Audi A4 (2015 – 2025) ABS Pump

Audi A4 ABS Pump and Brake Control Repair

A “Brake servo restricted” message on the A4’s display, sometimes with fault code C123EF0 for the hydraulic brake booster limit being exceeded, can trace back to the ABS pump and module. On this A4 the unit also plays a part in brake assistance and stability control, so a fault may bring several warnings at once. ABS and ESC are normally disabled when it faults, while the ordinary brakes still work; any brake-servo warning should be checked promptly, and a lit ABS light is an MOT fail. We repair your own unit and return it to your garage for refitting.

Reported A4 ABS Faults

• Brake servo restricted warning on the display
• C123EF0 hydraulic brake booster code
• Brake fluid not reaching one or more wheels
• ABS or traction control lights on
• ESC warnings appearing with the ABS light

Mechanic Found Nothing Wrong?

A servo warning on brakes that inspect as normal is where the ABS unit is worth a closer look — though a wheel-speed sensor, wiring or low fluid should still be ruled out. Our A4 ABS diagnose-and-repair guide sets out the signs; then describe yours on the repair form or contact us.

Why Choose Sinspeed?

✅ Lifetime warranty, with unlimited mileage built in

✅ Pressure delivery to every wheel circuit verified on our bench

✅ Your own unit returned, so no replacement-unit coding is normally required

Open an A4 ABS repair request and we will confirm how to post the unit.