engine MERCEDES-BENZ B-CLASS HATCHBACK 2008 Manual Online

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
245_AKB; 2; 7, en-GB
wdomann,
Version: 2.11.4 2008-10-17T11:22:31+02:00 - Seite 232Dateiname: 6515_1640_02_buchblock.pdf; preflight

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
245_AKB; 2; 7, en-GB
wdomann,
Version: 2.11.4
2008-10-17T11:22:31+02:00 - Seite 233 ZDateiname: 6515_1640_02_buchblock.pdf; preflight

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
245_AKB; 2; 7, en-GB
wdomann,
Version: 2.11.4 2008-10-17T11:22:31+02:00 - Seite 234Dateiname: 6515_1640_02_buchblock.pdf; preflight

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
245_AKB; 2; 7, en-GB
wdomann,
Version: 2.11.4
2008-10-17T11:22:31+02:00 - Seite 235 ZDateiname: 6515_1640_02_buchblock.pdf; preflight

Troubleshooting
239Key
Problem Possible cause/consequence Suggested solutions
You cannot lock or unlock the
vehicle using the key. The key batteries are discharged
or nearly discharged. X
Point the tip of the key at the driver's door handle from close range
and try to unlock or lock the vehicle again.
If this does not work:
X Unlock the vehicle using the emergency key element
(Y page 241).
X Check the key batteries (Y page 244) and replace them if neces-
sary (Y page 244). The key is faulty. X
Unlock the vehicle using the emergency key element
(Y page 241).
X Have the key checked at a qualified specialist workshop. The battery charge indicator lamp
of the key does not go on during
the test. The key batteries are discharged. X
Change the batteries (Y page 244).You have lost a key. X
Have the key cancelled at a Mercedes-Benz Service Centre.
X Report the loss immediately to the vehicle insurers.
X If necessary, have the manual locks changed too. You have lost the emergency key
element. X
Report the loss immediately to the vehicle insurers.
X If necessary, have the manual locks changed too. The engine cannot be started
using the key. The steering lock is mechanically
blocked. X
Remove the key and reinsert it into the ignition lock. While doing
this, turn the steering wheel in both directions. Practical advice
245_AKB; 2; 7, en-GB
wdomann,
Version: 2.11.4
2008-10-17T11:22:31+02:00 - Seite 239 ZDateiname: 6515_1640_02_buchblock.pdf; preflight

Changing bulbs
246
Rear bulbs Bulb Type
7
Third brake
lamp LED
8
Turn signal lamp PY 21 W
9
Reversing lamp P 21 W
a
Licence plate
lamp C 5 W
b
Rear foglamp P 21 W
c
Tail lamp P 5 W
d
Brake lamp P 21 W
Before changing bulbs
You can replace the following bulbs:
R
Dipped-beam headlamps (halogen head-
lamps)
R Main-beam headlamps (halogen head-
lamps)
R Side lamp/parking lamp
R Cornering light* (vehicles with bi-xenon
headlamps *)
R Front turn signal lamp R
Brake lamp
R Tail lamp
R Turn signal lamp (rear)
R Licence plate lamp
Observe the following points:
R Use only the bulb types specified here.
R To prevent a short-circuit, switch off the
lights before changing a bulb.
R Only hold bulbs with a clean, lint-free cloth.
R Do not work with wet or greasy fingers.
R If the new bulb still does not light up, con-
sult a qualified specialist workshop, e.g. a
Mercedes-Benz Service Centre.
i Due to the location of the bulbs in the
front headlamps, it is best to have these
changed at a qualified specialist workshop,
e.g. a Mercedes-Benz Service Centre.
i Have the headlamp setting checked reg-
ularly at a qualified specialist workshop,
e.g. a Mercedes-Benz Service Centre. Changing the front bulbs
Removing/fitting the washer fluid res-
ervoir You must remove the washer fluid reservoir
from the engine compartment before you can
replace the bulbs in the front left-hand head-
lamp.
X
To remove: turn retaining screw 1anti-
clockwise.
X Remove washer fluid reservoir 2from
bracket 3.
X Put washer fluid reservoir 2to one side
and leave the lines and hoses connected.
Make sure that no washer fluid escapes.
X To fit: guide the lower retaining lug into the
rubber grommet on the longitudinal mem- Practical advice
* optional
245_AKB; 2; 7, en-GB
wdomann,
Version: 2.11.4 2008-10-17T11:22:31+02:00 - Seite 246Dateiname: 6515_1640_02_buchblock.pdf; preflight

