What is the cause of unusual engine noise in an Audi A4?

My Audi A4 just started making a strange noise from the engine. It sounds like a rattling or clanging noise. What could be causing this and how can I fix it?

There are a few possible causes for unusual engine noise in an Audi A4. One possibility is that there could be an issue with the timing chain tensioner, which is responsible for keeping the timing chain in place and ensuring proper engine timing. Another possible cause could be a worn or damaged timing belt, which can also cause noise when it starts to fail. It's important to get this checked and repaired by a qualified mechanic to avoid any potential damage to your engine.