service MERCEDES-BENZ B-CLASS HATCHBACK 2021 Repair Manual

N
N
o
ot
tes on t
es on t ec
echnical data
hnical data
The tech nical data was de term ined in accordance
with EU Directives. The data stated only applies to
ve hicles with standard equipment. You can obtain
fur ther information from a Mercedes-Benz Service
Centre.
Onl
Onl y f y for cert
or cert ain countr
ain countr ies:
ies:you can /n dvehicle-
speci/c vehicle data in theCO C documents (CER-
TIFIC ATE OF CONFORMITY). These documents
are deli vered with your vehicle. On-boar
On-boar
d electr
d electronics
onics N
No
ot
tes on t
es on t am
amper
per ing wit
ing wit h t
h the engine electr
he engine electr onics
onics*
N
NOOTE
TE Prematu rewe arthro ugh improper
maintenance Improper maintenance may cause
vehicle
components towe ar more quickly and the
ve hicle's operating permit may be in validated. #
Always ha veworkon the engine elec-
tronics and related components car ried
out at a quali/ed specialist workshop. T
T
w
w o-wa
o-wa y r
y radios
adios N
No
ot
tes on
es on /tting
/tting tw
two-wa
o-wa y r
y radios
adios &
W
WARNING
ARNING Risk of accident due to
improper workon two-w ayradios
If two-w ayradios are manipulated or retro/t-
ted incor rectl y,the electromagnetic radiation
from the two-w ayradios can inter fere with the
ve hicle elect ronics and jeopardise the operat-
ing saf ety of theve hicle. #
You should ha veall workon electrical
and electronic components car ried out
at a quali/ed specialist workshop. &
W
WARNING
ARNING Risk of accident due to
improper operation of two-w ayradios
If yo u use two-w ayradios in theve hicle
improper ly,th eir electromagnetic radiation
can disrupt theve hicle's elect ronics. This is
th e case in thefo llowing situations, in particu-
lar: R
The two-w ayradio is not connected toan
ex terior aerial.
R The exterior aerial is /tted incor rectly or is
not a lo w-re0ection aerial.
This could jeopardise the operating saf ety of
th eve hicle. #
Have the lo w-re0ection exterior aerial /t-
ted at a quali/ed specialist workshop. #
When operating two-w ayradios in the
ve hicle, alw ays connect them tothe lo w-
re 0ection exterior aerial. *
N
NOOTE
TE Inva lidation of the operating permit
due tofailure tocomply with the inst ruc-
tions for installation and use The operating permit may be in
validated if the
inst ructions for installation and use of two-w ay
ra dios are not obser ved. #
Only use appr oved frequency bands. #
Obser vethe maximum permissible out-
put po wer in these frequency bands. #
Only use appr oved aerial positions. 392
392
Te
ch nical data

In some countries,
the fuel available may not ha ve
su1cient additives. Deposits could build up in the
fuel injection system as a result. In this case, in
consultation with a Mercedes-Benz service
centre, mix the fuel with the cleaning additive rec-
ommended byMercedes-Benz. Obser vethe no tes
and mixing ratios indica ted on theta nk.
Inf
Inf or
ormation on fuel q
mation on fuel q uality f
uality for v
or vehicles wit
ehicles wit h a die-
h a die-
sel engine
sel engine
Gener Gener al not
al notes
es
No tethe inst ructions about operating 0uids
(/ page 396). &
W
W ARNING
ARNING Risk of /re from fuel mixture
If yo u mix diesel fuel with petrol, the 0ash
point of the fuel mixture is lo werth an that of
pure diesel fuel. #
Neverre fuel using petrol in diesel
engines. #
Never mix petrol with diesel fuel. *
N
NOOTE
TE Damage caused bythe wrong fuel Even small amounts of
the wrong fuel could
re sult in damage tothe fuel system, the
engine and the emission control system.
V V ehicles wit ehicles wit h a diesel par
h a diesel par ticulat
ticulate
e/lt
/lt er:
er: #
Only refuel using sulphur-free diesel fuel
th at conforms toEuropean standard
EN 590, or an equivalent speci/cation.
In count ries without sulphur-free diesel
fuel, refuel using only lo w-sulphur diesel
fuel with a sulphur content less than
50 ppm.
V
V ehicle wit
ehicle wit hout diesel par
hout diesel par ticulat
ticulate
e/lt
/lt er:
er: #
Only refuel using diesel fuel wi tha sul-
phur content less than 500 ppm.
Ne verre fuel wi thone of thefo llowing fuels:
R Petrol
R Marine diesel
R Heating oil R
Pure fatty acid me thyl ester or veget able
oil
R Para1n or kerosene
If yo u ha veacciden tally refuelled wi th the
wrong fuel: #
Do not switch on theve hicle. #
Consult a quali/ed specialist workshop. The
following compatibility indication for fuel
applies toyour vehicle: 1
For diesel fuel with a maximum of 7% byvol-
ume bio-diesel (fatty acid me thyl ester) Te
ch nical data
399
399

