2012 MERCEDES-BENZ B-CLASS warning lights

Display messages Possible causes/consequences and
M SolutionsThe red
F (USA only)/! (Canada only) indicator lamp
flashes and the yellow ! warning lamp lights up.
The electric parking brake is malfunctioning.
To release:
X Switch off the ignition and turn it back on.
X Release the electric parking brake manually.
To apply:
X Switch off the ignition and turn it back on.
X Apply the electric parking brake manually.
If the red F (USA only)/! (Canada only) indicator lamp
continues to flash:
X Do not drive on.
X Secure the vehicle against rolling away ( Y page 320).
X Shift the transmission to P.
X Turn the front wheels towards the curb.
X Consult a qualified specialist workshop. The yellow
! warning lamp lights up. The red F (USA
only)/! (Canada only) indicator lamp flashes for about ten
seconds after the electric parking brake has been applied or
released. It then goes out or remains lit.
The electric parking brake is malfunctioning.
X Switch off the ignition and turn it back on.
X Apply the electric parking brake.
If it is not possible to engage the electric parking brake:
X Shift the transmission to P.
X Visit a qualified specialist workshop.
If it is not possible to release the electric parking brake:
X Release the electric parking brake automatically ( Y page 150).
If the electric parking brake still cannot be released:
X Consult a qualified specialist workshop. Display messages
205On-board computer and displays Z
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Display messages Possible causes/consequences and
M SolutionsThe yellow
! warning lamp lights up. If you manually apply or
release the electric parking brake, the red F (USA
only)/! (Canada only) indicator lamp flashes.
The electric parking brake is malfunctioning. It is not possible to
apply the electric parking brake manually.
X Shift the transmission to P.
X Visit a qualified specialist workshop. F(USA
only)!(Canada
only)
Parking Brake
Inoperative The yellow
! warning lamp lights up. The red F (USA
only)/! (Canada only) indicator lamp flashes for about ten
seconds after the electric parking brake has been applied or
released. It then goes out or remains lit.
The electric parking brake is malfunctioning, e.g. because of
overvoltage or undervoltage.
X Remove the cause for the overvoltage or undervoltage, e.g. by
charging the battery or restarting the engine.
X Engage or release the electric parking brake.
If it remains impossible to apply or release the electric parking
brake:
X Switch off the ignition and turn it back on.
X Engage or release the electric parking brake.
If the electric parking brake still cannot be released:
X Consult a qualified specialist workshop. The display message is only shown while the vehicle is in motion.
The yellow
! warning lamp lights up and the red F (USA
only)/ ! (Canada only) indicator lamp flashes.
It is not possible to apply the electric parking brake manually.
X Shift the transmission to P.
X Visit a qualified specialist workshop. F(USA
only)!(Canada
only)
Turn On the
Ignition to
Release the
Parking Brake The red
F (USA
only)/ ! (Canada only) indicator lamp lights
up.
You attempted to release the electric parking brake while the
ignition was switched off.
X Turn the SmartKey to position 1 in the ignition lock.206
Display messages
On-board computer and displays
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Display messages Possible causes/consequences and
M Solutions$(USA
only)J(Canada
only)
Check Brake Fluid
Level There is not enough brake fluid in the brake fluid reservoir.
In addition, the $ (USA only)/J (Canada only) warning
lamp lights up in the instrument cluster and a warning tone
sounds.
G WARNING
The braking effect 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 Secure the vehicle against rolling away ( Y page 149).
X Consult a qualified specialist workshop.
X Do not add brake fluid. This does not correct the malfunction. #
Check Brake Pad
Wear The brake pads/linings have reached their wear limit.
X
Visit a qualified specialist workshop. G
mbrace Inoperative One or more main features of the mbrace system are
malfunctioning.
X
Have the mbrace system checked immediately at a qualified
specialist workshop. 6
SRS Malfunction
Service Required There is a malfunction in the SRS (Supplemental Restraint
System). The 6 warning lamp also lights up in the instrument
cluster.
G WARNING
The air bags or Emergency Tensioning Devices may either be
triggered unintentionally or, in the event of an accident, may not
be triggered.
There is an increased risk of injury.
X Visit a qualified specialist workshop.
Further information on occupant safety (Y page 38). Display messages
207
On-board computer and displays Z
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Display messages Possible causes/consequences and
M Solutions6
Front Left
Malfunction
Service Required 
or Front Right
Malfunction
Service Required SRS has malfunctioned at the front on the left or right. The
6
warning lamp also lights up in the instrument cluster.
G WARNING
The air bags or Emergency Tensioning Devices may either be
triggered unintentionally or, in the event of an accident, may not
be triggered.
There is an increased risk of injury.
X Visit a qualified specialist workshop. 6
Rear Left
Malfunction
Service Required 
or Rear Right
Malfunction
Service Required SRS has malfunctioned at the rear on the left or right. The
6
warning lamp also lights up in the instrument cluster.
G WARNING
The air bags or Emergency Tensioning Devices may either be
triggered unintentionally or, in the event of an accident, may not
be triggered.
There is an increased risk of injury.
X Visit a qualified specialist workshop. 6
Rear Center
Malfunction
Service Required SRS has malfunctioned at the rear center. The
6 warning lamp
also lights up in the instrument cluster.
G WARNING
The air bags or Emergency Tensioning Devices may either be
triggered unintentionally or, in the event of an accident, may not
be triggered.
There is an increased risk of injury.
X Visit a qualified specialist workshop. 6
Left Side Curtain
Airbag
Malfunction
Service Required  
or 
Right Side
Curtain Airbag
Malfunction
Service Required There is a malfunction in the left-hand or right-hand window
curtain air bag. The
6 warning lamp also lights up in the
instrument cluster.
G WARNING
The left or right window curtain air bag may either be triggered
unintentionally or, in the event of an accident, may not be
triggered.
There is an increased risk of injury.
X Visit a qualified specialist workshop. Lights
i Display messages about LEDs:208
Display messages
On-board computer and displays
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Display messages Possible causes/consequences and
M Solutionsb
Switch Off Lights The lights are still switched on when you leave the vehicle. A
warning tone also sounds.
X
Turn the light switch to Ã. Adaptive Highbeam
Assist Inoperative Adaptive Highbeam Assist is faulty.
X
Visit a qualified specialist workshop. Adaptive Highbeam
Assist Currently
Unavailable See
Operator's Manual Adaptive Highbeam Assist is deactivated and temporarily
inoperative. Possible causes are:
R
the windshield in the camera's field of vision is dirty.
R visibility is impaired due to heavy rain, snow or fog.
X Clean the windshield.
If the system detects that the camera is fully operational again,
the Adaptive Highbeam Assist Now Available message is
displayed.
Adaptive Highbeam Assist is operational again. Engine
Display messages Possible causes/consequences and
M Solutions+
Check Coolant
Level See
Operator's Manual The coolant level is too low.
!
Avoid making long
journeys with too little coolant in the engine
cooling system. The engine will otherwise be damaged.
X Add coolant, observing the warning notes before doing so
(Y page 269).
X If coolant needs to be added more often than usual, have the
engine coolant system checked at a qualified specialist
workshop. ? The fan motor is faulty.
X
At coolant temperatures below 248 ‡ (120 †), drive to the
nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic.212
Display messages
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Warning and indicator lamps in the instrument cluster
Seat belts
Problem Possible causes/consequences and
M Solutionsü
After starting the
engine, the red seat
belt warning
lamp
lights
up for six seconds. The seat belt warning lamp reminds the driver and front passenger
to fasten their seat belts.
X
Fasten your seat belt ( Y page 45).ü
After starting the
engine, the red seat
belt warning
lamp

