Rear Wheel Speed Sensor Circuit Malfunction
What does C0055 mean?
The C0055 code means the vehicle's onboard diagnostic system has detected: Rear Wheel Speed Sensor Circuit Malfunction. This is a critical severity code.
Common Symptoms
- ABS warning light on
- Traction control disabled
- Stability control warning light illuminated
- Reduced braking performance in slippery conditions
- Speedometer reads incorrectly
Probable Causes (Ranked by Likelihood)
- Faulty rear wheel speed sensor Very High
- Corroded wiring connector at the sensor High
- Excessive air gap between sensor and tone ring Moderate
- Tone ring loosened or slipped on the axle shaft Moderate
- ABS hydraulic control module fault Low
Step-by-Step Diagnostic Procedure
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Retrieve DTCs and note which rear wheel is affected
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Inspect sensor connector for corrosion and ensure a tight fit
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Measure sensor resistance -- should read 1000-2500 ohms typically
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Use scan tool live data to compare rear wheel speeds while driving
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Check tone ring for looseness or damage by removing the brake rotor
Frequently Asked Questions
What is the difference between C0055 and C0045 or C0050?
C0045 and C0050 are specific to the left and right rear sensors respectively. C0055 is a general rear wheel speed sensor circuit code used by some manufacturers when the system detects a rear sensor fault without specifying which side.
Can a wheel bearing cause a wheel speed sensor code?
Yes. Excessive wheel bearing play changes the air gap between the sensor and tone ring, causing erratic or lost signal. Always check for wheel bearing play when diagnosing speed sensor codes.
How long does it take to replace a rear wheel speed sensor?
Most rear wheel speed sensor replacements take 30 minutes to 1 hour. The sensor is usually accessible from behind the brake rotor or backing plate. Rusted bolts can add time to the job.