See also:

Faults in the system
If the information symbol illuminates and Park assist syst Service required is shown on the information display, this indicates that the system is not functioning properly and has been disengaged. ...

Activation
PAC is activated when the gear selector is moved to R if the system is selected in the MY CAR menu system or by pressing the CAM button in the center console. See page 133 for a description ...

Reverse ®)
The vehicle must be stationary when position R is selected. ...