I have looked for a trouble shoot on this on and off a few times and have found limited info. All 4 rear sensors click when in reverse (which seems to suggest that they are working (?)) but I can't find the next step in a logical process to continue to trouble shoot the problem as there is no sound in the cabin. When I put the journey in reverse, I instantly see alert that the Parking Assist is not working. Can this be a home fix or a shop repair?