2008 MERCEDES-BENZ CLS COUPE check engine

Troubleshooting
247Problem Possible cause/consequence Suggested solutions
D
The red coolant warning
lamp comes on while the
engine is running. You will
also hear a warning tone. The coolant level is too low.
The coolant temperature has
exceeded 120 †. The engine is
not being cooled sufficiently and
may be damaged. X
Stop the vehicle as soon as possible. Pay attention to the traffic
conditions as you do so.
X Allow the engine and coolant to cool.
X Check the coolant level. Observe the warning notes
(Y page 196). Top up the coolant if necessary.
X Have the coolant system checked at a qualified specialist work-
shop if the coolant needs topping up more often than usual. D
The red coolant warning
lamp comes on while the
engine is running. You will
also hear a warning tone. If the coolant level is correct, the
radiator fan may be faulty.
The coolant temperature has
exceeded 120 †. The engine is
not being cooled sufficiently and
may be damaged. X
Do not continue driving under any circumstances.
X Consult a qualified specialist workshop. ±
The yellow engine diagnos-
tics warning lamp comes
on
while the engine is run-
ning. Vehicles with a diesel engine: the
fuel tank has run dry. X
Start the engine three to four times after refuelling.
Emergency running mode is cancelled. The vehicle need not be
checked. Practical advice
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Troubleshooting
248 Problem Possible cause/consequence Suggested solutions
±
The yellow engine diagnos-
tics warning lamp comes
on
while the engine is run-
ning. There may be a malfunction:
R
in the fuel injection system
R in the exhaust system
R in
the ignition system (on vehi-
cles with a petrol engine)
The emission limit values may be
exceeded and the engine may be
running in emergency mode. X
Have the vehicle checked as soon as possible at a qualified spe-
cialist workshop. H
The yellow tyre pressure
monitor* warning lamp is
on. G
Risk of accident
The tyre pressure monitor* has
detected a sudden or significant
pressure loss in at least one of
the tyres. X
Stop the vehicle without making any sudden steering or braking
manoeuvres. Pay attention to the traffic conditions as you do so.
X Observe the additional messages in the multi-function display
(Y page 219).
The warning light will go out after the flat tyre has been changed
and you have been driving for a few minutes. 1
The red SRS warning lamp
is lit while the engine is
running. G
Risk of injury
The restraint systems are faulty.
The airbags or belt tensioners
may either be triggered uninten-
tionally

or, in the event of an acci-
dent, not be triggered at all. X
Visit a qualified specialist workshop immediately. Practical advice
* optional
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Troubleshooting
256 Problem Possible cause/consequence Suggested solutions
Vehicles with a petrol engine:
The engine is not running
smoothly and is misfiring. The engine electronics or a
mechanical component of the
engine control unit have been
damaged. 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 110). 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 196). 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. when driving on
mountain roads and stop/start driving. Practical advice
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Troubleshooting
257Automatic transmission
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 transmission no longer
changes gear. The transmission is in emergency
mode.
It is only possible to shift into
2nd gear and reverse gear. X
Stop the vehicle.
X Move the selector lever to P.
X Turn the key to position 0 in the ignition lock.
X Wait at least 10 seconds before restarting the engine.
X Move the selector lever to position D or R.
If D
is selected, the transmission shifts into 2nd gear; if R is selec-
ted, the transmission shifts into reverse gear.
X Have the transmission checked at a qualified specialist workshop
immediately. Practical advice
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Troubleshooting
262 Problem Possible cause/consequence Suggested solutions
The key cannot be turned in the
ignition lock. The key has been in position
0 for
a considerable time. X
Remove the key and reinsert it into the ignition lock.
X Check the starter battery and recharge it if necessary
(Y page 290).
X Start the engine. The on-board voltage is too low. X
Switch off non-essential consumers, e.g. seat heating* or interior
lighting, and try to turn the key again.
If this does not work:
X Check the starter battery and recharge it if necessary
(Y page 290).
or
X Jump-start the vehicle (Y page 291).
or
X Consult a qualified specialist workshop. Practical advice
* optional
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Troubleshooting
264 Problem Possible cause/consequence Suggested solutions
The vehicle cannot be started
using the KEYLESS GO key and
the
KEYLESS GO button. The KEY-
LESS GO key is in the vehicle. A door is open. The key therefore
cannot be detected so easily. X
Close the door and try to start the vehicle again. You did not depress the brake
when starting the engine. X
Depress the brake and press the KEYLESS GO button. There is interference from a pow-
erful source of radio waves. X
Start your vehicle using the KEYLESS GO key in the ignition lock. You have lost the KEYLESS GO
key. X
Have the KEYLESS GO 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. Auxiliary heating/ventilation*
Problem Possible cause/consequence Suggested solutions
The auxiliary heating is not work-
ing. The fuel level is down to the
reserve level. X
Refuel at the nearest filling station. The battery is not sufficiently
charged. X
Charge the battery. The auxiliary heating is faulty. X
Have the auxiliary heating checked at a qualified specialist work-
shop. Practical advice
* optional
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Battery
289step out of the vehicle first and touch the
bodywork.
R Do not wipe the battery using a cloth. The
battery may explode as a result of elec-
trostatic charge or through the creation
of sparks.
! Switch the engine off and remove the key
before unscrewing or disconnecting the
terminal clamps from the battery. You may
otherwise destroy electronic components
such as the alternator.
Have the battery checked and, if neces-
sary, replaced at a qualified specialist
workshop, e.g. a Mercedes-Benz Service
Centre, every two years or at least every
20,000 km.
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
boot. It is located under the cover in the spare
wheel well. 1
Electrostatic protection
2 Battery 1
Positive terminal (under cover)
2 Negative terminal Electrostatic protection G
Risk of injury
Only use rechargeable batteries with elec-
trostatic protection fitted. The electrostatic
protection prevents the creation of sparks
due to electrostatic buildup, thereby pre-
venting the highly explosive mixture of
gases in the battery from igniting.
i You can obtain the electrostatic protec-
tion from any Mercedes-Benz Service
Centre.
X To remove: pull the electrostatic protec-
tion upwards and remove.
X To fit: push the electrostatic protection
firmly onto the battery. Practical advice
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Jump-starting
292 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 Depress the parking brake.
X Move the selector lever to P.
X Switch off all electrical consumers.1 Positive terminal of your vehicle's battery
2 Positive terminal of donor battery
3 Negative terminal of donor battery
4 Connection for suitable earth point on the
vehicle
X Connect positive contact on your vehi-
cle 1 to positive terminal of the donor
battery 2 using the jump lead, connecting
the jump lead to your own battery first.
X Start the engine of the donor vehicle and
run it at idling speed.
X Connect the negative terminal of the donor
battery 3 and the earth contact on your
vehicle 4 using the jump lead, connecting
the jump lead to the donor battery first.
X Start the engine. X
Electrical consumers can be switched on
again. Do not switch the lights on however,
as this will overload the battery.
X Remove the jump lead from the suitable
earthing point 4 and negative termi-
nal 3 first, then from the positive termi-
nals 1 and 2, each time disconnecting
from the battery on your own vehicle first.
X Have the battery checked at a qualified
specialist workshop, e.g. a Mercedes-Benz
Service Centre.
Practical advice
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