2007 Chevrolet Cobalt • 71,000 miles

The check engine light came on in my car a few weeks ago. The coolant temperature was not reading numbers (just dashes). The light went off. The light came on again last night and the coolant temperature was not reading. Now the coolant temperature is reading, but the light is still on. I have checked to make sure the gas cap was on tightly, the coolant level is where it should be. The owners' manual said that bad gas could make the light come on as a fuel system indicator. I did recently get gas. I was wondering if you might have an idea of what's going on. I took the car the first time to Advance Auto and their system check said something about the thermostat. Thanks for your help.
October 30, 2012.

Check out the related content below while we wait for the question to be answered by a professional mechanic.