Nissan X-Trail e-POWER 2023 Owners Manual
8.15.4.1. Another vehicle approaching from behind
Illustration 1: The side indicator light illuminates if a vehicle enters the detection zone from behind in an adjacent lane.
Illustration 2: If the driver activates the turn signal while another vehicle is in the detection zone, then the system chimes (twice) and the side indicator light and BSW indicator flash.
The radar sensors may not detect vehicles which are approaching rapidly from behind.
Owners Manual