engine overheat MERCEDES-BENZ C-CLASS COUPE 2021 Owners Manual

&
WARNING Risk of skidding and of an
accident due toshifting down on slippery
ro ad sur faces
If yo u shift down on slippery road sur faces to
inc rease the engine braking ef fect, the drive
wheels may lose traction. #
Do not shift down on slippery road sur‐
fa ces toinc rease the engine braking
ef fect. &
DANG ER Risk of fata l injury due topoi‐
sonous exhaust gases
If th eta ilpipe is bloc ked or suf ficient ventila‐
tion is not possible, poisonous exhaust gases
such as carbon monoxide may enter theve hi‐
cle. This is the case when theve hicle
becomes stuck in sn ow,fo rex ample. #
Keep theta ilpipe and the area around
th eve hicle free from snow when the
engine or thest ationary heater are run‐
ning. #
Open a window on the side of theve hi‐
cle facing away from the wind toensure
an adequate supply of fresh air. &
WARNING Risk of accident due tothe
brake sy stem overheating
If yo u lea veyour foot on the brake pedal
when driving, the brake sy stem may over‐
heat.
This increases the braking dis tance and the
brake sy stem may evenfa il. #
Never use the brake pedal as a foot re st. #
Do not depress the brake pedal and the
accelerator pedal at the same time
while driving. *
NO
TEEngine dama gedue toexcessively
high engine speeds The engine will be damaged if
you drive with
th e engine in theov errevving range. #
Do not drive wi th the engine in theove r‐
re vving range. *
NO
TECausing wearto the brake linings
by permanently depressing the brake
pedal #
Do not permanently depress the brake
pedal while driving. #
Touse braking ef fect of the engine,
shift toa lo werge ar in good time. *
NO
TEDama getothe driv etra in and
engine when pulling away #
Do not warm upthe engine while the
ve hicle is stationar y.Pull away immedi‐
atel y. #
Avoid high engine speeds and driving at
full thro ttle until the engine has reached
its operating temp erature. *
NO
TEDama getothe catalytic con verter
due tonon-combu sted fuel The engine is not
running smo othly and is
misfiring. 15 0
Driving and pa rking

#
Toavo id creating ano ther electros tatic
ch arge , do not getinto theve hicle again
during there fuelling process. &
WARNING Risk offire from fuel mixture
Ve hicles with a diesel engine:
If yo u mix diesel fuel with petrol, theflash
point of the fuel mixture is lo werth an that of
pure diesel fuel.
While the engine is running, component
pa rts in theex haust sy stem may overheat
without warning. #
Neverre fuel using petrol. #
Never mix petrol with diesel fuel. *
NO
TEDama gecaused bythe wrong fuel Ve
hicles with a petrol engine:
Even small amounts of the wrong fuel could
re sult in damage tothe fuel sy stem, the
engine and the emission control sy stem. #
Only refuel using unleaded, sulphu r-free
petrol that con form sto European
EN 228, or an equi valent specification.
Fu el of this specification may con tain up to
10 %ethanol. Your vehicle is suitable for use
with E10 fuel.
Ne verre fuel with one of thefo llowing fuels:
R diesel
R regular petrol with an octane number
lo we rth an 91 RON
R petrol with more than 10%ethanol byvol‐
ume, e.g. E15, E20, E85, E100
R petrol with more than 3% me thanol by
vo lume, e.g. M15, M30
R petrol with additives con taining me tal
If yo u ha veacciden tally refuelled with the
wrong fuel: #
do not swit ch the ignition on. #
Consult a qualified specialist workshop. *
NO
TEDama gecaused bythe wrong fuel Ve
hicles with a diesel engine:
Even small amounts of the wrong fuel could
re sult in damage tothe fuel sy stem, the
engine and the emission control sy stem. #
Only refuel using sulphu r-free diesel
fuel that con form sto European stand‐
ard EN 590, or an equivalent specifica‐
tion.
In countries without sulphur-f ree diesel
fuel, refuel using only lo w-sulphur diesel
fuel with a sulphur content less than
50 ppm. #
Vehicles without diesel particulate
fi lter: refuel using only diesel fuel with
a sulphur content less than 500 ppm.
Ne verre fuel using any of thefo llowing fuels:
R petrol
R marine diesel
R heating oil
R pure bio-diesel fuel or vege table oil Driving and parking
16 3

