warning light MERCEDES-BENZ C-CLASS COUPE 2021 Repair Manual

#
With your hand flat, push down active bonnet
1 inthe area around the hinges on bo th
sides (ar rows).
In doing so, the actuator is depressurised
and you may hear a hissing sound.
The engine bonnet must en gage in position. #
Ifth e active bonn etcan be raised slight lyat
th ere ar in the area of the hinges, repeat the
st ep until it engages cor rectl y. Opening and closing
the bonnet &
WARNING Risk of accident due todriv‐
ing with the bonn etunlo cked
The bonn etmay open and block your vie w. #
Neverre lease the bonn etwhen driving. #
Before every trip, ensure that the
engine bonn etis loc ked. &
WARNING Risk of accident and inju ry
when opening and closing the bonn et
The bonnet may suddenly drop into the end
position.
There is a risk of injury for an yone in the
engine bonn et's range of mo vement. #
Do not open or close the bonn etifth ere
is a person in the bonn et's range of
mo vement. &
WARNING Risk of bu rns when opening
th e bonn et
If yo u open the bonn etwhen the engine has
ove rheated or when there is a fire inthe
engine compartment, thefo llowing situations
may occur:
R You could come into contact with hot
ga ses.
R You could come into contact with other
hot, escaping operating fluids. #
Before opening the bonn et, allow the
engine tocool down. #
Intheeve nt of a fire inthe engine com‐
partment, keep the bonn etclosed and
call thefire service. &
WARNING Risk of inju rydue tomoving
parts
Components in the engine compartment may
continue running or start up sudden ly,even if
th e ignition is switched off.
Make sure of thefo llowing before per form ing
ta sks in the engine compartmen t: #
Switch the ignition off. #
Neverre ach into the danger zone sur‐
ro unding moving co mponents, e.g. the
ro tation area of thefa n. #
Remo vejewe llery and watches. #
Keep items of clo thing and hair away
from moving parts. Maintenance and care
363

#
Push handle 1ofthe bonn etcatch up wards
and lift the bonn etuntil it opens automati‐
call y.
Closing the bonnet #
Lowe rth e bonn etto a height of around
20 cm and then allow it tofall, applying a lit‐
tle forc e as you let it go. #
Ifth e bonn etcan still be lif ted slightl y,open
th e bonn etagain and close it with a little
more forc e until it engages cor rectly. Engine oil
Che
cking the engine oil le vel using the oil
dip stick &
WARNING Risk of bu rns from hot com‐
ponent parts in the engine compartment
Cer tain component parts in the engine com‐
partment can be very hot, e.g. the engine,
th e cooler and parts of theex haust sy stem. #
Allow the engine tocool down and only
to uch co mponent parts described in
th efo llowing. Re
quirements:
R The engine has an oil dipstic k.If not, the
engine oil le vel can be checked only with the
on-board computer (/ page 366) . Depending on
the engine, the oil dipstick may be
ins talled in the engine compartment in dif fere nt
locations.
The waiting time before checking the oil le vel
when the engine is at normal operating temp era‐
ture is five minutes. #
Park theve hicle on a le vel sur face. #
Pull oil dipstick 1out and wipe off. Maintenance and care
365

Note
s on care of car parts &
WARNING Risk of entrapment if the
windscreen wipers are swit ched on while
th e windscreen is being cleaned
If th e windscreen wipers are set in motion
while you are cleaning the windscreen or
wiper blades, you can be trapped bythe
wiper arm. #
Alw ays switch off the windscreen wip‐
ers and the ignition before cleaning the
windscreen or wiper blades. &
WARNING Risk of bu rns from theta il‐
pipe and tailpipe trims
The exhaust tailpipe and tailpipe trims can
become very hot. If you come into contact
with these parts of theve hicle, you could
burn yourself. #
Alw ays be particular lycareful around
th eta ilpipe and theta ilpipe trims and
supervise children especially closely in
th is area. #
Allow vehicle parts tocool down before
to uching them. To
avo id damage totheve hicle, obser vethe
no tes on cleaning and care of thefo llowing vehi‐
cle parts:
Wheels and rims
R Use wate r and acid-free alloy wheel cleaners.
R Do not use acidic alloy wheel cleaners to
re mo vebrake dust. This could damage wheel
bolts and brake components.
R Toavo id cor rosion of the brake disks and
brakepads, drive theve hicle for a few
minutes af ter cleaning before parking it. The
brake disks and brakepads warm up and dry
out.
Wi ndo ws
R Clean the windo wsinside and outside with a
damp clo thand with a cleaning agent recom‐
mended for Mercedes-Benz.
R Do not use dry clo ths or abrasive or sol vent-
based cleaning agents toclean the inside of
windo ws. %
Remo veextern al fogging or dirt on the wind‐
screen in front of the multifunction camera.
Otherwise, driving sy stems and driving
saf ety sy stems may be impaired or not avail‐
able (/ page175).
Wi per blades
R Movethe wiper arms into there placement
position (/ page130).
R With th e wiper arms folded out, clean the
wiper blades with a damp clo th.
R Do not clean the wiper blades too of ten.
Ex terior lighting
R Clean the lenses with a wet sponge and mild
cleaning agent, e.g. car sha mpoo.
R Only use cleaning agents or cleaning clo ths
th at are suitable for plast ic lenses.
Sensors R Clean the sensors in the front and rear
bumpers with a soft clo thand car shampoo
(/ page 175).
R When using a high -pressure cleaner,maintain
a minimum dis tance of 30 cm. Maintenance and care
373

