Method and device for controlling a vehicle

1. A method for controlling a vehicle, the method comprising:

sensing the presence of a switch-off signal indicative of a command to switch off an ignition of a drive assembly of the vehicle,

measuring a voltage value of an on-board power system voltage in an on-board power system of the vehicle in response to sensing the switch-off signal,

comparing the measured voltage value to a predetermined voltage threshold value,

switching an assistance system of the vehicle into an emergency operating state if the measured voltage value exceeds the predetermined voltage threshold value.

2. The method as claimed in claim 1 , further comprising authenticating a vehicle key and switching the assistance system into the emergency operating state only if the vehicle key is authenticated.

3. The method as claimed in claim 1 , wherein a steering wheel of the vehicle is not locked when the measured voltage value exceeds the predetermined voltage threshold value.

4. The method as claimed in claim 3 , wherein the steering wheel is not locked only when the vehicle key is authenticated positively.

5. The method as claimed in claim 3 , wherein the steering wheel is locked when the measured voltage value does not exceed the predetermined voltage threshold value.

6. The method as claimed in claim 1 , wherein the assistance system is switched off when the measured voltage value does not exceed the predetermined voltage threshold value.