Why does my Audi A3's engine make a rattling noise at start?

Every time I turn on my Audi A3, the engine makes a rattling noise for about 5 seconds before it begins to run smoothly. What could be causing this and is it something I should be concerned about?

The rattling noise during startup could be caused by a loose exhaust heat shield. It's a quick fix at a mechanic and shouldn't cost too much.

The rattling noise you hear is most likely due to a worn timing chain tensioner. It's recommend to have this checked by a mechanic to avoid any potential engine damage.

I had a similar issue with my Audi A3 and it turned out to be a faulty fuel pump. It's best to have this checked and replaced if necessary.