Page 26 of 257

24Keys, doors and windows
1. To unclip the cover insert a smallscrewdriver between the back
cover and the remote control.
2. Remove the back cover.
3. Extract the flat battery from its location.
4. Replace battery with a battery of the same type. Pay attention to
the installation position.
5. Clip the cover in place.
Fault
If the central locking system cannot
be operated with the radio remote
control, the cause may be one of the
following:
● Fault in radio remote control.
● The range is exceeded.
● The battery voltage is too low.
● Frequent, repeated operation of the radio remote control while not
in range, which will require re-
synchronisation.
● Overload of the central locking system by operating at frequent
intervals, the power supply is
interrupted for a short time.
● Interference from higher-power radio waves from other sources.
Manual unlocking 3 25.Electronic key system
Enables a keyless operation of the
following functions:
● central locking system 3 25
● ignition switching on and starting the engine 3 136
The electronic key simply needs to be on the driver's person.
Additionally, the electronic key
includes the functionality of the radio
remote control 3 23.
Handle with care, protect from
moisture and high temperatures and
avoid unnecessary operation.
Page 27 of 257

Keys, doors and windows25Replacing battery in electronic
key
Replace the battery as soon as the
system no longer operates properly or the range is reduced. The need for battery replacement is indicated by a
message in the Driver Information
Centre 3 102.
Batteries do not belong in household
waste. They must be disposed of at
an appropriate recycling collection
point.
1. To unclip the cover insert a small screwdriver in the cutout.
2. Remove the cover.
3. Extract the flat battery from its location.
4. Replace battery with a battery of the same type. Pay attention to
the installation position.
5. Clip the cover in place.
Fault
If the central locking cannot be operated or the engine cannot be
started, the cause may be one of the
following:
● Fault in electronic key.
● Electronic key is out of reception range.
● The battery voltage is too low.
● Overload of the central locking system by operating at frequentintervals, the power supply is
interrupted for a short time.
● Interference from higher-power radio waves from other sources.
To rectify the cause of the fault,
change the position of the electronic
key.
Manual unlocking 3 25.
Central locking system Unlocks and locks doors, load
compartment and fuel filler flap.
Pull an interior door handle fully to
unlock and open the respective door.
Page 252 of 257

250IndexAAccessories and vehicle modifications .......................... 185
Active emergency braking ..........157
Adaptive forward lighting ...........113
AdBlue .................................. 94, 142
Adjustable air vents ...................129
Advanced parking assist ............164
Airbag and belt tensioners ...........91
Airbag deactivation ................57, 91
Airbag label................................... 52 Airbag system .............................. 52
Air conditioning regular operation ................................ 131
Air conditioning system .............. 121
Air intake .................................... 130
Air vents...................................... 129
Antilock brake system ................ 149
Antilock brake system (ABS) .......92
Anti-theft alarm system ................33
Anti-theft locking system .............. 32
Appearance care ........................221
Armrest ................................... 47, 48
Ashtrays ....................................... 81
Automatic anti-dazzle ..................37
Automatic light control ...............112
Automatic locking ........................29
Automatic transmission .............145
Autostop ............................... 95, 138
Auxiliary heater ........................... 128B
Battery discharge protection ......119
Battery voltage ........................... 102 Belts.............................................. 49
BlueInjection ............................... 142
Bonnet ....................................... 187
Brake and clutch fluid .................226
Brake and clutch system .............92
Brake assist ............................... 150
Brake fluid .................................. 190
Brakes ............................... 149, 190
Breakdown.................................. 219
Bulb replacement ....................... 192
C
Capacities .................................. 238
Catalytic converter .....................141
Central locking system ................25
Centre console lighting ..............118
Centre console storage ...............66
Changing tyre and wheel size ...209
Charging system .......................... 91
Child locks ................................... 30
Child restraint installation locations ................................... 61
Child restraints.............................. 58
Child restraint systems ................58
Cigarette lighter ........................... 81
Climate control ............................. 16
Climate control systems .............120