R
Ifyo u unfas tenyo ur seat belt and open the
driver's door (e.g. tochange drivers or take a
break).
Setting ATTENTION ASSI ST
Multimedia sy stem:
4 Vehicle 5
k Assistance
5 ATTENTION ASSIST
Setting options #
Select Standard, SensitiveorOff.
Suggesting a rest area #
Select Suggest rest area . #
Activate Oor deacti vate the function ª.
If AT TENTION ASSIST de tects fatigue or
increasing la ckof attention, it suggests a
re st area in the vicinit y. #
Select a sugges tedre st area: you are gui‐
ded tothe selected rest area. Cruise cont
rol and limiter Fu
nction of cruise control
Cruise cont rolre gulates the speed totheva lue
selec tedby the driver.
If yo u accelerate toove rtake, forex ample, the
st ored speed is not dele ted. If youre mo veyour
fo ot from the accelerator pedal af terove rtaking,
cruise control will resume speed regulation back
to thestored speed.
Yo u can store any speed abo ve20 km/h up to
th e maximum design speed or up tothe set win‐
te r tyre limit.
Obser vethe no tes on driving sy stems and your
re sponsibility; you may otherwise failto recog‐
nise dangers (/ page 175).
Me rcedes‑AMG vehicles: cruise control is avail‐
able up toa maximum speed of 250 km/h.
Displ ays on the multifunction display
R h (gre y): cruise cont rol is selec ted but
not yet acti vated.
R h (green): cruise control is active. A
stored speed appears along with theh dis‐
pla y.
% The segments extending from the cur rent
st ored speed tothe end of the scale, or to
th e set winter tyre limit, light up in the
speedome ter.
Sy stem limits
Cruise control may be unable tomaintain the
st ored speed on uphill gradients. The stored
speed is resumed when the gradient evens out.
Change into a lo werge ar in good time on long
and steep downhill gradients. Take particular
no te ofthis when driving a laden vehicle. By
doing so, you will make use of the engine's brak‐
ing ef fect. This relie vesth e load on the brake
sy stem and pr events the brakes from overheat‐
ing and wearing tooqu ickl y.
Do not use cruise control in thefo llowing situa‐
tions:
R In traf fic situations whi chrequ ire frequent
ch anges of speed, e.g. in heavy traf fic, on
winding roads. Driving and parking
18 3

&
WARNING Risk of an accident due to
va pour poc kets form ing in the brake sys‐
tem
The brake fluid constantly absorbs moisture
from the air. This lo wersthe boiling point of
th e brake fluid. If the boiling point is too lo w,
va pour poc kets may form inthe brake sys‐
te m when the brakes are applied hard.
This impairs the braking ef fect. #
Have the brake fluid rene we d at the
specified inter vals. Ha
ve the brake fluid regularly replaced at a
qu alified specialist workshop.
Only use a brake fluid appr ovedby Mercedes-
Benz according toMB-F reigabe or MB-Appr oval
33 1.0. Coolant
Note
s on coolant
Obser vethe no tes on operating fluids
(/ page 420). &
WARNING Risk offire ‑ and inju ryfrom
antifreeze
If antifreeze comes into contact with hot
component parts in the engine compart‐
ment, it may ignite. #
Allow the engine tocool down before
yo uto p up the antif reeze. #
Make sure that no antifreeze spills out
next tothefiller opening. #
Thoroughly clean the antif reeze from
component parts before starting the
ve hicle. *
NO
TEDama gecaused byincor rect cool‐
ant #
Only use coolant that has been pre‐
mixed with therequ ired antifreeze pro‐
te ction. Information on coolant is
available at thefo l‐
lowing locations:
R inthe Mercedes-Benz Specification for
Operating Fluids 310.1
- at https://be vo.mercedes-benz.com
- inthe Mercedes-Benz BeVo app
R at a qualified specialist workshop *
NO
TEOverheating at high outside tem‐
peratures If an inapp
ropriate coolant is used, the
engine cooling sy stem is not suf ficiently pro‐
te cted against overheating and cor rosion at
high outside temp eratures. #
Alw ays use coolant appr ovedby
Mercedes-Benz. #
Obser vethe instructions in the
Mercedes-Benz Specifications for Oper‐
ating Fluids 310.1. Ha
ve the coolant regularly replaced at a qualified
specialist workshop. 428
Tech nical da ta

