According to BMW WDS.
Ultrasonic Interior Protection
The ultrasonic interior protection system is based on a movement detector that detects movements in the vehicle interior and sends corresponding signals to the ZKE general module.
Function
Ultrasonic module
The ultrasonic module contains the electronics and ultrasonic sensors (transmitter and receiver). It is installed in the headlining in the centre area of the vehicle. Two pairs of sensors (transmitter and receiver) monitor the entire vehicle interior.
Movements in the vehicle interior are detected in that the reflections of the ultrasonic waves (echo) change. The ultrasonic module then signals an alarm triggering to the general module.
Arming/disarming
When the antitheft alarm system is armed, the ultrasonic interior protection is activated by the ZKE general module via the STDWA line and deactivated when the system is disarmed (the same line also activates and deactivates the tilt alarm sensor and siren).
Interior monitoring begins 30 seconds after arming the antitheft alarm system. The interior is not monitored when a vehicle door or the boot (trunk) lid is open. Opening the boot (trunk) lid or convenience closing of the windows interrupts the interior protection function.
If the ultrasonic module detects a triggered alarm this status is signalled to the general module via the INRS line.
In order to avoid false alarms being triggered under unfavourable ambient conditions, the interior protection function can be switched off with the antitheft alarm system armed as follows:
Arm antitheft alarm system via door lock or remote control
Repeat arming procedure within 10 seconds
Self-Test
After being armed, the ultrasonic module carries out a self-test. If a fault occurs, it is signalled to the ZKE general module via the INRS line. A fault code for interior protection is stored in the general module.
The following faults can be detected as part of the self-test. Module electronics faults, sensors interrupted, sensor short-circuit, sensors covered over, INRS line faulty.
A faulty module is not activated in order to avoid false alarms being triggered.
According to the above highlight, you have to arm it twice within 10 seconds. Since you try the procedure with remote key and it does NOT work, maybe try it with the key.
