Why is my BMW 5 Series engine making a rattling noise?

I recently noticed that my BMW 5 Series engine is making a rattling noise. It doesn't happen all the time, but it's definitely noticeable when it does occur. What could be causing this and how can I fix it?

It's possible that there may be an issue with your engine's timing chain. This can often cause a rattling noise when it's worn or loose. It's important to have this checked and repaired by a qualified mechanic as soon as possible to avoid any further damage to your engine.