Hello All,
I have had the problem of the P0440 code for about the last month on a
2000 GMC Jimmy. Tried the gas cap and a new air filter to no avail and the code would come back, once reset, after about 200 miles of driving. It needed an air filter, which I am embarrassed about, because there is no excuse for that.So I went outside and put the -just stand there and look at the engine treatment on it-. I found this solenoid thing on the passenger side, mid to back of the engine with what looked like it needed a connector on it. I am not sure what this part does but I found the wires tucked down into the wiring harness. I snapped it back on the solenoid, and reset the computer. I will let you all know if this fixes the problem. I can take a picture of it and show you guys the part I am talking about.
Take care, Rob