The charcoal canister is part of the Evaporative Emission Control System. This system prevents the escape of raw gasoline vapors from the fuel tank and carburetor (if equipped).
The charcoal canister is designed to absorb fuel vapors under certain conditions.
For a more detailed description, see Emission Controls .
The canister does not require periodic replacement. The entire system requires a careful operational check with a vacuum gauge at 60,000 miles (96,500 km). See Emission Controls for testing procedures.