Possible causes – Faulty EVAP canister vent valve– Faulty EVAP canister pruge valve– Plugged EVAP canister condition– Faulty EVAP pressure sensor When is the obd code mean? The ECM has detected pressure in the EVAP system during a non-purge condition. P0496 BUICK OBD Code Description The evaporative emission (EVAP) control system limits fuel vapors from…