Subaru Legacy BN/BS (2015-2019) Owners Manual: To arm the system using the keyless access function (if equipped)

1. Close all windows and the moonroof (if equipped)
2.  Turn the push-button ignition switch to the "OFF" position.
3.  Open the doors and get out of the vehicle.
4.  Make sure that the engine hood is locked.
5.  Close all doors and the rear gate/trunk lid.

1) Door lock sensor

Security indicator light

6. Carry the access key and touch the door lock sensor. All doors (for Outback, including the rear gate) will lock, an electronic chirp will sound once, the hazard warning flashers will flash once, and the security indicator light will start flashing rapidly. After rapid flashing for 30 seconds (standby time), the security indicator light will then flash slowly (twice approximately every 2 seconds), indicating that the system has been armed for surveillance.

If any of the doors or the rear gate is not fully closed, an electronic chirp sounds five times, the hazard warning flashers flash five times to alert you that the doors (or the rear gate/trunk lid) are not properly closed. When you close the door, the system will automatically arm and doors will automatically lock.