Ever since the introduction of lambda control on vehicles with a catalytic converter, all emissions from a vehicle have been subject to legal regulations.
This also includes evaporating fuels (hydrocarbons) from the fuel tank. Since these so-called volatile hydrocarbons are not allowed to enter the atmosphere, they need to be captured and stored for reuse. In order to comply with legal regulations, retention and recirculation systems for fuel vapors are used here.
One important component in this system is the activated charcoal canister.