[vettestr]

Dan, I didn't pick up on the fact this one has haunted you so far. I know the feelings all to well from my own collection of haunted houses.

Are you thinking the solenoid is hung open or leaking -- can you bypass or trick system to think it seals properly by plugging vent hose? What if it would pass the tests and not throw a code with hose blocked and prove fault before replacement? Just a shot in the dark. Jeff C