My friend was cruising down the road at 80 mph in 6th gear when he went to put it in cruise control and his EPC light turned on and his car went into limp mode. He has a B6 A4 2004. He couldnt rev or go any higher than 1000rpms in gear. Everything was fine after he pulled over and turned his car off and back on again. But what could of been the problem to do this? Any advise is appreciated.

thanks in advance.