Why is my Audi A5 making a rattling noise under the hood?

I've noticed a rattling noise coming from my Audi A5 whenever I accelerate. What could be causing this and how can I fix it?

The rattling noise could be due to a loose or worn out serpentine belt. Check the belt for any signs of wear and tighten or replace it if necessary.

Another possible cause could be a failing tensioner pulley. This is responsible for maintaining tension on the belt, so if it's worn out it can cause the belt to slip and make noise. Have a mechanic check and replace the tensioner if needed.

It could also be an issue with the spark plugs or ignition system. If they are worn out, they can cause the engine to misfire and make a rattling noise. Consider getting a tune-up and replacing any worn out components.