service MERCEDES-BENZ C-CLASS CABRIOLET 2021 Manual PDF

Fu
rther information can be obtained at a quali‐
fi ed specialist workshop.
Charging #
Connect positive contact 3oftheve hicle to
th e positive term inal of thech arge r using the
ch arging cable. Alw ays begin with positive
contact 3oftheve hicle. #
Connect the negative term inal of thech arger
and ear thpoint 4ontheve hicle with the
ch arging cable. Start with thech arge r. #
Start thech arging process.
When thech arging process is comple te:#
First,re mo vethech arging cable from ear th
point 4and the negative term inal of the
ch arge r,th en from positive conta ct3 and
th e positive term inal of thech arge r.Begin
ea ch time wi th the conta cts oftheve hicle. #
Afterre moving thech arging cable, close
co ver2 of positive contact 3.#
Close co ver1.
Fu rther information can be obtained at a quali‐
fi ed specialist workshop. Re
placing the 12V battery #
Obser vethe no tes on the12 V battery
(/ page 381).
Mercedes-Benz recommends that you ha vethe
12 V battery replaced at a qualified specialist
wo rkshop, e.g. at a Mercedes-Benz Service
Centre.
Obser vethefo llowing no tes if youwa ntto
re place the battery yourself:
R Alw aysre place a faulty bat tery with a battery
which meets the specific vehicle require‐
ments.
The vehicle is equipped with an AGMtech nol‐
ogy battery (Absorbent Glass Mat) or a li th‐
ium-ion batter y.Fu llve hicle functionality is
only guaranteed with an AGM battery or lith‐
ium-ion batter y.Fo r saf etyre asons,
Mercedes-Benz recommends that you on ly
use bat teries which ha vebeen tested and
appr ovedfo ryo ur vehicle byMercedes-Benz.
R Carryove r de tach able parts, such as vent
hoses, elbow fittings or term inal co vers from
th e battery being replaced. R
Make sure that theve nt hose is al ways con‐
nected tothe original opening on the side of
th e batter y.
Fit any existing or supplied cell caps.
Otherwise, gases or battery acid could
escape.
R Make sure that de tach able parts are recon‐
nected in the same way. To
w- starting or towing away Pe
rm itted towing me thods *
NO
TEDama gefrom auto matic braking If one of
thefo llowing functions is switched
on, theve hicle brakes automatically in cer‐
ta in situations:
R Active Brake Assi st
R Active Dis tance Assi stDISTRONIC
R HOLD function
R Active Parking Assist 386
Breakdown assis tance

#
Turn retai ning clip 2on co ver1 aqu arter-
turn anti-clo ckwise. #
Fold co ver1 up in the direction of the
ar row. #
Remo veany existing moisture from the fuse
box using a dry clo th. #
Loosen scr ews3 and remo vefuse box lid
4 upwards.
Closing #
Che ckwhe ther the seal is positioned cor‐
re ctly in lid 4. #
Insert lid 4into the brac ket at there ar of
th e fuse box. #
Fold down lid 4ofthe fuse box and tighten
scr ews3. #
Fold down co ver1. #
Turn retai ning clip 2on co ver1 aqu arter-
turn clo ckwise. #
Close the bonn et. Opening and closing
the fuse box in the
cockpit Re
quirements:
R Obser vethe no tes on electrical fuses
(/ page 391).
The fuse box is on the driver's side on the side of
th e cockpit under a co ver. #
Con tact a Mercedes-Benz Service Centre for
fur ther information. Breakdown assis
tance 393

