Loud noise and engine light on

You may not realize this but I can't hear the noise, even when I step outside. Do you have an idea of which area it's coming from? What does it sound like? You can run the engine for a short time with the serpentine belt removed to see if one of the driven items is responsible for the noise.

There's well over a thousand potential problems the Engine Computer can detect. When it does, it sets a diagnostic fault code, and about half of them will turn on the Check Engine light. The place to start is by having the code(s) read and recorded. Many auto parts stores will do that for you for free.