Once repaired you can install this locking cap to keep debri out:
http://www.amazon.com/gp/product/B001...
In this video I show you how to replace this common failure for the 2009-2012 Ford Fusion causing the check engine light to come on. This pipe may set a variety of codes including P0455 P0456 P0457 and most common of all P0442.
Clearing codes properly-
   • How To Clear Your PCM'S Memory On For...