2008 MERCEDES-BENZ B-CLASS HATCHBACK Owners Manual

Troubleshooting
230 Warning tones
Problem Possible cause/consequence Suggested solutions
The anti-theft warning alarm* is
triggered. You have opened the vehicle with
the anti-theft alarm system still
activated*. X
Switch off the alarm (Y page 57).You hear a warning tone. A message appears in the multi-
function display. X
See the explanations for the display message (Y page 202). You are driving with the parking
brake applied. X
Release the parking brake. The light is switched on when you
leave the vehicle. X
Turn the light switch to MorU.
or
X If the rear foglamp is switched on: press the light switch in to the
stop. G
Risk of injury
The driver or front passenger has
not fastened their seat belt X
Fasten your seat belt (Y page 72).Practical advice
* optional
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Troubleshooting
231Problem Possible cause/consequence Suggested solutions
You hear a warning tone.
Vehicles with AUTOTRONIC*:
You have:
R
switched off the engine
R opened the driver's door
R not moved the selector lever to
position P X
Move the selector lever to P.Accident
Problem Possible cause/consequence Suggested solutions
Fuel is leaking from the vehicle.
G
Risk of fire
The fuel line or the fuel tank has
been damaged. The leaking fuel
creates a risk of fire or explosion. X
Switch off the ignition immediately.
X Remove the ignition key.
Do not restart the engine under any circumstances. The leaking fuel
creates a risk of fire or explosion.
X Consult a qualified specialist workshop. You are unable to determine the
extent of the damage. X
Consult a qualified specialist workshop. You cannot detect any damage. X
Start the engine as normal. Practical advice
* optional
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Troubleshooting
232 Fuel and fuel tank
Problem Possible cause/consequence Suggested solutions
Fuel is leaking from the vehicle.
G
Risk of explosion or fire
The fuel line or the fuel tank is
defective. X
Turn the key to position 0(Y page 62) in the ignition lock immedi-
ately and remove it.
X Do not restart the engine under any circumstances.
X Consult a qualified specialist workshop. The fuel filler flap cannot be
opened. The fuel filler flap is not released. X
Unlock the vehicle ( Ypage 241).
or
X Unlock the vehicle manually (Y page 242). The opening mechanism is jam-
med. X
Consult a qualified specialist workshop. The fuel tank in a diesel engine
vehicle has been run completely
dry and the engine will not start. There is air in the fuel system. X
Refuel the vehicle.
X Switch on the ignition for approximately 10 seconds (key in posi-
tion 2(Y page 62) in the ignition lock).
X Start the engine continuously for up to 40 seconds until it runs
smoothly.
The fuel system is now free of air.
If the engine does not start:
X Wait two minutes.
X Repeat the starting procedure for up to 40 seconds.
If the engine still does not start:
X Consult a qualified specialist workshop. Practical advice
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Troubleshooting
233Engine
Problem Possible cause/consequence Suggested solutions
The engine will not start. You can
hear the starter motor operating. R
The engine electronics system
is malfunctioning.
R There is a malfunction in the
fuel supply.
R The on-board voltage is too low
because the starter battery is
too weak or discharged. X
Turn the key back to position 0(Y page 62) in the ignition lock
before the next starting attempt.
X Try to start the engine again (Y page 86). When doing so, remember
that excessively long and frequent attempts to start the engine will
drain the battery.
If the engine does not start after several attempts:
X Consult a qualified specialist workshop. The engine will not start. You can
hear the starter motor operating.
The reserve fuel warning lamp is
on and the fuel gauge shows
0. The fuel tank has been run dry. X
Refuel the vehicle.
X Bleed the fuel system (Y page 232).The engine will not start. You can-
not hear the starter motor oper-
ating. The on-board voltage is too low
because the starter battery is too
weak or discharged. X
Jump-start the vehicle (Y page 266).
