p0440 code

emissions place tested cap as ok, where do i go from here, what is the most common problem for the p0440 code?

P0440 - Evaporative Emission Control System

Try This Link...
http://www.automotiveforums.com/vbulletin/search.php?searchid=1775965

The cap may be within spec and still leak. Its' leak combined with a bunch of other little leaks can combine to set error code.

My gas cap also "didn't leak" but at $5 it was cheap insurance and I replaced it anyway. My error code went away. IT still means I'm right at the hairy edge but it passed emissions testing.