ECU MERCEDES-BENZ B-CLASS HATCHBACK 2021 Manual Online

#
V
Vehicles wit
ehicles wit h tyr
h tyre pr
e pressur
essur e loss w
e loss w ar
ar ning sy
ning sy s-
s-
t
t em:
em: restart the tyre pressure loss warning
system (/ page 379). #
V
Vehicles wit
ehicles wit h a tyr
h a tyre pr
e pressur
essur e monit
e monit or
oring sy
ing sy s-
s-
t
t em:
em: restart the tyre pressure monitoring sys-
te m (/ page 378). Emerg
Emerg
ency spar
ency spar e wheel
e wheel N
No
ot
tes on t
es on t he emerg
he emerg ency spar
ency spar e wheel
e wheel &
W
W ARNING
ARNING Risk of accident caused by
incor rect wheel and tyre dimensions
The wheel or tyre size and the tyre type of the
emer gency spa rewheel or spare wheel and
th e wheel tobe replaced may di.er. The emer-
ge ncy spa rewheel or spare wheel can signi/-
cantly impair driving characteristics of the
ve hicle.
To prev ent hazardous situations: #
Drive carefull y. #
Never /t more than one emer gency
spa rewheel or spare wheel that di.ers
in size. #
Only use an emer gency spa rewheel or
spare wheel brie0y. #
Do not deacti vate ESP ®
. #
Have the emer gency spa rewheel or
spare wheel of a di.erent size replaced
at the nearest quali/ed specialist work-
shop. The new wheel must ha vethe cor-
re ct dimensions. %
The de0ated emer gency spa rewheel is
secured in the emer gency spa rewheel bag in
th e load compartment and is secured tothe
adjustable load compartment 0oor in the
lo we r position.
Obser vethefo llowing no tes on removing an emer-
ge ncy spa rewheel:
R Before st owing the emer gency spa rewheel,
make sure there is no air leT in the tyre.
If necessar y,allow the air toescape. R
T
To r
o r elease air fr
elease air fr om t
om the tyr
he tyr e:
e: remo vetheva lve
cap of the tyre.
R Press down the me tal insert in theva lve using
a pointed object, e.g. a pen.
R Screw theva lve cap onto theva lve.
% V
V ehicles wit
ehicles wit h adjust
h adjustable load com
able load com par
partment
tment
0oor:
0oor: always st owthe de0ated emer gency
spa rewheel in the lo wer position on the
adjustable load compartment 0oor.
Obser vethefo llowing no tes on /tting an emer-
ge ncy spa rewheel:
R The maximum permissible speed with an
emer gency spa rewheel /tted is 80 km/h.
R Do not /t the emer gency spa rewheel with
snow chains.
R Replace the emer gency spa rewheel aTer six
ye ars at the latest, rega rdless of wear.
R Check the tyre pressure of the emer gency
spa rewheel /tted. Cor rect the pressure as
necessar y.
% The speci/ed tyre pressure is stated on the
label of the emer gency spa rewheel. Wheels and tyres
389
389

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences and0050
0050Solutions
Solutions
Front-passenger airbag
enabled See Owner's Man-
ual *T
he front passen ger airbag will be enabled while theve hicle is in motion in thefo llowing situations:
R even when a child, a small adult or an object weighing less than the system weight thre shold is located on the front
passenger seat
R even when the front passenger seat is not occupied
The system may de tect objects or forc es that are adding tothewe ight applied tothe seat. &
W WARNING
ARNING Risk of injury or death when using a child restraint system while the front passenger airbag is ena-
bled
If yo u secure a child in a child restraint system on the front passenger seat and the front passenger airbag is ena-
bled, the front passenger airbag can deploy in theev ent of an accident.
The child could be struck bythe airbag. #
Ensure, bo thbefore and during the journe y,that the status of the front passenger airbag is cor rect.
NEVER use a rear wa rdfacing child restraint on a seat pro tected byan ACTIVE AIRBAG in front of it, DEATH or
SERIOUS INJURY tothe CHILD can occur. #
Stop theve hicle immediately in accordance with the tra1c conditions. #
Make sure that no objects are trapped under the front passenger seat. #
Check the status of automatic front passenger airbag actuation (/ page 57).#
If necessar y,consult a quali/ed specialist workshop immediatel y.416
416
Display message
s andwarning/indicator lamps

