ECU MERCEDES-BENZ B-CLASS HATCHBACK 2021 Service Manual

Dr
Dr
iving
iving N
No
ot
tes on plug-in h
es on plug-in h ybr
ybrids
ids N
No
ot
tes on plug-in h
es on plug-in h ybr
ybrid oper
id oper ation
ation &
W
WARNING
ARNING Risk ofchemical burns and poi-
soning from damaged high-voltage battery
If th e housing of the high-voltage battery has
been damaged, electrolyte and gases may
leak out. #
Avoid contact with the skin, eyes or
clo thing. #
Immediate lyrinse electrolyte splashes
o. with water and seek medical atten-
tion straight away. &
D
DAN
AN GER
GER Risk of explosion from excessive
internal pressure of the high-voltage bat-
te ry
Flammable gas may escape and ignite in the
eve nt of a vehicle /re. #
Stop thech arging process immediately
in case of unusual odours, smoke or
burn mar ks. #
Leavethe danger zone immediatel y.
Secure the danger zone at a su1cient
distance. #
Call the /re brigade. The
hybrid system combines a combustion engine
with an electric mo tor.
Characteristics when theve hicle is at a standstill:
R The combustion engine is generally switched
o..
R Idle speed only occurs in cer tain instances.
Characteristics when starting theve hicle:
R Ifth e high-voltage battery is su1ciently
ch arge d, theve hicle can be star ted with the
electric drive without the combustion engine
(noiseless start).
R Ifth e high-voltage battery forth e electrical
drive is not su1ciently charge d or the operat-
ing temp erature of the combustion engine has not been
reached, theve hicle can start with
th e combustion engine.
% Depending on the system, it may happen that
ev en though the high-voltage battery is
ch arge d, electric mode has restric ted or no
av ailabilit y.Once the combustion engine has
been operated for long enough, electric mode
is again available without restriction.
% Tostart the combustion engine, the high-volt-
age battery can be used as a star ter batter y.
Characteristics with moderate po wer output
re qu ests:
R The combustion engine is switched o. as
oTen as possible during the journe y.
R The vehicle can, depending on the drive pro-
gr am selected and the battery charge leve l, be
accelerated electrically up tospeeds of about
140 km/h.
Characteristics with high po wer output requ ests:
R The electric mo tor supports the combustion
engine (boost e.ect), e.g. when pulling away
or accelerating.
R The high-voltage battery is discharging. 166 166
Driving and parking

#
Neverto uch damaged components of
th e high-voltage on-board electrical sys-
te m. #
ATer an accident, do not touch any com-
ponents of the high-voltage on-board
electrical system. #
ATer an accident, ha vetheve hicle trans-
por tedawa y. #
Have the components of the high-voltage
on-board electrical system checked at a
qu ali/ed specialist workshop and
re placed if necessar y.R
R
eq
eq uir
uir ements:
ements:
Only disconnect the high-voltage on-board electri-
cal system manually in thefo llowing situations:
R The 0075 restraint system warning lamp lights
up in the Instrument Displa y,e.g. aTer an
accident.
R The vehicle is badly damaged, e.g. aTer an
accident, and there straint system co mpo-
nents ha venot been triggered. T
T
o oper
o oper at
ate t
e t he high-v
he high-v olt
oltag
age disconnect de
e disconnect de vice
vice #
Switch o. theve hicle. #
ShiT the transmission toposition 005D. #
Apply the electric parking brake. #
Secure theve hicle against rolling away (see
th eve hicle Owner's Manual). #
Open the bonnet. #
Press release tab1 inthe direction of the
ar ro w and pull it out. #
Pull high- voltage disconnect device 2inthe
direction of the ar row until it engages.
The high- voltage on-board electrical system is
switched o..
All workon thehy brid drive system (including
aTer disconnecting the high-voltage on-board
electrical system manually) may only be car ried
out byaqu ali/ed specialist workshop. Switc
Switc
hing on t
hing on t he pow
he power suppl
er suppl y or t
y or the v
he vehicle
ehicle &
W
WARNING
ARNING Risk of accident and injury due
to leaving children unattended in theve hi-
cle
If ch ildren are leT unattended in theve hicle,
th ey could, in particular:
R open doors, thereby endangering other
persons or road users.
R get out and be struck byoncoming tra1c. 168
168
Driving and parking

