The canister purge valve is located on top of the engine next to the egr valve. The evap canister and vent valve is located underneath the vehicle near the gas tank along the body crossmember.You will have to lift the rear of the vehicle to access it.Ask Your Own Car Question.t an appropriate time, the PCM turns the EVAP canister purge valve ON (open) and the EVAP canister vent valve ON (closed). This allows the engine to draw a vacuum on the system. At a calibrated time or vacuum level, the PCM turns the purge valve OFF (closed), and tests the system vacuum.