Why is the engine in my Audi A2 making a strange rattling noise?

I recently noticed that my Audi A2's engine is making a strange rattling noise. It occurs when I accelerate or when driving at high speeds. What could be causing this issue and how can I fix it?

It's possible that a loose or damaged heat shield on the exhaust system is causing the rattling noise. It's a good idea to have a mechanic inspect and tighten or replace any loose or damaged heat shields.

Another possibility could be a worn out or damaged serpentine belt. If the rattling noise is accompanied by a squealing or chirping sound, it's likely due to a worn out serpentine belt. Have it replaced as soon as possible to prevent further engine damage.