Here is a stumper. Last week, while driving around 40 MPH, the check engine light on my 2007 G6 2.4L with 60,500 miles came on and the DIC said engine power reduced. I pulled over and shut the car down and restarted it, but it still had little power. I went to Autozone and their scan tool would not link up with it, however upon leaving there, it ran at full power, though the light was still on. Later that day, it went out. Today, I went to start it and there was a delay in the starter engaging, and then the light came back on and the engine stuttered badly and struggled to hit 20 MPH. When I got home, I restarted it and it ran fine, but the light was still on. I took it to my nephew who is an ASE certified mechanic and a former GM mechanic who couldnt get it to link with a Mac diagnostic computer. He said that usually means a sensor is shorting out and causing the computer port to get no power. Anyone heard of this? I am aware there is a catalytic converter notification about them failing (I got one last November). I am hoping this is the problem though I dont get any weird smells. I really can't afford the $100 the dealer wants just to scan the car and internet searches aren't really finding anything. My last Pontiac was a POS, I am really hoping this one isn't going to be the same.