Looking for advice on a code

[tranzlusent]

So my car is throwing a P0442-Evaporative emission sys leak detected (small leak).

I have searched all around and have seen the basic possible fixes for this; I've replaced the gas cap with a brand new Audi cap, also the fuel level sensor seal in the trunk hoping that would fix it but the code still comes back after deleting it. An odd thing is, and I'm hoping this might be a clue to the problem is, my gas gauge will occasionally and slowly bounce around a bit. Some days I get in and the gauge says 1/4 tank and after driving for a while will go up to 3/4. Also when I refuel it to full the needle doesn't always go all the way to full. Obviously there is an issue with the level sensor but I'm hoping someone has seen this same problem and has some input related to the code. I really don't want to keep throwing parts at it but would also like to save some by not having someone VAG the car if there is an easy fix. Any advice on this would be greatly appreciated. Thanks

[Corradovolksb]

The fuel gauge issue is prob a bad level sensor. The small Evap leak can be a bitch to diag on our cars due to the complex Evap system. Some things that will cause that fault are a leaking N80 valve, bad ldp pump, bad Evap vent valve or a small crack in a line or charcoal canister. You may have to have the system smoke pressure tested to make sure you don't have an external leak.

[Mille Bornes]

x2 on the smoke test. A small leak could be a pinhole, tiny crack, any leaking seal... things that are just about impossible to check without smoke.

Corradovolksb is spot on. My first steps for evap leaks are smoke test and test the n80 because they're both so easy to do. You can just unplug the n80 electrical connector, disconnect the hose that goes to the back of the vehicle, start the engine, and see if vacuum leaks through. It's easy to see with latex gloves on because it'll cling to your glove a bit.

[Calif_Kid]

I hope that the issue is what they're mentioning above. I bought a B5 S4 years ago with an aftermarket sub in the trunk. I got the 'small leak detected' code, and the dealer ended up tracking the issue to being that when the aftermarket sub was installed, that they had used screws that were long enough to pierce the top of the gas tank, and luckily, the company that did the sub install paid for replacing the gas tank. I hope that yours is a simple fix and not that, but I also wanted to mention this in case anyone is installing an aftermarket sub. - Jim

[tranzlusent]

Thanks for the input. I don't have a subwoofer so I think I can rule out the holes in the tank lol. One more thing I forgot to mention, I did the ghetto f-hose delete and am killing birds with vapors, would that have anything to do with the code? Figured it was worth mentioning. I'll probably take the N80 valve off this weekend and check if it's working correctly and hopefully I get lucky and only have to buy a 15$ part. If that's not it, looks like I'll be having it smoke tested. Thanks again for the input.