Beeeeeep

[Norretal]

Not sure if I'm posting in the correct place, but here goes....

Can't find anything else relating to the same issue on here so I'm asking for guidance. Since yesterday I've had a warning when putting the car into reverse, the continuous beep and asking if it's safe for me to reverse. The only thing I did was wash the car yesterday and the fault arrived just after. So, is it a failed sensor and is the only option to replace it? I'd obviously be happier if it's a common thing and there's a cheap, easy fix