Display messages
Possible causes/consequences and M
MSolutions
+ Top up coolant See Own-
er’s Manual *T
he coolant le vel is too lo w.
* NO
TEEngine dama gedue toinsuf ficient coolant #
Avoid long journe yswith insuf ficient coolant. #
Add coolant (/ page 368). #
Have the engine cooling sy stem checked at a qualified specialist workshop.
ÿ
Coolant Stop vehicle
Switch engine off *T
he coolant is too hot. #
Stop theve hicle immediately in accordance with the traf fic conditions and switch off the engine. &
WARNING Risk of bu rns when opening the bonn et
If yo u open the bonn etwhen the engine has overheated or when there is a fire inthe engine compartment, the
fo llowing situations may occur:
R You could come into contact with hot gases.
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 compartment, keep the bonn etclosed and call thefire service. #
Wait until the engine has cooled down. 448
Displaymessa ges and warning/indicator lamps

Display messages
Possible causes/consequences and M
MSolutions #
Consult a qualified specialist workshop.
Stop vehicle Leave engine
running Wait Transmission
cooling *T
he transmission is overheating. Pulling away may be temp orarily impaired or not possible. #
Stop theve hicle immediately in accordance with the traf fic conditions. Do not continue driving. #
Lea vethe engine running. #
Wait until the display message disappears before pulling away.
Auxiliary battery malfunc-
tion (whitedisplay mes‐
sage) *T
he auxiliary batteryforth e transmission is no longer being charge d. #
Consult a qualified specialist workshop. #
Untilthen, alw ays select park position jmanually before you swit choff the engine. #
Before leaving theve hicle, apply the electric parking brake.
Auxiliary battery malfunc-
tion (red display message) *T
he auxiliary batteryforth e transmission is no longer being charge d. #
Consult a qualified specialist workshop. #
Untilthen, alw ays select park position jmanually before you swit choff the engine. #
Before leaving theve hicle, apply the electric parking brake. 452
Display messages and warning/indicator lamps

Wa
rning/indicator lamp
Possible causes/consequences and M
MSolutions
R The coolant pump is faulty
If th ere is an additional warning tone, the coolant temp erature has exceeded 120°C. &
WARNING Risk of bu rns when opening the bonn et
If yo u open the bonn etwhen the engine has overheated or when there is a fire inthe engine compartment, the
fo llowing situations may occur:
R You could come into contact with hot gases.
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 compartment, keep the bonn etclosed and call thefire service. #
Stop theve hicle immediately in accordance with the traf fic conditions and switch off the engine. Do not continue
driving. #
Notethe messages on the multifunction displa y.
If th e coolant temp erature display is at the lo wer end of thete mp erature scale: #
Consult a qualified specialist workshop.
If th e coolant temp erature display is at the upper end of thete mp erature scale: #
Exit theve hicle and keep a safe dis tance from it until the engine has cooled down. #
Check the coolant le vel (/ page 368). 492
Display messages and warning/indicator lamps