Audi vehicles in MLBevo platform, commonly experience ABS failure which will cause the fault code C123EF0 – Hydraulic Brake Booster Limit Value Reached to be permanently stored within the ABS system. This fault is caused by failing vacuum sensor. But even after replacing vacuum sensor C123EF0 fault is still permanent in ABS unit.

Till now solution was replacing ABS unit. We have spent a lot of time reverse engineering ABS unit to understand how it operates and we made simple OBD solution for fixing this fault. Our solution does not permanently dissable C123EF0 but it just reset it. In case of failure of vacuum you will be warned again.