Please help. I have a 2009 C5 exclusive tourer with park assist. The parking system is faulty, I connected a "Snap on " diagnostic and got 2 faults.. The left rear exterior sensor and " 43972 (ABC4) undiagnosed fault. I replaced the sensor it erarsed the first fault code but the parking system is giving a fault reading every ime I start the car. The secong fault code remains and I have no idea what it is for .. Can anybody help or do I have to visit my main dealer and spend money ???