How do I troubleshoot a faulty brake system on my Audi 80?

I am experiencing issues with my brakes, such as a spongy pedal and decreased braking power. What could be causing this and how can I fix it?

First, check your brake fluid levels. If they are low, top them off and see if that improves the pedal feel. If the issue persists, it could be a problem with your brake lines or master cylinder. It's best to have a professional mechanic diagnose and repair these components.

Another possible cause could be air in your brake lines. You can try bleeding the brakes to see if that improves the pedal feel. If not, it's best to have a mechanic check for any other underlying issues.