Hi, I have a 02 silverado 5.3L. It is throwing a P0440 code. I replaced the gas cap. That really changed nothing. It used to only happen above 60 degrees outside and under half a tank of fuel. Now it comes on when I get to 3/4 of a tank. I was messing around and grabbed the purge valve on the manifold. I could wiggle it back and forth easily. So I pulled it off and found that the oring looks pretty bad. There were remnants of the blue oring on the ID of the manifold hole. Could this bad oring be causing my code? I am not concerned with how loose it is. My 03 yukon's is the same way. Does anyone know of a source to get just the oring at? Thanks.