Charcoal Canister

Image courtesy of ClearMechanic.com

Part of the car’s emissions controls, this charcoal-filled canister’s job is to absorb fuel vapor that would otherwise vent out to the atmosphere, causing pollution. Vapors trapped by the charcoal are released back into the engine through the purge valve and then burned.

Charcoal canister problems can often cause the check engine light to go on, and they are often difficult for mechanics to diagnose.