Reducing the energy consumption of the key
Deactivate key function
If you do not use the vehicle or a key for an extended period of time, you can also deactivate the function of the key to reduce the energy consumption of the key.
Press and hold the key 
button.
button. With the key button pressed, immediately press key button 
twice in quick succession.
pressed, immediately press key button twice in quick succession. The indicator light of the key lights up once briefly and once for a long time.
Deactivate key function
Press any key on the key.
The key function is automatically activated when the vehicle is started with the key in the gearshift console slot.
Overview of the Mercedes-Benz emergency call system
The Mercedes-Benz emergency call system can help to decisively reduce the time between an accident and the arrival of emergency services at the site of the accident. It helps locate an accident site in places that are difficult to access.
The emergency call can be triggered automatically More.
You also have the option of triggering the emergency call manually More. Only make emergency calls if you or others are in need of rescue. Do not make an emergency call in the event of a breakdown or a similar situation.
Message in the media display:
SOS NOT READY: the vehicle is not switched on or the emergency call system is malfunctioning.
This does not necessarily indicate a total failure of the emergency call system. Emergency calls can still be transmitted.
The display refers only to the vehicle and does not take account of the availability of mobile phone networks and the Mercedes-Benz emergency call centre.
The functional readiness of the emergency call system on the vehicle can be seen when the SOS NOT READY display disappears once the vehicle is switched on.
During an active emergency call, 
appears in the display.
You can find more information on the regional availability of the Mercedes-Benz emergency call system at: Mercedes-Benz emergency call system
If there is a malfunction of the emergency call system, the loudspeakers, microphone, airbag or the SOS button, for example, are faulty.
You can recognise a fault in the emergency call system by the following displays:
The red SOS NOT READY message appears in the display of the instrument cluster or in the media display.
The SOS button lights up red continuously.