What it means
The control module monitors brake pressure sensor B for a steady, plausible signal. It sets this code when the signal is intermittent or erratic.
At a glance
- Usually lights the ABS or stability-control warning light
- The engine or gearbox may go into limp mode
How it works
Brake pressure sensor B reports hydraulic pressure to the brake control module so it can manage functions such as ABS and stability control. The module sets C056C when sensor B’s signal changes unpredictably or drops in and out instead of remaining plausible.
Common causes
Most likely first.
- Connector loose or chafed wiring
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Brake or ABS warning light
- Brake pressure or stability-control functions may be limited
How to diagnose it
- Read the ABS or brake module’s freeze-frame data and live reading for pressure sensor B to see when the signal became erratic.
- Inspect sensor B’s connector for looseness, corrosion, damaged pins, or signs that vibration could interrupt contact.
- Trace sensor B’s harness and check for chafing or routing against a vibrating part that could disturb the signal.
- With a scan tool connected, gently move the connector and harness while watching sensor B’s reading for dropouts.
- If the wiring and connections look sound, test sensor B’s signal circuit and sensor response against the manufacturer’s specification.
Common fixes
- Secure a loose sensor B connector and repair damaged terminals.
- Repair chafed wiring in the sensor B circuit.
- Reroute and secure the harness away from vibrating components.
- Replace pressure sensor B if its signal remains erratic with sound wiring and connections.
Can I keep driving?
A brake or ABS warning light may mean pressure-based ABS or stability-control functions are limited. Avoid hard braking and slippery roads, and stop if braking feels abnormal; have the system checked promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.