engine overheat MERCEDES-BENZ C-CLASS CABRIOLET 2018 Owner's Manual

GWARNING
If you switch off the ignition while driving,
safety-relevant functions are only available
with limitations, or not at all. This could affect, for example, the power steering and the brake
boosting effect. You will require considerably
more effort to steer and brake. There is a risk
of an accident.
Do not switch off the ignition while driving.
GWARNING
If the parking brake has not been fully
released when driving, the parking brake can:
Roverheat and cause a fire
Rlose its hold function.
There is a risk of fire and an accident. Release
the parking brake fully before driving off.
!Do not warm up the engine with the vehicle
stationary. Drive off immediately. Avoid high
engine speeds and driving at full throttle until
the engine has reached its operating temper-
ature.
Only shift the automatic transmission to the
desired drive position when the vehicle is sta-
tionary.
Where possible, avoid spinning the drive
wheels when pulling away on slippery roads.
You could otherwise damage the drive train.
!Mercedes-AMG vehicles: at low engine oil
temperatures below 68 ‡ (+20 †), the max-
imum engine speed is restricted in order to
protect the engine. To protect the engine and
maintain smooth engine operation, avoid driv-
ing at full throttle when the engine is cold.
Key positions
SmartKey
gTo remove the SmartKey
1Power supply for some consumers, such as
the windshield wipers
2Ignition (power supply for all consumers)
and drive position
3To start the engine
iThe SmartKey can be turned in the ignition
lock even if it is not the correct SmartKey for
the vehicle. The ignition is not switched on.
The engine cannot be started.
Start/Stop button
General notes
When you insert the Start/Stop button into the
ignition lock, the system needs approximately
two seconds recognition time. You can then use
the Start/Stop button.
Pressing the Start/Stop button several times in
succession corresponds to the different Smart-
Key positions in the ignition lock. This is only the
case if you are not depressing the brake pedal.
If you depress the brake pedal and press the
Start/Stop button, the engine starts immedi-
ately.
A check which periodically establishes a radio
connection between the vehicle and the Smart-
Key determines whether a valid SmartKey is in
the vehicle. This occurs, for example, when
starting the engine.
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This helps you to avoid overheating the
brakes and wearing them out excessively.
When you take advantage of engine braking, a
drive wheel may not turn for some time, e.g.
on a slippery road surface. This could cause
damage to the drive train. This type of damage is not covered by the Mercedes-Benz war-
ranty.
Heavy and light loads
GWARNING
If you rest your foot on the brake pedal while
driving, the braking system can overheat. This increases the stopping distance and can even
cause the braking system to fail. There is a
risk of an accident.
Never use the brake pedal as a footrest. Never
depress the brake pedal and the accelerator
pedal at the same time.
!Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
If the brakes have been subjected to a heavy
load, do not stop the vehicle immediately. Drive
on for a short while. This allows the airflow to
cool the brakes more quickly.
Wet roads
If you have driven for a long time in heavy rain
without braking, there may be a delayed reac-
tion from the brakes when braking for the first
time. This may also occur after the vehicle has
been washed or driven through deep water.
You have to depress the brake pedal more
firmly. Maintain a greater distance from the
vehicle in front.
After driving on a wet road or having the vehicle
washed, brake firmly while paying attention to
the traffic conditions. This will warm up the
brake discs, thereby drying them more quickly
and protecting them against corrosion.
Limited braking performance on salt-
treated roads
If you drive on salted roads, a layer of salt resi-
due may form on the brake discs and brake
pads. This can result in a significantly longer
braking distance.
RIn order to prevent any salt build-up, apply the
brakes occasionally while paying attention to
the traffic conditions.
RCarefully depress the brake pedal and the
beginning and end of a journey.
RMaintain a greater distance to the vehicle
ahead.
Servicing the brakes
!The brake fluid level may be too low, if:
Rif the red brake warning lamp lights up in
the instrument cluster and
Ryou hear a warning tone while the engine is
running
Observe additional warning messages in the
multifunction display.
The brake fluid level may be too low due to
brake pad wear or leaking brake lines.
Have the brake system checked immediately.
Consult a qualified specialist workshop to
arrange this.
!Vehicles with 4MATIC: function or per-
formance tests may only be carried out on a 2-
axle dynamometer. If you wish to operate the
vehicle on such a dynamometer, please con-
sult a qualified specialist workshop in
advance. You could otherwise damage the
drive train or the brake system.
!Vehicles with 4MATIC: the ESP®system
operates automatically. If the electric parking
brake is tested on a brake dynamometer, the
engine and ignition must be switched off: turn
the SmartKey in the ignition lock to position
u or1 or press the Start/Stop button
repeatedly in accordance with the given
SmartKey positions.
