What are the common causes for the engine light to turn on in an Audi A4?

I recently bought an Audi A4 and noticed that the engine light has turned on. I want to know what could be causing this and if I should be concerned.

The most common cause for the engine light to turn on in an Audi A4 is a faulty oxygen sensor. If this is the case, it is important to get it replaced as soon as possible to avoid further damage to the engine.

Another frequent cause for the engine light to turn on is a loose gas cap. Make sure to always tighten your gas cap properly after filling up your Audi A4 to avoid any issues.