Anyone know what would cause a P401 and a P404 OBD II to show up? My tech had replaced my gas cap after he put it on a smoke machine. He said the filler neck grommet was leaking a little but shouldnt be a aproblrm. Well I think its a problem. My question is...wouldn;t a EVAP leak at the fille rneck set of a small EVAP code as well?

 

A bad EGR valve.