What it means
Left Rear 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 rear wheel speed sensor B provides the ABS control module with a signal for that wheel, which the module also uses for stability and traction control. This code sets when the module detects an open in the sensor B circuit, so it cannot reliably receive the left rear wheel-speed signal.
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
- Record freeze-frame data and compare live speeds for all four wheels at a safe, low speed to confirm the left rear reading is missing or drops out.
- Inspect the left rear sensor B connector for a pushed-back pin, poor seating, corrosion, or damage.
- Trace the left rear sensor B wiring toward the ABS module and look for a break, stretched section, or impact damage.
- With the circuit safely isolated as specified by the manufacturer, check continuity through the sensor and its wiring to locate the open.
- If wiring and connections pass, test the sensor and ABS module connections using the manufacturer's procedure before replacing either component.
Common fixes
- Seat the left rear sensor B connector and secure the harness.
- Repair or replace the broken left rear sensor B wiring or terminal.
- Replace the failed left rear sensor B if its circuit is open.
- Repair the affected internal connection or module only after external wiring and the sensor test good.
Can I keep driving?
The vehicle may still brake normally, but ABS and stability or traction control may be unavailable, and brake assist or the speedometer may be affected. Drive cautiously, leave extra stopping distance, and avoid slippery roads until repaired.
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.