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Display messagesPossible causes/consequences and0050Solutions
00AF
Key Not Detected(reddisplay message )
The SmartKey is no tin th evehicle.
A warning tone also sounds.
If th eengin eis switched off ,you can no longer loc kth evehicl ecen-
trally or start th eengine.
XPull ove rand stop th evehicl esafely as soo nas possible, payin g
attention to roa dand traffic conditions.
XSecur eth evehicl eagainst rollin gaway (Ypage 137).
XLocate th eSmartKey.
XPress 0076on thesteering whee lto confirm th edisplay message .
Becausethere is interferenc efrom astron gsource of radi owaves, th e
SmartKey is no tdetecte dwhils tth eengin eis running.
A warning tone also sounds.
XPull ove rand stop th evehicl esafely as soo nas possible, payin g
attention to roa dand traffic conditions.
XSecur eth evehicl eagainst rollin gaway (Ypage 137).
XInsertth eSmartKey int oth eignition loc kand bring int oke ymode.
00AF
Remove 'Start 'But ‐ton and Insert Key
The SmartKey is continually undetected.
The SmartKey detection function has atemporar ymalfunction or is
faulty. Awarning tone also sounds.
XInser tth eSmartKey int oth eignition loc kand tur nit to th edesire d
position .
XVisitaqualified specialist workshop .
Warning and indicat orlamps in the instrume nt cluster
General notes
Some systems carry out aself-diagnosis when th eignition is switched on .Therefore ,som eindicator
and warning lamp smay ligh tup or flas htemporarily. This behavio ris non-critical .These indicator
and warning lamp sonly indicat e amalfunction if they ligh tup or flas hafter starting th eengin eor
whils tdriving.
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Safety
Seat belts
Warning/
indicator
lamp0051Signal type
Possible causes/consequences and 0050
Solutions
00E90051After starting the engine, the red seat belt warning lamp lights up for 6 seconds.
The seat belt warning lamp reminds the driver and front passenger to fasten their
seat belts.
XFasten your seat belt (Ypage 44).
00E90051 After starting the engine, the red seat belt warning lamp lights up. In addition, a
warning tone sounds for up to 6 seconds.
The driver's seat belt is not fastened.
XFasten your seat belt (Ypage 44).
The warning tone ceases.
00E90051 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 front passenger has not fastened their seat belt.
XFasten your seat belt (Ypage 44).
The warning lamp goes out.
There are objects on the front-passenger seat.
XRemove the objects from the front-passenger seat and stow them in a secure
place.
The warning lamp goes out.
00E90051 The red seat belt warning lamp flashes and an intermittent audible warning
sounds.
The driver or front passenger has not fastened their seat belt. The vehicle is being driven faster than 15 mph (25 km/h) or has briefly been driven faster than 15 mph
(25 km/h).
XFasten your seat belt (Ypage 44).
The warning lamp goes out and the intermittent warning tone ceases.
There are objects on the front-passenger seat. The vehicle is being driven faster
than 15 mph (25 km/h) or has briefly been driven faster than 15 mph (25 km/h).
XRemove 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.
232Warning and indicator lamps in the instrument cluster
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Safety systems
Warning/
indicator
lamp0051Signal type
Possible causes/consequences and 0050
Solutions
0027004D00510027 (USA only) or 004D(Canada only): the red brake system warning lamp is
lit while the engine is running.
A warning tone also sounds.
GWARNING
The brake boosting effect is malfunctioning and the braking characteristics may be
affected.
There is a risk of an accident.
XPull over and stop the vehicle safely as soon as possible, paying attention to road
and traffic conditions. Do not continue driving under any circumstances.
XSecure the vehicle against rolling away (Ypage 137).
XConsult a qualified specialist workshop.
XObserve the additional display messages in the multifunction display.
0027004D0051 0027 (USA only) or 004D(Canada only): the red brake system warning lamp is
lit while the engine is running.
A warning tone also sounds.
There is not enough brake fluid in the brake fluid reservoir.
