Spongy Brake Pedal Feedback on Skoda Fabia

The symptoms you describe sound similar to an issue I experienced with my Skoda, though I'm uncertain if it's precisely the same Fabia model year. In my instance, the feedback from the brake pedal, a sort of inconsistent resistance, was linked to the brake system. Have you inspected the brake pads and metal brakes for wear or damage?

Brake pads and metal brakes, gotcha. How exactly did undervoltage mess with your brake system? I thought hydraulic brakes were pretty straightforward.

Undervoltage can wreak havoc on the ABS module, which influences the behaviour of the hydraulic brakes. Considering the age of your Fabia, there's a strong possibility that the brake pads themselves are also worn. I'd recommend having a qualified technician inspect the entire brake system, including the ABS module, to ascertain the precise cause of the issue.

Thanks for the insight! The workshop confirmed it. Undervoltage fried the ABS module, and the brake shoes and brake pads were totally gone. Repair cost 240€.