Anyone know how to fix error P0441 on a 1999 VW Pat 4 cyl?

I am diagnosing error P0441 on my 1999 Pat, I learned it is an Evaporative Emission Control System Incorrect Purge Flow. I heard it could be the check valves or the purge valve or other hoses. Can anyone tell me where to start and what things to look for? If you have any picture or figure that will be great.