#
Remo vetheke y1 from theke yring. #
Place theke y1 inthe mar ked space 2on
th e symbol 3.
The vehicle will start aTer a short time.
When youre mo vetheke y1 from the mar ked
space 2,theve hicle can be driven. For fur-
th er engine starts ho wever,theke y1 must
be located in the mar ked space 2onthe
symbol 3during the entire journe y. #
Have theke y1 checked at a quali/ed spe-
cialist workshop.
If t
If t he v
he v ehicle does no
ehicle does no t st
t st art:
art: #
Place theke y1 inthe mar ked space 2and
lea veitth ere. #
V
Vehicles wit
ehicles wit h manual tr
h manual tr ansmission:
ansmission: Depress
th e clutch pedal. #
Depress the brake pedal and start theve hicle
using the start/s top button.
% You can switch on the po wer supply or the
ve hicle with the start/s top button. Obser
veany information rega rding display mes-
sages that can be displ ayed on the inst rument
displa y. S
S
t
tar
ar ting t
ting t he v
he vehicle via R
ehicle via R emot
emote Online Ser
e Online Ser vices
vices Cooling or heating t
Cooling or heating t
he v
he vehicle int
ehicle int er
erior bef
ior bef ore
ore
st
st ar
ar ting t
ting t he jour
he jour ney
ney
Ensu rethefo llowing before starting the engine:
R The legal stipulations in the area where your
ve hicle is par ked allow engine starting via
smartphone.
R It is safe tostart and runth e engine where
yo ur vehicle is par ked.
R The fuel tank is su1cient lyfull.
R The star ter battery is su1ciently charge d.
Char
Char ging t
ging t he st
he start
arter batt
er batt er
ery bef
y bef or
ore st
e st ar
arting t
ting t he
he
jour
jour ney
ney
Yo u can receive a message on your smartphone
when the state of charge ofthe star ter battery is
lo w. You can then start theve hicle with the smart-
phone tocharge the batter y.The vehicle is auto-
matically switched o. aTer ten minutes. Ensure
thefo llowing before starting the engine:
R The legal stipulations in the area where your
ve hicle is par ked allow engine starting via
smartphone.
R It is safe tostart and runth e engine where
yo ur vehicle is par ked.
R The fuel tank is su1cient lyfull.
S
S t
tar
ar ting t
ting t he v
he vehicle (R
ehicle (R emot
emot e Online)
e Online) &
W
WARNING
ARNING Risk of crushing or entrapment
due tounintentional starting of the engine
Limbs could be crushed or trapped if the
engine is star ted unintentionally during service
or maintenance work. #
Always secure the engine against unin-
te ntional starting before ca rrying out
main tenance or repair work. R
R
eq
eq uir
uir ements:
ements:
R Park position 005Dis selected.
R The anti-theT alarm system is not activated.
R The hazard warning light system is switched
o.. Driving and parking
171
171

R
The bonnet is closed.
R The doo rsare closed and loc ked.
R The windo wsand sliding sunroof are closed. #
Start theve hicle using the smartphone.
ATer every engine start, the engine runs for
te n minutes.
Yo u can car ryout a maximum of two consecutive
starting attem pts. You must start the engine with
th eke y before trying tostart theve hicle again
with the smartphone.
Yo u can switch o. theve hicle at any time as fol-
lo ws:
R Viath e Smartphone App
R By pressing theÜ orß button on the
key
% Further information can be found in the
smartphone app.
Secur
Secur ing t
ing the v
he v ehicle ag
ehicle ag ains
ainst st
t star
arting bef
ting bef or
ore car ry-
e car ry-
ing out maint
ing out maint enance or r
enance or repair w
epair wor
ork:
k: #
Switch on the hazard warning light system.
or #
Unlock the doors.
or #
Open a side window or the sliding sunroof. R
R
unning-in not
unning-in not es
es To
preser vethe engine during the /rst 1,500 km:
R Drive at varying road speeds and engine
speeds.
R Do not drive at speeds greater than
140 km/h.
R Drive theve hicle in drive prog ram A
or ;.
R ShiT tothe next highest gear at theve ry latest
when the needle reaches the last third before
th ere d area in there v counter.
R Do not shiT down manual lyin order tobrake.
R Avoid overstraining theve hicle, e.g. driving at
full thro ttle.
R V
V ehicles wit
ehicles wit h aut
h automatic tr
omatic tr ansmission:
ansmission: do not
depress the accelerator pedal be yond the
pressure point (kickdown). R
Only increase the engine speed gradually and
accelerate theve hicle tofull speed aTer
1,500 km.
This also applies when the engine or parts of the
driv etra in ha vebeen replaced.
Please also obser vethefo llowing running-in
no tes:
R In cer tain driving and driving saf ety sy stems,
th e sensors adjust automatically while a cer-
ta in distance is being driven aTer theve hicle
has been deli vered or aTer repairs. Full sys-
te m e.ectiveness is not reached until the end
of this teach-in process.
R Brakepads, brake disks and tyres that are
either new or ha vebeen replaced only achie ve
optimum braking e.ect and grip aTer se veral
hund red kilometres of driving. Compensate for
th ere duced braking e.ect byapplying greater
fo rc eto the brake pedal. 172
172
Driving and parking

