2018 MERCEDES-BENZ C-CLASS SEDAN maintenance

Overview of climate control systems
General notes
Observe the settings recommended on the fol-
lowing pages. The windows could otherwise fog
up.
To prevent the windows from fogging up:
Rswitch off climate control only briefly
Rswitch on air-recirculation mode only briefly
Rswitch on the cooling with air dehumidifica-
tion function
Ractivate the "Windshield defrosting" function
briefly, if required
Climate control regulates the temperature and
air humidity in the vehicle interior. The interior
filter cleans the air, thus improving the interior
climate.
The "Cooling with air dehumidification" function
is only available when the engine is running.
Optimum climate control is only achieved with
the side windows and roof closed.
If you start the engine using your smartphone,
the last selected climate control setting is reac-
tivated (
Ypage 139).
The residual heat function can only be activated
or deactivated with the ignition switched off
(
Ypage 131). The integrated filter filters out most particles of
dust and soot and completely filters out pollen.
It also reduces gaseous pollutants and odors. A
clogged filter reduces the amount of air suppliedto the vehicle interior. For this reason, you
should always observe the interval for replacing
the filter, which is specified in the Maintenance
Booklet. As it depends on environmental condi-
tions, e.g. heavy air pollution, the interval may
be shorter than stated in the Maintenance Book-
let.
iVentilate the vehicle for a brief period during
warm weather, e.g. using the convenience
opening feature (
Ypage 92). This will speed
up the cooling process and the desired inte-
rior temperature will be reached more
quickly.
iIt is possible that the blower may be activa-
ted automatically 60 minutes after the Smart-
Key has been removed depending on various
factors, e.g. the outside temperature. The
vehicle is then ventilated for 30 minutes to dry
the automatic climate control.
iHybrid vehicles: be sure to observe the
notes in the supplement. Otherwise, you may
not recognize dangers.
Control panel for dual-zone automatic climate control
Example: control panel for dual-zone automatic climate control
:
Sets the temperature, left (Ypage 128)
;Sets the air distribution (Ypage 128)
124Overview of climate control systems
Climate control

The Start/Stop button can be used to start the
vehicle manually without inserting the SmartKey
into the ignition lock. The Start/Stop button
must be inserted in the ignition lock and the
SmartKey must be in the vehicle. This mode for
starting the engine operates independently of
the ECO start/stop automatic engine start func-
tion.
You can start the engine if a valid SmartKey is inthe vehicle. Switch off the engine and always
take the SmartKey with you when leaving the
vehicle, even if you only leave it for a short time.
Pay attention to the important safety notes.
XDepress the brake pedal and keep it
depressed.
XPress the Start/Stop button once
(Ypage 137).
Vehicles with a gasoline engine: the engine
starts.
Vehicles with a diesel engine: preglow is
activated and the engine starts.
Starting procedure via smartphone
Observe the important safety notes on starting
the engine (Ypage 138).
You can also start your engine via your smart-
phone from outside the vehicle. In this case, the
previously selected climate control setting is
activated. In this way you can cool or heat the
interior of the vehicle before starting the jour-
ney.
Only start the engine via your smartphone if it is
safe to start and run the engine where your vehi-
cle is parked.
Observe the legal stipulations in the area where your vehicle is parked. Engine start via smart-
phone may be limited to certain countries or
regions.
You can execute a maximum of two consecutive
starting attempts via your smartphone. If you
press the start/stop button or insert the Smart-
Key into the ignition lock, you can carry out two
more starting attempts with your smartphone.
The engine runs for ten minutes when starting
with the smartphone.
Once you have started the engine, you can
switch the engine off via your smartphone at any
time. You can only start the engine via your smart-
phone if:
Rthe SmartKey is in the ignition lock
Rpark position
jis selected
Rthe accelerator pedal is not depressed
Rthe anti-theft alarm system is not activated
Rthe panic alarm is not activated
Rthe hazard warning lamps are switched off
Rthe hood is closed
Rthe doors are closed and locked
Rthe windows and sliding sunroof are closed
Also make sure that:
Rthe fuel tank is sufficiently filled
Rthe starter battery has been sufficiently
charged
GWARNING
Limbs could be crushed or trapped if the
engine is started unintentionally during ser-
vice or maintenance work. There is a risk of
injury.
Always secure the engine against uninten-
tional starting before carrying out mainte-
nance or repair work.
Make sure that the engine cannot be started via
your smartphone before carrying out mainte-
nance or repairs. You can prevent an engine
start via your smartphone, for example, if you:
Rswitch on the hazard warning lamps
Rdo not lock the doors
Ropen a side window
Ropen the sliding sunroof
Pulling away
General notes
GWARNING
If the engine speed is above the idling speed
and you engage transmission position Dor R,
the vehicle could pull away suddenly. There is
a risk of an accident.
When engaging transmission position Dor R,
always firmly depress the brake pedal and do not simultaneously accelerate.
Driving139
Driving and parking
Z

