Grasp the door handle on the driver's or front passenger door completely, arrow.
This corresponds with pressing the button on the remote control.
Locking
Touch the surface on the door handle of the driver's or front passenger door, arrow, with your finger for approx. 1 second without grasping the door handle.
This corresponds with pressing the button on the remote control. To save battery power, ensure that the ignition and all electronic systems and/or power consumers are turned off before locking the vehicle.
BMW X3 Service & Repair Manual > Electrical: Description
WARNING: Vehicles are equipped with air bag supplemental restraint
system. Before attempting any repairs involving steering column, instrument
panel or related components.
CAUTION: When battery is disconnected, vehicle computer and memory systems may
lose memory data. Driveability problems m ...