fiestaturbo.com

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Glad to be back - it's been a while.

My mother has a 2018 Mk8 UK Fiesta 3 door. Last week she got rear ended at low speed. There's a little cosmetic damage on the rear bumper, scratch and small dent, and apparently that was all. Not so.

Having driven the car today I have discovered the reversing distance sensor beep thing is dodgy. Sometimes it doesn't make any sound at all when reversing at a wall, then if I drive forward a bit and try again it'll be similar to normal operation but not as "smooth", ie the beeps kind of jump instead increasing in frequency with proximity to hazard. Other times it just sort of beeps randomly although I always got the impression it does kind of beep more when closer to the wall. It definitely does not work as intended.

I've been out of cars for about 15 years, I've been pulling bikes apart instead. I haven't car stuffed since mid to late 2000's when I was playing with XR2i and RS turbos, one of which remains alive and well to this day.

I know absolutely nothing about stuff like parking sensors. I'd guess with the problem not behaving in a consistent manner it's probably a dodgy connection somewhere rather than the sensor themselves being FUBAR'd. I imagine when you engage reverse gear the ECU starts sending pulses from the sensor, waits for echo and calculates distance from it. This would make misaligned sensors behave consistently against a flat (almost) brick wall. That said, with the bumper taking a whack, I would guess the problem is there!

Could someone with any experience with this sort of thing point in the right direction please? I'd ideally like to narrow the problem down to a particular part so I can fix or replace. I've no idea where the wiring connections are lurking or even really how they connect to the sensors, this sort of thing on modern cars is a whole new thing for me sorry.