engine MERCEDES-BENZ B-CLASS HATCHBACK 2021 Repair Manual

Ke
ep children away. Obser
vethis Owner's Manual.
If yo u do not intend touse theve hicle over an
ex tended period of time:
R activate standby mode, or
R connect the battery toa battery charger
appr ovedby Mercedes-Benz, or
R consult a quali/ed specialist workshop todis-
connect the battery N
No
ot
tes on st
es on st ar
arting assist
ting assist ance and c
ance and c har
harging t
ging t he 12
he 12
V batt
V batt ery
ery When
charging the battery and during starting
assistance, alw ays use the jump-start connection
point in the engine compartment. *
N
NO OTE
TE Damage tothe battery from over-
vo ltage When
charging using a battery charge r without
a re striction of the maximum charging voltage,
th e battery or the on-board electronics can be
damaged. #
Only use battery charge rs with a maxi-
mum charging voltage of 14.8 V. &
W
WARNI NG
ARNI NGRisk of explosion due tohydro-
ge nga s igniting
If, when charging a batter y,there is a short
circuit or spar ksstart toform ,th ere is a dan-
ge r of hydrogen gas igniting. #
Take care that the positive clamp con-
nected toa battery does not come into
contact with vehicle parts. #
Never place me tal objects or tools on a
batter y. #
When connecting and disconnecting the
batter y,alw ays obser vethe sequence of
battery clamps described. #
Take care toonly connect battery term i-
nals of identical polarity when receiving
starting assistance. #
Obser vethe sequence described for
connecting and disconnecting the jump
leads when receiving starting assistance. #
Do not connect or disconnect the bat-
te ry term inals while the engine is run-
ning. &
W
WARNI NG
ARNI NGRisk of explosion due toexplo-
sive mixture of gases
An explosive mixture of gases can escape
from the battery during charging and starting
assis tance. #
Fire , naked 0ames, smoking and creating
spar ksmust be avoided. #
Make sure there is adequate ventilation. #
Do not stand overth e batter y. 362
362
Breakdown assistance

&
W
W ARNI NG
ARNI NGRisk of explosion from a frozen
battery
A dischar ged battery may freeze at temp era-
tures slightly abo veor below freezing point.
During starting assistance or battery charging,
battery gas can be released. #
Always allow a battery tothaw before
ch arging it or per form ing starting assis-
ta nce. If
th e indicator/warning lamps in the inst rument
cluster do not light up at low temp eratures, it is
ve ry likely that the dischar ged battery has frozen.
In this case you may neither jump-start theve hi-
cle nor charge the batter y.
The service life of a bat tery that has been thawed
may be dramatically shor tened. The starting char-
acteristics may be impaired, especially at low
te mp eratures.
It is recommended that you ha veath awe d battery
ch ecked at a quali/ed specialist workshop. *
N
NO OTE
TE Damage caused bynume rous or
ex tended attem ptsto start the engine Numerous or
extended attem ptsto start the
engine may damage the catalytic con verter
due tonon-combusted fuel. #
Avoid numerous and extended attem pts
to start the engine. Obser
vethefo llowing points during starting assis-
ta nce and when charging the batter y:
R Only use undamaged jump lead/charging
cables with a su1cient cross-section and
insulated term inal clamps.
R Non-insulated parts of thete rm inal clamps
must not come into contact with other me tal
parts while the jump lead/charging cable is
connected tothe battery/jump-start connec-
tion point.
R The jump lead/charging cable must not come
into contact with any parts which may mo ve
when the engine is running.
R Always make sure that nei ther you nor the bat-
te ry is electros tatically charge d. R
Keep awa y from /re and naked 0ames.
R Do not lean overth e batter y.
Obser vethe additional following points when
ch arging the batter y:
R Only use battery charge rs tested and
appro vedfo r Mercedes-Benz.
R Read the battery charge r's operating inst ruc-
tions before charging the batter y.
Obser vethe additional following points during
starting assistance:
R For starting assistance, only use batteries with
a nominal voltage of 12 V.
R The vehicles must not touch.
R P
P e etr
tr ol engine:
ol engine: only accept starting assistance
if th e engine and exhaust system are cold. S
S
t
tar
ar ting assist
ting assist ance and c
ance and c har
harging t
ging t he 12 V batt
he 12 V batt ery
ery R
R
eq
eq uir
uir ements:
ements:
R The vehicle is secured with the electric par k-
ing brake. Breakdown assistance
363
363