#
Neverfit snow chains on the front
wheels. #
Only fit snow chains on there ar wheels
in pairs. *
NO
TEDama getocomponents of the
ve hicle body or chassis due tofitted
snow chains If
yo ufit snow chains tothe front wheels of
4MATIC vehicles, you may damage co mpo‐
nents of theve hicle body or chassis. #
Onlyfit snow chains tothere ar wheels
of 4MATIC vehicles. Obser
vethefo llowing no tes when using snow
ch ains:
R Snow ch ains are on ly permissible for cer tain
wheel/tyre combinations. You can obtain
information about this from a Mercedes-Benz
Service Cent re.
R For saf etyre asons, on lyuse sn ow chainsthat
ha ve been specifically appr ovedfo ryo ur ve
hicle byMercedes-Benz, or snow chains
with the same quality standard.
R If sn ow ch ains are fitted, the maximum per‐
missible speed is 50 km/h.
R Vehicles with Active Park ing Assis t:do
not use Active Parking Assist when snow
ch ains are fitted.
R Vehicles with le vel control: if snowchains
are fitted, only drive at raised vehicle le vel
( / page 202).
% You can permanently limit the maximum
ve hicle speed for driving with winter tyres
(/ page 179).
% You can deactivate ESP ®
to pull away
( / page 172). This all owsth e wheels to
spin, achieving an increased driving forc e. Ty
re pressure Note
s on tyre pressure &
WARNING Risk of accident due toinsuf‐
fi cient or excessive tyre pressure
Ty res with either too low or too high a pres‐
sure present thefo llowing hazards:
R the tyres could bur st
R the tyres could wearexcessively and/or
une venly
R the driving characteristics as well as
st eering and braking characteristics may
be se verely impaired #
Obse rveth ere commended tyre pres‐
su res and check the tyre pressures of
all tyres including the spare wheel:
R monthly
R if altering the load on theve hicle
R prior tolong journe ys
R ifth e operating conditions change, for
ex ample when driving off- road 396
Wheels and tyres

#
Adjust the tyre pressure where neces‐
sar y. Ty
re pressure which is too high or too low can:
R Shor tenth e service life of the tyres.
R Cause increased tyre damage.
R Adversely af fect driving characteristics and
th us driving saf ety, e.g. due toaquaplaning. &
WARNING Risk of accident due torepea‐
te d pressure drop in the tyres
The wheels, valves or tyres could be dam‐
aged.
To o low a tyre pressure can lead tothe tyres
bur sting. #
Examine the tyres forfo re ign objects. #
Check whe ther the tyre has a puncture
or theva lve has a leak. #
Ifyo u are unable torectify the damage,
conta ct aqualified specialist workshop. Information on
there commended tyre pressure
fo rth eve hicle's factor y-fitted tyres can be found on
the tyre pressure table on the inside of the
fuel filler flap (/ page 397).
Use a suitable pressure gauge tocheck the tyre
pressure. The outer appearance of a tyre does
not permit any reliable conclusion about the tyre
pressure.
Only cor rect tyre pressures when the tyres are
cold. Conditions for cold tyres:
R The vehicle has been par ked with the tyres
out of direct sunlight for at least thre e hours.
R The vehicle has tr avelled less than 1.6 km.
The vehicle's tyres heat up when driving. As the
te mp erature of the tyres increases, so too does
th e tyre pressure.
Ve hicles with a tyre pressure monitoring sys‐
te m: you can also check the tyre pressure using
th e on-board computer.
Note s on trailer operation
Alw ays inflate there ar axle tyres tothere com‐
mended tyre pressures on the tyre pressure
ta ble for increased load. Ty
re pressure table The tyre pressure
table is on the inside of the
fuel filler flap. If one or more tyre sizes precede a tyre pres‐
sure, thefo llowing tyre pressure information is
only valid forth ose tyre sizes and their respec‐
tive load condition. Wheels and tyres
397

