after fuel cap loose, reset at autozone "check engine light",.drove 1300 miles and light come back again.
checked at autozone ,same code po442.reset again and replaced volvo fuel cap .drove 50 miles light come back.
engine works ok rpm fine in warious speed, no power loss,any idea?

 

Probably a leak in the cap. Make sure the cap is on right.

 

cap brand new from volvo dealer replaced fiew days ago.anyone know aboutvacum diagram including evap valve?

 

their is a vacuum diagram on the underside of the hood.