How can I diagnose a faulty oxygen sensor in an Audi 80?

I've been noticing a decrease in fuel efficiency and some strange exhaust emissions from my Audi 80. I suspect that the oxygen sensor may be malfunctioning, but I'm not sure how to confirm this or what steps to take. Can anyone provide guidance on diagnosing and potentially replacing a faulty oxygen sensor in an Audi 80?

Start by using an OBD-II scanner to check for any stored error codes related to the oxygen sensor. If there are codes present, it's likely that the sensor needs to be replaced. However, you can also perform a real-time scan and look at the sensor's voltage readings for a more accurate diagnosis.

Another way to check if the oxygen sensor is faulty is by performing a visual inspection. Look for any physical damage or corrosion on the sensor. Additionally, if the sensor's wires are damaged or disconnected, it may be causing issues. Make sure to also check the sensor's connection to the exhaust system and ensure it is secure.

Before replacing the oxygen sensor, try cleaning it with a specialized sensor cleaner. Sometimes deposits and build-up can cause a faulty reading. If cleaning the sensor doesn't improve its performance, then it's likely that it needs to be replaced.