2021 MERCEDES-BENZ A-CLASS HATCHBACK sensor

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:
Malfunction See Owner's
Manual *T
heexterior lighting is malfunctioning. #
Consult a quali/ed specialist workshop.
*V Vehicles wit ehicles wit h a tr
h a trailer hitc
ailer hitc h:
h:a fuse may ha veblown. #
Stop theve hicle in accordance with the tra1c conditions. #
Check the fuses and replace them if necessary (/ page 364).
:
Automatic driving lights
inoperative *T
he light sensor for automatic driving lights is malfunctioning. #
Consult a quali/ed specialist workshop.
:
Active Light System inoper-
ative *T
he active headlamps are malfunctioning. #
Consult a quali/ed specialist workshop. Displ
aymessages and warning/indicator lamps
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417

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Ã
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temporarily unavailable
Sensors dirty *F
ront and corner radar sensors (hereaTer "sensors") are malfunctioning. Possible causes:
R The senso rsare dirty
R Heavy rain or snow
R Extended country driving without other tra1c, e.g. in the desert
Driving systems and driving saf ety sy stems ma y be malfunctioning or temp orarily una vailable. The brake system, steer-
ing and drive system will continue tofunction normall y. #
Drive on
Once the causes of the problem are no longer present, the driving systems and driving saf ety sy stems will be available
again and the cor responding symbols will be switched o..
If th e display message does not disappear: #
Stop theve hicle in accordance with the tra1c conditions. #
Clean all sensor co vers from outside (/ page 220). #
Restart theve hicle. 456 456
Displ
aymessages and warning/indicator lamps

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#
Stop vehicle Leave engine
running *T
he 12 V battery charge leve l is too lo w. #
Stop theve hicle immediately in accordance with the tra1c conditions. Do not continue driving. #
Leavetheve hicle running #
Ifth e display message disappears: drive on. #
Ifth e display message does not disappear: consult a quali/ed specialist workshop. T T
yr
yr e pr
e pr essur
essur e monit
e monit or
or Displa
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Tyre press. monitor cur-
rently unavailable *T
here is inter fere nce from a po werful radio signal source. As a result, no signals from the tyre pressure sensors are
being received. The tyre pressure monitoring system is temp orarily una vailable.
The tyre pressure monitoring system will restart au tomatically as soon as the cause has been recti/ed. #
Drive on.
Tyre press. monitor inoper-
ative *T
he tyre pressure moni toring system is malfunctioning. &
W WARNI NG
ARNI NGThere is a risk of an accident if the tyre pressure monitoring system is malfunctioning
The tyre pressure monitoring system cannot issue a warning if there is pressure loss in one or more of the tyres.
Ty res with insu1cient tyre pressure may impair the driving characteristics as well as steering and braking. #
Have the tyre pressure monitoring system checked at a quali/ed specialist workshop. 466
466
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Tyre press. monitor inoper-
ative No wheel sensors *T
he wheels /tted do not ha vesuitable tyre pressure senso rs. The tyre pressure monitoring system is deactivated. #
Fit wheels with suitable tyre pressure sensors.
h
Wheel sensor(s) missing *T
here is no signal from the tyre pressure sensor of one or more wheels. No pressure value is displa yedfo rth e a.ected
tyre. #
Have thefa ulty tyre pressure sensor replaced at a quali/ed specialist workshop.
h
Check tyre(s) *T
he tyre pressure in one or more tyres has dropped signi/cantl y.
The wheel position is displa yed. A warning tone also sounds. &
W WARNI NG
ARNI NGRisk of an accident due toinsu1cient tyre pressure
R The tyres can burst.
R The tyres can wearexcessively and/or une venly.
R The driving characteristics as well as the steering and braking may be greatly impaired.
Yo u could then lose control of theve hicle. #
Obser vethere commended tyre pressures. #
Adjust the tyre pressure if necessar y. #
Stop theve hicle in accordance with the tra1c conditions. #
Check the tyre pressure (/ page 369) andthe tyres. Display messages and
warning/indicator lamps
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467

