gascap light came on, replaced gas cap. Now check engine light or MIL comes on with code P0440 small evap system leak. Engine sounds like it has a vacuum leak, but all hoses and fittings are fine. Could the purge valve solenoid cause this?, either that or theres a small hole in EVAP canister that is not coming up. Dealer mechanic said "I don't know" so now what? EVAP system has been fogged no leaks found. Local mechanic buddy and myself are just as confused.