Why does the Audi A2's engine make a rattling noise when idling?

I recently purchased a used Audi A2 and have noticed a rattling noise when the engine is idling. What could be causing this issue and what can I do to fix it?

The rattling noise could be caused by a loose or damaged heat shield on the exhaust system. You can try tightening any loose bolts or taking it to a mechanic for a professional inspection.

Another possible cause could be a worn or damaged bearing in the engine. It's best to have a mechanic take a look and potentially replace the bearing if needed.

It's also possible that the rattling noise is just a normal characteristic of the Audi A2's engine design. However, if you're concerned, it's always best to have a mechanic check it out just in case.