Problems with fuel and the fuel tank
ProblemPossible causes/consequences andMSolutions
Fuel is leaking from the
vehicle.GWARNING
The fuel line or the fuel tank is faulty.
Risk of explosion or fire.
XApply the electric parking brake.
XSwitch off the engine.
XRemove the SmartKey from the ignition lock.
or, in vehicles with KEYLESS-GO start-function or KEYLESS ‑GO
XOpen the driver's door.
The vehicle electronics are now in positionu. This is the same as
the key having been removed.
XDo not restart the engine under any circumstances.
XConsult a qualified specialist workshop.
The engine does not
start.The fuel tank of a vehicle with a diesel engine has been run completely
dry.
XRefuel the vehicle with at least 5.3 US qt (5 l) of diesel.
XTurn the ignition on for approximately ten seconds (Ypage 136).
XStart the engine continuously for up to ten seconds until it runs
smoothly.
If the engine does not start:
XTurn the ignition on again for approximately ten seconds
(Ypage 136).
XStart the engine again continuously for up to ten seconds until it
runs smoothly.
If the engine does not start after three attempts:
XConsult a qualified specialist workshop.
The fuel filler flap cannot
be opened.The fuel filler flap is not unlocked.
XUnlock the vehicle (Ypage 78).
The SmartKey battery is discharged or nearly discharged.
XUnlock the vehicle using the mechanical key (Ypage 80).
The fuel filler flap is unlocked, but the opening mechanism is jammed.
XConsult a qualified specialist workshop.
DEF (BlueTEC vehicles only)
General notes
To function properly, BlueTEC exhaust gas after-
treatment must be operated with the reducing
agent DEF. On vehicles with a 2.4 gal (9.0
l)DEF tank, add-
ing DEF is not part of the maintenance work.
When the DEF supply drops to a minimum, the
Check Additive See Owner's Manualmes-
sage is shown in the multifunction display.
If you drive the vehicle at a speed greater than
10 mph (16 km/h) after topping up, the Check
158Refueling
Driving and parking

