Any thoughts would be appreciated.

I've got a 2003 S6 with 190,000 km on it. It's currently up for sale and the last guy who came by to take it for a test drive discovered the transmission in a "limp home" mode. When he shifted from Park to Drive, he found it clunked rather heavily. Then, it drove like a dog. When I jumped behind the wheel I realized that it must be stick in 3rd gear. It didn't shift up or down. It didn't matter if it was in "D" or "S" or tiptronic. It wouldn't shift from that gear. Additionally, the display had all the letters lit up "PNRDS".

I shut off the ignition and restarted it and then it ran fine.

It had never done this before, but needless to say, it scared the potential purchaser away.

Any ideas on the issue? Thanks.