A critical component of the EVAP system, the canister purge valve regulates the flow of fuel vapours being released for the engine to burn instead of the vapours just being released into the atmosphere. When your canister purge valve is bad it may trigger a CEL (Check Engine Light) with a code P0496. The canister purge evap valve can easily be located inside the engine bay usually beside the throttle body.
If you are experiencing rough idle, hard to start especially after fuelling, poor fuel economy and the CEL with code P0496 then you may have a problem with your canister purge valve.