Braking triggered automatically by ESP
®may
cause severe damage to the brake system.
All checks and maintenance work on the brake
system must be carried out at a qualified spe-
cialist workshop.
Have brake pads installed and brake fluid
replaced at a qualified specialist workshop.
If the brake system has only been subject to
moderate loads, you should test the functional-
ity of your brakes at regular intervals.
Information on BAS (Brake Assist System)
(
Ypage 65) and Active Brake Assist with cross-
traffic function (Ypage 71).
Driving tips149
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Winter driving
GWARNING
If you shift down on a slippery road surface in an attempt to increase the engine's braking
effect, the drive wheels could lose their grip.
There is an increased danger of skidding and
accidents.
Do not shift down for additional engine brak-
ing on a slippery road surface.
GDANGER
If the exhaust pipe is blocked or adequate
ventilation is not possible, poisonous gases
such as carbon monoxide (CO) may enter the vehicle. This is the case, e.g. if the vehicle
becomes trapped in snow. There is a risk of
fatal injury.
If you leave the engine or the auxiliary heating
running, make sure the exhaust pipe and area
around the vehicle are clear of snow. To
ensure an adequate supply of fresh air, open a
window on the side of the vehicle that is not
facing into the wind.
Have your vehicle winter-proofed at a qualified
specialist workshop at the onset of winter.
Drive particularly carefully on slippery road sur-
faces. Avoid sudden acceleration, steering and
braking maneuvers. Do not use cruise control or
Distance Pilot DISTRONIC.
If the vehicle threatens to skid or cannot be
stopped when moving at low speed:
XShift the transmission to position i.
The outside temperature indicator is not
designed to serve as an ice-warning device and is therefore unsuitable for that purpose.
Changes in the outside temperature are dis-
played after a short delay.
Indicated temperatures just above the freezing
point do not guarantee that the road surface is
free of ice. The road may still be icy, especially in
wooded areas or on bridges. The vehicle could
skid if you fail to adapt your driving style. Always
adapt your driving style and drive at a speed to
suit the prevailing weather conditions.
You should pay special attention to road condi-
tions when temperatures are around freezing
point. For more information on driving with snow
chains, see (
Ypage 315).
For more information on driving with summer
tires, see (
Ypage 314).
Observe the notes i n the "Winter operation" sec-
tion (
Ypage 314).
Driving systems
Mercedes-Benz Intelligent Drive
Mercedes-Benz Intelligent Drive stands for inno-
vative driver assistance and safety systems
which enhance comfort and support the driver in
critical situations. With these intelligent co-ordi- nated systems Mercedes-Benz has set a mile-
stone on the path towards autonomous driving.
Mercedes-Benz Intelligent Drive embraces all
elements of active and passive safety in one well thought out system – for the safety of the vehi-
cle occupants and that of other road users.
Further information on driving safety systems
(
Ypage 64).
Cruise control
General notes
Cruise control maintains a constant road speed
for you. It brakes automatically in order to avoid
exceeding the set speed. Change into a lower
gear in good time on long and steep downhill
gradients. This is especially important if the
vehicle is laden. By doing so, you will make use
of the braking effect of the engine. This relieves
the load on the brake system and prevents the
brakes from overheating and wearing too
quickly.
Use cruise control only if road and traffic con-
ditions make it appropriate to maintain a steady
speed for a prolonged period. You can store any
road speed above 20 mph (30 km/h).
Important safety notes
Cruise control can neither reduce the risk of an
accident if you fail to adapt your driving style nor
override the laws of physics. Cruise control can-
not take into account the road, traffic and
weather conditions. Cruise control is only an
aid. You are responsible for maintaining a safe
distance to the vehicle in front, for vehicle
Driving systems151
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the cruise control lever up:or down ;to
the pressure point.
Every time the cruise control lever is pressed
up : or down ;the last speed stored is
increased or reduced.
XTo adjust the set speed in 5 mph incre-
ments (10 km/h increments): briefly press
the cruise control lever up :or down ;
beyond the pressure point.
Every time the cruise control lever is pressed
up : or down ;the last speed stored is
increased or reduced.
iCruise control is not deactivated if you
depress the accelerator pedal. If you acceler-
ate to overtake, cruise control adjusts the
vehicle's speed to the last speed stored after
you have finished overtaking.
Deactivating cruise control
There are several ways to deactivate cruise con-
trol:
XBriefly press the cruise control lever forward
=.
or
XBrake.
