Frayed, chafed, or internally broken wiring in the brake pressure sensor circuit, often near the master cylinder or along the ABS harness; Corroded or loose electrical connector at the brake pressure sensor or ABS module; Failing brake pressure sensor B itself, producing an erratic output as it heats up or vibrates; Low or contaminated brake fluid causing pressure pulsations that the sensor reads as erratic; Air trapped in the hydraulic system after recent brake work, creating pressure spikes the sensor interprets as faults; Internal fault in the ABS control module affecting the sensor reference voltage or signal processing; Poor ground connection for the ABS module or sensor circuit, causing voltage fluctuations

DTC codes / C05xx · Brakes, steering and suspension / C056C

C056CBrake Pressure Sensor B Intermittent/Erratic

Q: What does code C056C mean?

Brake Pressure Sensor B Intermittent/Erratic. C056C means the antilock braking system (ABS) module has detected an intermittent or erratic signal from brake pressure sensor B, which is typically the master cylinder pressure sensor or a second pressure sensor in the hydraulic circuit. The computer sees the sensor voltage jumping, dropping out, or not matching expected values under braking, so it flags the circuit as unreliable rather than completely failed.

C056C means the antilock braking system (ABS) module has detected an intermittent or erratic signal from brake pressure sensor B, which is typically the master cylinder pressure sensor or a second pressure sensor in the hydraulic circuit. The computer sees the sensor voltage jumping, dropping out, or not matching expected values under braking, so it flags the circuit as unreliable rather than completely failed.

SystemChassis

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaBrakes, steering and suspension

Symptoms you may notice

ABS warning light illuminated on the dashboard, often with the traction control light
Brake pedal feels normal in most driving situations because the fault is intermittent
Momentary loss of ABS or traction control assistance during hard braking or slippery conditions
Occasional brake pedal pulsation or unusual pedal feel when the sensor signal drops out
Stability control or hill-start assist disabled message on vehicles equipped with those systems
Often no symptoms besides the warning light, especially if the erratic signal is brief

Common causes, most likely first

Frayed, chafed, or internally broken wiring in the brake pressure sensor circuit, often near the master cylinder or along the ABS harness
Corroded or loose electrical connector at the brake pressure sensor or ABS module
Failing brake pressure sensor B itself, producing an erratic output as it heats up or vibrates
Low or contaminated brake fluid causing pressure pulsations that the sensor reads as erratic
Air trapped in the hydraulic system after recent brake work, creating pressure spikes the sensor interprets as faults
Internal fault in the ABS control module affecting the sensor reference voltage or signal processing
Poor ground connection for the ABS module or sensor circuit, causing voltage fluctuations

How to diagnose and fix it

Inspect the brake pressure sensor B connector and wiring for corrosion, chafing, or loose pins, and repair as needed
Check brake fluid level and condition, then bleed the brakes if the fluid is dark or air is suspected in the system
Use a scan tool to view live brake pressure sensor B data while wiggling the harness and tapping the sensor to reproduce the erratic signal
Measure sensor reference voltage and signal voltage with a multimeter, comparing against manufacturer specifications
Perform a resistance and continuity test on the sensor circuit wiring back to the ABS module
Replace brake pressure sensor B if live data confirms an erratic output that is not caused by wiring or fluid issues
Clear the code and verify the repair by test-driving the vehicle and monitoring live data for stable pressure readings

Intermittent brake pressure sensor traps

A chafed wire inside the harness loom often causes this code only when the engine moves under load or the vehicle hits bumps, so a stationary wiggle test may not reproduce it.
Technicians sometimes replace the brake pressure sensor only to find the real fault is a corroded ground strap on the ABS module, which creates voltage offsets that mimic a bad sensor.
Low brake fluid or a failing master cylinder can produce pressure pulsations that the sensor reports as erratic, so always verify hydraulic health before condemning the sensor.
This code does not always mean the sensor is failing; a weak battery or charging system can cause the ABS module to log erratic sensor signals during cranking.
After replacing the sensor, some vehicles require a brake pedal calibration or ABS bleed procedure with a scan tool, otherwise the code may return immediately.

Can I keep driving with C056C?

You can usually drive the vehicle with this code because the fault is intermittent, but avoid hard braking, towing, or driving in slippery conditions until it is repaired. If the ABS light is on continuously or the pedal feels abnormal, have the system inspected before continuing to drive.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.