If
th e preceding tyre sizes are complemented by
th e+ symbol, the tyre pressure information
fo llowing sho wsalternative tyre pressures. Fuel
consum ption may then increase slightl y.
The load conditions "partially laden" and "fully
laden" are defined in theta ble for dif fere nt num‐
be rs of passengers and amounts of luggage. The
actual number of seats may dif fer from this. Ty
re pressure moni toring sy stem Fu
nction of the ty repressure moni toring sys‐
tem
The sy stem checks the tyre pressure and the
tyre temp erature of the tyres fitted totheve hicle
by means of a tyre pressu resensor.
The tyre pressure and the tyre temp erature
appear in the on-board computer (/ page 398).
If th ere is a subs tantial pressure loss or if the
tyre temp erature is excessive, you will be
wa rned with display messages (/ page475) or
th eh warning lamp in the instrument clus ter
( / page 498). The tyre pressure monitoring sy
stem is only an
aid. It is the driver's responsibility toset the tyre
pressure tothere commended cold tyre pressure
suitable forth e operating situation.
In most cases, the tyre pressure monitoring sys‐
te m will auto matically update the new refere nce
va lues af teryo u ha vechanged the tyre pressure.
Yo u can, ho wever,also update there fere nce val‐
ues byrestarting the tyre pressure monitoring
sy stem manually (/ page 399).
Sy stem limits
The sy stem may be impaired or may not function
particularly in thefo llowing situations:
R the tyre pressure has been set incor rectly
R sudden pressure loss caused byafo re ign
object penetrating the tyre, forex ample
R there is a malfunction caused byano ther
ra dio signal source
Checking the ty repressure with the tyre
pressure moni toring sy stem
Requ irements:
R The ignition is switched on. On-board computer:
4 Service 5
Tyres
One of thefo llowing displa ysappears:
R Cur rent tyre pressure and tyre temp erature
of the individual wheels: R
Tyre pressures will be displayed after a few
minutes of driving
R Tyre pressure monitor active: thete ach-in
process of the sy stem is not yet compl ete.
The tyre pressures are already being moni‐
to re d. #
Compare the tyre pressure with there com‐
mended tyre pressure forth e cur rent operat‐ 398
Wheels and tyres

ing condition (/
page 397). Observethe
no tes on tyre temp erature (/ page 396).
% The values displa yed in the on-board com‐
puter may deviate from those of the tyre
pressure gauge as they referto sea le vel.At
high ele vations, the tyre pressure values
indicated bya pressure gauge are higher
th an those shown bythe on-board computer.
In this case, do not reduce the tyre pressure.
Re starting the ty repressure moni toring sys‐
tem
Re quirements:
R The recommended tyre pressure is cor rectly
set forth ere spective operating status on all
of the wheels (/ page 396).
Re start the tyre pressure monitoring sy stem in
th efo llowing situations:
R The tyre pressure has changed.
R The wheels or tyres ha vebeen changed or
newly fitted. On-boa
rdcompu ter:
4 Service 5
Tyres #
Swipe down wards on Touch Control on the
left-hand side of thesteering wheel.
The Use current tyre pressures as new refer-
ence values? message is shown in the multi‐
function displa y. #
Torestart, press Touch Control on the left-
hand side of thesteering wheel.
The Tyre press. monitor restarted message is
shown in the multifunction displa y.
Cur rent wa rning messages are dele ted and
th eye llow h warning lamp goes out.
Af teryo u ha vebeen driving for a few
minutes, the sy stem checks whe ther the cur‐
re nt tyre pressures are wi thin the specified
ra nge. The cur rent tyre pressures are then
accep ted as refere nce values and monitored.
Be sure toalso pay attention tothefo llowing
re lated topic:
R Notes on tyre pressure (/ page 396) Ty
re pressure loss warning sy stem Fu
nction of the ty repressure loss warning
sy stem
The tyre pressure loss warning sy stem warnsthe
driver bymeans of display messa ges when there
is a se vere tyre pressu reloss.
Sy stem limits
The sy stem may be impaired or may not function
particular lyin thefo llowing situations:
R incor rectly set tyre pressure
R sudden pressure loss caused, forex ample,
by afo re ign object penetrating the tyre
R steady pressure loss in se veral tyres
The sy stem has a restricted or del ayed function
particularly in thefo llowing situations:
R poor ground cond itions, e.g. snow or gr avel
R driving with snow chains
R when adopting a very sporty driving style
with high cornering speeds or sudden accel‐
eration
R driving with a very heavy or lar getrailer Wheels and tyres
399

