Cause
Faulty brake system control module
The module that runs ABS, stability control and — on many modern cars — the electric brake booster and regenerative blending. It is the last conclusion rather than the first, because almost everything that presents as a module fault is a sensor, a supply, an earth or the fluid.
Work through those first, in cost order: brake fluid condition, the wheel speed sensors and their shared supply, the module's power and earth, then its connectors. A module reporting implausible values is usually repeating what a sensor told it.
Replacement is rarely a plug-in job. These modules are coded to the vehicle and frequently need programming, calibration of the steering angle and yaw sensors, and a scan-tool bleed afterwards — so an exchange unit fitted without those steps produces a car with the same warning lights and a larger bill.
Typically specialist work. Needs equipment or training most home workshops do not have.
Codes this can cause (7)
Codes where this is a likely explanation first, rather than merely a possible one.
- C055F BSCM/EBBC Hydraulic Unit Performance High
- C0582 Brake Booster Motor A Phase U-V-W Circuit Range/Performance High
- C058A Brake Booster Motor A Position Sensor Circuit Range/Performance High
- C058E Brake Booster Motor B Position Sensor Circuit Range/Performance High
- U0129 Lost Communication With Brake System Control Module A High
- U0418 Invalid Data Received From Brake System Control Module A High
- U0438 Invalid Data Received From Trailer Brake Control Module High
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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