See also:

Important safety notes
WARNING   The PARKTRONIC is a supplemental system. It is not intended to, nor does it replace, the need for extreme care. The responsibility during parking and other critical maneuvers ...

Problems with the SmartKey
Problem Possible causes/consequences and Solutions You cannot lock or unlock the vehicle using the SmartKey. The SmartKey battery is discharged or nearly discharged. ...

Changing the battery
You require a CR 2025 3 V cell battery. - Take the mechanical key out of the SmartKey. - Press mechanical key 2 into the opening in the SmartKey in the direction of the arrow until battery t ...