V
V
ehicle
ehicle Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/conseq uences and
uences and0050
0050Solutions
Solutions
0072
Vehicle is operational
Switch off ignition before
exiting *Y
ou are leaving theve hicle in a ready-to-drive state. #
Get out of theve hicle, secure it against rolling away and take theke y with you. #
Ifyo u do not lea vetheve hicle, switch o. the electrical consumers, e.g. the seat heating. Otherwise, the 12‑V bat-
te ry may dischar geand starting the engine may be possible only with the help of a second battery (jump start).
ï
Check trailer hitch
lock (white display message) *T
he trailer hitch is not operational during a jou rney with a trailer. &
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. #
Initiate a new swivel mo vement (/ page 274). #
When the display message disappears, couple up the trailer and drive on.
If th e display message does not disappear, the trailer hitch is malfunctioning and the ball neck is not loc ked. 432
432
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 #
Do not couple up the trailer. Drive on without the trailer. No tethere duced ground clearance due tothe unloc ked
ball nec k. #
Consult a quali/ed specialist workshop.
*W hen theve hicle is stationary with a coupled trailer, the trailer hitch is not operational. #
Uncouple the coupled trailer and secure it against rolling away. #
If t If the ball nec he ball nec k has been f
k has been f olded in:
olded in:unlockthe ball neck (/ page 274). #
Swivel the ball neck into the end position manually and let it engage. #
If t
If the ball nec
he ball nec k has been f
k has been f olded out
olded out::unlock the ball neck (/ page 274). #
Swivel the ball neck beneath the bumper manually and let it engage.
If th e display message does not disappear, the trailer hitch is malfunctioning and the ball neck is not loc ked. #
Do not couple up the trailer. Drive on without the trailer. No tethere duced ground clearance due tothe unloc ked
ball nec k. #
Consult a quali/ed specialist workshop.
Head-up display currently
unavailable See Owner's
Manual *T
he head-up displ ayistemp orarily una vailable. Possible causes:
R malfunctions in the po wer supply
R signal inter fere nce #
Stop in accordance with the tra1c conditions and switch theve hicle o. and on again. #
Ifth e display message still appears, consult a quali/ed specialist workshop. Displ
aymessages and warning/indicator lamps
433 433

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences and0050
0050Solutions
Solutions
0080
Trans. oil overheated Drive
on with care *T
he transmission is overheating. When the display message is active, start-up and driving characteristics may be tem-
porarily impaired. #
Drive at low engine speed. #
Avoid sporty driving. #
Before pulling away on uphill gradients, let the transmission cool down until the display message disappears.
Parking lock inoperative
Apply the parking brake *T
he transmission is malfunctioning. The park position 005Dcann otbe selected. #
Park theve hicle safel y. #
Use the electric parking brake tosecure theve hicle against rollingaway.
Teaching in transmission
Operate selector lever
Brake for XX seconds Risk
of vehicle rolling *T
he transmission is being taught in. There is a risk of theve hicle rolling away. #
Depress and hold the brake pedal until thete ach-in process has been comple ted.
The electric parking brake is applied automatically during thete ach-in process. #
Switch on theve hicle. #
Select park position 005D, transmission position 005Eor neutral 005C.
Risk of vehicle rolling away
Apply parking brake See
Owner's Manual *T
he transmission position cann otbe reliably identi/ed. #
Use the electric parking brake tosecure theve hicle against rollingaway.
Teaching in transmission
complete *T
he transmission's teach-in process is comple te. All transmission positions can be selected again. 444 444
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 #
Until then, alw ays select park position 005Dmanually before you switch o. theve hicle. #
Before leaving theve hicle, apply the electric parking brake.
Auxiliary battery malfunc-
tion (red display message) *V
Vehicles wit ehicles wit h manual tr
h manual tr ansmission:
ansmission: There is afault with the auxiliary batter y.
V
V ehicles wit
ehicles wit h aut
h automatic tr
omatic tr ansmission:
ansmission: The auxiliary battery forth e transmission is no longer being charge d. #
Consult a quali/ed specialist workshop. #
V
Vehicles wit
ehicles wit h aut
h automatic tr
omatic tr ansmission:
ansmission: untilthen, alw ays select park position 005Dbefore you switch o. theve hicle. #
Before leaving theve hicle, apply the electric parking brake. Br
Br
ak
ak es
es Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/conseq uences and
uences and0050
0050Solutions
Solutions
0024
Parking brake See Owner's
Manual *T
heyellow 0024 indicator lamp is lit. The electric parking brake is malfunctioning.
T
T o apply o apply :
: #
Switch theve hicle o. and switch it back on #
App lythe electric parking brake manually (/ page 221).
If it is not possible toapply the electric parking brake: #
Consult a quali/ed specialist workshop. #
Where necessar y,also secure the par kedve hicle against rolling away. 446
446
Display message
s andwarning/indicator lamps

