Why does my Audi A3 produce high exhaust emissions?

I've recently noticed that my Audi A3 is producing high levels of exhaust emissions. How can I fix this issue and what could be causing it?

The most common reason for high exhaust emissions in an Audi A3 is a malfunctioning oxygen sensor. This sensor measures the level of oxygen in the exhaust and sends signals to the engine to adjust the fuel-to-oxygen ratio. If it's faulty, the engine may not be getting the correct amount of fuel, causing higher emissions.

Another possible cause is a clogged catalytic converter. This part is responsible for converting harmful exhaust gases into less harmful ones. A buildup of debris or carbon can hinder its function and lead to increased emissions. Have it checked and replaced if necessary.