GWARNING
The braking effect may be impaired.
There is a risk of an accident.
XPull over and stop the vehicle safely as soon as possible, paying attention to road
and traffic conditions. Do not continue driving under any circumstances.
XSecure the vehicle against rolling away (Ypage 137).
XDo not add brake fluid. Adding more will not correct the malfunction.
XConsult a qualified specialist workshop.
XObserve the additional display messages in the multifunction display.
00270051 USA only: the red brake system warning lamp is lit while the engine is running.
The multifunction display also shows a display message with the 0026symbol.
The brake pads/linings have reached their wear limit.
XVisit a qualified specialist workshop.
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Warning/
indicator
lamp0051Signal type
Possible causes/consequences and 0050
Solutions
00250051The yellow ABS warning lamp is lit while the engine is running.
ABS (anti-lock braking system) is malfunctioning.
If there is an additional warning tone, the EBD (electronic brake force distribution)
is malfunctioning.
Other driving systems and driving safety systems may also malfunction.
GWARNING
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 in an emergency braking situation can increase.
If ESP
®is not operational, ESP®is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
XObserve the additional display messages in the multifunction display.
XDrive on carefully.
XVisit 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 not be available.
0027004D
00E500250051 0027 (USA only), 004D(Canada only): the red brake warning lamp, the yellow
ESP®warning lamp and the yellow ABS warning lamp are lit while the engine is
running.
ABS and ESP
®are malfunctioning.
Other driving systems and driving safety systems may also malfunction.
GWARNING
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 in an emergency braking situation can increase.
If ESP
®is not operational, ESP®is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
XObserve the additional display messages in the multifunction display.
XDrive on carefully.
XVisit a qualified specialist workshop immediately.
234Warning and indicator lamps in the instrument cluster
On-board computer and displays
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Warning/
indicator
lamp0051Signal type
Possible causes/consequences and 0050
Solutions
00E50051The 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.
XWhen pulling away, only depress the accelerator pedal as far as necessary.
XEase off the accelerator pedal while the vehicle is in motion.
XAdapt your driving style to suit the road and weather conditions.
XDo not deactivate ESP®.
In exceptional cases, it may be better to deactivate ESP®:
Rwhen using snow chains
Rin deep snow
Ron sand or gravel
Observe the important safety notes on ESP®(Ypage 67).
00E50051 The yellow ESP®warning lamp is lit while the engine is running.
ESP®is malfunctioning.
Other driving systems and driving safety systems may also malfunction.
GWARNING
The brake system continues to function normally, but without the functions listed
above.
The braking distance in an emergency braking situation can thus increase.
If ESP
®is not operational, ESP®is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
XObserve the additional display messages in the multifunction display.
XDrive on carefully.
XVisit a qualified specialist workshop immediately.
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Warning/
indicator
lamp0051Signal type
Possible causes/consequences and 0050
Solutions
00BB0051The yellow ESP®OFF warning lamp is lit while the engine is running.
ESP®is deactivated.
GWARNING
If ESP
®is switched off, ESP®is unable to stabilize 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 brake applica-
tions.
There is an increased risk of skidding and an accident.
XReactivate ESP®.
In exceptional cases, it may be better to deactivate ESP®:
Rwhen using snow chains
Rin deep snow
Ron sand or gravel
Observe the important safety notes on ESP®(Ypage 67).
XAdapt your driving style to suit the road and weather conditions.
If ESP
®cannot be activated:
XDrive on carefully.
XContact a qualified specialist workshop and have ESP®checked.
004900240051 0049 (USA only) or 0024(Canada only): 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.
XObserve the additional display messages in the multifunction display.
00750051 The red restraint system warning lamp is lit while the engine is running.
The restraint system is malfunctioning.
GWARNING
The air bags or Emergency Tensioning Devices may either be triggered uninten-
tionally or, in the event of an accident, may not be triggered.
There is an increased risk of injury.
XObserve the additional display messages in the multifunction display.
