2004 a4 b6 gas cap warning light fix
 

After searching the various Audi sites, I fixed my gas cap missing/loose warning light. Fix - not really. Made it turn off - yes.

Remove back seat by pulling up at center of each left/right seating area and hooks will release.

Open the triangular panel under the passenger side seat - three phillips head screws.

You will find a couple of fuel lines and a couple of electrical connections.

Release/disconnect the smaller of the two electrical connections.

Circuit is now permanently open and the light will not come on again.

Reassemble.

Try to keep up with your gas cap without Audi engineers reminding you that you need it.

End.

Yeah I'm on board with that-my sensor went kaput over the fall, and this is a nice quick uhhh "fix."