable for the operating situation
(Y page 269). Note that the correct tyre pres-
sure for the current operating situation must
first be taught-in to the tyre pressure monitor. If
there is a substantial loss of pressure, the warn-
ing threshold for the warning message is aligned to the reference values taught-in. Restart the
tyre pressure monitor after adjusting to the cold tyre pressure (Y page 272). The current pres-
sures are saved as new reference values. This
will ensure that a warning message will only
appear if the tyre pressure drops significantly.
The tyre pressure monitor does not warn you of
an incorrectly set tyre pressure. Observe the
notes on the recommended tyre pressure
(Y page 269).
The tyre pressure monitor is not able to warn
you of a sudden loss of pressure, e.g. if the tyre
is penetrated by a foreign object. In the event of a sudden loss of pressure, bring the vehicle to a
halt by braking carefully. Avoid abrupt steering
manoeuvres.
The tyre pressure monitor has a yellow warning lamp in the instrument cluster for indicating a
pressure loss or malfunction. Depending on how
the warning lamp flashes or lights up, a tyre
pressure that is too low or a malfunction in the
tyre pressure monitor is indicated:
R if the warning lamp is lit continuously, the tyre
pressure on one or more tyres is significantly
too low. The tyre pressure monitor is not mal-
functioning.
R if the warning lamp flashes for around a
minute and then remains lit constantly, the
tyre pressure monitor is malfunctioning.
In addition to the warning lamp, a message
appears in the multifunction display. Observe
the information on display messages
(Y page 209).
It may take up to ten minutes for a malfunction
of the tyre pressure monitor to be indicated. A
malfunction will be indicated by the tyre pres-
sure warning lamp flashing for approximately
one minute and then remaining lit. When the
fault has been rectified, the tyre pressure warn- ing lamp goes out after you have driven for a few
minutes.
The tyre pressure values indicated by the on-
board computer may differ from those meas-
ured at a filling station using a pressure gauge. The tyre pressures shown by the on-board com-
puter refer to those measured at sea level. At
high altitudes, the tyre pressure values indica-
ted by a pressure gauge are higher than those
shown by the on-board computer. In this case,
do not reduce the tyre pressures.
The operation of the tyre pressure monitor can
be affected by interference from radio transmit- ting equipment (e.g. radio headphones, two-way
radios) that may be being operated in or near the vehicle.
Checking the tyre pressure electroni-
cally X
Make sure that the key is in position 2in the
ignition lock (Y page 126).
X Press =or; on the steering wheel to
select the Serv. Serv.menu.
X Press the 9or: button to select
Tyre pressure Tyre pressure.
X Press the abutton.
The current tyre pressure for each wheel will
be displayed in the multifunction display.
If the vehicle was parked for longer than
20 minutes, the Tyre pressures will be Tyre pressures will be
displayed
displayed after
aftera
afew
few minutes
minutes of
ofdriv‐
driv‐
ing
ing message is shown.
After a teach-in period, the tyre pressure moni-
tor automatically detects new wheels or new
sensors. As long as a clear allocation of the tyre pressure values to the individual wheels is not
possible, the Tyre Tyrepressure
pressure monitor
monitoractive
active
message is shown instead of the tyre pressure
display. The tyre pressures are already being
monitored.
If an emergency spare wheel is fitted, for a few
minutes the system may continue to show the
tyre pressure of the wheel that has been
removed. If this occurs, note that the value dis-
played for the position where the spare wheel is fitted is not the same as the current tyre pres-
sure of the emergency spare wheel.
Warning messages of the tyre pressure monitor If the tyre pressure monitor detects a pressure
loss in one or more tyres, a warning message is
shown in the multifunction display. The yellow
tyre pressure warning lamp then lights up.
R If the Please correct tyre pressure Please correct tyre pressure
message appears in the multifunction display, Tyre pressure
271Wheels and tyres Z