Why is my Ford Focus's check engine light on?

I recently bought a Ford Focus and the check engine light keeps coming on. I'm not sure what could be causing it. Any advice?

It's possible that there could be an issue with your oxygen sensor. It's best to get it checked by a mechanic to be sure.

I had a similar issue with my Ford Focus and it turned out to be a faulty gas cap. Try replacing yours and see if that helps.

Make sure you're using the right type of gas for your car. Using the wrong octane level can cause the check engine light to come on.