N
N
o
ot
tes on dr
es on dr iving
iving &
W
W ARNING
ARNING Risk of accident due toobjects
in the driver's foot we ll
Objects in the driver's foot we ll may impede
pedal tr avel or block a depressed pedal.
This jeopardises the operating and road saf ety
of theve hicle. #
Stow all objects in theve hicle securely
so that they cannot getinto the driver's
fo ot we ll. #
Always /t the 0oor mats securely and as
prescribed in order toensure that there
is alw ays su1cient room forth e pedals. #
Do not use loose 0oor mats and do not
place 0oor mats on top of one ano ther. &
W
W ARNING
ARNING Risk of accident due toincor-
re ct foot we ar
Incor rect foot we ar includes, forex ample:
R shoes with plat form soles R
shoes with high heels
R slippers
There is a risk of an accident. #
Alwayswe ar suitable foot we ar so that
yo u can operate the pedals safel y. &
W
WARNI NG
ARNI NGRisk of accident if theve hicle is
switched o. while driving
If yo u switch o. theve hicle while driving,
saf ety functions are restric ted or no longer
av ailable.
This may a.ect the po wer steering system and
th e brake forc e boosting, forex ample.
Yo u will need touse considerably more force
to steer and brake, forex ample. #
Do not switch o. theve hicle while driv-
ing. &
D
DAN
AN GER
GER Risk of fatal injuries caused by
ex haust gases
Combustion engines emit poisonous exhaust
ga ses such as carbon monoxide. Inhaling
th ese exhaust gases is hazardous tohealth
and leads topoisoning. #
Never lea vetheve hicle or, if present, the
stationa ryheater running in an enclosed
space without su1cient ventilation. &
W
WARNI NG
ARNI NGRisk of skidding and of an acci-
dent due toshiTing down on slippery road
sur faces
If yo u shiT down on slippery road sur faces to
increase the engine braking e.ect, the drive
wheels may lose traction. #
Do not shiT down on slippery road sur fa-
ces toincrease the engine braking
e.ect. Driving and parking
173
173

The lettering in
the segment will light up brightl y,
th e outer edge will light up and the segment will
/ll up when thefo llowing driving style is adop ted:
R 1 Steady speed
R 2 Gentle deceleration and rolling
R 3 Moderate acceleration
The lettering in the segment will be grey ,th e outer
edge will be dark and the segment will em pty
when thefo llowing driving style is adop ted:
R 1 Fluctuations in speed
R 2 Heavy braking
R 3 Sporty acceleration
The ECO display will show you when you ha ve
driven economicall y:
R The thre e segments will /ll up comple tely at
th e same time
R The edges around all thre e segments will light
up
The additional range achie ved as a result of your
driving style in comparison with a driver with a
ve ry sporty driving st yle will be shown in thecent
reof display 4. Therange displa yed does
not indicate a /xed reduction in consum ption. R R
eg
eg ener
ener ativ
ative br
e br ak
ake syst
e syst em (plug-in h
em (plug-in h ybr
ybrid)
id) F F
unction of t unction of t he r
he recuper
ecuper ativ
ative br
e br ak
ake syst
e syst em
em
Depending on the selected recuperation le vel,the
electric mo tor is operated as an alternator when
in ove rrun mode and during braking in order to
ch arge the high-voltage battery while driving. As
soon as youre lease the accelerator pedal when
th eve hicle is in motion, recuperation in overrun
mode is initiated.
The higher there cuperation, the more sharply the
ve hicle is braked when coasting and the more
electrical energy is fed into the high-voltage bat-
te ry.
The rege nerative brake system has thefo llowing
ch aracteristics:
R supports braking with elect ronically cont rolled
brake force boosting
R con verts th e kinetic energy of theve hicle into
elect ric energy %
Ifyo u brake hard, the mechanical brake is
also used. This means that the maximum
re cuperative energy cann otbe reco vered. The
more you drive and brake in an anticipatory
manner, the more e1cient lyenergy can be
re cuperated.
Syst
Syst em limits em limits
The braking e.ect of the electric mo tor during
re cuperation in overrun mode may be reduced or
may not be available at all in thefo llowing situa-
tions:
R when the high-voltage battery charge level
increases
R ifth e high-voltage battery is not yet at a nor-
mal operating temp erature
R when driving at speeds close tozero
R in transmission position 005C
R during and aTer ESP ®
inter venes
In these cases, the desired deceleration is set by
th e brake control system. Also brake with the
service brake if necessar y.178
178
Driving and parking

