Hello! My CEL came on last week with the code P1457. I'm thinking of ordering the CVS valve, and bypass valve based on what I've read these are the two most common parts needed and are cheaper to replace than to get a diagnostic. However, I'm unsure if I'll need the purge valve or the possibility that what I've read is incorrect. What are the best parts to replace in regards to this issue? I live in CA in case that makes a difference on what parts go bad.