How to troubleshoot coolant loss in an Audi A2?

I've noticed that my Audi A2 is losing coolant, but I can't find any leaks or other obvious signs of a problem. How can I troubleshoot and fix this issue?

First, check the radiator and hoses for any visible leaks. If none are found, try using a pressure tester to identify any small leaks. If still no leaks are found, it could be an issue with the water pump or head gasket. It's best to take it to a mechanic for further diagnosis and repair.

Before taking it to a mechanic, try checking the coolant reservoir cap. A faulty cap can cause coolant loss as it allows the liquid to escape in the form of steam. If the cap is damaged, it's an easy and inexpensive fix.