Audi, Volkswagen, Porsche, Bentley, Lamborghini · Diagnostics & repairs

VAG C123EF0 ABS Reset & Fault Repair

C123EF0 — Hydraulic Brake Servo Limit Reached

ABS, ESC or brake warning lights showing? C123EF0 is an ABS/ESP fault relating to the hydraulic brake assistance system. Repeated brake-assistance vacuum faults can cause the hydraulic boost compensation (HBC) activation limit to be reached, leaving a stored fault that a normal fault-code clear may not resolve.

We can repair this fault while you wait at Premier Coding in Blackburn. Contact us with your registration, model and diagnostic fault report to confirm suitability and book your visit.

The underlying vacuum, brake booster or related electrical fault must be diagnosed and corrected as part of resolving the problem. A reset alone does not repair that cause.