Help- Any direction for Evap CEL?

[AudiNFS]

Hey guys, my car has a CEL on for the evap system, and was wondering if it could be narrowed down any as to what it is. The code was (I believe, working on getting Vag-com) P0422- Gross Leak.

Now, my MPG's seem fine, they were around 21MPG last I did the math about a month ago. My gas gauge does not read accurately for me. For example, I will be sitting at idle letting the car warm up and this morning it jumped around from a little above 1/4 tank, down to "E", to 1/8 tank, and back up to 1/4 tank. Today, I had the gas light on the LCD screen, and I decided to get gas since the gauge was on "E" and I don't want to take any chances. I filled up about 10.5 gallons, turned the car back on and the gas light was still on the LCD screen. It stayed on there for about my 30 minute drive, shut the car off for 5 minutes, came back out and the light was gone. Also, after I fill up, the gas gauge never hits "full." It's always a little before the full line.

Any guesses? Car is a 2000 S4.

Thanks for any help guys

[AudiNFS]

Bump?

[zillarob]

If you have a twin exhaust, look at the line by the spare tire well. Did you fill it while running or not tighten the gas cap? Maybe n80 valve.

[Malmhead]

p0422 is small leak.
p0455 is gross leak.

Both require you to check the EVAP system and tank system for leaks. You'll need to VAG it for this.

Here is a link to the diagnostic procedure using VAGCOM

You can also test your n80 with a multi meter as zillarob reccomended although the code would probably be 1425 or 1426 if it was the N80, it should be between 22-30ohms

Here is a link to the N80 diagnostic procedure

[AudiNFS]

Thanks guys

The car is straight piped from the cats back, which was done while not in my posession. I've always tightened the gas cap, usually to 3 clicks. I also have no knowledge if the car was filled or not while it was running. I will check the suggested things.

Do you guys know if I could use the "shareware" version of vag-com to diagnose this? Thanks again