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C0051Right Rear Wheel Speed Sensor Circuit Range/Performance

The ABS module has detected that the right rear wheel speed sensor signal is implausible or inconsistent compared to the other three wheels.

Definition

The ABS/EBCM continuously compares all four wheel speed sensor signals while driving. C0051 sets when the right rear sensor produces a signal that is electrically present but out of range — erratic, intermittent, or reading a speed that does not agree with the other wheels. When the code is active the module typically disables ABS, traction control, and stability control and illuminates their warning lamps; base hydraulic braking remains, but anti-lock intervention is lost.

Common causes

  • Contaminated or damaged tone/reluctor ring at the right rear hub (rust jacking, cracked ring, packed debris)
  • Excessive air gap or a loose/incorrectly seated wheel speed sensor
  • Chafed, corroded, or intermittently open sensor wiring in the harness run to the rear axle
  • Failing wheel bearing/hub assembly allowing sensor-to-ring runout
  • Internal wheel speed sensor failure producing a weak or dropout-prone signal
  • Water intrusion or corrosion in the sensor connector

Common misdiagnoses

  • Replacing the wheel speed sensor when the tone ring or hub bearing is the real fault
  • Replacing the ABS module for what is a wiring or connector problem
  • Replacing sensors on the wrong wheel because the axle position was not confirmed with live data
  • Condemning the sensor when a mismatched tire size is skewing the speed comparison

Troubleshooting steps

  1. 1.Compare live wheel speed data

    Drive the vehicle while graphing all four wheel speeds on a scan tool and watch for the right rear signal dropping out, spiking, or diverging above roughly 5 mph.

  2. 2.Inspect the sensor and tone ring

    Remove the right rear sensor and check for metallic debris on the magnetic tip, rust buildup on the reluctor ring, and cracked or missing ring teeth.

  3. 3.Check the wiring and connector

    Wiggle-test the harness from the sensor to the body connector while watching live data, and inspect for chafing, green corrosion, and water intrusion.

  4. 4.Test sensor output

    For passive sensors, verify AC voltage rises smoothly with wheel speed (typically 0.3 V AC or more when spun by hand); for active sensors, confirm supply voltage and a clean square-wave signal with a scope.

  5. 5.Check hub bearing play

    Rock the wheel at 12 and 6 o'clock — any perceptible play in the bearing can vary the sensor air gap and corrupt the signal.

  6. 6.Clear codes and retest

    Clear the DTC, road test above 25 mph with several moderate stops, and confirm the code does not reset before returning the vehicle.

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