Why does my Audi A6's engine make a knocking sound when starting up?

I recently noticed that my Audi A6 makes a loud knocking sound when I start the engine. It usually lasts for a few seconds before going away. What could be the cause of this and is it something I should be concerned about?

The knocking sound could be due to a malfunctioning starter or a damaged flywheel. It's best to have a mechanic inspect and diagnose the issue to avoid potential damage to the engine.

It could be a sign of low oil pressure or a worn out oil pump. Check your oil levels and have them topped up if needed. If the problem persists, take your car to a certified mechanic for further inspection.

Sometimes, a knocking sound on startup can be caused by a faulty fuel filter. Have it inspected and replaced if needed to see if it fixes the issue.