Well my check engine light came on a few months ago. I've had it in to the mechanic her in California(recommended with 4.5 of 5 stars) and they did a diagnostic workup on it. The result was a P0440 (emissions) code from the computer and not a whole lot more. I was told to replace my gas cap before they could troubleshoot anymore. Well the gas cap was relatively new (changed it with other work in Virginia) and seemed to me to be a quick brush off. Being tech friendly, I looked up some info on the net and found that the fuel tank filler neck can crack or rust causing a leak. Sure enough I have a lot of rust on mine. I called the mechanic (who had one of his guys do it) and he said they checked it both ways but wouldn't go into more detail (and even asked me to tell him what it is once I take it to a Chevy dealership!). Needless to say I don't want to use him anymore but other than the filler neck, what else can it be? It's going to cost quite a bit through the dealership and the filler neck replacement seems within my level of ability. If that's the case I'd like to do it myself. If there's other stuff then I'll atleast get it diagnosed at Chevy. Please help!
They supposedly checked the sensors and smoked the system "from the front and back."