I have had the EVAP P0440 code for a while now and finally got it fixed by replacing the EVAP Solenoid and the hose that goes from the bottom feed to the switch. I was finally going to get my car inspected this week (new state law in NY need the SES light off = horrible) and the SES light came on again. I checked under the hood and the hose that goes from the throttle body to the passenger side valve cover was disconnected at the valve cover and probably happend when I was driving. Im not sure, but would this cause the code to come up. I figure this would cause it to see flow when it wasn't supposed to, but if its not this then it may be the switch?? All hoses are clean.