2018 MERCEDES-BENZ CLS change key battery

tions of KEYLESS-GO with those of a conven-
tional SmartKey. Unlock the vehicle by using
KEYLESS-GO, for instance, and lock it using the
7 button on the SmartKey.
When locking or unlocking with KEYLESS-GO,
the distance between the SmartKey and the cor-
responding door handle must not be greater
than 3 ft (1 m).
A brief radio connection between the vehicle
and the SmartKey determines whether a valid
SmartKey is in, or in the direct vicinity of, the
vehicle. This occurs, for example: R
when the external door handles are touched R
when starting the engine R
while the vehicle is in motion
X
To unlock the vehicle: touch the inner sur-
face of the door handle. X
To lock the vehicle: touch sensor sur-
face C .X
Convenience closing feature: touch
recessed sensor surface D for an extended
period.
Further information on the convenience clos-
ing feature ( Y
page 88).X
To unlock the trunk lid: pull the handle on
the trunk lid.
The vehicle only unlocks the trunk lid.
Deactivating and activating If you do not intend to use a SmartKey for an
extended period of time, you can deactivate the
KEYLESS-GO function of the SmartKey. The
SmartKey will then use very little power, thereby
conserving battery power. For the purposes of
activation/deactivation, the vehicle must not be
nearby. X
To deactivate: press the 7 button on the
SmartKey twice in rapid succession.
The battery check lamp of the SmartKey
( Y
page 79) flashes twice briefly and lights
up once, then KEYLESS-GO is deactivated. X
To activate: press any button on the Smart-
Key.
or X
Insert the SmartKey into the ignition lock.
KEYLESS-GO and all of its associated features
are available again.
Changing the settings of the locking
system You can change the settings of the locking sys-
tem. This means that only the driver's door and
the fuel filler flap are unlocked when the vehicle
is unlocked. This is useful if you frequently travel
alone. X
To change the setting: press and hold down
the 6 and 7 buttons simultaneously
for approximately six seconds until the bat-
tery check lamp ( Y
page 79) flashes twice.
If the setting of the locking system is changed
within the signal range of the vehicle, pressing
the 7 or 6 button: R
locks or R
unlocks the vehicle
The SmartKey now functions as follows: X
To unlock: press the 6 button once.X
To unlock centrally: press the 6 button
twice. X
To lock centrally: press the 7 button.
The KEYLESS-GO function is changed as fol-
lows: X
To unlock the driver's door: touch the inner
surface of the door handle on the driver's
door. X
To unlock centrally: touch the inner surface
of the door handle on the front-passenger
door or the rear door. X
To lock centrally: touch the outer sensor
surface on one of the door handles. X
To restore the factory settings: press and
hold the 6 and 7 buttons simultane-
ou
sly fo r approximately six seconds until theSmartKey 77
Opening and closing Z

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 79).
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 78). 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 .
X
Repeatedly tap the SmartKey against your
palm until battery

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 284).
or X
Jump-start the vehicle ( Y
page 285).
or X
Consult a qualified specialist workshop.
The engine cannot be
started using KEYLESS-
GO. The SmartKey is in
the vehicle. The vehicle is locked. X
Unlock the vehicle and try to start the vehicle again.
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 PR
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.
Unlocking and opening doors from
the inside You can open a door from inside the vehicle
even if it has been locked.
If the vehicle has previously been locked from
the outside, opening a door from the inside will
trigger the anti-theft alarm system. Switch off
the alarm ( Y
page 75).
You can only open the rear doors from inside the
vehicle if they are not secured by the child-proof
locks ( Y
page 63). Doors 81
Opening and closing Z