*
N
NO
OTE
TE Engine damage caused byan inco r-
re ct oil /lter, incor rect oil or additi ves #
Do not use engine oils or oil /lters other
th an those which meet the speci/cations
necessary forth e prescribed service
inter vals. #
Do not alter the engine oil or oil /lter in
order toachie velonger change inter vals
th an prescribed. #
Do not use additives. #
Have the engine oil changed aTer the
prescribed inter vals. Mercedes-Benz
recommends having the oil
ch anged at a quali/ed specialist workshop.
Only use engine oils appr ovedfo ryo ur vehicle by
Mercedes-Benz.
P
P e etr
tr ol engines:
ol engines: for cer tain countries, di.erent
engine oils can be used in conjunction with
re duced maintenance inter vals. Further informa-
tion on di.erent engine oils can be obtained at a
qu ali/ed specialist workshop.
Quality and capacity of engine oil
Quality and capacity of engine oil
No No t f
t for plug-in h
or plug-in h ybr
ybrid:
id:
Engine oil
Engine oil speci/cations
speci/cations (pe
(petr
trol engines)
ol engines) Model
Model
MB-Fr
MB-Freig
eigabe or MB-
abe or MB-
Appr ov
Approv al
al
All models 229.51, 229.52,
229.61, 229.71*, 229.72 Engine oil
Engine oil
speci/cations
speci/cations (diesel engines)
(diesel engines) Model
Model
MB-Fr
MB-Freig
eigabe or MB-
abe or MB-
Approv
Approv al
al
All models 229.52, 229.61,
229.71*, 229.72 *
re commended for fuel consum ption
To achie vethe lo west possible fuel consum ption,
it is recommended touse the engine oil speci/ca-
tions mar ked in theta ble forth e lo westSA E vis-
cosity class. Obser veany possible restrictions of
th e appr ovedSA E viscosity classes.
% Ifth e engine oils listed in theta ble are not
av ailable, you may add a maximum of 1.0 litre
of thefo llowing engine oils once onl y.
V
V ehicles wit
ehicles wit h a pe
h a petr
trol engine:
ol engine: MB-Freigabe or
MB-Appr oval 229.31 or ACEA C3
V
V ehicles wit
ehicles wit h a diesel engine:
h a diesel engine: ACEA C3
No
No t f
t for plug-in h
or plug-in h ybr
ybrid:
id: 402
402
Te
ch nical data

