What happened: I put the Tiptronics tranny into Park, but felt a resistance on the shifter as I did so. Tried it again, same. Stopped the engine, and the key would not come out.
Problem: The most common cause is the silver button gets stuck part way in.
Fixes: I was able to just depress the button with my thumb, then slide my thumb off the edge of the button so that it jumped out. Other fixes included shifting into the Tip gate slowly, then back slowly; or banging on top of the shifter while in Park. One thread suggests that the park sensor may sometimes become damaged.
Examples of older threads:
http://forums.audiworld.com/a6/msgs/9639.phtml
http://forums.audiworld.com/a4/msgs/222074.phtml
http://search.audiworld.com/index.mhtml?q=tip+park+key+ignition&wf=022210&cat=01&dt=range&db=01%2F01%2F1999&de=06%2F19%2F2003
http://forums.audiworld.com/a4/msgs/203078.phtml
http://forums.audiworld.com/a6/msgs/9499.phtml
http://forums.audiworld.com/a6/msgs/23080.phtml
http://forums.audiworld.com/a4/msgs/220136.phtml
http://forums.audiworld.com/a4/msgs/202887.phtml
http://search.audiworld.com/index.mhtml?q=tip+park+key+ignition&wf=022210&cat=01&ps=20&dt=range&db=01/01/1999&de=06/19/2003&np=1
http://forums.audiworld.com/a4/msgs/214625.phtml
http://forums.audiworld.com/a6/msgs/9503.phtml
http://forums.audiworld.com/tt/msgs/25730.phtml
http://forums.audiworld.com/a6/msgs/23051.phtml
http://forums.audiworld.com/a6/msgs/23062.phtml
http://forums.audiworld.com/a4/msgs/1283734.phtml
http://forums.audiworld.com/a4/msgs/214554.phtml
http://forums.audiworld.com/s4/msgs/899064.phtml
http://forums.audiworld.com/9080/msgs/92673.phtml
http://forums.audiworld.com/a6/msgs/23049.phtml
http://forums.audiworld.com/a6/msgs/23078.phtml
http://forums.audiworld.com/a4/msgs/215278.phtml
http://forums.audiworld.com/a4/msgs/220788.phtml
http://forums.audiworld.com/a4/msgs/202889.phtml
http://forums.audiworld.com/a4/msgs/214432.phtml
http://forums.audiworld.com/a4/msgs/214561.phtml
http://forums.audiworld.com/a4/msgs/220127.phtmlA6 (C5 platform) FAQ
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Email: jds@sonolithics.RemoveThisPart.com (delete the middle part, intended to reduce spam)

Stoney's Nemo Blue 4.2
2001 A6 4.2L, Sport, Premium, Nemo Blue, Melange Interior
* Still shopping for high-end stereo to go with "AUDIO" license plates...
...email me with advice on speaker fitment and Silicon Valley installers!
* Pulled Servotronic module 605 but put in a 628 (2002).
* Wife drives a 97 A4 1.8T, and is considering a BMW 3 series.