On Sunday I was driving along and the ABS & traction control lights came on. Stopped the car and started again and the lights persisted. About 10 minutes later the glow plug light came on and was flashing. The brake lights also weren't working. It persisted for the day. Consulted the site and it said the brake light switch needs to be changed. On Monday rang around a few Audi garages and found one with the part. Off I went and bought the part. Sods law being as it is on the way home from the garage the lights went off and the brake lights were working again! Should I change the part anyway or is it OK to go on as it is?