R
driving with a high load
The tyre pressure loss warning sy stem is only an
aid. It is the driver's responsibility toset the tyre
pressure tothere commended cold tyre pressure
suitable forth e operating situation and tocheck
it.
Be sure toalso obse rveth efo llowing fur ther
re lated subjects:
R Notes on tyre pressure (/ page 396)
R Display messages about the tyres
(/ page 475)
Rest arting the ty repressure loss warning
sy stem
Requ irements:
R The recommended tyre pressure is cor rectly
set forth ere spective operating status on all
wheels.
Re start the tyre pressure loss warning sy stem in
th efo llowing situations:
R The tyre pressure has changed.
R The wheels or tyres ha vebeen changed or
newly fitted. On-boa
rdcompu ter:
4 Service 5
Tyres #
Swipe down wards on Touch Control on the
left-hand side of thesteering wheel.
The Run Flat Indicator active Restart: press
Touch Control message is shown in the mul‐
tifunction displa y. #
Tobegin restart, press Touch Control on the
left-hand side of thesteering wheel.
The Tyre pressure now OK? message is
shown in the multifunction displa y. #
Select Yes. #
Toconfirm restart, press Touch Control on
th e left-hand side of thesteering wheel.
The Run Flat Indicator restarted message is
shown in the multifunction displa y.
Af teryo u ha vedriven for a few minutes, the
tyre pressu reloss warning sy stem monitors
th e set tyre pressures of all the tyres.
Be sure toalso pay attention tothefo llowing
re lated topic:
R Notes on tyre pressure (/ page 396) Wheel
change Note
s on selecting, fitting and replacing
tyres *
NO
TEMercedes-AMG vehicles #
Obser vethe no tes in the Supplement.
Yo u could otherwise failto recognise
dangers. &
WARNING Risk of inju rythro ugh incor‐
re ct sizes of wheels and tyres
If wheels and tyres of the wrong size are fit‐
te d, the wheel brakes or components in the
brake sy stem and in the wheel suspension
may be damaged. #
Alw aysre place wheels and tyres with
th ose that fulfil the specifications of the
original part.
Fo r wheels, pay attention tothefo llowing:
R Designation
R Type 400
Wheels and tyres

Note
s ontech nical data
* NO
TEMercedes-AMG vehicles #
Obser vethe no tes in the Supplement.
Yo u could otherwise failto recognise
dangers. The
tech nical da tawa s de term ined in accord‐
ance with EU Directives. The data stated on ly
applies tovehicles with standard equipment. Yo u
can obtain fur ther information from a Mercedes-
Benz Service Centre.
Only for ce rtain countries: you can find vehi‐
cle-specific vehicle data in the COC documents
(CERTIFIC ATE OF CONFORMITY). These pape rs
are included with theve hicle. On-board electronics
Note
s on tampering with the engine elec‐
tronics *
NO
TEPremature wearthro ugh improper
main tenance Improper maintenance may cause
vehicle
components towe ar more quickly and the
ve hicle's operating permit may be in valida‐
te d. #
Alw ays ha vewo rkon the engine elec‐
tronics and related components car ried
out at a qualified specialist workshop. Tw
o-w ayradios Note
s onfitting two-w ayradios &
WARNING Risk of accident due to
improper workon two-w ayradios
If two-w ayradios are manipulated or retrofit‐
te d incor rectl y,the electromagnetic radiation
from the two-w ayradios can inter fere with th
eve hicle electronics and jeopardise the
operating saf ety of theve hicle. #
You should ha veall workon electrical
and electronic components car ried out
at a qualified specialist workshop. &
WARNING Risk of accident from incor‐
re ct ope ration of two-w ayradios
If yo u use two- wayra dios in theve hicle
improperly, their electromagnetic radiation
can disrupt theve hicle's electronics. This is
true in thefo llowing situations, in particular:
R The two-w ayradio is not connec tedto an
ex terior aerial.
R The exterior aerial is fitted inco rrectly or
is not a lo w-reflection aerial.
This could jeopardise the operating saf ety of
th eve hicle. #
Have the lo w-reflection exterior aerial
fi tted at a qualified specialist workshop. 412
Tech nical da ta