AdditiveSeeOwner'sManualmessage dis-
appears after approximately one minute.
When the DEF supply drops to a minimum, the
Remaining Starts: 16
message is shown in
the multifunction display.
The Remaining Starts: 16
message in the
multifunction display indicates how many more
times you can start the vehicle. If DEF is not
refilled, you will subsequently be unable to
start the engine.
If the 10 starts display message is shown and a
warning tone also sounds, then the DEF system
is malfunctioning. Have the DEF system
checked at a qualified specialist workshop.
XAdd at least 1.1 gal (4.0 l)of DEF.
XSwitch on the ignition for at least 60 seconds.
XStart the engine.
iHave the DEF tank refilled at a qualified spe-
cialist workshop.
Use the special DEF refill bottle when adding
DEF between maintenance intervals. Contact an
authorized Mercedes-Benz Center with any
questions or, if necessary, contact Roadside
Assistance (
Ypage 30).
If the outside temperature is below 12 ‡(Ò11 †)
it may be difficult to top up. If DEF is frozen and
there is an active warning indicator, it may not
be possible to add DEF. Park the vehicle in a
warmer place, e.g. in a garage, until DEF has
become fluid again. It will then be possible to
add DEF again. Alternatively, have the DEF tank
refilled at a qualified specialist workshop.
Further information about BlueTEC exhaust gas aftertreatment and DEF is available at any
authorized Mercedes-Benz Center.
Important safety notes
DEF is a water-soluble fluid for the exhaust gas
aftertreatment of diesel engines. It is:
Rnot poisonous
Rcolorless and odorless
Rnot flammable
When you open the DEF container, small
amounts of ammonia vapor may be released.
Ammonia vapors have a pungent odor and are
particularly irritating to the skin, to mucous
membranes and to the eyes. You may experi-
ence a burning sensation in your eyes, nose and
throat. Coughing and watering of the eyes are
possible. Do not inhale ammonia vapors. Fill the DEF tank
only in well-ventilated areas.
DEF must not come into contact with your skin,
eyes or clothing and must not be swallowed.
Keep DEF away from children.
If you or other persons come into contact with
DEF, observe the following:
RRinse DEF from your skin immediately with
soap and water.
RIf DEF comes into contact with your eyes,
immediately rinse them thoroughly with clean
water. Seek medical assistance without
delay.
RIf DEF has been swallowed, rinse your mouth
out immediately. Drink plenty of water. Seek
medical assistance without delay.
RChange out of clothing contaminated with
DEF immediately.
!Only use DEF in accordance with
ISO 22241. Do not mix any additives with
DEF, and do not dilute DEF with water. This
may destroy the BlueTEC exhaust gas after-
treatment system.
!The vehicle must be parked on level ground
to fill the DEF tank. The DEF tank can only be
filled as intended with the vehicle parked on a
level surface. This avoids false level readings. Filling the tank is not permitted if the vehicle
is not parked on a level surface. There is a
danger of overfil
ling, which could result in
damage to components of the BlueTEC
exhaust gas aftertreatment.
!Rinse surfaces that have come into contact
with DEF immediately with water or remove
DEF using a damp cloth and cold water. If the
DEF has already crystallized, use a sponge
and cold water to clean it. DEF residues crys-
tallize after time and contaminate the affec-
ted surfaces.
!DEF is not a fuel additive and must not be
added to the fuel tank. If DEF is added to the
fuel tank, this can lead to engine damage.
Have the DEF tank refilled at a qualified special-
ist workshop. However, you can also refill the
DEF tank:
Rat a gas station with a DEF filling pump
Rwith DEF refill bottles
Rwith a DEF refill canister
When the pump nozzle switches off automati-
cally during filling at a filling pump, the DEF tank
Refueling159
Driving and parking
Z

handle:is depressed, the greater the brak-
ing force.
During braking:
Ra warning tone sounds
Rthe Please Release Parking Brakemes-
sage appears
Rthe red F(USA only) or !(Canada
only) indicator lamp in the instrument cluster
flashes
When the vehicle has been braked to a stand-
still, the electric parking brake is engaged.
Parking the vehicle for a long period
If you leave the vehicle parked for longer than
four weeks, the battery may be damaged by
exhaustive discharging.
If you leave the vehicle parked for longer than six
weeks, the vehicle may suffer damage as a
result of lack of use.
XVisit a qualified specialist workshop and seek
advice.
iYou can obtain information about trickle
chargers from a qualified specialist work-
shop.
Hybrid vehicles: be sure to observe the notes
in the supplement. Otherwise, you may not rec-
ognize dangers.
Driving tips
General driving tips
Important safety notes
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 you operate mobile communication equip-
ment when driving, you may be distracted
from the traffic situation. You could also lose
control of the vehicle. There is a risk of an
accident.
Only operate this equipment when the vehicle
is stationary.
Observe the legal requirements for the country
in which you are driving. Some jurisdictions pro-
hibit the driver from using a mobile phone while driving a vehicle.
If you make a call while driving, always use
hands-free mode. Only operate the telephone
when the traffic situation permits. If you are
unsure, pull over to a safe location and stop
before operating the telephone.
Bear in mind that at a speed of only 30 mph
(approximately 50 km/h), the vehicle covers a
distance of 44 ft (approximately 14 m)per sec-
ond.
Drive sensibly – save fuel
Observe the following tips to save fuel:
XThe tires should always be inflated to the rec-
ommended tire pressure.
XRemove unnecessary loads.
XRemove roof racks when they are not needed.
XWarm up the engine at low engine speeds.
XAvoid frequent acceleration or braking.
XHave all maintenance work carried out as
indicated by the service intervals in the Main-
tenance Booklet or by the service interval dis-
play.
Fuel consumption also increases when driving in cold weather, in stop-start traffic and in hilly ter-
rain.
Drinking and driving
GWARNING
Drinking and driving and/or taking drugs and driving are very dangerous combinations.
Even a small amount of alcohol or drugs can
affect your reflexes, perceptions and judg-
ment.
164Driving tips
Driving and parking

