Why is my Audi A4's engine making a loud knocking sound?

I recently noticed that my Audi A4's engine has been making a loud knocking sound. It seems to occur more often when the engine is cold. What could be causing this and how can I fix it?

Hi Sophia, it sounds like your engine may be experiencing an issue with the timing belt or a faulty bearing. It's important to have this checked and fixed as soon as possible to avoid any further damage to your engine. I recommend taking your Audi to a trusted mechanic for a diagnosis and repair.