I have an O1E 6 speed in my Passat, the same transmission used in the Audi S4. It has had two problems.
This is how it has happened:
I pushed in the clutch and put in it first gear with the engine off, then when I started the engine it moved ever so slightly pulling as if it were in gear although I had the clutch pushed all the way in. Then I drove 35 miles with no problem, stopped to eat and when I got back in the car to leave it did the same thing. Then that seemed to clear up and not happen again.
However, the following day when I started the car in neutral and tried to put it in gear it would not go in gear, any gear. I then turned the engine off and it still would not go in any gear. I tried this with the engine on/off and the clutch pedal up/down and still it would not go in gear. There were no grinding noises at all.
Later that day I tried it again and everything worked fine. I drove it to the dealer and there were no problems. I had the dealer flush the hydraulic system, the owner's manual said every two years, I've only owned the car one year but I doubt it had ever been done. They also checked the motor mounts and transmission linkage and there were no problems with either. They did a test drive and all was fine.
They called me to come pick it up but when they tried to move it the same problem happened, it would not go in any gear with the engine on/off and the clutch pedal up/down.
Any idea what this could be? Any help and opinions are appreciated.