CanadianQtip

Not really the milestone I was looking to hit but when I left the house this morning the car threw a code.

Scanned it with the VAG and saw the following:

Mode 03: Emission related fault codes

Address 7E8: 1 Fault Found:
P0456 - EVAP System: Very Small Leak Detected

I did a search on the forums and didn't find anyone with this issue on the B8 so I must be the lucky one.

I re-filled the gas tank, checked the gas cap, and cleared the code. So far it hasn't returned after about 50km of driving.

Car only has 3000km so far.

rktskicar

that normally is from not having gas cap screwed on. not sure about your sitiuation. I would clear it and see if it comes back....

Bruce

CanadianQtip

Thanks Bruce. The gas cap seemed fine but I did refuel and play around with the cap just in case.

I also cleared it in case it was just a fluke situation that threw the code.

helix139

I had one of those a while ago after washing my car. I believe I knocked the gas cap slightly loose while wiping everything inside the lid dry. Mine went away after a day or so.

vincenz0

Sorry to revive an old thread, but I'm having this problem on my 2010 S4. I've cleared the code, tightened the gas cap, but it keeps coming back in 500 or so miles.

My car has about 83k on it. Is it possible that the gas cap is worn out and not sealing properly anymore? It's certainly been on and off a lot in 83k miles but I wouldn't think an item like that would fail.

Other than the cap, what else should I be checking?

m444

The tank vent system: hoses to the EVAP purge valve (under the hood) or leak in charcoal canister?

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/charcoal-canister/8k0201801c/

B8 S4 Engine Study Guide

"Evaporative Emission (EVAP) Canister Purge Regulator Valve N80"

arn560

Who thinks of these things to put in cars? Charcoal canister, really???

m444

It is part of the OBDII EVAP system and has been in all the US cars since the 1970s, to prevent gasoline vapors from being released to the atmoshere.

"Evaporative emission controls were first required on cars sold in California in 1970. EVAP has been used on all cars and light trucks since the early 1970s. "

EVAP Evaporative Emission Control System

In the older cars, it was a metal canister, but many newer canisters are plastic, which degrades over time.