C0050 C0xxx · Chassis (C) High severity
Left Rear Wheel Speed Sensor Circuit
Left rear wheel speed signal lost. On rear sensors, also check for hub bearing wear changing the air gap.
Severity guidance: High — stop driving and diagnose now; risk of further damage
Symptoms you will notice
- ABS lamp on
- Handbrake or ESP lamp on some vehicles
- ABS inactive
Common causes
Ordered from most to least likely — start at the top.
- 1 Failed sensor
- 2 Worn hub bearing altering the sensor gap
- 3 Wiring damage
- 4 Corroded tone ring
How to diagnose it
Cheapest and least invasive first — most of these codes are not a parts problem.
- ✓ Compare live wheel speeds.
- ✓ Check hub play — excessive movement points to bearing wear, not the sensor.
- ✓ Inspect the connector near the trailing arm.
- ✓ Scope the output while rotating the wheel.
Repair options
- Replace the sensor
- Replace the hub assembly if bearing play exists
- Repair the wiring
C0050 — frequently asked questions
Why did it fail right after a wheel bearing job? +
The sensor or tone ring was usually damaged during fitting, or installed on the wrong side.
Can I clean the tone ring? +
Light cleaning is fine, but a cracked or heavily rusted ring must be replaced.
Confirm the diagnosis before you buy parts
Send us the code, freeze-frame data and the vehicle — our engineers will tell you what to test first.