Manuall
Manuall
y se
y setting r
tting r ecuper
ecuper ativ
ative deceler
e deceler ation
ation
% IntheÎ drive prog ram, you can use the
stee ring wheel gearshiT paddles tomanually
adjust the intensity of recuperation in overrun
mode. %
When theve hicle is star ted again or transmis-
sion position 005Bis engaged again, the stand-
ard setting is automatically set.
The following recuperation le vels are available:
R 005B0058 Intelligent, anticipa tory recuperation
with ECO Assist (standard setting)
(/ page 179)
R 005B0064 Norecuperation: theve hicle rolls freely R
005B Normal recuperation
R 005B0058 Increased recuperation; st rong deceler-
ation in overrun mode, e.g. for driving on
downhill gradients
R 005B00580058 Maximum recuperation: maximum
decele ration in overrun mode #
T
To incr
o incr ease r
ease r ecuper
ecuper ation:
ation:brie0y pull gearshiT
paddle 1. #
T
To r
o r educe r
educe r ecuper
ecuperation:
ation:brie0y pull gearshiT
paddle 2. #
S
St
tandar
andar d se
d setting:
tting: pull and hold gearshiT pad-
dle 1 or2 or engage transmission position
005B again. The Instrument Displ
aysho wscurrently set recu-
peration le vel1, forex ample, 005B0058. Eco Assis
Eco Assis
t function (plug-in h
t function (plug-in h ybr
ybrid)
id) %
The following function is countr y-dependent
and available only in conjunction with an inte-
gr ated hard drive navigation system.
ECO Assist is active only in drive prog rams A,
Î, Ïand;, and only in transmission
positions 005Bor005B0058. Perm anent manual gear-
shiTing 0063must be switched o. (/ page 189).
ECO Assist anal yses data forth eve hicle's expec-
te dro ute. This allo ws the system tooptimally
adjust the driving style forth ero ute ahead, sa ve
fuel and recuperate.
ECO Assist is displa yed on theAssistance
menu(/ page 282). Driving and parking
179
179

1
Event ahead, e.g. roundabout
2 Distance display forth eev ent ahead
3 "Foot o. the accelerator" prom ptDispla
yable pr evious events 1 The
following events 1can be de tected and dis-
pla yedfo rth ero ute section ahead:
R Vehicle in front
R Speed limit
R Downhill and uphill gradients
R Junctions and roundabouts
R Bends
The segments of dis tance display 2show the
distance totheeve nt ahead as follo ws:
R Afew segments light up: theeve nt ahead is
near.
R Many segments light up: theev ent ahead is
fur ther awa y.
If ECO Assist is acti ve,th e "Foot o. the accelera-
to r" symbol 3will appear on the inst rument dis-
play and on the head-up display beside the trans-
mission position displa y.
When theve hicle nears an event, ECO Assist will
calculate the optimal speed for minimal energy
consum ption based on the distance, speed and
gr adient. The "Foot o. the accelerator" symbol 3
will appear on the inst rument displa y. If
yo uta ke your foot o. the accelerator pedal in
good time, there maining segments on the display
will successively turn green until theev ent shown
is reached. The driv etra in will be set for minimal
energy consum ption. The vehicle will recuperate
autonomously and thus charge the batter y.
% You can also manually increase or reduce the
re cuperation in drive prog ram Î. Ho wever,
ECO Assist is available only in the005B0058
setting (/ page 179).
If th ere is no response tothe "Foot o. the accel-
erator" prom pt3 ,th e segments will remain
white.
The event will be shown for a short time aTer it
has been passed.
If th eev ent in volves a vehicle in front, the symbol
will be shown in green as soon as there is a
re sponse to"Foot o. the accelerator" prom pt3 .
If th e system does not inter vene during theev ent
ahead, no thing will be displa yed. The system will
be passive. 180 180
Driving and parking

