See also:

Office
...

Sound output
Switching on/off When the ignition is switched off: press ON/OFF button on the radio. Muting When the ignition is switched on or the engine is running: press the ON/OFF button on the radio. ...

Functional readiness of the airbag system
When the ignition is switch on, the warning lamp in the instrument cluster lights up briefly and thereby indicates the operational readiness of the entire airbag system and the belt tension ...