Leaderboard

I would agree with your logic, i'm not wildly familiar with the XF but would imagine it's electrical architecture to be similar to the S Type. There is a general module that's in the boot on the S Type (which could be a clue) and i'm not sure what other modules might be involved. I'd suggest checking in the boot, see if you can find any signs of water ingress/dampness, also check your sunroof drain holes/hoses in cae one or both is leaking water into the boot and causing your problem. As for hearing ultrasonic sensors, the clue is in the name - ultrasonic. They tend to operate in the 22-40KHz range, most humans can only hear up to ~18kHz so if someone says they can hear it, check them for bat DNA or assume they're mistaken or very lucky. Good luck with it, let us know how you get on.