What it means
Left Front Wheel Speed Sensor B Circuit High: the signal voltage is above the expected range. 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 reports wheel rotation to the brake control module for ABS and stability functions. This code sets when the module detects that this sensor circuit’s signal is above its expected range, which can occur if the signal is shorted to a power source.
Common causes
Most likely first.
- Signal wire shorted to battery
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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 left front sensor B speed with the other wheels to confirm whether its signal is stuck high or implausible.
- Inspect the left front sensor B connector and harness for corrosion, pin damage, or wiring pinched against a power source.
- Move the harness gently while watching live data to see whether the high reading changes with harness position.
- Use the wiring diagram to check the sensor B signal circuit for a short to battery voltage and inspect its supply and connections as specified by the manufacturer.
- If the circuit is sound, inspect the sensor and tone ring or encoder and test the sensor output against the manufacturer's specification.
Common fixes
- Repair a left front sensor B signal wire shorted to a power source.
- Clean and secure corroded or loose connector terminals.
- Replace a damaged connector or repair wiring pinched against a power source.
- Replace sensor B if its signal remains high with a verified circuit.
Can I keep driving?
ABS and stability control may be disabled, and the speedometer may behave erratically. Drive cautiously, leave extra stopping distance, and avoid slippery roads where those systems would be important.
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.