Why is my Audi A3's check engine light continuously on?

I recently noticed that my Audi A3's check engine light is continuously on, even after resetting it. What could be the cause of this and what steps should I take?

It is possible that there is a malfunction in one of your car's sensors or systems. It is important to have an experienced mechanic check and diagnose the issue as soon as possible. Ignoring the check engine light could lead to further damage and potentially expensive repairs.