Safety systems
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions J
N
The red brake system warning lamp lights up 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 Stop the vehicle immediately, paying attention to road and traffic conditions. Do
not continue driving.
X Secure the vehicle against rolling away (Y page 168).
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction display. J
N
The red brake system warning lamp lights up while the engine is running.
A warning tone also sounds.
G WARNING
There is insufficient brake fluid in the brake fluid reservoir.
There is a risk of an accident.
X Stop the vehicle immediately, paying attention to road and traffic conditions. Do
not continue driving.
X Secure the vehicle against rolling away (Y page 168).
X Do not top up the brake fluid. Topping up will not correct the fault.
X Consult a qualified specialist workshop.
X Observe the additional display messages in the multifunction display. J
N
The yellow brake system warning lamp lights up while the engine is running.
A warning tone also sounds.
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. 292
Warning and indicator lamps in the instrument clusterOn-board computer and displays
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions !
N
The yellow ABS warning lamp lights up while the engine is running.
ABS (Anti-lock Braking System) has been deactivated due to a fault.
Other driving and driving safety systems may also be malfunctioning.
In addition, the ÷andå warning lamps may light up in the instrument
cluster.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the functions listed above. The wheels could therefore lock if you brake hard, for example.
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. Warning and indicator lamps in the instrument cluster
293On-board computer and displays Z
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
M Solutions !
N
The yellow ABS warning lamp lights up while the engine is running.
ABS is temporarily unavailable.
Other driving and driving safety systems may also be malfunctioning.
In addition, the ÷andå warning lamps may light up in the instrument
cluster.
ATTENTION ASSIST is deactivated.
Possible causes:
R Self-diagnosis is not yet complete.
R The on-board voltage may be insufficient.
G WARNING
The brake system continues to function normally, but without the functions listed above. The front and rear wheels could therefore lock if you brake hard, for exam-
ple.
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 a risk of an accident.
X Carefully drive on a suitable stretch of road, making slight steering movements
at a speed above 20 km/h.
The functions mentioned above are available again when the warning lamp goes
out.
If the warning lamp is still on: X Observe the additional display messages in the multifunction display.
X Drive on carefully.
X Consult a qualified specialist workshop immediately. 294
Warning and indicator lamps in the instrument clusterOn-board computer and displays
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions !
N
The yellow ABS warning lamp lights up while the engine is running.
EBD is unavailable due to a malfunction.
Other driving and driving safety systems may also be malfunctioning.
In addition, the ÷andå warning lamps may light up in the instrument
cluster.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the functions listed above. The front and rear wheels could therefore lock if you brake hard, for exam-
ple.
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. J÷
å!
N
The red brake system warning lamp and the yellow ESP ®
, ESP ®
OFF and ABS
warning lamps are lit while the engine is running.
ABS and ESP ®
are malfunctioning.
Other driving and driving safety systems may also be malfunctioning.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the functions listed above. The front and rear wheels could therefore lock if you brake hard, for exam-
ple.
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
295On-board computer and displays Z
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 ®
, BAS, Active Brake Assist, Active Brake Assist with Cross-Traffic Assist,
ESP ®
trailer stabilisation, PRE ‑SAFE®
, PRE‑SAFE ®
PLUS, the HOLD function, hill
start assist, Crosswind Assist, adaptive brake lights, STEER CONTROL, Active Lane
Keeping Assist and Active Blind Spot Assist are not available due to a malfunction.
ATTENTION ASSIST is deactivated.
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. ֌
N
The yellow ESP ®
and ESP ®
OFF warning lamps are lit while the engine is running.
ESP ®
, BAS, Active Brake Assist, Active Brake Assist with Cross-Traffic Assist,
ESP ®
trailer stabilisation, PRE ‑SAFE®
, PRE‑SAFE ®
PLUS, the HOLD function, hill
start assist, Crosswind Assist, adaptive brake lights, STEER CONTROL, Active Lane
Keeping Assist and Active Blind Spot Assist are not available due to a malfunction.
ATTENTION ASSIST is deactivated.
Self-diagnosis is not yet complete.
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 Carefully drive on a suitable stretch of road, making slight steering movements
at a speed above 20 km/h.
The functions mentioned above are available again when the warning lamp goes out.
If the warning lamp is still on: 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
297On-board computer and displays Z
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
M Solutions !
N
The red indicator lamp for the electric parking brake flashes or is lit and/or the
yellow warning lamp for the electric parking brake is lit.
X Observe the additional display messages in the multifunction display. 6
N
The red restraint system warning lamp is lit while the engine is running.
The restraint system is malfunctioning.
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 Contact a qualified specialist workshop immediately and have the restraint sys-
tem checked.
Further information about the restraint system (Y page 42).Engine
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
M Solutions ;
N
The yellow engine diagnostics warning lamp lights up while the engine is run-
ning.
A fault may exist with the following, for example:
R Engine management
R In the fuel injection system
R Exhaust system
R Ignition system (for vehicles with petrol engines)
R 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 165).
X Start the engine three to four times after refuelling.
If the yellow engine diagnostics warning lamp goes out, emergency running
mode is cancelled. The vehicle does not have to be 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. 298
Warning and indicator lamps in the instrument clusterOn-board computer and displays
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ?
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 malfunctioning.
The coolant temperature is no longer being monitored. The engine could be dam-
aged 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.
X Safeguard the vehicle against rolling away (Y page 168).
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
299On-board computer and displays Z
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions X
Make sure that the air supply to the engine radiator is not blocked, e.g. by frozen
slush.
X If the coolant temperature is below 120 †, you can continue driving to the
nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in mountainous terrain
and stop-start traffic. Driving systems
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
MSolutions ·
N
The red distance warning lamp lights up while the vehicle is in motion.
The distance to the vehicle in front is too small for the speed selected.
X Increase the distance. ·
N
The red distance warning lamp lights up while the vehicle is in motion. A warning
tone also sounds.
You are approaching a vehicle, a pedestrian or a stationary obstacle in your line of travel at too high a speed.
X Be prepared to brake immediately.
X Pay careful attention to the traffic situation. You may have to brake or take
evasive action.
Further information on Distance Pilot DISTRONIC (Y page 184).
Further information on the distance warning function of Active Brake Assist
(Y page 70). Warning and indicator lamps in the instrument cluster
301On-board computer and displays Z