my service engine soon light stays on on 2000 Oldsmobile Silhouette

my service engine light stays on. I have tightened by gas cap (maybe I need a new cap?). Could an additive to my gas make a difference. thanks

Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
1 answer
This is the check engine light, and it's reacting to a fault in your emissions control system. If the gas cap doesn't resolve the light, it will be something else, and you'll need diagnosis. A fuel additive is extremely unlikely to make a difference.

http://repairpal.com/check-engine-light