Cruise control is automatically deactivated if:
Ryou engage the electric parking brake
Ryou are driving at less than 20 mph (30 km/h)
RESP®intervenes or you deactivate ESP®
Ryou shift the transmission to position i
while driving
If cruise control is deactivated, a warning tone
sounds. You will see the Cruise Control Off
message in the multifunction display for approx-
imately five seconds. The message on the mul-
tifunction display disappears and the segments
on the speedometer go out.
iWhen you switch off the engine, the last
speed stored is cleared.
Distance Pilot DISTRONIC
General notes
Distance Pilot DISTRONIC regulates the speed
and automatically helps you maintain the dis-
tance to the vehicle detected in front. Vehicles
are detected with the aid of the radar sensor
system. Distance Pilot DISTRONIC brakes auto-
matically so that the set speed is not exceeded. Change into a lower gear in good time on long
and steep downhill gradients. This is especially
important if the vehicle is laden. By doing so, you
will make use of the braking effect of the engine.
This relieves the load on the brake system and
prevents the brakes from overheating and wear-
ing too quickly.
If Distance Pilot DISTRONIC detects that there is a risk of a collision, you will be warned visually
and acoustically. Without your intervention, Dis-
tance Pilot DISTRONIC cannot prevent a colli-
sion. An intermittent warning tone will then
sound and the distance warning lamp will light
up in the instrument cluster. Brake immediately in order to increase the distance to the vehicle in
front or take evasive action provided it is safe to
do so.
Distance Pilot DISTRONIC operates in the range
between 0 mph (0 km/h) and 120 mph
(200 km/h).
Do not use Distance Pilot DISTRONIC whi
le driv-
ing on roads with steep gradients.
Since Distance Pilot DISTRONIC transmits radar
waves, it can resemble the radar detectors of
the responsible authorities. You can refer to the
relevant chapter in the Operator's Manual if
questions are asked about this.
iUSA only: This device has been approved by
the FCC as a "Vehicular Radar System". The
radar sensor is intended for use in an auto-
motive radar system only. Removal, tamper-
ing, or altering of the device will void any war-
ranties, and is not permitted by the FCC. Do
not tamper with, alter, or use in any non-
approved way.
Any unauthorized modification to this device
could void the user's authority to operate the equipment.
iCanada only: This device complies with
RSS-210 of Industry Canada. Operation is
subject to the following two conditions:
1. This device may not cause interference,
and
2. This device must accept any interference
received, including interference that may
cause undesired operation of the device.
Removal, tampering, or altering of the device
will void any warranties, and is not permitted.
Do not tamper with, alter, or use in any no
n-
approved way.
Driving system s153
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Tachometer
!
Do not drive in the overrevving range, as this
could damage the engine.
The red band in the tachometer indicates the
engine's overrevving range.
The fuel supply is interrupted to protect the
engine when the red band is reached.
Outside temperature display
You should pay special attention to road condi-
tions when temperatures are around freezing
point.
Bear in mind that the outside temperature dis-
play indicates the temperature measured and
does not record the road temperature.
The outside temperature display is in the multi-
function display (
Ypage 194).
Changes in the outside temperature are dis-
played after a short delay.
Coolant temperature gauge
GWARNING
Opening the hood when the engine is over-
heated or when there is a fire in the engine
compartment could expose you to hot gases
or other service products. There is a risk of
injury.
Let an overheated engine cool down before
opening the hood. If there is a fire in the
engine compartment, keep the hood closed
and contact the fire department.
!If the coolant temperature is too high, a dis-
play message is shown.
If the coolant temperature display is in the
area marked in red, do not continue driving.
Otherwise, the engine will be damaged.
The coolant temperature gauge is in the lower
section of the tachometer (
Ypage 36).
Under normal operating conditions and at the
correct coolant level, the display may rise to the
red mark.
Operating the on-board computer
:Multifunction display
;Right control panel
=Left control panel
XTo activate the on-board computer: switch
on the power supply.
You can control the multifunction display and
the settings in the on-board computer using the
buttons on the multifunction steering wheel.
Left control panel
òROpens a menu list
9
:Press briefly:
RScrolls in lists
RSelects a menu or function
RIn the RadioorMediamenu:
opens a track or station list and
selects a station, an audio track or
a video scene.
RIn the Telephonemenu: switches
to the phone book and selects a
name or a telephone number
9
:Press and hold:
RScrolls quickly through all lists
RIn the RadioorMediamenu:
selects a station, audio track or
video scene using rapid scrolling
RIn the Telephonemenu: starts
rapid scrolling if the phone book is
open
Displays an doperation193
On-boa rd computer and displays
Z

Engine
Display messagesPossible causes/consequences andMSolutions
+
CheckCoolantLevelSee Operator's Man‐ual
The coolant level is too low.