Displa
Displa
y messag
y messag es P
es Possible causes/conseq
ossible causes/consequences and uences and0050
0050Solutions
Solutions #
Do not continue driving. Consult a quali/ed specialist workshop. #
Where necessar y,also secure the par kedve hicle against rolling away.
*T heyellow 0024 indicator lamp is lit and there d0024 indicator lamp 0ashes for appr oximately ten seconds aTer the
electric parking brake has been applied or released. It then remains lit or goes out. The electric parking brake is mal-
functioning.
If t
If t he st he st at
ate of c
e of c harg
harge is t
e is t oo low
oo low :
: #
Char gethe 12 V batter y.
T
T o apply
o apply :
: #
Switch o. theve hicle.
The elect ric parking brake will be applied automatical ly.
If yo u do not wantthe electric parking brake tobe applied, e.g. at an automatic car wash or when theve hicle is being
to we d, lea vetheve hicle switched on. This does not include having theve hicle towe d with there ar axle raised.
If th e electric parking brake is not applied automaticall y: #
Switch theve hicle o. and switch it back on #
Release and then apply the electric parking brake manually (/ page 221).
If it is still not possible toapply the electric parking brake: #
Consult a quali/ed specialist workshop. #
Where necessar y,also secure the par kedve hicle against rolling away. 448
448
Display message
s andwarning/indicator lamps

W
W
ar
ar ning/indicat
ning/indicat or lampP
or lam pP ossible causes/conseq
ossible causes/consequences and uences and0050
0050Solutions
Solutions
ï
Tr ailer tow hitch warning
lamp *T
hered trailer hitch warning lamp is lit.
The trailer hitch is not operational. &
W
W ARNING
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 and0050
0050Solutions
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 484
484
Display message
s andwarning/indicator lamps

