Fuel Hoses Lines/piping And Fittings problems of the 1999 Subaru Outback

My 1999 Subaru Outback wagon issued a cel with a 440 code. In finding the source of the problem, I discovered that the gas fill pipe below the gas cap has rotted out and has developed, holes leading to raw gas spillage and failure of the emissions system. The design of the cover around the outside of this pipe caused the accumulation of dirt and debris over the years that has rusted the pipe from the outside in. This is a poor design that allows the dirt to collect here. There is nothing in the manual that indicates any cleaning of this area is required to prevent this from occurring.