My A3 has started having an odd issue. After I start the car when I put the gearbox in reverse I get a long tone, instead of the short beep to let me know it is in reverse. Then the parking sensors don't work, and any subsequent shift into reverse I no longer get the short beep that it is in reverse. I have no faults on the dash, and OBD11 does not give me any faults.

Any ideas?