The charcoal canister, also known as an evaporative emission control (EVAP) canister, on a Dodge truck (and most modern vehicles) is used to
store fuel vapors that evaporate from the fuel tank and fuel system. These vapors are harmful pollutants, and the canister prevents them from escaping into the atmosphere.
When the engine is running, a purge valve opens, allowing the stored vapors to be drawn into the engine to be burned during combustion, thus reducing emissions.