EBD (Electronic Brake
forc e Distribu-
tion).......................................................2 27
HOLD function....................................... 228
Limited braking e.ect (salt-treated
ro ads)................................................... .173
Ne w/replaced brake linings/brake
discs...................................................... 172
Po st-collision brak e.................................. 60
Ru nning-in no tes.................................... 172
Br
Br ak ak es
es
see Recuperation
Br
Br aking assist
aking assist ance
ance
see BAS (Brake Assist System)
Br
Br eakdo
eakdo wn
wn
Assistance overview. ................................ 20
To w- starting........................................... 370
To wing away.......................................... 367
Tr anspo rting theve hicle........................ .368
Wheel chang e........................................ 383
Br
Br ea kdo
eakdo wn
wn
see Flat tyre
Butt
Butt ons
ons
St eering wheel....................................... 282 C
C
Calls
Calls Mercedes me......................................... 314
Camera
Camera
Information............................................ 223
Camera Camera see 360° Camera
see Dashcam
see Reversing camera
Car key
Car key
see Key
Car w Car w ash
ash
see Care
Car w
Car w ash (car
ash (car e)
e)............................................ 343
Car
Car -t
-to-X
o-X -Communication
-Communication
Displaying hazard warnings.................... 308
Care
Care 360° camera......................................... 348
Air-water duct........................................ 343
Automatic car wash.............................. .343
Carpet................................................... 349
Decorative foil........................................ 347
Display................................................... 349 Exterior lighting...................................... 348
Head-up display..................................... 349
High-pressure cleaner............................3
45
Pa int...................................................... 346
Plastic trim............................................3 49
Re alwo od/trim elements..................... .349
Re versing camera..................................3 48
Ro of lining............................................. 349
Seat belt................................................ 349
Seat co ver............................................. 349
Sensors.................................................3 48
St eering wheel....................................... 349
Ta ilpipes................................................ 348
Tr ailer hitc h............................................ 348
Ve hicle soc ketfo rth e high-voltage
battery................................................... 348
Wa shing byhand.................................... 346
Wheels/rims.......................................... 348
Wi ndo ws................................................ 348
Wi per blades.......................................... 348
Car
Car pe pet (Car
t (Car e)
e)............................................... 349
Changing bulbs Changing bulbs Dipped beam......................................... 149
Fitting/removing co ver (front wheel
ar ch )...................................................... 148 Index
499 499

Main beam............................................. 149
No tes..................................................... 147
Overview................................................ 148
Re versing lights......................................1 49
Tu rn signal lights (rear)........................... 149
Changing g
Changing g ears
ears
Manually................................................ 189
Changing hub caps Changing hub caps ....................................... 384
Char Char ging
ging
Char geleve l displa y............................... 214
Charg ing cable control panel.................. 203
Ending thech arging process (alternat-
ing cur rent, mode 2/3).......................... 209
Ending thech arging process (direct
cur rent, mode 4).................................... 213
Indica tor lamps on vehicle soc ket........... 205
No tes - charging station (mode 3)......... .201
No tes - fast charging station (mode 4)... .202
No tes - mains soc ket (Mode 2)............... 200
No tes - wallbox (mode 3)........................ 201
No tes on charging the high-voltage
battery................................................... 198
On-board electrical system battery
(12 V).................................................... 363 Setting
the maximum possible charg-
ing cur rent (mains soc ket)...................... 203
St arting thech arging process (alter-
nating cur rent, mode 2/3)..................... 206
St arting thech arging process (direct
cur rent, mode 4).................................... 211
St ow ing thech arging cable.................... 198
USB port............................................... .134
Char
Char ging cable ging cable
Control panel......................................... 203
St ow ing................................................. 198
Child safe Child safe ty lock
ty lock
Re ar door................................................ .78
Re ar side wind ows................................... 80
Child seat
Child seat
Appr oval catego ries.................................66
At tach ing (no tes)..................................... .66
Basic instructions.................................... 61
Fr ont passenger seat (no tes).................... 76
Fr ont passenger seat (without auto-
matic airbag shuto.)............................... .76
ISOFIX/i-Size (/tting).............................. .70
No tes on risks and danger s...................... 62
Re commendations forch ild restraint
systems................................................... 65 Seats suitable
for belt-secured child
re straint systems..................................... 73
Seats suitable for i‑Size child restraint
systems................................................... 69
Seats suitable for ISOFIX child
re straint systems..................................... 68
Securing on the co-driver seat..................77
Securing on there ar seat......................... 74
To pTe ther................................................ 72
Childr
Childr en en
Av oiding dangers in theve hicle............... .62
Basic instructions.................................... 61
Chock
Chock Storage location..................................... 383
Chock
Chock see Chock
City lighting
City lighting.................................................. 142
Cleaning
Cleaning
see Care
Cleaning
Cleaning 0uid
0uid
see windscreen washer 0uid
Climat
Climat e contr
e contr ol
ol
Ac tivating/deactivating.......................... 158 500
500
Index