If the engine does not start despite attempting to jump-start it:
X Consult a qualified specialist workshop. The starter motor was exposed to
a thermal load that was too high. X
Allow the starter motor to cool down for approximately two
minutes.
X Try to start the engine again.
If the engine still does not start:
X Consult a qualified specialist workshop. Practical advice
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Troubleshooting
234 Problem Possible cause/consequence Suggested solutions
Vehicles with a petrol engine:
The engine is not running
smoothly and is misfiring. There is a malfunction in the
engine electronics or a mechani-
cal component of the engine con-
trol unit. X
Only depress the accelerator pedal slightly.
X Have the cause rectified immediately at a qualified specialist work-
shop.
Otherwise, non-combusted fuel may get into the catalytic converter
and damage it. A coolant temperature of over
120 °C is displayed. The coolant
warning lamp may also be on and
a warning tone may sound
(Y
page 97). The coolant level is too low. The
coolant is too hot and the engine
is no longer being cooled suffi-
ciently. X
Stop as soon as possible and allow the engine and the coolant to
cool down.
X Check the coolant level (Y page 175). Observe the warning notes
as you do so and top up the coolant if necessary. If the coolant level is correct, the
radiator fan may be faulty. The
coolant is too hot and the engine
is no longer being cooled suffi-
ciently. X
If the coolant temperature is less than 120 °C, you can continue
driving to the nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving on
mountain roads and stop/start driving. Practical advice
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Troubleshooting
235AUTOTRONIC*
Problem Possible cause/consequence Suggested solutions
The transmission has problems
shifting gear The transmission is losing oil. X
Have the transmission checked at a qualified specialist workshop
immediately. The acceleration ability is deteri-
orating.
The one-touch gearshifting is no
longer working.
The transmission no longer
changes gear. The transmission is in emergency
mode. X
Stop the vehicle.
X Move the selector lever to position P.
X Turn the key to position 0in the ignition lock.
X Wait at least 10 seconds before restarting the engine.
X Move the selector lever to position Dor R.
X Have the transmission checked at a qualified specialist workshop
immediately. Practical advice
* optional
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Troubleshooting
236 Parktronic*
Problem Possible cause/consequence Suggested solutions
Only the red segments in the
Parktronic warning display are lit.
You also hear a warning tone for
approximately two seconds.
Parktronic is deactivated after
approximately 20 seconds and
the indicator lamp in the Park-
tronic button lights up. Parktronic has malfunctioned
and has switched itself off. X
If problems persist, have Parktronic checked at a qualified spe-
cialist workshop. Only the red segments in the
Parktronic warning display are lit.
Parktronic is deactivated after
approximately 20 seconds. The Parktronic sensors are dirty
or there is interference. X
Clean the Parktronic sensors ( Ypage 196).
X Switch the ignition back on. Only the red segments in the
Parktronic warning display are lit.
Parktronic is deactivated after
approximately 20 seconds. The problem may be caused by an
external source of radio or ultra-
sound waves. X
See if Parktronic functions in a different location. Practical advice
* optional
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Troubleshooting
237Headlamps
Problem Possible cause/consequence Suggested solutions
The headlamps or the turn signals
in the exterior mirrors are misted
up on the inside. Air humidity is very high. X
Drive with the headlamps switched on.
The headlamps are demisted after a short distance. The headlamp housing is not
sealed and moisture has been
able to enter. X
Have the headlamps checked at a qualified specialist workshop. Windscreen wipers
Problem Possible cause/consequence Suggested solutions
The windscreen wipers are jam-
med. Leaves or snow, for example, may
be obstructing the windscreen
wiper movement. The wiper
motor has been deactivated. X
For safety reasons, you should remove the key from the ignition
lock.
X Remove the cause of the obstruction.
X Switch the windscreen wipers back on. The windscreen wipers fail com-
pletely. G
Risk of accident
The windscreen wiper drive is
malfunctioning. X
Select another wiper speed on the combination switch.
X Have the windscreen wipers checked at a qualified specialist work-
shop. Practical advice
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