EVAP Emissions System
WARNING: This page is about a different car, the 2001 Audi S4 and 2001 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
When vehicle is not in operation, an EVAP (charcoal) canister stores fumes produced through evaporation in the fuel tank and other related system components. During engine operation, fumes are purged from EVAP canister and consumed in the combustion process.
To test EVAP emissions system, see appropriate DTC under DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article.