2018 MERCEDES-BENZ C-CLASS SEDAN change key battery

KEYLESS-GOstart function
Gene ral notes
Bear in min dthat th eengin ecan be started by
any of th evehicl eoccupant sif there is aSmart -
Key in th evehicl e (
Ypage 138).
Changing the settings ofthe locking
system
You can chang eth esetting sof th elocking sys-
tem. This mean sthat only th edriver's door and
th efuel filler flap are unlocke dwhen th evehicl e
is unlocked. This is useful if you frequentl ytravel
alone.
XTo change th esetting: press and hold down
th e% and& buttons simultaneousl y
for approximately six seconds until th ebat -
tery chec klamp (
Ypage 81) flashes twice .
If th esetting of th elocking system is changed
within th esignal range of th evehicle, pressing
th e& or% button:
Rlocks or
Runlocks th evehicl e
The SmartKey no wfunction sas follows :
XTo unlock: press the% buttononce .
XTo unlock centrally: press the% button
twice .
XTo lock: press the& button.
XTo restor eth efactory settings: press and
hold th e% and& buttons simultane -
ousl yfor approximately six seconds until th e
battery chec klamp (
Ypage 81) flashes
twice .
The KEYLESS-GO function scan be changed as
follows :
XTo unlock th edriver's door :touch th einner
surfac eof th edoor handle on th edriver's
door .
XTo unlock centrally: touch theinner surfac e
of th edoor handle on th efront-passenger
door or there
ar door .
XTo lock centrally: touch theouter sensor
surfac eon on eof th edoor handles .
Mechanical key
Gene ral notes
If th evehicl ecan no longer be locke dor
unlocke dwit hth eSmartKey or KEYLESS-GO ,
use th emechanical key.
If you use th emechanical ke yto unloc kand
open th edriver's door ,th eanti-thef talarm sys-
te m will be triggered .Switc hoff th ealarm
(
Ypage 76) .
If you unloc kth evehicl eusin gth emechanical
key, th efuel filler flap will no tbe unlocke dauto -
matically.
XTo unlock th efuel filler flap: insert the
SmartKey int oth eignition lock.
Removing the mechanical key
XPush release catch :in th edirection of th e
arrow and at th esam etime remove mechan -
ical ke y; from th eSmartKey.
Further information on locking/unlocking th e
driver's door (
Ypage 85).
Inserting the mechanical key
XPush mechanical ke y; completely int oth e
SmartKey until it engage sand release
catch :is bac kin it sbasic position .
SmartKey battery
Import ant safety notes
GWARNIN G
Batterie scontain toxic and corrosiv esubstan -
ces. If batterie sare swallowed, it can result in
80SmartKey
Opening and closing

severe health problems. There is a risk of fatalinjury.
Keep batteries out of the reach of children. If
a battery is swallowed, seek medical attention immediately.
HEnvironmental note
Batteries contain dangerous
substances. It is against the
law to dispose of them with
the household rubbish. They
must be collected separatelyand recycled to protect the
environment.
Dispose of batteries in an
environmentally friendly
manner. Take discharged
batteries to a qualified spe-
cialist workshop or a special
collection point for used bat-
teries.
The SmartKey batteries contain perchlorate
material, which may require special handling
and regard for the environment. National guide-
lines must be observed during disposal. In Cal-
ifornia, see www.dtsc.ca.gov/
HazardousWaste/Perchlorate/index.cfm.
Mercedes-Benz recommends that you have the
batteries replaced at a qualified specialist work-
shop.
Checking the battery
XPress the &or% button.
The battery is working properly if battery
check lamp :lights up briefly. The battery is discharged if battery check
lamp
:does not light up briefly.
XChange the battery (Ypage 81).
If the SmartKey battery is checked within the
signal reception range of the vehicle, pressing
the & or% button:
Rlocks or
Runlocks the vehicle
iYou can get a battery at any qualified spe-
cialist workshop.
Replacing the battery
You require a CR 2025 3 V cell battery.
XTake the mechanical key out of the SmartKey
(Ypage 80).
XPress mechanical key ;into the SmartKey
opening in the direction of the arrow until bat-
tery compartment cover :opens. Do not
hold battery compartment cover :closed
while doing so.
XRemove battery compartment cover :.
SmartKey81
Opening and closing
Z

