2004 2500hd code PO446

Lately my ses light has been coming on quite frequently (3 times in the past 3 weeks). The most recent time was this morning. The first time the ses came on the service tech said the code "PO446" came up and that the EVAP canister needed to be replaced. The second time the same code came up and the same service department said the fuel pressure sensor needed to be replaced.

This morning I had my wife drop the truck off at a different dealer. I am willing to bet the same code will come up. Has anyone had this code/problem with their truck. I would appreciate any help/suggestions to this problem. It is getting really old having to take this truck in every week!

Thanks,