Page 249 of 345

Display messages
Possible causes/consequences and
M
MSolutions A strong source of radio waves is causing interference, this means that
the KEYLESS-GO key is not recognised when the engine is running.
A warning tone also sounds.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 150).
X Insert the key into the ignition lock and bring into key mode. Â
Key not detected Key not detected
(white display message) The KEYLESS-GO key cannot be detected at present.
X Change the location of the key with the KEYLESS-GO functions in
the vehicle.
If the KEYLESS-GO key is still not detected: X Operate the vehicle with the key in the ignition lock if necessary. Â
Remove Remove
starting
starting but‐
but‐
ton,
ton, then
theninsert
insert key
key The KEYLESS-GO key is not continually detected.
KEYLESS-GO is temporarily malfunctioning or is defective. A warning tone also sounds.
X Insert the key into the ignition lock and turn it to the desired posi-
tion.
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
General notes
Some systems carry out a self-diagnosis when the ignition is switched on. Several warning and
indicator lamps can thereby temporarily light up or flash. This behaviour is non-critical. These
warning and indicator lamps only indicate a malfunction if they light up or flash after the engine is started or during a journey. 246
Wa
rning and indi cator lamps in the instrument clusterOn-board computer and displays
Page 250 of 345

Safety
Seat belts Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ü
N
Only for certain countries: the red seat belt warning lamp lights up for 6 seconds
after the engine starts.
The seat belt warning lamp reminds the driver and front passenger to fasten their
seat belts.
X Fasten your seat belt (Y page 39).ü
N
Only for certain countries: the red seat belt warning lamp lights up after the
engine starts. In addition, a warning tone sounds for up to 6 seconds.
The driver's seat belt is not fastened.
X Fasten your seat belt (Y page 39).
The warning lamp goes out and the warning tone ceases. ü
N
The red seat belt warning lamp lights up after the engine starts, as soon as the
driver's or the front-passenger door is closed.
The driver or passenger has not fastened their seat belt.
X Fasten your seat belt (Y page 39).
The warning lamp goes out.
There are objects on the front-passenger seat.
X Remove the objects from the front-passenger seat and stow them in a secure
place.
The warning lamp goes out. ü
N
The red seat belt warning lamp flashes and an intermittent audible warning
sounds.
The driver or 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 39).
The warning lamp goes out and the intermittent warning tone ceases.
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 in a secure
place.
The warning lamp goes out and the intermittent warning tone ceases. Warning and indicator lamps in the instrument cluster
247On-board computer and displays Z
Page 251 of 345

Safety systems
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions J
N
The yellow brake system warning lamp lights up while the engine is running.
G WARNING
The brake system is malfunctioning and the braking characteristics may be affec- ted.
There is a risk of an accident.
X If the multifunction display shows a display message, please observe this.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. J
N
The red brake system warning lamp comes on while the vehicle is moving. A
warning tone also sounds.
You are driving with the parking brake applied.
X Release the parking brake.
The warning lamp goes out and the warning tone ceases. J
N
The red brake system warning lamp is lit while the engine is running. A warning
tone also sounds.
G WARNING
The brake boosting effect is malfunctioning and the braking characteristics may be
affected.
There is a risk of an accident.
X Pull over and stop the vehicle safely as soon as possible, paying attention to road
and traffic conditions. Do not continue driving under any circumstances.
X Safeguard the vehicle against rolling away (Y page 150).
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction display. J
N
The red brake system warning lamp is lit while the engine is running. A warning
tone also sounds.
G WARNING
There is insufficient brake fluid in the brake fluid reservoir.
Braking efficiency may be impaired.
There is a risk of an accident.
X Pull over and stop the vehicle safely as soon as possible, paying attention to road
and traffic conditions. Do not continue driving under any circumstances.
X Safeguard the vehicle against rolling away (Y page 150).
X Do not top up the brake fluid. Topping up will not rectify the fault.
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction display. 248
Warning and indicator lamps in the instrument clusterOn-board computer and displays
Page 252 of 345

Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions !
N
The yellow ABS warning lamp is lit while the engine is running.
ABS (Anti-lock Braking System) is faulty.
An additional warning tone indicates that EBD (electronic brake force distribution) is faulty.
Other driving and driving safety systems may also be faulty.
G WARNING
The brake system continues to function normally, but without the functions listed above. The front and rear wheels could therefore lock, for example, if you brake
hard.
The steerability and braking characteristics may be severely affected. The braking
distance may increase in an emergency braking situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction display.
X Drive on carefully.
X Consult a qualified specialist workshop immediately.
If the ABS control unit is faulty, there is also a possibility that other systems, such as the navigation system or the automatic transmission, will be unavailable. J÷
å!
N
The red brake system warning lamp and the yellow ESP ®
, ESP ®
OFF and ABS
warning lamps are lit while the drive system is running.
ABS and ESP ®
are faulty.
Other driving and driving safety systems may also be faulty.
G WARNING
The brake system continues to function normally, but without the functions listed above. The front and rear wheels could therefore lock, for example, if you brake
hard.
The steerability and braking characteristics may be severely affected. The braking
distance may increase in an emergency braking situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction display.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. Warning and indicator lamps in the instrument cluster
249On-board computer and displays Z
Page 253 of 345

Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
M Solutions ÷
N
The yellow ESP ®
warning lamp flashes while the vehicle is in motion.
ESP ®
or traction control has intervened because there is a risk of skidding or at
least one wheel has started to spin.
Cruise control or DISTRONIC PLUS is deactivated.
X Only depress the accelerator pedal as far as necessary when pulling away.
X Accelerate more gently while the vehicle is in motion.
X Adapt your driving style to suit the road and weather conditions.
X Do not deactivate ESP ®
.
In rare cases (Y page 68) it may be better to deactivate ESP ®
.
Observe the important safety notes on ESP ®
(Y page 67). å
N
The yellow ESP ®
OFF warning lamp is lit while the engine is running.
ESP ®
is deactivated.
G WARNING
If ESP ®
is deactivated, ESP ®
is unable to stabilise the vehicle.
Further driving systems or driving safety systems are thus restricted, e.g. Active
Blind Spot Assist. The system does not perform course-correcting braking appli-
cations.
There is an increased danger of skidding and risk of an accident.
X Reactivate ESP ®
.
In rare cases (Y page 68) it may be better to deactivate ESP ®
.
Observe the important safety notes on ESP ®
(Y page 67).
X Adapt your driving style to suit the road and weather conditions.
If ESP ®
cannot be activated:
X Drive on carefully.
X Contact a qualified specialist workshop immediately and have the ESP ®
system
checked. 250
Warning and indicator lamps in the instrument clusterOn-board computer and displays
Page 254 of 345

Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ֌
N
The yellow ESP ®
and ESP ®
OFF warning lamps are lit while the engine is running.
ESP ®
is faulty.
Other driving and driving safety systems may also be faulty.
G WARNING
The brake system continues to function normally, but without the functions listed above.
The braking distance may thus increase in an emergency braking situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Observe the additional display messages in the multifunction display.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. 6
N
The red restraint system warning lamp is lit while the engine is running.
The restraint system is faulty.
G WARNING
The airbags or belt tensioners may either be triggered unintentionally or, in the
event of an accident, may not be triggered.
This poses an increased risk of injury. X Observe the additional display messages in the multifunction display.
X Drive on carefully.
X Have the restraint system checked immediately at a qualified specialist work-
shop.
Observe the additional information on the restraint system (Y page 36).Warning and indicator lamps in the instrument cluster
251On-board computer and displays Z
Page 255 of 345

Engine
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ;
N
The yellow engine diagnostics warning lamp lights up while the engine is run-
ning.
There may be a fault, for example:
R in the engine management
R in the fuel injection system
R in the exhaust system
R in the ignition system (for vehicles with petrol engines)
R in the fuel system
The emission limit values may be exceeded and the engine may be running in
emergency mode.
X Consult a qualified specialist workshop immediately.
Vehicles with a diesel engine: the fuel tank has been run dry (Y page 150).
X After refuelling start the engine three to four times.
If the yellow engine diagnostics warning lamp goes out, emergency running
mode is cancelled. You do not need to have the vehicle checked. 8
N
The yellow reserve fuel warning lamp is on while the engine is running.
The fuel level has dropped into the reserve range.
Operation of the auxiliary heating is deactivated if the fuel level drops into the
reserve range.
X Refuel at the nearest filling station. ?
N
The red coolant warning lamp lights up while the engine is running and the
coolant temperature gauge is at the start of the scale.
The temperature sensor for the coolant temperature gauge is faulty.
The coolant temperature is no longer being monitored. There is a risk of engine
damage if the coolant temperature is too high.
X Stop the vehicle immediately, paying attention to road and traffic conditions,
and switch off the engine. Do not continue driving under any circumstances.
X Safeguard the vehicle against rolling away (Y page 150).
X Consult a qualified specialist workshop. 252
Warning and indicator lamps in the instrument clusterOn-board computer and displays
Page 256 of 345

Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ?
N
The red coolant warning lamp comes on while the engine is running.
The coolant level is too low.
If the coolant level is correct, the airflow to the engine radiator may be blocked or the electric engine radiator fan may be malfunctioning.
The coolant is too hot and the engine is no longer being cooled sufficiently.
X Observe the additional display messages in the multifunction display.
X Stop the vehicle immediately, paying attention to road and traffic conditions,
and switch off the engine.
X Safeguard the vehicle against rolling away (Y page 150).
X Leave the vehicle and keep a safe distance from the vehicle until the engine has
cooled down.
X Check the coolant level and top up the coolant, observing the warning notes
(Y page 286).
X If you have to top up the coolant frequently, have the engine cooling system
checked.
X Make sure that the air supply to the engine radiator is not blocked, e.g. by frozen
slush.
X Do not start the engine again until the coolant temperature is below 120 †. The
engine may otherwise be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid putting the engine under heavy load as you do so, e.g. driving in moun-
tainous terrain and stop-start traffic. ?
N
The red coolant warning lamp comes on while the engine is running. A warning
tone also sounds.
The coolant temperature has exceeded 120 †. The airflow to the engine radiator
may be blocked or the coolant level may be too low.
G WARNING
The engine is not being cooled sufficiently and may be damaged.
Never drive with an overheated engine. Driving when your engine is overheated
can cause some fluids which may have leaked into the engine compartment to
catch fire.
In addition, steam from an overheated engine can cause serious burns, which can
occur just by opening the bonnet.
There is a risk of injury.
X Observe the additional display messages in the multifunction display.
X Stop the vehicle immediately, paying attention to road and traffic conditions,
and switch off the engine.
X Safeguard the vehicle against rolling away (Y page 150).
X Leave the vehicle and keep a safe distance from the vehicle until the engine has
cooled down.
X Check the coolant level and top up the coolant, observing the warning notes
(Y page 286).
X If you have to top up the coolant frequently, have the engine cooling system
checked. Warning and indicator lamps in the instrument cluster
253On-board computer and displays Z