Check fuel cap displayed then code p0455 and p0442

[speedfreek]

I can erase codes start car after about 10 mins of driving the display says to check fuel cap which I know is tight and check a number of times and i know its tight. After 3-4 starts and drives it will set the check engine light p0455 and p0442. what can the problem be ?

[slvrb7]

bad fuel cap gasket take off and flip or a leaking fuel cap replace fuel cap 30 bucks at dealer something like that.

[slvrb7]

it's bad fuel cap gasket or cap itself for sure just buy new one but you can flip gasket sometimes and get a little more life out of old cap ^

[speedfreek]

I will try the fuel cap i changed the seal on it and no change but I will try the cap. Will post results thanks ....

[slvrb7]

any results because if it's not the cap then you may have an n80 issue or lpfp issue.

[gdlkn84as]

I started off with P0442 after replacing my n80. Would clear it, 3 days later, it comes back. Tightened the clamps, reset. 3 days later, P0442 and P0455. I went ahead and order new gas cap, forge vacuum hose, and a new n80 (just to be on safe side). Since i last reset with vag, I they havent come back but I will be installing the new stuff when I got home from Florida!

I'm thinking that gas cap will fix the codes from ever returning, but I wanted to make sure I covered all my bases for such inexspensive parts... hope that helps.

I did a lot of research, as always, but I should have just done the cap and hoses with the n80 the first time around....

My lpfp, sounds fine whenever I open the door or even turn key to ignition so I dont think (hope lol) there is anything wrong there. I would also rec you check/clean your charcoal canister filter, pretty easy fix and many DIY for the job. Since I replaced my n80, regardless of codes, I can fill gas much quicker now, still cant let it sit, but I can squeeze the handle much more!!!! Almost able to properly fill my gas tank!!!! LOL

[Image is Style]

Hi everyone. Just had the N80 valve replaced at the dealership this morning. Codes P0455 and 0456 pulled when I went to Advanced Auto Parts this past weekend. I too was getting that "Close your fuel cap" message a couple of times within the past couple of months. I bought 1 of their aftermarket gas caps there for the heck of it for $11. That was a no go since Engine light still came back on after about 70 miles of driving-cleared engine light by disconnecting the battery. Anyway, the dealer said needed new Audi gas cap for the P0455 Evap Gross Leak. Then they had to replace the N80 valve for the P0456 Evap Small Leak. Lucked out because my car is CPO'd, Audi Care, so only paid around $133 because CPO Deductible=$85 and gas cap=$48. I have an automatic so I feel no difference in the drive before and after the job. I was just getting annoyed with the check engine light plus under warranty anyway. Without the Audi Care, it would've cost me around $275 for everything done.