Troubleshooting
285Problem Possible cause/consequence Suggested solutions
<
After the engine starts you
will hear a warning tone for
up to 6 seconds 34
. G
Risk of injury
The driver's seat belt is not fas-
tened. X
Fasten your seat belt (Y page 94).
The warning tone ceases. <
The red seat belt warning
lamp lights up after start-
ing the engine, as soon as
the driver's door or the
front-passenger door is
closed. G
Risk of injury
The driver or front passenger has
not fastened their seat belt. X
Fasten your seat belt (Y page 94).
The warning lamp goes out. G
Risk of injury
There are objects on the front-
passenger seat. X
Remove the objects from the front-passenger seat and stow them
safely.
The warning lamp goes out. <
The red seat belt warning
lamp flashes and you hear
an intermittent warning
tone. G
Risk of injury
The driver or front passenger has
not fastened their seat belt. At
the same time, you are driving
faster than 25 km/h or have
briefly driven faster than
25 km/h. X
Fasten your seat belt (Y page 94).
The warning lamp goes out and the intermittent warning tone
ceases. G
Risk of injury
There are objects on the front-
passenger seat. At the same
time, you are driving faster than
25 km/h or have briefly driven
faster than 25 km/h. X
Remove the objects from the front-passenger seat and stow them
safely.
The warning lamp goes out and the intermittent warning tone
ceases. 34
Only for certain vehicles. Practical advice
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Troubleshooting
286 Problem Possible cause/consequence Suggested solutions
The yellow reserve fuel warning
lamp comes on while the engine
is running. The fuel level has fallen below the
reserve range. The operation of
the auxiliary heating* can no lon-
ger be guaranteed. X
Refuel at the nearest filling station. Warning tones
Problem Possible cause/consequence Suggested solutions
The anti-theft warning alarm* is
triggered. You have opened the vehicle
using the emergency key element
without deactivating the anti-
theft alarm system* first. X
Switch off the alarm (Y page 63).You hear a warning tone. A message appears in the multi-
function display. X
See the explanations for the display message (Y page 255).You hear a warning tone. You are driving with the parking
brake applied. X
Release the parking brake. You hear a warning tone. You did not switch off the lights
when leaving the vehicle. X
Turn the light switch to MorU.
or
X If the rear foglamp is switched on: press the light switch in as far
as it will go. Practical advice
* optional
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Troubleshooting
287Problem Possible cause/consequence Suggested solutions
You hear a warning tone.
G
Risk of injury
The driver or front passenger has
not fastened their seat belt. X
Fasten your seat belt (Y page 94).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. The NECK-PRO head restraints
on the driver's and front-
passenger seats have been trig-
gered. Your vehicle has been involved in
a rear-end collision. X
Reset the NECK-PRO head restraints (Y page 304). Practical advice
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Troubleshooting
290 Engine
Problem Possible cause/consequence Suggested solutions
The engine will not start. You can
hear the starter motor operating. R
There is a malfunction in the
engine electronics.
R There is a malfunction in the
fuel supply. X
Turn the key back to position 0(Y page 76)in the ignition lock
before the next starting attempt.
X Try to start the engine again (Y page 110). When doing so, remem-
ber 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 289).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 329).
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
291Problem 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. You also
hear a warning signal. 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 223). 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. The engine does not switch off. The ignition lock is faulty. X
Open the fuse box in the engine compartment ( Ypage 334).
X Remove fuse 120 using the fuse extractor.
The engine stops.
If you wish to start the engine again:
X Replace the fuse. Practical advice
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Troubleshooting
293Parktronic*
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 247).
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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Flat tyre
313Flat tyre
Flat tyre equipment variants
Your vehicle may be equipped with:
R a TIREFIT kit (Y page 252)
R an emergency spare wheel* ( Ypage 252)
R the MOExtended run-flat sys-
tem* (Y page 322) Preparing the vehicle
i Vehicle preparation is not necessary on
vehicles with MOE tyres*.
X Vehicles with the AIRMATIC package*:
Make sure that highway level* is selected
(Y page 154).
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 Firmly depress the parking brake.
X Move the selector lever to P.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.
Vehicles without KEYLESS GO* X
Remove the key from the ignition lock.
Vehicles with KEYLESS GO* X
Open the driver's door.
The on-board electronics have status 0,
which is the same as the key having been
removed.
X Vehicles with the AIRMATIC package* and
the Off-Road Pro engineering package*:
Remove the KEYLESS GO button from the
ignition lock. For all vehicles X
Get out of the vehicle.
X Close the driver's door.
X Place the warning triangle ( Ypage 250) at
a suitable distance. Observe legal require-
ments.
i To operate the electric air-pump, you can
use the power socket in the luggage com-
partment (Y page 207) or 2nd row of seats
(Y page 207), even when the ignition is
switched off. For example, to use TIREFIT
or to inflate the collapsible emergency
spare wheel*.
An emergency cut-off ensures that the on-
board voltage does not drop too low. If the
on-board voltage is too low, power to the
sockets is automatically cut-off. This
ensures that there is sufficient power to
start the engine. Practical advice
* optional
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Flat tyre
316
If a pressure of 1.8 bar is not reached after
five minutes:
X Switch off and disconnect the electric air
pump and drive the vehicle forwards or
backwards approximately 10 m.
This distributes the TIREFIT more evenly.
X Remove TIREFIT sealant filler bottle 1
from the electric pump.
X Pump up the tyre again. G
Risk of accident
If a pressure of 1.8 bar is not achieved after
five minutes, the tyre is too badly damaged.
Do not drive any further. Consult a qualified
specialist workshop which has the neces-
sary specialist knowledge and tools to carry
out the work required. Mercedes-Benz rec-
ommends that you use a Mercedes-Benz
Service Centre for this purpose. In particu-
lar, work relevant to safety or on safety-
related systems must be carried out at a
qualified specialist workshop.
If a tyre pressure of 1.8 bar is reached:
X Press on/off switch 4on the electric air
pump to 0.
The electric air pump is switched off.
X Disconnect the electric air pump and stow
it away. X
Fold up the warning triangle and stow it
away.
X Pull away immediately.
This distributes the TIREFIT more evenly
around the tyre.
X Stop after driving for approximately ten
minutes and check the tyre pressure with
the electric air pump. G
Risk of accident
If the tyre pressure is now lower than
1.3 bar, the tyre is too badly damaged. Do
not drive any further. Consult a qualified
specialist workshop which has the neces-
sary specialist knowledge and tools to carry
out the work required. Mercedes-Benz rec-
ommends that you use a Mercedes-Benz
Service Centre for this purpose. In particu-
lar, work relevant to safety or on safety-
related systems must be carried out at a
qualified specialist workshop.
X If the tyre pressure is still at least 1.3 bar,
correct it (see fuel filler flap for values).
To increase the tyre pressure: switch on
the electric air pump. To reduce the tyre pressure:
open pres-
sure release screw aon pressure
gauge b.
X Drive to the nearest workshop and have the
tyre changed there.
X Have the TIREFIT kit replaced as soon as
possible at a qualified specialist workshop,
e.g. at a Mercedes-Benz Service Centre. G
Risk of accident
Do not exceed the maximum speed of
80 km/h.
The "max. 80 km/h" sticker must be affixed
within the driver's field of vision.
The vehicle's handling characteristics may
be affected. H
Environmental note
Have the used TIREFIT kit disposed of pro-
fessionally, e.g. at a Mercedes-Benz
Service Centre.
X Have the TIREFIT kit replaced every four
years at a qualified specialist workshop,
e.g. a Mercedes-Benz Service Centre. Practical advice
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