The possibility of a serious or even fatal acci-dent is greatly increased when you drink or
take drugs and drive.
Do not drink or take drugs and drive or allow
anyone to drive who has been drinking or tak-
ing drugs.
Emission control
GWARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Inhaling
these exhaust gases leads to poisoning. There
is a risk of fatal injury. Therefore never leave
the engine running in enclosed spaces with-
out sufficient ventilation.
Certain engine systems are designed to keep
the level of poisonous components in exhaust
fumes within legal limits.
These systems only work at peak efficiency if
they are serviced exactly in accordance with the
manufacturer's specifications. Always have
work on the engine carried out at a qualified
specialist workshop. Mercedes-Benz recom-
mends that you use an authorized Mercedes-
Benz Center for this purpose. In particular, work
relevant to safety or on safety-related systems
must be carried out at a qualified specialist
workshop.
The engine settings must not be changed under any circumstances. Furthermore, all specific
service work must be carried out at regular
intervals and in accordance with the Mercedes-
Benz service requirements. Details can be found in the Maintenance Booklet.
ECO display
The ECO display shows you how economical
your driving style is. The ECO display assists you
in achieving the most economical driving style
for the selected settings and prevailing condi-
tions. Your driving style can significantly influ-
ence the vehicle's consumption.
:Acceleration
;Coasting
=Constant
?Additional range achieved
Range ?is shown under Bonus
fr.Startand
represents the additional range achieved since
the beginning of the journey as a result of an
adapted driving style.
If the fuel level has dropped into the reserve
range, the Reserve Fuel
display message is
shown instead of range ?in the multifunction
display. The 8warning lamp in the instru-
ment cluster also lights up (
Ypage 265).
Driving tips165
Driving and parking
Z

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 66) and Active Brake Assist with cross-
traffic function (Ypage 73).
Driving tips167
Driving and parking
Z

Engine compartment
Hood
Important safety notes
GWARNING
If the hood is unlatched, it may open up when the vehicle is in motion and block your view.
There is a risk of an accident.
Never unlatch the hood while driving. Before
every trip, ensure that the hood is locked.
GWARNING
When opening and closing the hood, it may
suddenly fall into the closed position. There is a risk of injury to persons within range of
movement of the hood.
Open and close the hood only when no one is
within its range of movement.
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.
GWARNING
The engine compartment contains moving
components. Certain components, such as
the radiator fan, may continue to run or start
again suddenly when the ignition is off. There is a risk of injury.
If you need to do any work inside the engine
compartment:
Rswitch off the ignition
Rnever reach into the area where there is a
risk of danger from moving components,
such as the fan rotation area
Rremove jewelry and watches
Rkeep items of clothing and hair, for exam-
ple, away from moving parts
Hybrid vehicles: be sure to observe the notes
in the supplementary instructions. Otherwise,
you may not recognize dangers.
Opening the hood
GWARNING
Certain components in the engine compart-
ment, such as the engine, radiator and parts
of the exhaust system, can become very hot.
Working in the engine compartment poses a
risk of injury.
Where possible, let the engine cool down and touch only the components described in the
following.
GWARNING
When the hood is open and the windshield
wipers are set in motion, you can be injured by
the wiper linkage. There is a risk of injury.
Always switch off the windshield wipers and
the ignition before opening the hood.
!Make sure that the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield wip-
ers or the hood.
XMake sure that the windshield wipers are
turned off.
XPull release lever :on the hood.
The hood is released.
Engine compartment303
Maintenance and care
Z