OBD-II code C0544 indicates an open-circuit condition detected in Brake Pressure Sensor 'B' by the ABS/ESC (anti-lock brake / electronic stability control) module. The sensor monitors hydraulic pressure within the brake system and reports it to the control module, and an 'open' reading means the module has lost electrical continuity in the sensor's reference, ground, or signal circuit. As a result, ABS, traction control, and stability control functions are typically disabled until the fault is repaired.
Wires leading to the brake pressure sensor are exposed to underhood heat, vibration, road debris, and chemical contamination, and are the most common source of an open-circuit fault.
Mo intrusion, road salt, or simple mechanical loosening at the sensor's electrical connector interrupts the circuit and produces an open-circuit code.
The sensing element itself can fail open internally; this is a common cause once wiring and connector issues are ruled out.
A break in the 5-volt reference or sensor ground supply between the module and the sensor will register identically to an open circuit at the sensor.
Fluid leaks or contamination around the sensor connector can corrode terminals and create a high-resistance or open condition.
Rare. Internal module failure can mimic an open sensor circuit, but this should be considered only after the sensor, wiring, and connector are verified good.
The vehicle will usually still brake normally, but ABS, traction control, and stability control will be disabled. It can be driven cautiously to a repair facility, but should be diagnosed soon, especially in wet, icy, or uneven-road conditions.
Wiring and connector problems at or near the brake pressure sensor are the most frequent cause, with the sensor itself a close second. A proper circuit test should be done before replacing any part.
Almost never. C0544 is a sensor-circuit code and the control module is the least likely cause. Despite this, it is common for drivers to be told a module replacement is needed. Always confirm the sensor, wiring, and connector are good first, because module replacement is expensive and rarely the real fix.
A basic scan tool capable of reading chassis codes, plus a digital multimeter, are sufficient for the diagnosis in most cases. Service information for wiring colors, connector pinouts, and sensor resistance values for the specific vehicle is also required.