ProblemPossible causes/consequences andMSolutions
KEYLESS-GO is malfunctioning.
XLock/unlock the vehicle using the remote control function of the
SmartKey.
XHave the vehicle and SmartKey checked at a qualified specialist
workshop.
If the vehicle can also not be locked/unlocked using the remote con-
trol function:
XLock or unlock the vehicle using the mechanical key (Ypage 85).
XHave the vehicle and SmartKey checked at a qualified specialist
workshop.
The engine cannot be
started using the Smart-
Key.The on-board voltage is too low.
XSwitch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work:
XCheck the starter battery and charge it if necessary (Ypage 324).
or
XJump-start the vehicle (Ypage 325).
or
XConsult a qualified specialist workshop.
The engine cannot be
started using the Start/
Stop button. The Smart-
Key is in the vehicle.The vehicle is locked.
XUnlock the vehicle and try to start the vehicle again.
The SmartKey battery is discharged or nearly discharged.
XCheck the SmartKey battery (Ypage 81) and replace it if necessary
(Ypage 81).
If this does not work:
XStart your vehicle with the SmartKey in the ignition lock.
There is interference from a powerful source of radio waves.
XStart your vehicle with the SmartKey in the ignition lock.
You have lost a Smart-
Key.XHave the SmartKey deactivated at a qualified specialist workshop.
XReport the loss immediately to the vehicle insurers.
XIf necessary, have the locks changed as well.
You have lost the
mechanical key.XReport the loss immediately to the vehicle insurers.
XIf necessary, have the locks changed as well.
SmartKey83
Opening and closing
Z

Control panel in the grab handle (rear
compartment)
:Reading lamp
;pSwitches the reading lamp on/off
Interior lighting control
General notes
In order to prevent the vehicle's battery from
discharging, the interior lighting functions are
automatically deactivated after some time
except for when the SmartKey is in position 2
in the ignition lock.
The color and brightness of the ambient lighting
are set using the multimedia system (see Digital
Operator's Manual).
Automatic interior lighting control
XTo switch on or off: press the|button.
When the automatic interior lighting control is
activated, the button is flush with the over-
head control panel.
The interior lighting automatically switches on if
you:
Runlock the vehicle
Ropen a door
Rremove the SmartKey from the ignition lock
The interior lighting is switched on for a set time
when the SmartKey is removed from the ignition
lock. This delayed switch-off can be adjusted via the multimedia system (see Digital Operator's
Manual).
Replacing bulbs
Important safety notes
GWARNING
Bulbs, lamps and connectors can get very hot
when operating. If you change a bulb, you
could burn yourself on these components.
There is a risk of injury.
Allow these components to cool down before
changing a bulb.
Do not use a bulb if it has been dropped or if its glass tube has been scratched.
The bulb may explode if:
Ryou touch it
Rit is hot
Ryou drop it
Ryou scratch it
Use bulbs only in closed lamps that have been
designed for this purpose. Only install spare
bulbs of the same type and the specified volt-
age.
Marks on the glass tube reduce the service life
of the bulbs. Do not touch the glass tube with
your bare hands. If necessary, clean the glass
tube when cold with alcohol or spirit and rub it
off with a lint-free cloth.
Protect bulbs from moisture during operation.
Do not allow bulbs to come into contact with
liquids.
Replace only the bulbs listed (
Ypage 118).
Have the bulbs that you cannot change yourself
replaced at a qualified specialist workshop.
If you require assistance replacing bulbs, con-
sult a qualified specialist workshop.
If the new bulb still does not light up, consult a
qualified specialist workshop.
Headlamps and lights are an important aspect of
vehicle safety. You must therefore make sure
that these function correctly at all times. Have
the headlamp setting check ed r
egularly.
Vehicles with LED headlamps: the front and
rear light clusters of your vehicle are equipped
with LED bulbs. Do not replace the bulbs your-
self. Contact a qualified specialist workshop
which has the necessary specialist knowledge
and tools to carry out the work required.
Replacing bulbs117
Lights and windshield wipers
Z

Display messagesPossible causes/consequences andMSolutions
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 .
Phone No ServiceYour vehicleis outside th enetwork provider' stransmitter/receiver
range.
XWait until th emobile phone operational readiness symbol appear s
in th emultifunction display.
¥
Check Washer Fluid
The washer flui dlevel in th ewasher flui dreservoir has dropped belo w
th eminimum .
XAddwasher flui d (Ypage 307).
SmartKey
Display messagesPossible causes/consequences and MSolutions
Â
KeyDoesNotBelongto Vehicl e
You haveput th ewrong SmartKey in th eignition lock.
XUse th ecorrec tSmartKey.
Â
Tak eYou rKey fro mIgnition
The SmartKey is in th eignition lock.
A warning tone sounds
XRemove th eSmartKey.
Â
Obtain aNew Key
The SmartKey needs to be replaced.
XVisit aqualified specialist workshop .
Â
ReplaceKey Batter y
The SmartKey battery is discharged.
XChange thebatterie s (Ypage 81) .
Display messages257
On-board computer and displays
Z