A8 Brake Pedal Issues: Spongy Feedback & Squeaky Brakes

Having some experience working on Audi models, I encountered a similar issue with my 2017 A7. The brake system symptoms you describe match what I experienced, particularly that spongy brake pedal feel and inconsistent brake response. In my case, the problem stemmed from an electrical undervoltage issue affecting the hydraulic brake system components. The workshop diagnosed it using their diagnostic equipment, which revealed the voltage irregularities were impacting the brake control module. The repair involved: Full system diagnostic check, Replacement of faulty voltage regulator, Bleeding the brake system, Testing the brake fluid levels and pressure Total cost was 240 Euro for parts and labor. The repair took about 4 hours to complete. Before making specific recommendations, could you provide: Current mileage on your A8, Any warning lights on the dashboard, Whether the brake fluid was recently changed, If you notice the issue more during cold starts The combination of squeaky brakes and pedal feedback issues often points to either electrical problems or air in the brake system. Your brake rotors might also need inspection since squeaking is a common wear indicator.

Last serviced at 111564 KM with brake fluid change. The brake pedal problem has definitely gotten worse since then. Just checked the dashboard again, no warning lights showing. The squeaky brakes are most noticeable in the morning. Since others mentioned electrical issues, I should add that the brake pedal feels normal sometimes, but mostly spongy. Was hoping to avoid major brake caliper repairs, but it sounds like a proper diagnosis is needed. Will probably need to get those brake pads and rotors checked too, given the symptoms.

Thanks for the additional details. Given my experience with the similar issue on my A7, this sounds less like an electrical problem and more like a hydraulic brake system issue, especially since you're not seeing any warning lights. The morning squeaks combined with the spongy pedal feel strongly suggests air might have entered the brake system after your last fluid change. When brake fluid absorbs moisture over time, it can create air pockets in the hydraulic brakes, leading to inconsistent pedal feedback. On my A7, I initially thought I needed new brake calipers, but the real fix involved: Complete brake fluid flush and system bleeding, Inspection of brake line connections, Replacement of a worn brake master cylinder seal The total repair ended up costing 320 Euro, significantly less than what new brake calipers would have cost. The pedal feel returned to normal immediately after the repair. Given your mileage and symptoms, I recommend having the brake fluid pressure tested and the entire hydraulic system inspected before replacing any major components. Your brake pads and rotors should also be checked, but they might not be the primary issue here.

Thanks for sharing those details about the A7 repair. The spongy brake pedal is really concerning me now since you mentioned it could be air in the hydraulic brakes. My morning squeaking sounds exactly like what you described. At 111564 KM, I know these systems need regular maintenance, but was hoping to avoid major work on the brake calipers and other components. Will book it in for that pressure test and brake system inspection you suggested. The cost estimate of 320 Euro for your repair seems reasonable if it fixes the issue. Rather sort this properly than risk problems with the disc brakes getting worse. I appreciate the advice about checking the whole system before jumping to replacing parts. Will update once I get it looked at.