My 6 has a code U0100: lost communication with ECM/PCM Module A
The sympton is that sometimes after driving and rest for around 2 hours, the car cannot be started.
All the electrical things work properly, car has lights, audio, everything works fine
but just cannot be ignited, not even any 'tic tac' sound for ignition.

But if i rest the car for longer, say 4 hours, it can be started.
What will be reason?

 

Hi, did you get it fixed? I am having the same problem and my dealership is telling me my PCm is malfunctioned. It cost $990 for a replacement and installation at $125 per hour.