I had a quick look at this earlier (sister in-law's) with rear park sensors not working (fronts work fine). Kts showed no fault codes, live data showed all sensors at 255cm - not changing but showed trailer detected. I didn't think to check the rear fog light until now. My question is how does the module know there's a trailer connected? (It has the 13 pin euro type socket)

I've just checked with her & rear fog light not working (tell tail ok) so it would seem the car is "seeing" an invisible trailer but how?