I have brought it to a couple of mechanics, as well as to the GM Dealer who all told me that it was caused by a Lead Fuel Mixture Reading and just to ignore it. They all reset the light and within a few miles the "Check Engine" light was back on.

I had the vehicle in several times and each time I was told it was a different problem. However, the last couple of times I was told it was the gas tank lid. It has been replaced twice and the engine light is still on.