R
A
Aut
ut omatic tr
omatic tr ansmission:
ansmission: the transmission is in
position 005D.
R Manual tr
Manual tr ansmission:
ansmission: the transmission is in
neutral.
R The vehicle and all elect rical consume rsare
switched o..
R The bonn etis open. #
Slide co ver1 of positive clamp 2onthe
jump-starting connection point in the direction
of the ar row. #
Connect positive clamp 2onyour vehicle to
th e positive pole of the donor battery using
th e jump lead/charging cable. Alw ays begin
with positive clamp 2onyour ow nve hicle
/rst. #
Dur
Dur ing st
ing st ar
arting assist
ting assist ance:
ance:startthe engine of
th e donor vehicle and run at idle speed. #
Connect the negative pole of the donor bat-
te ry and ear thpoint 3ofyour ow nve hicle by
using the jump lead/charging cable. Begin
with the donor battery /rst. #
Dur
Dur ing st
ing st ar
arting assist
ting assist ance:
ance:startthe engine of
yo ur ow nve hicle. #
Dur
Dur ing t ing t he c
he char
harging pr
ging pr ocess:
ocess: startthech arg-
ing process. #
Dur
Dur ing st ing st ar
arting assist
ting assist ance:
ance:letthe engines run
fo r se veral minutes. #
Dur
Dur ing st ing st ar
arting assist
ting assist ance:
ance:before disconnect-
ing the jump lead, switch on an electrical con- sumer on
your ow nve hicle, e.g. there ar win-
dow heater or lighting.
When the starting assistance/charging process is
comple te: #
Firs t, re mo vethe jump lead/charging cable
from ear thpoint 3and the negative pole of
th e donor batter y,then from positive clamp
2 and the positive pole of the donor batter y.
Begin ea chtime with the contacts on your
ow nve hicle /rst. #
ATer removing the jump lead/charging cable,
close co ver1 of positive clamp 2.
Plug-in h
Plug-in h ybr
ybrid:
id:ifyo ur vehicle has been star ted
with starting assis tance, it may not be possible to
use the electric drive for appr oximately 30
minutes.
Fu rther information can be obtained at a quali/ed
specialist workshop. R R
eplacing t
eplacing t he 12 V batt
he 12 V batt ery
ery #
Obser vethe no tes on the 12 V battery
(/ page 361). 364
364
Breakdown assistance

T
T
o
o wing ey
wing eye st
e st or
orag
ag e location
e location The
towing eye is under the load compartment
0oor. F
F
itting and r
itting and r emo
emo ving t
ving t heto
he towing eye
wing eye #
Press the mark on co ver1 inwa rds and
re mo ve. #
Screw intheto wing eye clockwise as far as it
will go and tighten.
V
V ehicles wit
ehicles wit h a tr
h a trailer hitc
ailer hitc h:
h:vehicles with a trailer
hitch do not ha veare ar brac ketfo rth eto wing
ey e. Fasten theto w bar tothe trailer hitch. #
Make sure that co ver1 engages in the
bumper when youre mo vetheto wing eye.
* N
NOOTE
TE Damage totheve hicle due toincor-
re ct use of theto wing eye or trailer hitch When a
towing eye or trailer hitch is used to
re co ver a vehicle, theve hicle may be damaged
in the process. #
Only use theto wing eye or trailer hitch to
to w awa y or tow start theve hicle. #
Do not use theto wing eye or trailer hitch
to to wtheve hicle during reco very. T
T
o
o w
w -st
-st ar
arting t
ting t he v
he vehicle
ehicle V V
ehicles wit ehicles wit h aut
h automatic tr
omatic tr ansmission
ansmission
* NO
NOTE
TE Damage tothe automatic transmis-
sion due to tow-starting The au
tomatic transmission may be damaged
in the process of tow- starting vehicles with
automatic transmission. #
Vehicles with automatic transmission
must not be tow- star ted. #
Vehicles with an automatic transmission must
not be tow- star ted.
V V ehicles wit ehicles wit h manual tr
h manual tr ansmission
ansmission #
Obser vethe no tes on towing away
( / page 367). #
If necessar y,allow the engine and exhaust
system tocool down. #
Swit chon the ignition. #
Engage second gear. #
Release the electric parking brake. 370
370
Breakdown assistance