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Switch o. theve hicle. #
Add 1 l of engine oil (/ page 334). #
Check the engine oil le vel.
No tes on engine oil (/ page 399).
5
Engine oil pressure Stop
Switch off engine *T
he oil pressure is too lo w.
* N
N O OTE
TE Engine damage caused bydriving with insu1cient oil pressure #
Avoid driving with insu1cient oil pressure. #
Stop theve hicle immediately in accordance with the tra1c conditions. Do not continue driving. #
Switch o. theve hicle. #
Consult a quali/ed specialist workshop.
5
Engine oil level cannot be
measured *T
he elect rical connection tothe oil le vel sensor has been inter rupted or the oil le vel sensor is faulty. #
Consult a quali/ed speciali stwo rkshop. Displ
aymessages and warning/indicator lamps
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ar ning/indicat
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ï
Tr ailer tow hitch warning
lamp *T
hered trailer hitch warning lamp is lit.
The trailer hitch is not operational. &
W
WARNING
ARNING Risk of an accident if the ball neck is not loc ked
The trailer may become de tach ed. #
Stop theve hicle immediately in accordance with the tra1c conditions. Do not continue driving. #
Uncouple the trailer and secure it against rolling away. #
Initiate a new swivelling procedu reand do not re-couple the trailer until the display message disappears. #
Notethe messages on the instrument displa y.Engine
Engine
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ÿ
Coolant warning lamp (red) *T
he red coolant warning lamp is lit while the engine is running.
Po ssible causes:
R The temp erature sensor is malfunctioning
R The coolant le vel is too low
R The air supply tothera diator is obstructed
R The radiator fan is faulty Display message
s andwarning/indicator lamps
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481

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ar
ar ning/indicat
ning/indicat or lampP
or lam pP ossible causes/conseq
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Solutions #
Make sure that the air supply tothera diator is not obstructed. #
Avoiding high loads on the engine, drive tothe nearest quali/ed specialist workshop. In doing so, ensu rethat the
coolant temp erature display remains below 120°C.
ÿ
Coolant warning lamp (yel-
low) *T
he yellow coolant warning lamp is lit while the engine is running.
Po ssible causes:
R The temp erature sensor is malfunctioning
R The charge air, transmission oil or battery cooling is faulty
R The radiator shutters are bloc ked or defective #
Avoiding high loads on the engine, drive tothe nearest quali/ed specialist workshop.
; Engine diagnosis warning
lamp *T
he yellow engine diagnostics warning lamp is lit while the engine is running.
A malfunction has occur red in the engine, theex haust system or the fuel system.
The emissions limit value may ha vebeen exceeded and the engine may be running in eme rgency operation mode. #
Have theve hicle checked as soon as possible at a quali/ed specialist workshop.
V
V ehicles wit
ehicles wit h a diesel engine:
h a diesel engine: the fuel tank may ha vebeen run dr y. #
Start the engine thre eto four times aTer refuelling.
If th eye llow engine diagnosis warning lamp goes out, emer gency ope ration mode is cancelled. The vehicle need not
be checked. Display messages and
warning/indicator lamps
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483

Dr
Dr
iving syst
iving syst ems
ems W
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L
Wa rning lamp for distance
wa rning function *T
he red distance warning lamp lights up while theve hicle is in motion.
The dis tance totheve hicle in front is too small forth e speed selected.
If th ere is an additional warning tone, you are approaching an obstacle at too high a speed. #
Be prepared tobrake immediatel y. #
Increase the distance.
Fu nction of Active Brake Assist (/ page 241).
Ó Ac tive Brake Assist warning
lamp *T
heActive Brake Assist warning lamp is on.
Due todirty sensors or a malfunction, the system is not available or thera nge of functions is restric ted. #
Notethe messages on the instrument displa y.
ê
Ac tive Brake Assist warning
lamp *T
heActive Brake Assist warning lamp is on.
The system is switched o. or thera nge of functions has been automatically restric ted.
This may be the case if the driver is not wearing a seat belt or ano ther driving system has been activated. #
Obser vethe no tes on Active Brake Assist (/ page 241). Display messages and
warning/indicator lamps
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