Displa
Displa
y messag
y messag es
es Intr
Intr
oduction
oduction Inf
Inf
or
ormation about displa
mation about displa y messag
y messages
es
Display messages appear on the inst rument dis-
pla y.
Display messages with graphic symbols are sim-
pli/ed in the Owner's Manual and may di.er from
th e symbols on the inst rument displa y.The instru-
ment display sh ows high-priority display messages
in red. Cer tain display message s are accompa-
nied byawa rning tone.
Please act in accordance with the display mes-
sages and follow the additional no tes in the Own-
er's Manual.
Fo r some display messages, symbols will also be
shown:
R Õ Further information
R 00A4 Hide displ aymessage
Wi th th e leT-hand Touch Control, you can select
th ere specti vesymbol byswiping tothe leT or
ri ght. Pressing Õdispla ysfur ther information on th
e media displa y.Press the00A4 symbol tohide
th e display message.
Yo u can hide lo w-priority display messages by
pressing the back button Porthe leT-hand
To uch Control. The display message s willthen be
stored in the message memor y.
Re ctify the cause of a display message as quickly
as possible.
High-priority display message s cannotbe hidden.
The instrument display will show these display
messages permanently until the cause of the dis-
play message has been recti/ed.
Calling up sav
Calling up sav ed displa ed display messag
y messag es
es
On-board computer:
4 Service 5
1 message
If th ere are no display messages, No messages
will appear on the inst rument displa y. #
Scroll thro ugh the display messages byswip-
ing upwards or down wards on the leT-hand
To uch Control. #
T
T o e
o e xit t
xit t he messag
he messag e memory
e memory:
:press the back
button P. 412
412
Display messages and
warning/indicator lamps

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences and0050
0050Solutions
Solutions #
Request service personnel from the operator of thech arging station via the emer gency call button attached tothe
ch arging station or the emer gency call numbers.
Vehicle not currently being
charged Charging station
fault *A
malfunction has occur red in thech arging station or the RFID card is not recognised. #
Start thech arging process at a di.erent charging station.
or #
Have the RFID card checkedto ensure it is functioning.
Charging method currently
unavailable Please try
again or change charging
method *A
temp orary malfunction has occur red in thech arging station. #
Wait until the malfunction has passed.
or #
Start thech arging process at a di.erent charging station.
Charging fault Please
change charging method
See Owner's Manual *A
temp orary malfunction has occur red in thech arging station. #
Wait until the malfunction has passed.
or #
Start thech arging process at a di.erent charging station.
Only electric drive availa-
ble Power limited *T
he fuel tank is em pty and the combustion engine is switched o.. The output of your vehicle is limi ted because you
are driving in elect ric mode. Display messages and
warning/indicator lamps
427
427

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences and0050
0050Solutions
Solutions #
Refuel immedia tely.
Subse quentl y,there may be temp orary restrictions in theav ailability of elect ric mode over a driving distance of
50 km.
If th ere is fuel in theve hicle, there is a fault with the combustion engine. #
Consult a quali/ed specialist workshop.
"Electric" drive program
currently unavailable *T
hecharge leve l of the high-voltage battery is not su1cient forth e Electric drive prog ram.
Char gethe high-voltage battery (/ page 198).
Reduced drive system per-
formance See Owner's
Manual *T
he drive system switches toemer gency ope ration mode due toa malfunction. #
Drive on carefull y. #
Consult a quali/ed specialist workshop.
00D7
Battery overheated Stop,
everybody out! Outdoors if
possible *T
he high- voltage battery has overheated. There is a risk of /re. #
Stop theve hicle immediately in accordance with the tra1c conditions. #
If possible, stop theve hicle in the open air and ensure that all vehicle occupants getout.
% Supporting vehicle functions may activate automaticall y,e.g. the air-recirculation mode as part of climate control. #
Do not continue driving. #
If smoke is present, lea vethe danger zone and call the /re service immediatel y. #
Consult a quali/ed specialist workshop even if there are no extern al signs of a /re. 428 428
Displ
aymessages and warning/indicator lamps

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences and0050
0050Solutions
Solutions
00BD
Top up coolant See Own-
er’s Manual *T
he coolant le vel is too lo w.
* N
N O OTE
TE Engine damage due toinsu1cient coolant #
Avoid long journe yswith insu1cient coolant. #
Add coolant (/ page 342). #
Have the engine cooling system checked at a quali/ed specialist workshop.
ÿ
Coolant Stop vehicle
Switch engine off *T
he coolant is too hot. #
Stop immediately in accordance with the tra1c conditions and switch o. theve hicle. &
W WARNING
ARNING Risk of burns when opening the bonnet
If yo u open the bonnet in theev ent of an overheated engine or /re in the engine compartment, thefo llowing situa-
tions may occur:
R You may come into contact with hot gases.
R You may come into contact with other escaping hot operating 0uids. #
Before opening the bonnet, allow the engine tocool down. #
Intheev ent of a /re in the engine compartment, keep the bonnet closed and call the /re service. #
Wait until the engine has cooled down. Display messages and
warning/indicator lamps
439
439