Flat tyre
252X
Swivel spraying nozzles 1upwards or
downwards.
X Wipe briefly with washer fluid to test them
(Y page 82).
The spraying nozzles are correctly posi-
tioned if the stream of water hits the wind-
screen approximately in the centre. Flat tyre
Flat tyre equipment variants
Your vehicle may be equipped with:
R a TIREFIT kit (Y page 200)
R a "Minispare" emergency spare
wheel* (Y page 202)
R a spare wheel* (Y page 202)
R the MOExtended run-flat sys-
tem* (Y page 262) Preparing the vehicle
i Vehicle preparation is not necessary on
vehicles with MOE tyres*.
X Stop your vehicle as far away from traffic
as possible on solid, non-slippery, level
ground.
X Switch on the hazard warning lamps.
X Apply the handbrake.
Vehicles with manual transmission X
Shift to either first or reverse gear. Vehicles with AUTOTRONIC* X
Move the selector lever to P.
For all vehicles X
All occupants must get out of the vehicle.
Make sure that they are not endangered as
they do so.
X Make sure that no one is near the danger
area whilst a wheel is being changed. Any-
one who is not directly assisting in the
wheel change should, for example, stand
behind the barrier.
X Switch off the engine.
X Remove the key from the ignition lock.
X Get out of the vehicle.
X Close the driver’s door.
X Place the warning triangle ( Ypage 200) at
a suitable distance. Observe legal require-
ments. Practical advice
* optional
245_AKB; 2; 7, en-GB
wdomann
, Version: 2.11.4
2008-10-17T11:22:31+02:00 - Seite 252 Dateiname: 6515_1640_02_buchblock.pdf; preflight

Flat tyre
260 Otherwise, the jack will not be able to ach-
ieve its load-bearing capacity due to the
restricted height.
Do not start the engine at any time while
the wheel is being changed.
Do not lie under the vehicle when it is being
supported by the jack. If you do not raise
the vehicle as described, it could slip off the
jack (e.g. if the engine is started or a door
or the tailgate is opened or closed) and you
could be seriously injured. G
Risk of accident
If you fail to position the jack correctly, the
vehicle may:
R slip off the jack
R injure you or others
R be damaged
Thus, it is important to make sure that the
jack is positioned correctly in the respec-
tive jacking points. Before positioning the
jack, remove any dirt that may have collec-
ted in the jacking points.
The jacking points for the jack are located
behind the wheel housings of the front wheels
and in front of the wheel housings of the rear
wheels. 1
Jacking point
2 Jack
3 Ratchet ring spanner with socket wrench
X Position jack 2at jacking point 1. X
Make sure that the base of the jack is posi-
tioned directly under jacking point 1.
X Take ratchet ring spanner and socket 3
out of the vehicle tool kit.
X Take ratchet ring spanner 3out of the
vehicle tool kit and place it on the jack so
that the lettering AUFis visible.
X Raise the vehicle with ratchet ring spanner
3 until the tyre is at most three centime-
tres off the ground.
X Unscrew the wheel bolts.
! Do not place wheel bolts in sand or on a
dirty surface. This could cause damage to
the bolt and wheel hub threads.
X Remove the wheel.
Fitting a new wheel G
Risk of accident
Replace damaged or corroded wheel bolts.
Never oil or grease wheel bolts. G
Risk of accident
If a wheel hub thread is damaged, you must
not drive the vehicle any further. Consult a
qualified specialist workshop which has the Practical advice
245_AKB; 2; 7, en-GB
wdomann , Version: 2.11.4 2008-10-17T11:22:31+02:00 - Seite 260Dateiname: 6515_1640_02_buchblock.pdf; preflight

