2016 MERCEDES-BENZ C CLASS change key battery

KEYLESS- GO start function
Gene ra l notesBear in min d that th e engin e can be started by
any of th e vehicl e occupant s if there is a Smart -
Key in th e vehicle.
Changing the settings of the locking
system You can chang e th e setting s of th e locking sys-
tem. This mean s that only th e driver's door and
th e fuel filler flap are unlocke d when th e vehicl e
is unlocked. This is useful if you frequentl y travel
on your own .X
To change th e setting: press and hold down
th e 6 and 7 buttons simultaneousl y
for approximately six seconds until th e bat -
tery chec k lamp flashes twice ( Y
page 84).
If th e setting of th e locking system is changed
within th e signal range of th e vehicle, pressing
th e 7 or 6 button:R
locks or R
unlocks th e vehicl e
The SmartKey no w function s as follows :X
To unlock: press th e 6 butto n once .X
To unlock centrally: press th e 6 butto n
twice .X
To lock: press th e 7 button.
The KEYLESS-GO function s can be changed as
follows :X
To unlock th e driver's door : touch th e inner
surfac e of th e door handle on th e driver's
door .X
To unlock centrally: touch th e inner surfac e
of th e door handle on th e front-passenger
door or th e rear door .X
To lock centrally: touch th e outer sensor
surfac e on on e of th e door handles .X
To restor e th e factory settings: press and
hold th e 6 and 7 buttons simulta ne -
o
usl y for approximately six seconds until th e
battery chec k lamp flashes twice
( Y
page 84) . Mechanical key
Gene ra l notesIf th e vehicl e can no longer be locke d or
unlocke d wit h th e SmartKey or KEYLESS-GO ,
use th e mechanical key.
If you use th e mechanical ke y to unloc k and
open th e driver's door , th e anti-thef t alarm sys-
te m will be triggered . Switc h off th e alarm
( Y
page 79) .
If you unloc k th e vehicl e usin g th e mechanical
key, th e fuel filler flap will no t be unlocke d auto -
matically. X
To unlock th e fuel filler flap: insert th e
SmartKey int o th e ignition lock.
Removing the me chanical key
X
Push release catch C in th e direction of th e
arrow and at th e sam e time remove mechan -
ical ke y D from th e SmartKey.
Further information : R
Unlocking th e driver's door ( Y
page 89 )R
Locking th e vehicl e ( Y
page 89 )
Inserting the me chanical key X
Push mechanical ke y D completely int o th e
SmartKey until it engage s and release
catch C is bac k in it s basic position .SmartKey 83
Opening and closing Z

SmartKey battery
Important safety notes
G WARNING
Batteries contain toxic and corrosive substan-
ces. If batteries are swallowed, it can result in
severe health problems. There is a risk of fatal
injury.
Keep batteries out of the reach of children. If
a battery is swallowed, seek medical attention
immediately.
H Environmental note
Batteries contain dangerous
substances. It is against the
law to dispose of them with
the household rubbish. They
must be collected separately
and 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 X
Press the 7 or 6 button.
The battery is working properly if battery
check lamp C lights up briefly.
The battery is discharged if battery check
lamp C does not light up briefly. X
Change the battery ( Y
page 84).
If the SmartKey battery is checked within the
signal reception range of the vehicle, pressing
the 7 or 6 button: R
locks or R
unlocks the vehicle
i You can get a battery at any qualified spe-
cialist workshop.
Replacing the battery You require a CR 2025 3 V cell battery. X
Take the mechanical key out of the SmartKey
( Y
page 83).
X
Press mechanical key D into the SmartKey
opening in the direction of the arrow until bat-
tery compartment cover C opens. Do not
hold battery compartment cover C closed
while doing so. X
Remove battery compartment cover C .84
SmartKey
Opening and closing

