Why does my Audi A4's engine make a clicking noise upon start-up?

I recently purchased a used Audi A4 and have noticed that upon starting the engine from a cold start, there is a noticeable clicking noise coming from the engine. It disappears once the engine is warmed up. What could be causing this and is it something to be concerned about?

The clicking noise you are hearing is most likely caused by a worn valve or valve lifter. As the engine warms up, the metal expands and the noise disappears. It is not a major concern, but it is something that should be addressed by a mechanic in order to avoid any further damage to your engine.