lights
up. In addition, a
warning tone sounds
for up to six seconds. The driver's seat belt is not fastened.
X
Fasten your seat belt ( Y page 45).
The warning tone ceases. ü
The red seat belt
warning lamp lights up
after the engine starts,
as soon as the driver's
or the front-passenger
door is closed.
The driver or front passenger has not fastened their seat belt.
X
Fasten your seat belt ( Y page 45).
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 front passenger has not fastened their seat belt. In
addition,
you are

driving faster than 15 mph (25 km/h) or you have
briefly driven faster than 15 mph (25 km/h).
X Fasten your seat belt ( Y page 45).
The warning lamp goes out and the intermittent warning tone
ceases. There are objects on the front-passenger seat. In addition, you are
driving faster than 15 mph (25 km/h
) or you have briefly driven
faster than 15 mph (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.224
Warning and indicator lamps in the instrument cluster
On-board computer and displays
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Problem Possible causes/consequences and
M SolutionsF (USA only)
! (Canada only)
The red indicator lamp
for the electric parking
brake flashes or lights
up and/or the yellow
warning lamp for the
electric parking brake
lights up. X
Observe the additional display messages in the multifunction
display. 6
The red SRS warning
lamp is lit while the
engine is running.
There is a malfunction in the SRS (Supplemental Restraint
System).
G WARNING
The air bags or Emergency Tensioning Devices may either be
triggered unintentionally or, in the event of an accident, may not
be triggered.
There is an increased risk of injury.
X Drive on carefully.
X Have SRS checked at a qualified specialist workshop
immediately.
For further information about SRS, see (Y page 38). 230
Warning and indicator lamps in the instrument clusterOn-board computer and displays
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Engine
Problem Possible causes/consequences and
M Solutions;
The yellow Check
Engine warning lamp
lights up while the
engine is running.
There may be a malfunction, for example:
R
in the engine management
R in the fuel injection system
R in the exhaust system
R in the ignition system
R in the fuel system
The emission limit values may be exceeded and the engine may
be running in emergency mode.
X Have the vehicle checked as soon as possible at a qualified
specialist workshop.
i In some states, you must immediately visit a qualified
specialist workshop as
soon as the yellow Check Engine warning
lamp lights up. This depends on the locally applicable legal
requirements. If in doubt, check whether such legal regulations
apply in the state in which you are currently driving. æ
The yellow reserve fuel
warning lamp lights up
while the engine is
running.
The fuel level has dropped into the reserve range.
X
Refuel at the nearest gas station. æ
The yellow reserve fuel
warning lamp flashes
while the engine is
running.
The fuel system pressure is too low. The fuel filler cap is not closed
correctly or the fuel system is leaking.
X
Check that the fuel filler cap is correctly closed.
X If the fuel filler cap is not correctly closed:
close the

fuel filler
cap.
X If the fuel filler cap is closed: visit a qualified specialist
workshop. ?
The red coolant
warning lamp lights up
while the engine is
running and
the

coolant
temperature gage is at
the start of the scale. The temperature sensor for the coolant temperature gage is
defective.
The coolant
temperature
is no longer being monitored. There is a
risk of engine damage if the coolant temperature is too high.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to

road and traffic conditions. Do not continue
driving under any circumstances.
X Secure the vehicle against rolling away ( Y page 149).
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
231
On-board computer and displays Z
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