03 Check Engine Light Question

[Ed G.]

Had the same problem last week. Lost some performance and mpg went down.Then the light came on, so I called OnStar. They said it was a problem with the emission system.The dealer said it would a couple days before they could take a look at it. For the hell of it I disconnected the negative cable and let it sit for a few hours. The next time I drove it the light went off, performance and mpg went up. Haven't had any problems since.