Spongy Brake Pedal & Vibration in Giulietta Diesel

Having experienced similar symptoms on my 2015 Alfa Romeo Mito JTDm, I can relate to this brake pedal issue. The spongy feeling combined with vibration typically indicates air in the hydraulic brakes system or worn brake components. When this happened, inspection revealed two issues: the brake fluid was contaminated with moisture, and the brake rotors had developed uneven wear patterns. The spongy pedal feel came from air bubbles in the hydraulic brake lines, while the vibration was caused by warped rotors. The fix required a complete brake fluid flush, replacement of both front brake rotors, and new brake pads. Brake shoes and other components were inspected but found to be within acceptable wear limits. This is considered a serious safety issue that needs prompt attention. While driving remains possible, braking performance is compromised and could fail under emergency conditions. The squeaky brakes that followed the spongy pedal were an additional warning sign that should not have been ignored. Best approach is to have a certified mechanic perform a full brake system diagnostic, as these symptoms often indicate multiple related issues rather than a single problem.

Thanks for sharing that experience, sounds almost identical to what I am dealing with on my Giulietta. Had the same spongy brake pedal feel followed by vibrations. Did get it checked last week and indeed found contaminated brake fluid plus some issues with the brake calipers. Wondering if you remember roughly how much the repairs set you back? Also curious if the problem has stayed fixed or if you have had any brake system issues since the repair was done?

The total repair cost for my Mito came to around 240 Euro, mainly covering the undervoltage issue that was causing problems with the brake system electronics. The mechanic also did a complete brake fluid flush and adjusted the calipers during the same service. Since getting the work done six months ago, the braking system has performed flawlessly. No more spongy pedal feel, squeaky brakes, or unwanted vibrations. The brake pads are gripping properly now and the disc brakes work exactly as they should. What made a big difference was getting the electrical system sorted, turns out the undervoltage was affecting multiple brake components. Having a properly pressurized brake fluid system restored that firm pedal feel you expect from these cars. If your symptoms match what I experienced, you should see similar lasting results once repaired. Just make sure they do a thorough system check including the electrical components, not just the mechanical brake parts.

Thanks everyone. Finally got the car back from the shop yesterday after getting the full brake system sorted. Total bill came to 480 Euro, more than expected but worth every cent for proper braking. They found moisture in the brake fluid causing that spongy pedal feel, plus the metal brakes had some uneven wear. Ended up needing new brake pads, a fluid flush, and caliper adjustment. The mechanic showed me how the old brake calipers were sticking slightly, which explained the vibration. Test drove it this morning and the difference is night and day. Brake pedal is firm again, no more vibrations or squeaky brakes. Feels like a new car. Really glad I got a second opinion and found a better shop, their thorough inspection caught issues my previous mechanic missed completely. For anyone facing similar brake problems, definitely worth getting a proper diagnostic check rather than just assuming its worn pads. Sometimes multiple brake components need attention to fully solve the issue.