W
W
ar
ar ning/indicat
ning/indicat or lampP
or lam pP ossible causes/conseq
ossible causes/consequences and uences and0050
0050Solutions
Solutions
R The engine coolant pump is faulty
If th ere is an additional warning tone, the coolant temp erature has exceeded 120°C. &
W
WARNING
ARNING Risk of burns when opening the bonnet
If yo u open the bonnet in theeve nt of an overheated engine or /re in the engine compartment, thefo llowing situa-
tions may occur:
R You may come into contact with hot gases.
R You may come into contact with other escaping hot operating 0uids. #
Before opening the bonnet, allow the engine tocool down. #
Intheev ent of a /re in the engine compartment, keep the bonnet closed and call the /re service. #
Stop immediately in accordance with the tra1c conditions and switch o. theve hicle. Do not continue driving. #
Notethe messages on the instrument displa y.
If t If t he coolant t
he coolant t em
em per
per atur
atur e displa
e displa y is at t
y is at the low
he lower end of t
er end of t he t
he tem
emper
per atur
atur e scale:
e scale: #
Consult a quali/ed specialist workshop.
If t
If t he coolant t he coolant t em
emper
per atur
atur e displa
e displa y is at t
y is at the upper end of t
he upper end of t he t
he tem
emper
per atur
atur e scale:
e scale: #
Exit theve hicle and keep a safe distance from it until the engine has cooled down. #
Check the coolant le vel (/ page 342). Display message
s andwarning/indicator lamps
485
485

Pa
rking.................................................. 269
System limitations..................................2 68
A
A ctiv
ctiv e Ser
e Ser vice Sy
vice Sy st
stem PL
em PL US
US
see ASS YST PLUS
A
A ctiv
ctiv e Speed Limit Assist
e Speed Limit Assist
Display................................................... 239
Fu nction................................................ 239
A
A ctiv
ctiv eSt
e St eer
eer ing Assist
ing Assist
Ac tivating/deactivating.......................... 243
Ac tive Emer gency Stop Assist................ 243
Fu nction................................................ 241
System limits......................................... 241
A
A dap
dap tiv
tive br
e br ak
ake lights
e lights .................................... 229
A
A dap
dap tiv
tive cr
e cr uise contr
uise contr ol
ol
see Active Distance Assist DISTRONIC
A
A dap
dap tiv
tive Highbeam Assist
e Highbeam Assist
Ac tivating/deactivating.......................... 144
Fu nction................................................ 143
A
A dap
dap tiv
tive Highbeam Assis
e Highbeam Assist Plus t Plus
Fu nction................................................ 144
Switching on/o..................................... 145
A
A dBlue
dBlue ®
®
Ad ditives................................................ 400 Capacity................................................ 401
No tes..................................................... 195
Purit y.................................................... .400
To pping up............................................ .196
A
A dditional door lock
dditional door lock ....................................... 84
A A dditiv dditiv es
es
Ad Blue ®
................................................ .400
Engine oil............................................... 401
Fu el....................................................... 398
A
A dditiv
dditiv es (A
es (AdBlue
dBlue ®
®
)
)
see AdBlue ®
A A dditiv dditiv es (engine oil)
es (engine oil)
see Additives
A
A dditiv
dditiv es (fuel)
es (fuel)
see Fuel
A
A djus
djus ting t
ting t he headlam
he headlam p r
p range
ange ...................... 139
ATer
ATer -sales
-sales ser
service
vice
see ASS YST PLUS
Air conditioning menu
Air conditioning menu Calling up.............................................. 158
Air dis
Air distr tribution
ibution
Setting................................................... 157
Setting (MBUX multimedia system)......... 159 Air inlet
Air inlet
see Air-water duct
Air pr
Air pr essure
essure
see Tyre pressure
Air v
Air v ents
ents
Ad justing (front)..................................... 164
Ad justing (rear)...................................... 165
Air v
Air v ents
ents
see Air vents
Air
Air -conditioning syst
-conditioning syst em
em
see Climate cont rol
Air
Air -r
-recir
ecir culation mode (wit
culation mode (wit h
h/ne
/ne
par
par ticle
ticle pr
pre/lt
e/lt er)
er).......................................... 159
Air
Air -w
-wat
ater duct
er duct
Ke eping free.......................................... 343
Airbag
Airbag
Activation................................................ 47
Fr ont airbag (driver, front passenger)........ 52
Installation locations................................ 52
Knee airbag............................................. 52
Overview.................................................. 52
PA SSENGER AIR BAG indicator la mps...... 57
Pro tection................................................ 53
Re duced pr otection.................................. 54 496 496
Index

