What are common causes for the Audi 80's check engine light to come on?

I recently purchased a used Audi 80 and noticed that the check engine light has been coming on more frequently. However, the car still seems to be running fine. What are some possible reasons for this warning light to come on?

One common cause for the check engine light to come on in an Audi 80 is a faulty oxygen sensor. This sensor measures the amount of oxygen in the exhaust gases and helps regulate the fuel-to-air ratio. If it malfunctions, it can cause the check engine light to come on.

Another possible cause for your check engine light is a loose gas cap. The gas cap helps maintain pressure in the fuel system and a loose cap can trigger the warning signal. Make sure to tighten the cap properly and see if the light goes off.

A failing catalytic converter can also result in the check engine light coming on. This component is responsible for converting harmful exhaust gases into less harmful emissions. If it is failing, it can trigger the warning light.