How do I troubleshoot an issue with my Audi A3's turbocharger?

My Audi A3 seems to be experiencing issues with its turbocharger, causing loss of power and strange noises. What could be causing this and how can I fix it?

First, check for any clogs or damage in the air intake system. Then, make sure the turbocharger boost pressure and wastegate are functioning properly. If those are all good, it could be an issue with the turbo itself and may require replacement.

Another potential cause could be a faulty turbo diverter valve. If that's the case, you'll need to replace it with a high-quality, OE replacement part to ensure proper functionality.

If you hear a whistling noise when the turbo is spooling, it could be a sign of an intake or boost leak. Check all connections and hoses for leaks and make sure they're securely fastened.