What might be the problem? My engine coolant light comes on (and stays on) even though I've just filled up the engine coolant tank; The temp guage is also a little high. Before I filled up the coolant tank, I had no heat either.
If you had no heat, that leads me to believe the coolant was very low. Reconfirm that it is full. IF it is, there is a sensor in the overflow jug that must be bad. Check that. Keep an eye on the level and make sure to use the recommended coolant for your vehicle. DO NOT MIX GM'S DEXCOOL WITH ANY OTHER TYPE OF COOLANT.