Battery
264 step out of the vehicle first and touch the
bodywork.
R Do not wipe the battery using a cloth. The
battery could be destroyed as a result of
electrostatic charge or due to flying
sparks.
! Switch off the engine and remove the key
before disconnecting the terminal clamps
from the battery. Otherwise, you may
destroy electronic components, such as
the alternator.
i Mercedes-Benz recommends that you
have all work involving the battery, e.g.
removing, charging and replacing, carried
out at a qualified specialist workshop, e.g.
a Mercedes-Benz Service Centre.
Installation location of the battery Your vehicle is equipped with a battery in the
footwell in front of the front-passenger seat.
The main fuse box is also located there. 1
Retaining screw
2 Cap
X Remove the floormat*.
X Remove retaining screw 1by turning it
anti-clockwise, e.g. by using a coin.
X Lift up cover 2. 3
Negative terminal
4 Positive terminal Disconnecting the battery
G
Risk of accident
If the battery is disconnected:
R the brake boosting effect will not be avail-
able. Greater braking force will then be
required and the brake pedal travel will
be longer. If necessary, depress the
brake pedal with maximum force.
R you will no longer be able to turn the key
in the ignition lock.
R the selector lever is locked in position P
on vehicles with AUTOTRONIC*. Practical advice
* optional
245_AKB; 2; 7, en-GB
wdomann,
Version: 2.11.4 2008-10-17T11:22:31+02:00 - Seite 264Dateiname: 6515_1640_02_buchblock.pdf; preflight

Jump-starting
266 Reconnecting the battery
! Always reconnect the battery in the
sequence described below. Never swap the
terminal clamps. You may otherwise dam-
age the vehicle electronics.
X Switch off all electrical consumers.
X Connect the positive terminal clamp and
secure the cover.
X Connect the negative terminal clamp.
X Connect the breather hose. Make sure that
a cell cap is fitted on the side.
i If the battery power supply has been inter-
rupted (e.g. if it has been reconnected), you
must carry out the following tasks:
R set the time (Y page 108).
R reset the function for folding the exterior
mirrors in/out automatically* by folding
the mirrors out once (Y page 71).
R reset the side windows (Y page 84) Jump-starting
If your vehicle's battery is discharged, the
engine can be jump-started from another
vehicle or from an external battery using jump
leads.
Observe the following points:
R Jump-starting may only be performed when
the engine and catalytic converter are cold.
R Do not start the engine if the battery is fro-
zen. Let the battery thaw first.
R Jump-starting may only be performed from
batteries with a nominal voltage of 12 V.
R Only use jump leads which have a sufficient
cross-section and insulated terminal
clamps.
i Jump leads and further information about
jump-starting can be obtained from any
Mercedes-Benz Service Centre.
! Avoid repeated and lengthy starting
attempts.
Never start the vehicle using a rapid battery
charger. G
Risk of injury
There is a risk of acid burns when jump-
starting a vehicle due to the gases which
escape from the battery. Do not lean over
the battery while the engine is being jump-
started. G
Risk of explosion
Gases escaping from the battery during
jump-starting may cause minor explosions.
Avoid creating sparks. Keep naked flames
away from the battery, and do not smoke.
Comply with safety precautions and take
protective measures when handling batter-
ies. You will find these under "Battery" in
the index.
X Make sure that the two vehicles do not
touch.
X Apply the parking brake.
X Manual transmission: engage neutral.
X AUTOTRONIC*: move the DIRECT SELECT
selector lever to P.
X Switch off all electrical consumers.
X Open the bonnet (Y page 171). Practical advice
* optional
245_AKB; 2; 7, en-GB
wdomann,
Version: 2.11.4 2008-10-17T11:22:31+02:00 - Seite 266Dateiname: 6515_1640_02_buchblock.pdf; preflight