Side airbag.............................................. 52
Wi ndow airbag......................................... 52
Air0 ow
Air0ow
Setting................................................... 157
Alar
Alar m syst
m syst em
em
see ATA (anti-theT alarm system)
All-wheel dr
All-wheel dr ive
ive
see 4M ATIC
Ambient lighting
Ambient lighting Setting (MBUX multimedia system)........ .146
Andr
Andr oid A
oid A uto
uto
see Smartphone integ ration
Animals
Animals Pets in theve hicle.................................... 80
Anti-loc
Anti-loc k br
k braking syst
aking syst em
em
see ABS (Anti-lock Braking System)
Anti-skid c
Anti-skid c hains
hains
see Sn owchains
Anti-t
Anti-theT heTprot
pr otection
ection
Ad ditional door loc k................................. 84
Immobiliser............................................ 102
Anti-t
Anti-theT heTprot
pr otection
ection
see ATA (anti-theT alarm system) Anticipat
Anticipat
or
ory occupant pr ot
y occupant pr otection
ection
see PRE-SAFE ®
(anticipatory occu-
pant pr otection)
see PRE-SAFE ®
PLUS (anticipatory
occupant pr otection plus)
Apple CarPlay
Apple CarPlay ®
®
see Smartphone integ ration
Assist
Assist ance syst
ance syst ems
ems
see Driving saf ety sy stem
ASS YS
ASS YST PL
T PL US
US
Battery disconnection period s................ 337
Displaying the service due dat e.............. 336
Fu nction/no tes...................................... 336
Re gular maintenance work..................... 336
Special service requ irements................. 336
AT
ATA A(anti-t
(anti-theT heTalar
alarm syst
m syst em)
em)
Deactivating the alarm........................... 103
Fu nction................................................ 102
Interior pr otection function.....................1 04
Priming/deactivating interior pr otec-
tion........................................................ 104
Priming/deactivating tow- awa y pro-
te ction................................................... 104
To w- awa y protection function................. 103 A
A TTENTION ASSIST
TTENTION ASSIST
Function................................................ 230
Setting.................................................. .232
System limitations.................................. 230
A
A tt
tt ention assist
ention assist ant
ant
see ATTENTION ASSIST
A A ut ut hor
hor ised w
ised w ork
orkshop
shop
see Quali/ed specialist workshop
A
A ut
ut omatic car w
omatic car w ash mode
ash mode
Ac tivating............................................... 345
A
A ut
ut omatic co-dr
omatic co-dr iv
iver airbag
er airbag shut
shuto.
o.
Fu nction of co-driver airbag shuto........... 55
A
A ut
ut omatic dist
omatic dist ance contr
ance control
ol
see Active Distance Assist DISTRONIC
A
A ut
ut omatic dr
omatic dr iving lights
iving lights ................................ 139
A
A ut
ut omatic engine st
omatic engine st art
art
see ECO start/stop function
A
A ut
ut omatic engine st
omatic engine st op
op
see ECO start/stop function
A
A ut
ut omatic fr
omatic fr ont passeng
ont passeng er airbag
er airbagshut
shut o.
o.
PA SSENGER AIR BAG indicator la mps...... 57
A
A ut
ut omatic measur
omatic measur es
esaTer
aTer an accident
an accident........... .60 Index
497
497