What Causes Engine Knocking in an Audi 80?

I recently noticed a knocking sound coming from my Audi 80's engine. What could be causing this issue and how can I fix it?

The most common cause of engine knocking in an Audi 80 is low quality fuel. It's important to use high-octane fuel to prevent this issue.

Another possible cause of engine knocking is a faulty spark plug. Check and replace your spark plugs if needed.

Old and worn out engine parts, such as bearings or pistons, could also result in engine knocking. Regular maintenance and replacing old parts can help prevent this issue.