I noticed on Sunday night that the parking sensors weren't doing their job - no errors on dash but 'system unavailable' or similar when I go to the volume settings for them on the MMI. Restarted car on drive and they came back on, but on school run again this morning, not working until car restarted. Anyone got any clues what it might be? Without an error (and so I guess no fault code) I can't imagine dealership will have much to go on. Only have rear sensors not full pack.