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Troubleshooting
293Problem 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 259).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
298 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. 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 344).
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
300 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 251).
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
307Problem Possible cause/consequence Suggested solutions
The auxiliary heating cannot be
switched on or off using the
remote control. The remote control display shows
FAIL and the
¢symbol.
The signal transmission between
the remote control and the vehi-
cle is faulty. X
Change your position in relation to the vehicle, moving closer if
necessary.
X Make another attempt to switch the auxiliary heating on or off using
the remote control. The remote control display shows
FAIL and the
¡symbol.
There is not enough fuel in the
tank, or the auxiliary heating is
faulty. X
Refuel at the nearest filling station.
X Have the auxiliary heating checked at a qualified specialist work-
shop. 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 335). Practical advice
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Page 343 of 381

Towing and tow-starting
340
X
Electrical consumers can be switched on
again. Do not switch the lights on, however,
as this will overload the battery.
X First, remove the jump lead from earth
point 2and negative terminal 4, then
from positive terminal 1and positive ter-
minal 3, each time disconnecting from the
battery on your own vehicle first.
i The message Battery protection:
some convenience functions cur-
rently not available may appear in the
multi-function display. It disappears as
soon as the battery is sufficiently charged.
X Have the battery checked at a qualified
specialist workshop, e.g. a Mercedes-Benz
Service Centre. Towing and tow-starting
Points to remember
G
Risk of accident
If you tow the vehicle, you must use a rigid
towing bar if:
R the engine is not running
R there is a brake system malfunction
R the voltage supply or the vehicle's elec-
trical system is damaged
The electric power steering and the brake
force booster do not work when the engine
is not running. Greater braking force will
then be required and the brake pedal travel
will be longer. If necessary, depress the
brake pedal with maximum force.
Do not tow the vehicle if the key cannot be
turned in the ignition lock. If this is the case,
the steering is locked and the vehicle can-
not be steered.
If you tow or tow-start another vehicle, its
weight must not exceed the maximum per-
missible gross vehicle weight of your vehi-
cle.
It is better to have the vehicle transported
than to have it towed. When towing, observe the legal requirements
in all countries concerned.
!
When towing, pull away slowly and with-
out jerking. If the tractive power is too high,
the vehicles could be damaged.
! Do not use the towing eye for recovery,
as this will damage the vehicle. If in doubt
recover the vehicle with a crane.
! You may tow the vehicle for a maximum
of 50 km. A towing speed of 50 km/h must
not be exceeded.
With towing distances over 50 km, the
entire vehicle needs to be lifted up and
transported.
! On vehicles with KEYLESS GO*: use the
key instead of the KEYLESS GO * button.
Turn the key to position 2in the ignition
lock and set the automatic transmission to
N. Then turn the key back to 0and leave it
in the ignition lock.
! Only secure the tow cable or towing bar
to the towing eyes. You may otherwise
damage the vehicle. Practical advice
* optional
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