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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 batter y 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 87). 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
Onl y 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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Page 238 of 305
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
immediatel y. 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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Page 239 of 305

Troubleshooting
236 Parktronic*
Problem Possible cause/consequence Suggested solutions
Onl
y 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 (Y page 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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Page 240 of 305

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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Page 241 of 305

Troubleshooting
238 Side windows
Problem Possible cause/consequence Suggested solutions
A side window will not close. Objects are trapped between the
window and the door frame. X
Remove the objects.
X Close the side window. There are objects in the window
guide rail which are preventing
the window from closing. X
Remove the objects.
X Close the side window. You cannot see the cause. X
Close the side window with increased force or without the anti-
entrapment feature ( Ypage 85). Mirrors
Problem Possible cause/consequence Suggested solutions
An exterior mirror has been
pushed out of position. Vehicles with exterior mirrors that cannot be folded in/out electri-
call
y:
X Move the exterior mirror into the correct position manually.
Vehicles with electrically folding exterior mirrors *:
X Press the mirror-folding button* (Y page 71) repeatedly until you
hear a distinct click.
The mirror housing is engaged again and you can adjust the mirror
as usual (Y page 71). Practical advice
* optional
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Page 242 of 305

Troubleshooting
239Key
Problem Possible cause/consequence Suggested solutions
You cannot lock or unlock the
vehicle using the key. The key batteries are discharged
or nearl
y 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 ( Ypage 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 ( Ypage 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
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Page 243 of 305

Troubleshooting
240 Trailer towing
Problem Possible cause/consequence Suggested solutions
The ball coupling cannot be
locked.
The key cannot be removed from
the ball coupling.
G
Risk of accident
The ball coupling is dirty.
The trailer tow hitch is damaged. X
Remove the ball coupling and clean it (Y page 196). Ifthe ball cou-
pling still cannot be locked, remove the ball coupling. It must no
longer be used to tow a trailer, as safe operation is not guaranteed.
X Have the entire trailer tow hitch checked at a qualified specialist
workshop. Parking up the vehicle
Problem Possible cause/consequence Suggested solutions
The vehicle is to be left parked up
for longer than six weeks. Damage resulting from non-use
may occur if the vehicle is parked
up for long periods. X
Visit a qualified specialist workshop and seek advice.
X Disconnect the battery ( Ypage 265). Practical advice
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