What are the potential causes for a check engine light appearing in an Audi A4?

I recently purchased a used Audi A4 and the check engine light has come on. I'm not sure what the issue could be and I want to know if it's something serious that needs immediate attention or if it's something I can fix myself. Any insights would be greatly appreciated!

The check engine light in your Audi A4 can be caused by a variety of issues, ranging from minor to more serious problems. It's important to get your car diagnosed by a professional, but it's also good to check simple things like the gas cap and the air filter before taking it in for repairs.

The most common cause for a check engine light in an Audi A4 is a faulty oxygen sensor. This can be easily replaced and doesn't require a professional unless you're not comfortable with working on cars.

I had a similar issue with my Audi A4 and it turned out to be a loose gas cap. Make sure it's tightened all the way before going to a mechanic to prevent unnecessary charges.