gunbunny

Our 2008 A8 will throw P0456 code every now and then. I looked it up, and it's an EVAP error. Checked the gas cap and it's tight. My wife is worried (as in "get it to the dealer right away") but I keep telling her it's not a big deal.

Who wins this argument?

Petahs

You win! Reset it and see if it comes back. Just cleared this yesterday on a Jeep and it has not come back.

TSHong

Evap is part of the emissions system that monitors the fuel expansion with temp increase or decrease. Your car's operation will not be effected. If the light comes back on, you will not pass an emissions test.

mishar

She wins.

As it is part of emission control system it should be covered by warranty for life.

MP4.2+6.0

Not usually a biggie, but as Mishar says it should fall under the emissions warranty--its not open ended necessarily though. That varies by locale as far as time covered--not for life though in the U.S. at least. For a U.S. car, it can matter if it was sold in the states that use the California specs (generally west coast and NE I think) or the rest of the states that use the federal only specs. CA spec in general is longer.

But yes, also make sure cap was on tight, so it doesn't fall into "operator error" bucket.