HelloCustomer The service engine soon light can come on due to a loose/missing gas cap, but is is usually a little more involved than that. It also comes on when one of the engines sensors that control/monitor the emissions is acting up. When the light comes on, it sets a code that is stored in the vehicles memory. The code can be retrieved with a scan tool by any shop (auto zone does this for free). Once you get the code, you will know what part of the emissions system needs repair.
If you get me the code, I will help you repair the problem.