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DTC codes / C05xx · Brakes, steering and suspension / C050C

C050CLeft Rear Wheel Speed Sensor A Circuit/Open

C050C indicates that the anti-lock brake system (ABS) control module has detected an open circuit in the left rear wheel speed sensor A circuit. The module monitors the sensor's signal and wiring for continuity, and when it sees no return signal or an abnormal voltage drop, it stores this code and typically disables ABS and traction control.

SystemChassis
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaBrakes, steering and suspension

Symptoms you may notice

  • ABS warning light illuminated on the dashboard
  • Traction control or stability control warning light also on
  • Often no symptoms besides the warning light
  • ABS may not activate during hard braking, increasing stopping distance on slippery surfaces
  • Speedometer may fluctuate or read incorrectly if the sensor signal is used for vehicle speed
  • Cruise control may become inoperative on vehicles that use wheel speed for its operation

Common causes, most likely first

  1. Damaged or corroded wheel speed sensor connector at the left rear wheel
  2. Broken or chafed wire in the left rear sensor harness, often near suspension components
  3. Failed left rear wheel speed sensor
  4. Debris or metallic particles on the sensor tip or tone ring
  5. Damaged tone ring (reluctor ring) on the left rear axle or hub
  6. Water intrusion into the sensor connector or wiring
  7. Faulty ABS control module (less common)

How to diagnose and fix it

  1. Inspect the left rear wheel speed sensor connector for corrosion, water intrusion, or loose pins, and clean or repair as needed
  2. Check the sensor harness for chafing, breaks, or loose routing near the suspension and wheel well
  3. Measure the resistance of the left rear wheel speed sensor with a multimeter and compare to the manufacturer's specification
  4. Inspect the tone ring for cracks, missing teeth, or heavy contamination and clean or replace if necessary
  5. Perform a wiggle test on the sensor wiring while monitoring live wheel speed data to detect intermittent opens
  6. If the sensor and wiring test good, check for continuity between the sensor connector and the ABS module to rule out an open in the harness
  7. Replace the left rear wheel speed sensor if it fails electrical testing, then clear codes and verify the repair with a road test

Left rear sensor open circuit pitfalls

  • A common misdiagnosis is replacing the ABS module when the actual fault is a simple broken wire in the left rear harness, so always perform a continuity test before condemning the module.
  • Metallic debris from a worn brake rotor or road grit can bridge the sensor air gap and cause an open circuit code, so cleaning the sensor tip and tone ring often resolves the issue without parts replacement.
  • On some vehicles, the left rear wheel speed sensor shares a ground with other sensors, and a poor ground can set this code even when the sensor itself is good.
  • Intermittent opens often appear only when the suspension is flexed or the vehicle is driven over bumps, so a static resistance check may pass while a wiggle test reveals the fault.
  • The code can also be set by a damaged tone ring that has missing teeth, which mimics an open circuit because the sensor cannot generate a consistent signal.

Can I keep driving with C050C?

You can usually drive the vehicle with this code, but the ABS and traction control systems will be disabled, so avoid hard braking and slippery conditions until the fault is repaired. If the brake pedal feels normal and there are no other warning lights, a cautious drive to a repair shop is acceptable.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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