What it means
Left Rear Wheel Speed Sensor B Correlation: the value does not correlate with the related sensor or expected pattern. 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 reports wheel speed to the ABS control module, which compares it with related wheel signals and expected patterns. This code sets when the left rear sensor B reading does not correlate with those references, which can result from a damaged encoder, incorrect sensor gap, or a faulty signal.
Common causes
Most likely first.
- Wheel speed sensor B signal fault
- Damaged or contaminated tone ring or encoder
- Loose or damaged sensor wiring or connector
- Incorrect sensor installation or excessive sensor gap
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
How to diagnose it
- Use freeze-frame data and live data to compare left rear sensor B with the other wheel speeds while driving slowly and steadily.
- Inspect the left rear sensor B connector and wiring for looseness, damage, or intermittent contact.
- Check the left rear tone ring or encoder for contamination, cracks, missing features, or physical damage.
- Verify that sensor B is correctly seated and that its gap and mounting match the manufacturer's specification.
- If the mechanical parts and installation are sound, test the sensor signal and wiring with the manufacturer's procedure.
Common fixes
- Clean contamination from the left rear encoder or tone ring if appropriate.
- Correctly seat and secure left rear sensor B and restore the specified gap.
- Repair loose or damaged sensor B wiring and connector terminals.
- Replace the damaged encoder, tone ring, or sensor identified by testing.
Can I keep driving?
ABS and stability or traction control may be unavailable, and the speedometer may be unreliable. Drive carefully with more stopping distance and avoid slippery conditions until the left rear signal agrees with the other wheel readings.
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.