Re
versing camera and 360° Camera
R Open the camera co ver with the multimedia
sy stem (/ page216).
R Use clean water and a soft clo thtoclean the
came ralens.
R Do not use a high-pressure cleaner.
Ta ilpipes
R Clean with a cleaning agent recommended
fo r Mercedes-Benz, especially in the winter
and af terwa shing theve hicle.
R Do not use acidic cleaning agents.
Tr ailer hitch
R Obse rveth e no tes on care in the trailer hitch
manufacturer's operating instructions.
R Do not clean the ball neck with a high-pres‐
sure cleaner or solvent.
R Remo vetraces of rust on the ball, forex am‐
ple, with a wire brush.
R Remo vedirt with a lint-free clo th.
R After cleaning, lightly oil or grease the ball
head. %
Before using trailers with anti- torsional cou‐
pling, obser vethe manufacturer's operating
instructions. Note
s on care of the interior &
WARNING Risk of inju ryfrom pla stic
parts breaking off af terth e use of sol‐
ve nt-based care products
Ca reand cleaning products con taining sol‐
ve nts can cause su rfaces in the cockpit to
become porous. When the airbags are
deplo yed, plastic parts may break away. #
Do not use any care or cleaning prod‐
ucts containing sol vents toclean the
cockpit. &
WARNING Risk of inju ryor death from
bleached seat belts
Bleaching or dyeing seat belts can se verely
we aken them.
This can, forex ample, cause seat belts to
te ar or fail in an accident. #
Never blea chor dye seat belts. To
avo id damage totheve hicle, obser vethefo l‐
lowing no tes on cleaning and care:
Seat belts R Clean with luk ewarmand soapy water.
R Do not use chemical cleaning agents.
R Do not dry byheating them toove r 80°C or
ex posing them todirect sunlight.
Display
R Switch off the display and let it cool down.
R Clean the sur face carefully wi tha mic rofibre
clo thand a suitable display care product
(TF T-LC D).
R Do not use any other agents.
Plastic trim R Clean with a damp microfibre clo th.
R For heavy soiling: use a cleaner recommen‐
ded for Mercedes-Benz.
R Do not attach sticke rs,fi lms or similar mate‐
ri als. 374
Maintenance and care

*
NO
TEDama getothe battery from over‐
vo ltage When
charging using a bat tery charge r with‐
out a restriction of the maximum charging
vo ltage, the battery or the on-board electron‐
ics can be damaged. #
Only use battery charge rs with a maxi‐
mum charging voltage of 14.8 V. All
other vehicles
When charging the battery and during starting
assis tance, al ways use the jump-s tart connec‐
tion point in the engine compartment.
* NO
TEDama getothe battery from over‐
vo ltage When
charging using a bat tery charge r with‐
out a restriction of the maximum charging
vo ltage, the battery or the on-board electron‐
ics can be damaged. #
Only use battery charge rs with a maxi‐
mum charging voltage of 14.8 V. &
WARNING Risk ofexplosion from hydro‐
ge nga s igniting
There is a danger of hydrogen gas igniting
when charging the battery if there is a short
circuit or spar ksstart toform. #
Make sure that the positive term inal of
th e connected battery does not come
into conta ct withvehicle parts. #
Never place me tal objects or tools on a
batter y. #
The described order of the battery
clamps must be obser ved when con‐
necting and disconnecting the batter y. #
When giving starting assis tance, al ways
make sure that you on lyconnect bat‐
te ry term inals with identical polarity. #
During starting assis tance, you must
obse rveth e described order for con‐
necting and disconnecting the jump
lead. #
Do not connect or disconnect the bat‐
te ry cla mp s while the engine is running. &
WARNING Risk ofexplosion during
ch arging process and starting assis tance
During thech arging process and starting
assis tance, the battery may release an explo‐
sive gas mixture. #
Avoid fire , naked flames, creating
spar ksand smoking. #
Make sure there is suf ficient ventila‐
tion. #
Do not lean over a batter y. &
WARNING Risk ofexplosion from a fro‐
zen battery
A dischar ged battery may freeze at temp era‐
tures slightly abo veor below freezing point.
During starting assis tance or battery charg‐
ing, bat tery gas can be released. #
Alw ays allow a battery tothaw before
ch arging it or per form ing starting assis‐
ta nce. Breakdown assi
stance 387

