What it means
The brake pedal position sensor B has an open control circuit. The ECU loses analogue feedback about pedal travel - used by stop-start, regenerative braking and adaptive cruise to coordinate engine, motor and friction brakes.
At a glance
- Usually lights the check-engine light
How it works
Brake pedal position sensor B reports pedal movement to the control module, which uses the signal to coordinate functions such as stop-start and braking assistance. This code sets when the sensor B circuit is open and the module cannot receive a usable signal through that circuit.
Common causes
Most likely first.
- Open in sensor or wiring
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Check-engine or brake warning light may illuminate
- Stop-start or other brake-related functions may be unavailable
How to diagnose it
- Read freeze-frame data and live data for brake pedal sensor B, and compare its reading with sensor A while pressing and releasing the pedal.
- Inspect sensor B's connector and nearby wiring for a loose plug, damaged insulation, corrosion, or a pin pushed back into the connector body.
- Check the sensor B circuit continuity and connector terminal contact using the vehicle wiring diagram and manufacturer's procedure.
- Check for an open within the sensor or its wiring, and inspect accessible module or sensor connections for signs of a damaged joint.
- If wiring and connections are intact, test sensor B and the relevant module circuit according to the manufacturer's diagnostic procedure.
Common fixes
- Reconnect a loose sensor B plug and secure the wiring.
- Repair an open or damaged wire in the sensor B circuit.
- Restore a pushed-back or corroded connector terminal.
- Replace the faulty sensor or repair a confirmed internal connection fault.
Can I keep driving?
The vehicle's basic braking may remain available, but brake-related assistance, stop-start, or other electronic functions may be disabled. If a brake warning appears, pedal behavior changes, or braking feels abnormal, stop safely and have the system checked before continuing.
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.