1999_green_mustang

Hello I'm a newb to the forum but looking for guidance. I have a 1999 ford mustang. The CEL keeps coming on, the code is P0411. I've replaced the secondary air injection pump with a brand new motorcraft cx-1718. The CEL went away for a few months after that. Now it is back on again, and the same thing, P0411. When I installed the new pump, I also added a longer hose and ran it into the engine area with the mushroom cap, I heard that these pumps usually go bad from water getting inside them due to the hose position being behind the fender being susceptible to water. What could be causing me to be getting this CEL again? Is my pump defective? Is there something else I can check or try ? Any help is very appreciated! I'm hoping someone here has run into this same problem fingers crossed