1
For petrol with maximum 5% ethanol byvol‐
ume
2 For petrol with maximum 10%ethanol by vol‐
ume
Ac cording toEuropean standard EN 1694 2you
can find the compatibility indications at thefo l‐
lowing locations:
R ontheve hicle on the information label on the
fuel filler flap (/ page155).
R onthe fuel pump or pump nozzle suitable for
yo ur vehicle thro ughout Europe.
If th eav ailable fuel is not suf ficiently low in sul‐
phu r,th is can produce unpleasant odours. The
recommended octane number foryo ur vehi‐
cle can also be found on the information label in
th e fuel filler flap (/ page155).
As a temp orary measure, if there commended
fuel is not available, you may also use regular
unleaded petrol with at leas t:
R C18 0:93 RON
R allother models: 91RON
This may reduce engine output and increase fuel
consum ption.
Ne verre fuel using petrol with an even lo wer
RO N.
Fu rther information on fuel can be obtained at a
fi lling station or a qualified specialist workshop.
Information on additives in petrol
Obser vethe no tes on operating fluids
(/ page 416).
* NO
TEDama gefrom use of unsuitable
additives Even small amounts of
the wrong additive
may lead tomalfunctions occur ring. #
Only add cleaning additives recommen‐
ded byMercedes-Benz tothe fuel. Mercedes-Benz
recommends that you use
brand-name fuels with additives.
In some count ries, the fuel available may not
ha ve suf ficient additives. Residue could build up
in the fuel injection sy stem as a result. In this
case, in consultation with a Mercedes-Benz
service centre, mix the fuel with the cleaning
additive recommended byMercedes-Benz.
Obser vethe no tes and mixing ratios indica ted
on theta nk.
In fo rm ation on fuel grades forve hicles with
a diesel engine
Gene ral no tes
Obser vethe no tes on operating fluids
(/ page 416). &
WARNING Risk offire from fuel mixture
If yo u mix diesel fuel with petrol, theflash
point of the fuel mixture is lo werth an that of
pure diesel fuel. Te
ch nical da ta419

R
NOx exhaust gas af tertre atment malfunc‐
tions #
Avoid impurities in AdBlue ®
. Ad
Blue ®
re sidues cr ystallise af ter a period of
time, and contamina tethe sur faces wi thwhich
th ey come into contact. Clean the dirty sur faces
wi th wate r as soon as possible.
When you open theAd Blue ®
tan k,small
amounts of ammonia vapour may escape. Do
not inhale any ammonia vapours that may be
re leased. Only fill th eAd Blue ®
tank in well-venti‐
lated areas.
Ad Blue ®
filling capacity and consum ption Model
Total capacity
All models 14litres Ad
Blue ®
consu mption
The average AdBlue ®
consu mption is between
1% and 5% of fuel consumption. Li kefuel con‐
sum ption, AdBlue ®
consu mption is highly dependent upon driving
style and operating con‐
ditions. Forth is reason, your vehicle's actual
consum ption figures under da y-to -day operating
conditions may di ffer from the consum ption fig‐
ures calculated. The frequency at which you will
ha ve to to p up AdBlue ®
will also vary. Ha vethe
Ad Blue ®
supply checked at a qualified specialist
wo rkshop before making journe ysoutside of
Europe. Before a longer stay outside of Europe,
consult a qualified specialist workshop.
Ad Blue ®
ra nge and fill le vel
The AdBlue ®
fill le vel and range can be displ ayed
via the on-board computer. The AdBlue ®
ra nge
shown depends strongly on the driving style and
operating conditions. The actual range can
th erefore deviate from thera nge cur rently dis‐
pl ay ed in the on-board computer. The informa‐
tion supplied in the Owner's Manual rega rding
th ere ser vequantity at thefirs t display warning
and on the minimum top-up quantity when the
ta nk is em pty is also tobe under stood as guide
va lues. Engine oil
Note
s on engine oil
Obser vethe no tes on operating fluids
(/ page 416). *
NO
TEEngine dama gecaused byan
incor rect oil filter, incor rect oil or addi‐
tives #
Do not use engine oils or oil filters
which do not cor respond tothe specifi‐
cations explicitly prescribed forthe
service inter vals. 422
Tech nical da ta