!Avoid making long journeys with too little coolant in the engine
cooling system. The engine will otherwise be damaged.
XAdd coolant, observing the warning notes before doing so
(Ypage 284).
If you have to add coolant frequently:
XContact a qualified specialist workshop and have the engine cooling
system checked.
?The fan motor is malfunctioning.
XIf the coolant temperature is below the red marking in the coolant
temperature gauge, drive to the nearest qualified specialist work-
shop.
XAvoid heavy loads on the engine as you do so, e.g. driving in moun-
tainous terrain and stop-and-go traffic.
?
Coolant Too HotStop Vehicle TurnEngine Off
The coolant is too hot.
A warning tone also sounds.
GWARNING
Do not drive when your engine is overheated. This can cause some
fluids which may have leaked into the engine compartment to catch
fire.
Steam from the overheated engine can also cause serious burns which
can occur just by opening the hood.
There is a risk of injury.
XPull over and stop the vehicle safely and switch off the engine, pay- ing attention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 143).
XWait until the engine has cooled down.
XMake sure that the air supply to the engine radiator is not blocked,
e.g. by snow, slush or ice.
XDo not start the engine again until the display message goes out and
the coolant temperature gauge is below the red marking. Other-
wise, the engine could be damaged.
XPay attention to the coolant temperature gauge.
If the temperature increases again:
XVisit a qualified specialist workshop immediately.
Under normal operating conditions and with the specified coolant
level, the coolant temperature gauge may rise to the red marking.
Display messages225
On-board computer and displays
Z

Display messagesPossible causes/consequences andMSolutions
#
See Operator'sMan ‐ual
The battery is no tbein gcharged.
A warning tone also sounds.
Possibl ecauses are:
Radefective alternato r
Ratorn poly-V-belt
Ramalfunction in th eelectronics
!Do no tcontinu edriving. The engin ecould otherwise overheat.
XPull ove rand stop th evehicl esafely and switch off th eengine, pay-
ing attention to roa dand traffic conditions.
XSecur eth evehicl eagainst rollin gaway (Ypage 143).
XConsult aqualified specialist workshop .
#
StopVehicl eSeeOperator' sManual
The battery is no longer bein gcharged and th econdition of charg eis
to olow.
A warning tone also sounds.
XPull ove rand stop th evehicl esafely and switch off th eengine, pay-
ing attention to roa dand traffic conditions.
XSecur eth evehicl eagainst rollin gaway (Ypage 143).
XObserv eth einstruction sin th e# See Operator' sManualdisplay message .
XConsultaqualified specialist workshop .
#
StopVehicl eLeaveEngine Runnin g
The battery condition of charg eis to olow.
XPull ove rand stop th evehicl esafely as soo nas possible, payin g
attention to roa dand traffic conditions. Do no tcontinu edrivin g
under any circumstances.
XLeav eth eengin erunning.
XWait until th edisplay message disappear sbefore pullin gaway.
#
Start Engine SeeOperator' sManual
The engin eis switched off and th econdition of charg eis to olow.
XSwitc hoff electrical consumer sthat you do no tneed, suc has th e
rear window defroste rand interior lighting .
XLeaveth eengin erunnin gfor afew minute sor drive alon gdistance.
The battery is bein gcharged.
226Display messages
On-board computer and displays

Display messagesPossible causes/consequences andMSolutions
TirePressure Moni‐tor Inoperative NoWheel Sensor s
The wheels mounte ddo no thav e a suitable tire pressur esensor .The
tire pressur emonitor is deactivated.
XMoun twheels wit hsuitable tire pressur esensors.
The tire pressur emonitor is activated automatically after drivin gfor
a few minutes.
Tir ePress.Monito rInoperativeThe tire pressur emonitor is faulty.
XVisit aqualified specialist workshop .
Tires OverheatedThe tire temperature monitoring function is no tavailable in all vehi-
cles.
At least on etire has overheated. Affecte dtires are shown in red .At
temperatures close to th elimi tvalue ,th etires are shown in yellow .
XDrive moreslowly.
Tires Overheate dDecrease SpeedThe tire temperature monitoring function is no tavailable in all vehi-
cles.
At least on etire has overheated.
GWARNIN G
Overheated tires can burst, particularly at high speeds .
XDrive moreslowly so that th etires cool down .
Vehicle
Display messagesPossible causes/consequences and MSolutions
Shiftto'P'or'N'to Start EngineYou haveattempte dto start th eengin ewit hth etransmission in posi-
tion korh.