XDrive on carefully.
XContact a qualified specialist workshop and have the restraint system checked.
For further information about the restraint system, see (
Ypage 41).
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On-board computer and displays
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Engine
Warning/
indicator
lamp0051Signal type
Possible causes/consequences and 0050
Solutions
00B90051The yellow Check Engine warning lamp lights up while the engine is running.
There may be a malfunction, for example:
Rin the engine management
Rin the fuel injection system
Rin the exhaust system
Rin the ignition system
Rin the fuel system
The emission limit values may be exceeded and the engine may be in emergency
mode.
XVisit a qualified specialist workshop immediately.
iIn some states, you must immediately visit a qualified specialist workshop as
soon as the yellow Check Engine warning lamp lights up. This is due to the legal
requirements in effect in these states. If in doubt, check whether such legal
regulations apply in the state in which you are currently driving.
00B60051 The yellow reserve fuel warning lamp lights up while the engine is running.
The fuel level has dropped into the reserve range.
XRefuel at the nearest gas station.
00B60051 The yellow reserve fuel warning lamp flashes while the vehicle is in motion.
In addition, the 00B9Check Engine warning lamp may light up.
The fuel filler cap is not closed correctly or the fuel system is leaking.
XCheck that the fuel filler cap is correctly closed.
XIf the fuel filler cap is not correctly closed: close the fuel filler cap.
XIf the fuel filler cap is closed:visit a qualified specialist workshop.
00AC0051The red coolant warning lamp comes on while the engine is running. The coolant
temperature gauge is at the beginning of the cold range.
The temperature sensor for the coolant temperature gauge is malfunctioning.
The coolant temperature is no longer being monitored. There is a risk of engine
damage if the coolant temperature is too high.
XPull over and stop the vehicle safely and switch off the engine, paying attention
to road and traffic conditions. Do not continue driving under any circumstances.
XSecure the vehicle against rolling away (Ypage 137).
XConsult a qualified specialist workshop.
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Warning/
indicator
lamp0051Signal type
Possible causes/consequences and 0050
Solutions
00AC0051The 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 defective.
The coolant is too hot and the engine is no longer being cooled sufficiently.
XObserve the additional display messages in the multifunction display.
XPull over and stop the vehicle safely and switch off the engine, paying attention
to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 137).
XLeave the vehicle and keep a safe distance from the vehicle until the engine has cooled down.
XCheck the coolant level and add coolant, observing the warning notes
(Ypage 277).
XIf you have to add coolant frequently, have the engine cooling system checked.
XMake sure that the air supply to the engine radiator is not blocked, e.g. by snow,
slush or ice.
XDo not start the engine again until the coolant temperature is below 257 ‡
(125 †). Otherwise, the engine could be damaged.
XDrive to the nearest qualified specialist workshop.
XAvoid heavy loads on the engine as you do so, e.g. driving in mountainous terrain
and stop-and-go traffic.
00AC0051 The red coolant warning lamp comes on while the engine is running. A warning
tone also sounds.
The coolant temperature has exceeded 255 ‡(124 †). The airflow to the engine
radiator may be blocked or the coolant level may be too low.
GWARNING
The engine is not being cooled sufficiently and may be damaged.
Do not drive when your engine is overheated. This can cause some fluids which
may have leaked into the engine compartment to catch fire.
Steam from the overheated engine can also cause serious burns which can occur
just by opening the hood.
There is a risk of injury.
XObserve the additional display messages in the multifunction display.
XPull over and stop the vehicle safely and switch off the engine, paying attention
to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 137).
XLeave the vehicle and keep a safe distance from the vehicle until the engine has
cooled down.
XCheck the coolant level and add coolant, observing the warning notes
(Ypage 277).
XIf you have to add coolant frequently, have the engine cooling system checked.
XMake sure that the air supply to the engine radiator is not blocked, e.g. by snow,
slush or ice.
238Warning and indicator lamps in the instrument cluster
On-board computer and displays