The image that Loren put up....( The upper image), #5....Vacuum valve....I have replaced several of these. When it fails, it will give a secondary air code.

 

Same fault code ... I finally had this checked out on my car. Apparently I need a new check valve and air pump valve. one was corrodded / blocked and one they recommened be changed at the same time ... i dont recall which was which. Parts are about $75 each and labor is $300.
Likely lots of other points of failure but these were mine for this code.