Originally Posted by auditech79

Some of you may have noticed that there is a gas odor coming from the outside of your vehicle and on occasion on the inside of the vehicle. Its most likely a problem thats not easilly diagnosed that i discovered 4 years ago that applies to 97-04 A6's with all available engines. Most technicians replace the large O-ring for the fuel pump or fuel sender which is located under the rear seat. 90% of time thats not the cause of the leak and or smell.
About 4 years ago i had problems diagnosing a gas odor from both the inside and outside of the vehicle on a 3.0L A6. I found a few drops of gas on the floor after it sat over night but i could not see where the leak was coming from. In order to find the leak i had to remove the entire rear end and drop the gas tank out. What i discovered was 4 EVAP lines attached to the top of the tank, two of which has broken off. The reason the lines broke off the nipples on the tank was because a small steel insert had backed out the fitting causing it to bend with the movement of the car, eventually breaking off the nipple and causing a leak after topping off the gas tank. It will still leak if you are driving with a half full tank causing the gas odor. Replacement of the gas tank is the only cure for this condition which is a very expensive repair. I have since replaced 50 gas tanks for the same condition and i have heard from my friend at the dealer that there may be a recall out for this condition now. I sent several pictures to audi over the years trying to get it covered for you guys, but i had no luck while i was still working at the dealership. I would check with your local dealership and ask if there is a related recall for repairing this issue, or at the very least buying an extended warranty that will cover this repair.

If you have any questions about the issue you can PM me.

Edit: oc audica supplied this recall statement from volkswagen: http://nhthqnwws112.odi.nhtsa.dot.go...8V157-4839.pdf
but the recall appears to only cover 01-04 which i believe should take care of it since audi has probably done more research on the issue. I can't remember the year models i worked on but i do know i have replaced tanks on 2.8L,2.7T, 3.0L and 4.2L's. The 4.2L A6 doesn't appear to be in the recall as of right now, so hopefully that will change. Better yet i could be wrong about the 4.2L altogether and you 4.2L owners won't have a problem.