#
Tow- start theve hicle while the clutch pedal is
fully depressed. #
Slowly re leasethe clutch pedal. #
Immediately shiT toneutral if the engine
starts. #
Stop theve hicle in accordance with the tra1c
conditions. #
Remo vetheto w bar. #
Remo vetheto wing eye. #
Have theve hicle checked at a quali/ed spe-
cialist workshop. Electr
Electr
ical fuses
ical fuses N
No
ot
tes on electr
es on electr ical fuses
ical fuses &
W
WARNING
ARNING Risk of accident and injury due
to ove rloaded lines
If yo u manipulate or bridge a faulty fuse or if
yo ure place it with a fuse with a higher amper-
age, the electric line could be overloaded.
This could result in a /re. #
Alwaysre place faulty fuses with speci-
/ed new fuses containing the cor rect
amperage. *
N
NOOTE
TE Damage due toincor rect fuses Electrical components or systems may be
damaged
byincor rect fuses, or their function-
ality may be signi/cantly impaired. #
Only use fuses that ha vebeen appr oved
by Mercedes-Benz and which ha vethe
cor rect fuse rating. Blown fuses must be
replaced with fuses of the
same rating, whi chyou can recognise bythe col-
our and the label. The fuse ratings and fur ther
information tobe obser ved can be found in the
fuse assignment dia gram.
F F use assignment diagr
use assignment diagr am:
am:onthe fuse box in the
engine compartment (/ page 372). *
N
NOOTE
TE Damage or malfunctions caused by
moisture Moisture may cause damage
tothe electrical
system or cause it tomalfunction. #
When the fuse box is open, make sure
th at no moisture can enter the fuse box. #
When closing the fuse box, make sure
th at the seal of the lid is positioned cor-
re ctly on the fuse box. If
th e ne wlyinser ted fuse also blo ws, ha vethe
cause traced and recti/ed at a quali/ed specialist
wo rkshop.
Ensure thefo llowing before replacing a fuse:
R The vehicle is secured against rolling away.
R All electrical consume rsare switched o..
R The vehicle is switched o..
The elect rical fuses are located in various fuse
bo xes:
R Fuse box in the engine compartment on the
leT-hand side of theve hicle, when vie wed in
th e direction of tr avel (/ page 372) Breakdown assistance
371
371

R
Fuse box in the front passenger foot we ll
(/ page 372)
R Fuse box in the centre of the load compart-
ment (/ page 373) Opening and closing t
Opening and closing t
he fuse bo
he fuse box in t
x in the engine
he engine
com
com par
partment
tment R
R
eq
eq uir
uir ements:
ements:
R A dry clo thand a scr ewdriver are available.
Obser vethe no tes on elect rical fuses
(/ page 371).
Opening
Opening &
W
WARNING
ARNING Risk of injury from using the
windscreen wipers when the bonnet is
open
If th e windscreen wipers start moving when
th e bonnet is open, you could be trapped by
th e wiper linkage. #
Always switch o. the windscreen wipers
and vehicle before opening the engine
bonnet. #
Open the bonnet. #
Remo veany existing moisture from the fuse
box using a dry clo th. #
Loosen scr ews1. #
Press clamps 2and liT the fuse box lid up
and out. The fuse assignment diag
ram is in a recess on the
side of the fuse box.
Closing Closing #
Check whe ther the seal is positioned cor rectly
in the lid. #
Place the lid on the fuse box. #
Make sure that clamps 2engage. #
Tighten scre ws1. #
Close the bonnet. Opening and closing t Opening and closing t
he fuse bo
he fuse box in t
x in the fr
he front
ont
passeng
passeng er f
er foo
ootw
twell
ell Obser
vethe no tes on elect rical fuses
(/ page 371). 372
372
Breakdown assistance

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

The
following can be used in theve hicle without
re strictions:
R two- wayra dios with a maximum transmission
output of up to100 mW
R RF transmitters with transmitter frequencies in
th e 380 - 410 MHz frequency band and a
maximum transmission output of up to2 W
(TETRA)
R mobile phones (2G/3G/4G)
There are no restrictions when positioning the
aerial on the outside of theve hicle forth efo llo w-
ing frequency bands:
R Terrestrial Trunked Radio (TETRA)
R 70 cm frequency band
R 2G/3G/4G R
R
egulat
egulat or
ory r
y r adio
adio identi/cation
identi/cation and not
and notes
es R
R
egulat
egulat or
ory r
y r adio
adio identi/cation
identi/cation of small com
of small compo-
po-
nents
nents Manufacturer information about
radio-based vehi-
cle components can be found using thekey
phrase "Regulatory radio identi/cation" in the Dig- ital Owner's Manual in
theve hicle, on the internet
and in the app. R
R
egulat
egulat or
ory r
y r adio
adio identi/cation
identi/cation – Indonesia
– Indonesia Manufacturer information about
radio-based vehi-
cle components can be found using thekey
phrase "Regulatory radio identi/cation – Indone-
sia" in the Digital Operator's Manual in theve hi-
cle, on the internet and in the app.
% These are not small components. Information
about small components can be found using
th eke y phrase "Regulatory radio identi/cation
of small components". F F
urt
urt her
her com
com ponent-speci/c
ponent-speci/c inf
infor
ormation
mation Fu
rther component-speci/c information can be
fo und using theke y phrase "fur ther component-
speci/c information" in the Digital Owner's Man-
ual in theve hicle, on the internet and in the app. V
V
ehicle
ehicle identi/cation
identi/cation plat
plate, VIN and engine num-
e, VIN and engine num-
ber ov
ber overerview
view
V
V ehicle
ehicle identi/cation
identi/cation plate
plate 394
394
Te
ch nical data

