brake MERCEDES-BENZ B-CLASS HATCHBACK 2015 Repair Manual

Display messages
Possible causes/consequences and
M
MSolutions Further information on the automatic front-passenger front airbag
deactivation feature (Y page 42).Lights
i Vehicles with LED light bulbs in the light clusters:
The display message for the corresponding lamp only appears when all the LEDs in the lamp have
failed. Display messages
Possible causes/consequences and
M
MSolutions b
Left cornering Left cornering
light light
orRight cor‐
Right cor‐
nering light
nering light The left or right-hand cornering light is faulty.
X Check whether you are permitted to replace the bulb yourself
(Y page 103).
or
X Consult a qualified specialist workshop. b
Left dipped beam Left dipped beam
or
Right dipped beam
Right dipped beam The left or right-hand dipped-beam headlamp is faulty.
X Check whether you are permitted to replace the bulb yourself
(Y page 103).
or
X Consult a qualified specialist workshop. b
Rear Rear
left
leftindicator
indicator
or Rear right indi‐
Rear right indi‐
cator
cator The rear left-hand or rear right-hand turn signal is faulty.
X Check whether you are permitted to replace the bulb yourself
(Y page 103).
or
X Consult a qualified specialist workshop. b
Front left indica‐ Front left indica‐
tor tor
orFront right
Front right
indicator
indicator The front left-hand or front right-hand turn signal is faulty.
X Check whether you are permitted to replace the bulb yourself
(Y page 103).
or
X Consult a qualified specialist workshop. b
Left mirror indica‐ Left mirror indica‐
tor tor
orRight mirror
Right mirror
indicator
indicator The turn signal in the left-hand or right-hand exterior mirror is faulty.
X Consult a qualified specialist workshop. b
Third brake lamp Third brake lamp The third brake lamp is faulty.
X Consult a qualified specialist workshop. b
Left brake Left brake
lamp lampor
Right brake
Right brake
lamp
lamp The left or right-hand brake lamp is faulty.
X Consult a qualified specialist workshop. Display
messages
201On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions ì
Malfunction Visit Malfunction Visit
workshop workshop Malfunctions are present in the drive system and/or in the cooling
system.
X Consult a qualified specialist workshop immediately. Without starting Without starting
engine again, con‐ engine again, con‐
sult workshop sult workshop The vehicle's high-voltage electrical system is malfunctioning. A warn-
ing tone also sounds.
X Do not switch off the drive system.
X Consult a qualified specialist workshop immediately. ì
Stop Switch engine Stop Switch engine
off off There is a serious malfunction in the drive system. A warning tone also
sounds.
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 Do not tow the vehicle.
X Consult a qualified specialist workshop immediately. Driving systems
Display messages
Possible causes/consequences and
M MSolutions À
Attention Assist: Attention Assist:
Take a break! Take a break! Based on certain criteria, ATTENTION ASSIST has detected fatigue or
a lack of concentration on the part of the driver. A warning tone also
sounds.
X If necessary, take a break.
During long journeys, take regular breaks in good time so that you get
enough rest. À
Attention Assist Attention Assist
inoperative inoperative ATTENTION ASSIST is inoperative.
X Consult a qualified specialist workshop. ë
Off Off The HOLD function is deactivated. The vehicle is skidding.
A warning tone also sounds.
X Reactivate the HOLD function later (Y page 154). The HOLD function is deactivated. When the brake pedal is firmly
depressed, an activation condition is not fulfilled.
A warning tone also sounds.
X Check the activation conditions for the HOLD function
(Y page 154). Display
messages
205On-board computer and displays Z

