I started out with a p0400 (EGR) code. tested components and cleaned egr valve. Best guess was the egr solenoid. Replaced the solenoid and check engine light stayed out for about 4 days. When it came on again it had a code p0440 (EVAP). Changed gas cap to no avail, did this because it was quick and cheap. Could this be just coincidence or are the two codes somehow related? I have a 98 Impreza Outback Sport with 2.2L engine and automatic trans.
Thanks in advance.