See also:

Functional readiness of the airbagsystem
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 tensioner. ...

Indicator/warning lamps
The indicator and warning lamps can light up in a variety of combinations and colors. Several of the lamps are checked for proper functioning and light up temporarily when the engine is starte ...

Enabling operation in the rear
Only possible via the iDrive in the front. 1. "Settings" 2. "Allow rear control" 3. Select the desired priority. ...