What it means
Right 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 right rear Wheel Speed Sensor B measures wheel rotation for the brake control system. C066B sets when its reading does not agree with a related wheel-speed signal or the expected pattern, which can point to a sensor, encoder, installation, or signal problem.
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 and live wheel-speed data to compare right rear Sensor B with the other wheels, noting whether the mismatch appears at low speed, during turns, or continuously.
- Inspect the right rear Sensor B connector and wiring for looseness, corrosion, damage, or a poor connection.
- Check the tone ring or encoder for cracks, missing features, rust, or debris that could distort the Sensor B reading.
- Confirm Sensor B is the correct type, fully seated, and positioned with the gap specified by the manufacturer.
- If no physical cause is apparent, test the Sensor B signal and circuit against the manufacturer's specification, comparing readings as appropriate with the opposite side.
Common fixes
- Clean contamination from the right rear tone ring or encoder if this can be done without damaging it.
- Repair loose or damaged Sensor B wiring and connector terminals.
- Correct Sensor B seating or gap according to the manufacturer's procedure.
- Replace a damaged encoder or a sensor that fails testing against the manufacturer's specification.
Can I keep driving?
ABS and stability control may be disabled, and brake assist may be reduced. If the brakes feel normal, drive gently to a repair location, leaving 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.