sensor MERCEDES-BENZ A-CLASS HATCHBACK 2021 Owner's Guide

R
Furthermore, the use of cer tain tyre types in
cer tain regions and areas of operation can be
high lybene/cial.
R Only use tyres and wheels of the same type
(summer tyres, winter tyres, MOExtended
tyres) and the same make.
R Only /t wheels of the same size on one axle
(leT and right).
It is only permissible to/t a di.e rent wheel
size in theev ent of a 0at tyre in order todrive
to the specialist workshop.
R Do not make any modi/cations tothe brake
system, the wheels or the tyres.
The use of shims or brake dust shields is not
permitted and may in validate theve hicle's
ge neral ope rating permit.
R V
V ehicles wit
ehicles wit h a tyr h a tyre pr
e pressur
essur e monit
e monit or
or ing sy
ing sy s-
s-
t
t em:
em: all /t tedwheels must be equipped with
functioning sensors forth e tyre pressure mon-
itoring system.
R Attemp eratures below 7 °C use winter tyres
or all-season tyres mar kedi M+Sfor all
wheels. Wi
nter tyres pr ovide the best possible grip in
wintry road conditions.
R For M+S tyres, only use tyres with the same
tread.
R Obser vethe maximum permissible speed for
th e M+S tyres /t ted.
If th e tyre's maximum speed is below that of
th eve hicle, this must be indicated byan
appropriate label in the driver's /eld of vision.
R Run in new tyres at moderate speeds forthe
/r st 100 km.
R Replace the tyres aTer six years at the latest,
re ga rdless of wear.
R When r
When r eplacing wit
eplacing wit h tyr
h tyres t
es that do no
hat do no t f
t featur
eatur e
e
r
r un-0at
un-0at c
char
har act
act er
er is
istics:
tics: vehicles with
MOExtended tyres are not equipped with a
TIREFIT kit at thefa ctor y.Equip theve hicle
with a TIREFIT kit aTer replacing with tyres
th at do not feature run-0at characteristics,
e.g. winter tyres.
% You can permanently limit the maximum
speed for driving with winter tyres
(/ page 232). Fo
r more information on wheels and tyres, con-
ta ct a quali/ed specialist workshop.
Be sure toalso obser vethefo llowing fur ther rela-
te d subjects:
R Notes on tyre pressure (/ page 369)
R Tyre pressure table (/ page 370)
R Notes on the emer gency spa rewheel
(/ page 383) N
No
ot
tes on int
es on int erc
erchanging wheels
hanging wheels &
W
WARNING
ARNING Risk of injury thro ugh di.erent
wheel sizes
Inter changing the front and rear wheels can
se verely impair the driving characteristics.
The disk brakes or wheel suspension compo-
nents may also be damaged. #
Only inter change the front and rear
wheels if the wheels and tyres ha vethe
same dimensions. 376
376
Wheels and tyres

-
Athttps://be vo.mercedes-benz.com
- Inthe Mercedes-Benz BeVo App
R Ataqu ali/ed specialist workshop *
N
NOOTE
TE Overheating at high outside tempe r-
atures If an inappropriate coolant is used,
the engine
cooling system is not su1ciently pr otected
against overheating and cor rosion at high out-
side temp eratures. #
Only use coolant appr ovedby Mercedes-
Benz. #
Obser vethe inst ructions in the
Mercedes-Benz Speci/cations for Oper-
ating Fluids 320.1. Ha
ve the coolant regula rly re placed at a quali/ed
specialist workshop.
Proportion of antif reeze concentrate in the engine
cooling system:
R A minimum of 50% (antifreeze pr otection down
to about -37°C) R
A maximum of 55% (antif reeze pr otection
down to-45°C) N
No ot
tes on windscr
es on windscr een w
een washer
asher 0uid
0uid Obser
vethe no tes on operating 0uids
(/ page 393). &
W
WARNING
ARNING ‑ Risk of /re and injury due to
windscreen washer concent rate
Wi ndsc reen washer concent rate is highly 0am-
mable. It could ignite if it comes into contact
with hot engine component parts or the
ex haust system. #
Make sure that no windscreen washer
concent rate spills out next tothe /ller
opening. *
N NOOTE
TE Damage totheex terior lighting due
to unsuitable windscreen washer 0uid Unsuitable windscreen
washer 0uids may
damage the plastic sur face of theex terior
lighting. #
Only use windscreen washer 0uids which
are also suitable for use on plastic sur fa-
ces, e.g. MB SummerFit or MB WinterFit. *
N
NOOTE
TE Bloc ked spr aynozzles caused by
mixing windscreen washer 0uids #
Do not mix MB SummerFit and MB Win-
te rFit with other windscreen washer 0u-
ids. Do not use distilled or de-ionised
water. Other-
wise, the /ll le vel sensor may be triggered er rone-
ous ly.
Re commended windscreen washer 0uid:
R abo vefreezing point: e.g. MB SummerFit
R below freezing point: e.g. MB WinterFit
Fo rth e cor rect mixing ratio, referto the informa-
tion on the antifreeze container.
Mix washer 0uid with windscreen washer 0uid all
ye ar round. 402
402
Te
ch nical data

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences andM
MSolutions
Solutions
:
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
417
417

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences andM
MSolutions
Solutions
¸
Ã
ç
Ä
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

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences andM
MSolutions
Solutions
#
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
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/conseq uences and
uences andM
MSolutions
Solutions
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
Displ
aymessages and warning/indicator lamps

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences andM
MSolutions
Solutions
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
467
467

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences andM
MSolutions
Solutions #
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
475 475

W
W
ar
ar ning/indicat
ning/indicat or lampP
or lam pP ossible causes/conseq
ossible causes/consequences and uences andM
MSolutions
Solutions
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
W
W
ar
ar ning/indicat
ning/indicat or lampP
or lam pP ossible causes/conseq
ossible causes/consequences and uences andM
MSolutions
Solutions
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
481
481

W
W
ar
ar ning/indicat
ning/indicat or lampP
or lam pP ossible causes/conseq
ossible causes/consequences and uences andM
MSolutions
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
483
483

Dr
Dr
iving syst
iving syst ems
ems W
W
ar
ar ning/indicat
ning/indicat or lampP
or lam pP ossible causes/conseq
ossible causes/consequences and uences andM
MSolutions
Solutions
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
487
487