Boxer parking aid fault

Based on the symptoms and your initial inspection, a defective cable or plug connection is indeed likely. Have you inspected the wiring harness leading to the parking sensors, particularly where it might be subject to chafing or vibration? Is the rearview camera functionality also affected, or are only the ultrasonic sensors malfunctioning?

I've checked the accessible parts of the harness, but not exhaustively. Difficult to get at some of it. The rearview camera seems to be working perfectly fine, which I find strange. So, purely the parking sensors then, I believe. Any specific connectors or areas known to be problematic on the Boxer?

Given that the rearview camera is operational, it isolates the issue to the ultrasonic sensors and their wiring. I can't pinpoint specific connectors prone to failure on the Boxer, but I recommend a thorough inspection of all connectors related to the parking sensor control module. It is difficult to diagnose without appropriate equipment. At this point, it may be most efficient to consult a workshop with diagnostic equipment to pinpoint the break in the connection.

Understood. I appreciate the advice regarding the connectors and the recommendation to visit a workshop. I will take it in; they've quoted 95€ for the diagnostics and repair, which seems reasonable. Thank you for your help!