Problem
Possible causes/consequences and P Solutions
The engine cannot be
started using the Smart-
Key. The on-board voltage is too low. X
Switch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work: X
Check the starter battery and charge it if necessary ( Y
page 350).
or X
Jump-start the vehicle ( Y
page 352).
or X
Consult 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. X
Unlock the vehicle and try to start the vehicle again.
The SmartKey battery is discharged or nearly discharged. X
Check the SmartKey battery ( Y
page 84) and replace it if necessary
( Y
page 84).
If this does not work: X
Start your vehicle with the SmartKey in the ignition lock.
There is interference from a powerful source of radio waves. X
Start your vehicle with the SmartKey in the ignition lock.
You have lost a Smart-
Key. X
Have the SmartKey deactivated at a qualified specialist workshop. X
Report the loss immediately to the vehicle insurers. X
If necessary, have the locks changed as well.
You have lost the
mechanical key. X
Report the loss immediately to the vehicle insurers. X
If necessary, have the locks changed as well.
Doors
Important safety notes
G WARNING
If children are left unsupervised in the vehicle,
they could: R
open the doors, thus endangering other
people or road users. R
get out and disrupt traffic. R
operate the vehicle's equipment. Additionally, children could set the vehicle in
motion if, for example, they: R
release the parking brake. R
shifting the automatic transmission out of
park position P R
Start the engine.
There is a risk of an accident and injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children or animals unattended in the
vehicle. Always keep the SmartKey out of
reach of children. Doors 87
Opening and closing Z

Control panel in the grab handle (rear
compartment)
C
Reading lampD
= To switch 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 when the SmartKey is in position 2 in the
ignition lock.
The color, brightness and display lighting for the
ambient lighting are set using the multimedia
system (see the separate operating instruc-
tions).
Automatic interior lighting control X
To switch on/off: press the 3 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: R
unlock the vehicle R
open a door R
remove the SmartKey from the ignition lock
The interior light is activated for a short while
when the SmartKey is removed from the ignition
lock. This delayed switch-off can be adjusted via
the multimedia system (see the separate oper-
ating instructions). Replacing bulbs
Important safety notes
G WARNING
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 that has been dropped or if its
glass tube has been scratched.
The bulb may explode if: R
you touch it R
it is hot R
you drop it R
you scratch it
Only operate bulbs in enclosed lamps designed
for that purpose. Only install spare bulbs of the
same type and the specified voltage.
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.
Only replace the bulbs listed ( Y
page 123).
Have the bulbs that you cannot replace 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 checked regularly.
Veh icles with LED headlamps: t he front and
rear light clusters of your vehicle are equipped
with LED light bulbs. Do not replace the bulbs
yourself. Contact a qualified specialist work-
shop which has the necessary specialist knowl-
edge and tools to carry out the work required.122
Replacing bulbs
Lights and windshield wipers

Hybrid drive system Display messages
Possible causes/consequences and P Solutions
r Vehicle Operational
Switch the Ignition
Off Before Exiting PLUG-IN HYBRID vehicles:
You are exiting the vehicle when it is in a ready-to-drive state. The
READY indicator in the multifunction display is on. A warning tone also
sounds.
If you leave the vehicle: X
Secure the vehicle against rolling away ( Y
page 177).X
Switch off the ignition and remove the SmartKey.
If you do not leave the vehicle: X
Switch off the electrical consumers, e.g. automatic climate control,
seat heating.
Please note the following: The electrical consumers are supplied by
the 12 V battery. If the vehicle is left in a ready-to-drive state for an
extended period, it will switch off once the 12 V battery is almost
empty. It will then only be possible to start the vehicle using a second
battery (jump-starting).
Change the current
drive program
before changing the
operating mode. or
Exit manual drive
program M before
changing the operat‐
ing mode. PLUG-IN HYBRID vehicles:
You have attempted to change the operating mode in the automatic
drive program S (Sport), S+ (Sport Plus) or in the manual drive pro-
gram M . X
Activate drive program C (Comfort) or E (Economy) ( Y
page 229).X
Select the preferred operating mode HYBRID , E-MODE , E-SAVE or
CHARGE ( Y
page 226).
E-MODE Currently
Unavailable PLUG-IN HYBRID vehicles:
The condition of charge of the high-voltage battery has dropped to the
lower limit and the E-MODE operating mode has been switched off.
Driving with the internal combustion engine is activated and the oper-
ating mode switches to the basic HYBRID setting.X
Continue driving using the internal combustion engine.
You can switch to the E-SAVE or CHARGE operating mode as
required ( Y
page 226).
If you select CHARGE , the high-voltage battery is charged.
Once the charge level display for the high-voltage battery has
increased slightly, you can switch to the E-MODE operating mode
again.272
Display messages
On-board computer and displays