VIN and engine number
VIN and engine number
1
Engine number stamped into the crankcase
2 VIN (vehicle identi/cation number) stamped
into the crossmember
3 VIN (vehicle identi/cation number) as a label
at the lo wer edge of the windscreen
Onl
Onl y f y for cert
or cert ain countr
ain countr ies:
ies:the VIN as a label at
th e lo wer edge of windscreen 3is only available
in some countries. Further information can be
obtained at a quali/ed specialist workshop. Oper
Oper
ating
ating 0uids
0uids N
No
ot
tes on oper
es on oper ating
ating0uids
0uids &
W
WARNING
ARNING Risk of injury from operating
0uids harmful toyour health
Operating 0uids may be poisonous and harm-
ful toyour health. #
Obser vethete xt on the original contain-
ers when using, storing or disposing of
operating 0uids. #
Always store operating 0uids sealed in
th eir original containers. #
Alwayske ep children away from operat-
ing 0uids. +
ENVIR ENVIR
ONMENT
ONMENT AL NO
AL NOTE
TEPollution of the
environment due toirre sponsible disposal
of operating 0uids Incor
rect disposal of operating 0uids can
cause considerable damage tothe environ-
ment. #
Dispose of operating 0uids in an environ-
mentally responsible manner. Operating 0uids include
thefo llowing:
R fuels
R DeNOx agent AdBlue ®
forex haust gas aTer-
treatment
R lubricants
R coolant
R brake 0uid
R windscreen washer 0uid
R climate cont rol system refrigerant
Only use products appro vedby Mercedes-Benz.
Damage caused bythe use of products that ha ve
not been app rove d is not co veredby the
Mercedes-Benz warranty or goodwill gestu res.
The operating 0uids appr ovedby Mercedes-Benz
can be identi/ed bythefo llowing inscriptions on
th e container:
R MB-F reigabe (e.g. MB-F reigabe 229.51)
R MB-Appr oval (e.g. MB -Appr oval 229.51) 396 396
Te
ch nical data

Fu
rther information on appr oved operating 0uids:
R inthe Mercedes-Benz Speci/cations for Oper-
ating Fluids byentering the designation
- at https://be vo.mercedes-benz.com
- inthe Mercedes-Benz BeVo App
R Ata quali/ed specialist workshop &
W
WARNING
ARNING Risk of /re or explosion from
fuel
Fu els are highly 0ammable. #
Fire , naked 0ames, smoking and creating
spar ksmust be avoided. #
Before and during refuelling, switch o.
th eve hicle and, if /tted, the stationary
heater. &
W
W ARNING
ARNING Risk of injury from fuels
Fu els are poisonous and hazardous toyour
health. #
Do not swallow fuel or let it come into
contact with skin, eyes or clo thing. #
Do not inhale fuel vapour. #
Keep children away from fuel. #
Keep doors and windo wsclosed during
th ere fuelling process.
If yo u or other people come into contact with
fuel, obser vethefo llowing: #
Immediate lyrinse fuel o. your skin with
soap and water. #
If fuel comes into contact with your eyes,
immediately rinse them thoroughly with
clean water. Seek medical at tention
immedia tely. #
Ifyo u swallow fuel, seek medical atten-
tion immediatel y.Do not induce vomit-
ing. #
Change immediately out of clo thing that
has come into contact with fuel. Flexible-fuel
vehicles can be refuelled wi th thefo l-
lowing fuel types:
R unleaded petrol
R E85 fuel R
a mixture of E85 fuel and unleaded petrol
Flexible-fuel vehicles can be identi/ed bythe
Et
Et hanol up t
hanol up t o E85
o E85sticker on the inside of the fuel
/ller 0ap.
Depending on the countr y,the fuels you can use
in your vehicle may di.er from the information in
th e Owner's Manual. The fuels that ha vebeen
appr ovedfo ryo ur vehicle can be found on the
inst ruction label on the inside of the fuel /ller 0ap. F F
uel
uel Inf
Inf
or
ormation on fuel q
mation on fuel q uality f
uality for v
or vehicles wit
ehicles wit h a pe
h a pet-
t-
r
r ol engine
ol engine
No tethe inst ructions about operating 0uids
(/ page 396).
* NO
NOTE
TEDamage 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. #
Only refuel using unleaded, sulphu r-free
spar k-ignition engine fuel that conforms Te
ch nical data
397
397