My 2003 A4 has a habit of the gear selection bar/ indicator light of disappearing within the first five minutes of driving. In this state, the car goes into "fail safe mode". The car goes into reverse @ idle speed and the car won't go into triptronic mode. However, after a few minutes the indicator light comes back on and everything is fine. Any ideas? New TCM as the dealer suggests or other options? Please help any suggestion welcome. Thanks

Could be water in the tcm connector which connects to the transmission or rusty pins.
worth checking.