XShift th etransmission to position jori .
Apply Brake toShift fro m'P'You hav eattempte dto shift th etransmission to position h,kori
without depressing th ebrak epedal .
XDepress th ebrak epedal .
ToDeselectPorN,Depres sBrake andStart Engine
Wit hth eengin eswitched off ,you hav eattempte dto shift th etrans -
mission out of position jori intoanother transmission position .
XDepress thebrak epedal .
XStart th eengine.
To Engage Trans‐miss. Position RFirst DepresstheBrake
You hav eattempte dto shift from position hto position k.
XDepress thebrak epedal .
XShift th etransmission to position k.
236Display messages
On-board computer and displays

Display messagesPossible causes/consequences andMSolutions
StopVehicl eLeaveEngineRunnin gWaitTransmission Cool‐ing
The transmission has overheated. Pullin gaway can be temporarily
impaire dor no tpossible.
XPull ove rand stop th evehicl esafely as soo nas possible, payin g
attention to roa dand traffic conditions. Do no tcontinu edrivin g
under any circumstances.
XLeav eth eengin erunning.
XWait until th edisplay message disappear sbefore pullin gaway.
NThe trunk lid is open .
XCloseth etrunk lid.
MThe hoo dis open . Awarning tone also sounds.
GWARNIN G
The open hoo dmay bloc kyour vie wwhen th evehicl eis in motion .
There is aris kof an accident.
XPull ove rand stop th evehicl esafely as soo nas possible, payin g
attention to roa dand traffic conditions.
XSecur eth evehicl eagainst rollin gaway (Ypage 143).
XCloseth ehood.
CAt least on edoor is open . Awarning tone also sounds.
XClos eall th edoors.
_
Front Lef tSea tBackrestNotLockedorFront Right Sea tBackrest Not Locked
The driver's or fron tpassenger's seat backrest is no tengaged. A
warning tone also sounds.
XPush th ebackrest bac kuntil it engages.
Ð
Power Steering Mal ‐function See Opera‐tor's Manual
The powersteering is malfunctioning .
A warning tone also sounds.
GWARNIN G
You will need to use mor eforce to steer .
There is aris kof an accident.
XChec kwhether you are able to apply th eextr aforce required.
If you ar eabl eto steer safely:
XDrive on carefully.
XVisit aqualified specialist workshop immediately.
If you ar eunable to steer safely:
XDo no tdrive on .
XConsult aqualified specialist workshop .
238Display messages
On-board computer and displays

Warning/
indicator
lampNSignal type
Possible causes/consequences and M
Solutions
?NThe red coolant warning lamp comes on while the engine is running.
The coolant level is too low.
If the coolant level is correct, the airflow to the engine radiator may be blocked or
the electric engine radiator fan may be defective.
The coolant is too hot and the engine is no longer being cooled sufficiently.
XObserve the additional display messages in the multifunction display.
XPull over and stop the vehicle safely and switch off the engine, paying attention
to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 143).
XLeave the vehicle and keep a safe distance from the vehicle until the engine has cooled down.
XCheck the coolant level and add coolant, observing the warning notes
(Ypage 284).
XIf you have to add coolant frequently, have the engine cooling system checked.
XMake sure that the air supply to the engine radiator is not blocked, e.g. by snow,
slush or ice.
XDo not start the engine again until the coolant temperature gauge is below the
red marking. Otherwise, the engine could be damaged.
XDrive to the nearest qualified specialist workshop.
XAvoid heavy loads on the engine as you do so, e.g. driving in mountainous terrain
and stop-and-go traffic.
?N The red coolant warning lamp comes on while the engine is running. A warning
tone also sounds.
The coolant temperature gauge has reached the red marking. The airflow to the
engine radiator may be blocked or the coolant level may be too low.
GWARNING
The engine is not being cooled sufficiently and may be damaged.
Do not drive when your engine is overheated. This can cause some fluids which
may have leaked into the engine compartment to catch fire.
Steam from the overheated engine can also cause serious burns which can occur
just by opening the hood.
There is a risk of injury.
XObserve the additional display messages in the multifunction display.
XPull over and stop the vehicle safely and switch off the engine, paying attention
to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 143).
XLeave the vehicle and keep a safe distance from the vehicle until the engine has
cooled down.
XCheck the coolant level and add coolant, observing the warning notes
(Ypage 284).
XIf you have to add coolant frequently, have the engine cooling system checked.
XMake sure that the air supply to the engine radiator is not blocked, e.g. by snow,
slush or ice.
Warning and indicator lamps in the instrument cluster249
On-board computer and displays
Z