What it means
Left Front Wheel Speed Sensor B Circuit/Open: the circuit is open. Wheel-speed signals feed ABS, ESC, traction control and the speedometer.
At a glance
- Usually lights the ABS or stability-control warning light
- The engine or gearbox may go into limp mode
How it works
The left front wheel speed sensor B circuit provides wheel-speed information to the brake control module for ABS, stability control, traction control, and sometimes the speedometer. This code sets when the module detects an open circuit or loses the electrical connection to that specific sensor circuit.
Common causes
Most likely first.
- Sensor wiring broken
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
How to diagnose it
- Save freeze-frame data and compare live speeds for all wheels to confirm whether the left front sensor B reading is missing or drops out.
- Inspect the left front sensor B connector and nearby harness for a loose plug, pushed-back pin, corrosion, or a broken wire.
- Follow the left front sensor B wiring around the wheel and suspension for stretching, rubbing, impact damage, or a break at a flex point.
- Check circuit continuity and connector contact for the left front sensor B using the vehicle wiring diagram and the manufacturer's procedure.
- If the external circuit is intact, test the sensor and its control-module connection for an internal open.
Common fixes
- Reconnect and secure the left front sensor B connector.
- Repair a broken or damaged wire in the left front sensor B circuit.
- Replace a connector with a loose or pushed-back terminal.
- Replace the left front wheel speed sensor B if testing confirms it is internally open.
Can I keep driving?
ABS, stability control, and traction control may be unavailable, and the speedometer may be affected. Drive cautiously and leave extra stopping distance; stop if braking behavior changes.
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.