What is the cause of the rattling noise in my BMW 3 Series engine?

I have noticed a rattling noise coming from the engine of my BMW 3 Series. It is particularly noticeable when starting the engine and sometimes while driving. Does anyone know what could be causing this and how it can be fixed?

The most common cause of rattling noises in a BMW 3 Series engine is a loose or worn-out timing chain. It is best to have a professional mechanic inspect and potentially replace the timing chain to avoid any further damage to the engine.

Another possible cause could be a loose heat shield or exhaust mount. This is a relatively easy fix that can be done at home with the right tools. Just make sure to check all the components around the engine and exhaust to determine the source of the noise.