why would the engine light come on but the car runs great? on 2005 Cadillac Escalade

engine light just came on

Asked by for the 2005 Cadillac Escalade
Check this article in the Repairpal's Auto Repair Encyclopedia; http://repairpal.com/check-engine-light
1 more answer
Fuel cap could be loose. Tighten cap and drive for a day or two to see if light goes off.