Chevrolet: Check engine light, chev malibu, gas cap

Question
What cause the check engine light on a 2004 Chev. Malibu come on and stay on?

Answer
Katharine;
       there are a list of things that could do it, it is there for your own safty. The engines now have a lot of sensors that will tell you when a part is worn out or in need of cleaning or replacing.or that the engine is not running like it should be - so it could be on for many reasons, even if the gas cap was left off / or on wrong will cause it to come on. so do not over look the light as there is something that needs checking into.if it did not come on and you did not see or hear the problem you would soon break down and get towed and stuck with a big bill so the check engine light is there to help -- ok