Why does my Audi's engine make a rattling noise?

I recently noticed a strange rattling noise coming from the engine of my Audi. It seems to happen when the car is idling or at low speeds. What could be causing this and how can I fix it?

It sounds like your engine may have a loose belt or a worn out pulley. These components can cause a rattling noise when they are not functioning properly. I suggest bringing your Audi to a certified mechanic to have it inspected and repaired if necessary.