Why does my Audi A6's engine make a knocking noise?

I recently noticed that my Audi A6's engine is making a knocking noise when I start it up. What could be causing this and how can I fix it?

The knocking noise could be due to a few different reasons. It could be a sign of low oil levels or poor oil quality. It could also be a problem with the fuel system, such as dirty fuel injectors. I recommend checking your oil levels and getting an oil change if needed. If the issue persists, it's best to take your car to a mechanic for further diagnosis.