Tyres
Display messages
Possible causes/consequences and
M
MSolutions Rectify tyre pres‐
Rectify tyre pres‐
sure sure The tyre pressure is too low in at least one of the tyres, or the tyre
pressure difference between the wheels is too great.
X Check the tyre pressures at the next opportunity (Y page 270).
X If necessary, correct the tyre pressure.
X Restart the tyre pressure monitor (Y page 272).Check tyre(s)
Check tyre(s) The tyre pressure in one or more tyres has dropped significantly. The
wheel position appears in the multifunction display.
A warning tone also sounds.
G WARNING
Underinflated tyres pose the following risks:
R the tyres may burst, especially as the load and vehicle speed
increase
R the tyres may wear excessively and/or unevenly, which may greatly
impair tyre traction
R the driving characteristics, as well as steering and braking, may be
greatly impaired
There is a risk of an accident.
X Stop the vehicle without making any sudden steering or braking
manoeuvres. Pay attention to the traffic conditions as you do so.
X Safeguard the vehicle against rolling away (Y page 145).
X Check the tyres and, if necessary, follow the instructions for a flat
tyre (Y page 249).
X Check the tyre pressure (Y page 270).
X If necessary, correct the tyre pressure. Warning tyre defect Warning tyre defect The tyre pressure in one or more tyres has dropped suddenly. The
wheel position appears in the multifunction display.
G WARNING
If you drive with a flat tyre, there is a risk of the following hazards: R a flat tyre affects the ability to steer or brake the vehicle
R you could lose control of the vehicle
R continued driving with a flat tyre will cause excessive heat build-up
and possibly a fire
There is a risk of an accident.
X Stop the vehicle without making any sudden steering or braking
manoeuvres. Pay attention to the traffic conditions as you do so.
X Safeguard the vehicle against rolling away (Y page 145).
X Check the tyres and, if necessary, follow the instructions for a flat
tyre (Y page 249). Display
messages
209On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions Tyre
Tyre
press.
press. monitor
monitor
currently unavaila‐
currently unavaila‐
ble ble No signals can be received from the tyre pressure sensors due to
strong RF interference. The tyre pressure monitor is temporarily mal-
functioning.
X Drive on.
The tyre pressure monitor restarts automatically as soon as the
cause has been rectified. Wheel sensor(s) Wheel sensor(s)
missing missing There is no signal from the tyre pressure sensor of one or several
wheels. The pressure of the affected tyre is not displayed in the mul-
tifunction display.
X Have the faulty tyre pressure sensor replaced at a qualified spe-
cialist workshop. Tyre Tyre
press.
press. monitor
monitor
inoperative No
inoperative No
wheel sensors wheel sensors The wheels fitted do not have suitable tyre pressure sensors. The tyre
pressure monitor is deactivated.
X Fit wheels with suitable tyre pressure sensors.
The tyre pressure monitor is activated automatically after driving for
a few minutes. Tyre Tyre
press.
press. monitor
monitor
inoperative
inoperative The tyre pressure monitor is faulty.
X Consult a qualified specialist workshop. Vehicle
Display messages
Possible causes/consequences and
M
MSolutions Depress brake to
Depress brake to
start engine start engine You have attempted to start the drive system with the transmission in
position Nwithout depressing the brake pedal.
X Depress the brake pedal. To shift out of P
To shift out of P
or or
N,
N,depress
depress brake
brake
and start engine
and start engine You have attempted to shift the transmission to position
Ror Dwith-
out starting the drive system.
X Start the drive system.
X Depress the brake pedal.
i It is only possible to shift the transmission from position
Pto 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 At transmission fluid temperatures below
Ò20†you can only shift
out of position Pinto another transmission position when the
engine is running. Apply
Apply
brake
braketo
todese‐
dese‐
lect Park (P) posi‐
lect Park (P) posi‐
tion tion You have attempted to shift the transmission to position
R,Nor D
without depressing the brake pedal.
X Depress the brake pedal. 210
Display messagesOn-board computer and displays

Safety systems
Problem
Possible causes/consequences and
M
MSolutions J
The yellow brake system
warning lamp is lit while
the drive system is run-
ning. The brake system is malfunctioning.
G WARNING
The braking characteristics may be affected.
There is a risk of an accident.
X Drive on taking extra care.
X Consult a qualified specialist workshop immediately. J
The yellow brake system
warning lamp is lit while
the drive system is run-
ning. RBS (Recuperative Brake System) is unavailable due to a malfunction.
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
function listed above.
Braking efficiency may be impaired.
X Drive on taking extra care.
X Consult a qualified specialist workshop immediately. J
The red brake system
warning lamp is lit while
the drive system is run-
ning. A warning tone also
sounds. G
WARNING
The brake boosting effect is malfunctioning and the braking charac-
teristics may be affected.
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 Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction dis-
play. Warning and indicator lamps in the instrument cluster
215On-board computer and displays Z

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