If
th e indicator/warning lamps in the instrument
clus ter do not light up at low temp eratures, it is
ve ry likely that the dischar ged battery has fro‐
zen. In this case you may neither jump-s tart the
ve hicle nor charge the batter y.
The service life of a battery that has been
th awe d may be dramatically shor tened. The
st arting characteristics may be impaired, espe‐
cially at low temp eratures.
It is recommended that you ha veathaw ed bat‐
te ry checked at a qualified specialist workshop.
All vehicles
* NO
TEDama gecaused bynumerous or
ex tended attem ptsto start the engine Nume
rous or extended attem ptsto start the
engine may damage the catalytic con verter
due tonon-combu sted fuel. #
Avoid numerous and extended attem pts
to start the engine. Obser
vethefo llowing points during starting
assis tance and when charging the battery:
R Only use undamaged jump lead/charging
cables with a suf ficient cross-section and
insula tedte rm inal clamps.
R Non- insulated parts of thete rm inal clamps
must not come into con tact wi thother me tal
parts while the jump lead/charging cable is
connected tothe battery/jump-s tart connec‐
tion point.
R The jump lead/charging cable must not
come into contact wi thany parts which may
mo vewhen the engine is running.
R Alw ays make sure that nei ther you nor the
battery is elect rostatically charge d.
R Keep away from fire and naked flames.
R Do not lean overth e batter y.
Obser vethe additional following points when
ch arging the battery:
R Only use battery charge rs tested and
appr oved for Mercedes-Benz.
R Read the battery charge r's operating instruc‐
tions before charging the batter y. Obser
vethe additional following points during
st arting assis tance:
R Starting assis tance may only be pr ovided
using vehicles, batteries or other jump start
devices with a nominal voltage of 12V.
R The vehicles must not touch.
R Vehicles with a petrol engine: jump-start
th eve hicle only when the engine and exhaust
sy stem are cold. St
arting assi stance and charging the12 V
battery Preparing
starting assi stance/charging #
Secure theve hicle byapplying the electric
parking brake. #
Automatic transmission: shiftthe trans‐
mission toposition j. #
Manual transmission: shiftthe transmis‐
sion toneutral. #
Switch off the ignition and all electrical con‐
sumers. #
Open the bonn et. 388
Breakdown assis tance

#
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 401).
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
401

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 402).
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 (/ page477) or
th eh warning lamp in the instrument clus ter
( / page 500). 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 403).
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‐ 402
Wheels and tyres

Proportion of antifreeze concentrate in
the
engine cooling sy stem:
R a minimum of 50% (antifreeze pr otection
down toappr oximately -37°C)
R a maximum of 55% (antifreeze pr otection
down to-45°C) Note
s on windscreen washer fluid Obser
vethe no tes on operating fluids
(/ page 420). &
WARNING ‑ Risk of fire and injury due to
windscreen washer concentrate
Wi ndsc reen washer concentrate is highly
fl ammable. It could ignite if it comes into
con tact wi thhot engine component parts or
th eex haust sy stem. #
Make sure that no windsc reen washer
concentrate spills out next tothefiller
opening. *
NO
TEDama getotheex terior lighting
due tounsuitable windsc reen washer
fl uid Uns
uitable windsc reen washer fluids may
damage the plastic sur face of theex terior
lighting. #
Only use windscreen washer fluids
which are also suitable for use on plas‐
tic sur faces, e.g. MB SummerFit or MB
Wi nterFit. *
NO
TEBlocked spr aynozzles caused by
mixing windscreen washer fluids #
Do not mix MB SummerFit and MB Win‐
te rFit with other windscreen washer flu‐
ids. Do not use distilled or de-ionised
water.Other‐
wise, thefill le vel sensor may be triggered er ro‐
neously.
Re commended windscreen washer fluid:
R abo vefreezing point: e.g. MB SummerFit
R below freezing point: e.g. MB WinterFit Fo
rth e cor rect mixing ratio, referto the informa‐
tion on the antif reeze conta iner.
Mix washer fluid with windsc reen washer fluid all
ye ar round. Ve
hicle data Ve
hicle dimensions The heights speci
fied may vary as a result of the
fo llowing factors:
R tyres
R load
R condition of the suspension
R optional equipment Te
ch nical da ta429

Lights
Display messages
Possible causes/consequences and M
MSolutions
: Left dipped beam (examp le) *T
he cor responding light source is defective. #
Drive on carefully. #
Consult a qualified specialist workshop immediatel y.
% LED light sources: the display message forth e cor responding light appears only when allthe light-emitting
diodes in the light are faulty.
: Malfunction See Owner's
Manual *T
heexterior lighting is malfunctioning. #
Consult a qualified specialist workshop.
* Ve hicles with a trailer hitch: a fuse may haveblown. #
Stop theve hicle in accordance with the tra ffic conditions. #
Check the fuses and replace them if necessary (/ page 395).
:
Automatic driving lights
inoperative *T
he light sensor for auto matic driving lights is malfunctioning. #
Consult a qualified specialist workshop. Display messages and
warning/indicator lamps 439