D
D
YN
YNAMIC SELECT switch AMIC SELECT switch F
F
unction of t
unction of t he D
he DYN
YNAMIC SELECT switchAMIC SELECT switch %
Depending on the engine and equipment, the
ve hicle has di.erent drive prog rams.
Use theDY NAMIC SELECT switch tochange
between thefo llowing drive prog rams.
The drive prog ram selected appears in the inst ru-
ment displa y.
= Individual
R Individual settings
C Sport
R Continues too.er stability but with a sporty
setup
R Allo ws th e sporty driver a more active driving
style
R Driving with the combustion engine and rein-
fo rc ed boost e.ect (plug-in hybrid)
R Deactivation of the combustion engine when
stationary (plug-in hybrid)
R Only suitable for good road conditions, a dry
ro ad sur face and a clear st retch of road A
Comfort
R Comfor table and economical driving
R Balance between traction and stability
R The selection of the matching drive type by
th ehy brid system depends on the driving con-
ditions and the distance (plug-in hybrid)
R Recommended for all road conditions
Î Electric (plug-inhybrid)
R Electric mode – driving without the combus-
tion engine is possible up toappr ox.
140 km/h
R Adjustable recuperation in overrun mode
R Adaptation of Active Distance Assist
DISTRONIC for electric mode
R Depending on the equipment, the maximum
set speed for cruise control, limiter and Active
Distance Assist DISTRONIC can be limited to
th e maximum electrically drivable speed
R Activation of the combustion engine via the
pressure point of the accelerator pedal (kic k-
down) Ï
Battery Level (plug-inhybrid)
R Prioritised maintenance of the state of charge
of the high-voltage batter y,e.g. for subse-
qu ent journe ysinthe inner city/low emission
zones
R The selection of the matching drive type by
th ehy brid system depends on the driving con-
ditions and the distance
; Eco
R Only available forve hicles with automatic
transmission
R Particular lyeconomical driving
R Balance between traction and stability
R Recommended for all road conditions
R Full de velopment of all intelligent hybrid func-
tions and adap tation of the coasting charac-
te ristics of theve hicle totra1c (plug-in hybrid)
R The selection of the matching drive type by
th ehy brid system depends on the driving con-
ditions and the distance (plug-in hybrid) 182
182
Driving and parking

Use
the DIRECT SELECT le verto switch the trans-
mission position. The cur rent transmission posi-
tion is displa yed in the inst rument displa y. 005D
Park position
005E Reversege ar
005C Neutral
005B Drive position Eng
Eng
aging rev
aging rever
erse g
se g ear R
ear R #
Depress the brake pedal and push the DIRECT
SELECT le ver upwards past the /r stpoint of
re sis tance.
Eng
Eng aging neutr
aging neutr al N
al N #
Dep ress the brake pedal and push the DIRECT
SELECT le ver up or down tothe /rst point of
re sis tance.
% ToshiT into neutral 005Cwith theve hicle
switched on, push the selector le ver up or
down for se veral seconds tothe /rst point of
re sis tance.
Subsequently releasing the brake pedal will allow
yo uto mo vetheve hicle freel y,e.g. topush it or
to w it away.
Pr
Pr oceed as f
oceed as f ollow
ollow s if y
s if you w
ou w ant t
ant the aut
he aut omatic
omatic
tr
tr ansmission t
ansmission t o r
o remain in neutr
emain in neutr al
al005C
005C ev
even if t
en if t he
he
v
v ehicle is switc
ehicle is switc hed
hedo.
o.or t
or t he dr
he dr iv
iver's door is
er's door is
opened:
opened: #
Depress the brake pedal and engage neutral
005C when the car is stationar y. #
Release the brake pedal. #
Switch o. theve hicle. %
Ifyo uth en exitth eve hicle leaving theke y in
th eve hicle, the automatic transmission
re mains in neut ral005C.
Eng
Eng aging par
aging par k position P
k position P #
Obser vethe no tes on parking theve hicle
(/ page 215). #
Depress the brake pedal until theve hicle
comes toa standstill. #
When theve hicle is at a standstill, press but-
to n005D.
When the transmission position display sho ws
005D ,th e park position is engaged. If no trans-
mission position display 005Dappears, secure
th eve hicle toprev ent it from rolling away.
% Depending on the situation, it may take a
short time until 005Dis engaged. Therefore,
alw ays pay attention tothe transmission posi-
tion displa y.
Pa rk position 005Dis engaged automatically if one
of thefo llowing conditions is met:
R You switch the stationary vehicle o. in trans-
mission position 005Bor005E. 188
188
Driving and parking