C0055 critical

Rear Wheel Speed Sensor Circuit Malfunction

The C0055 code means the vehicle's onboard diagnostic system has detected: Rear Wheel Speed Sensor Circuit Malfunction. This is a critical severity code.

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Keep driving?: Short distances only
DIY difficulty: moderate
Estimated cost: $100 - $350 (parts and labor)

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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

Retrieve DTCs and note which rear wheel is affected
Inspect sensor connector for corrosion and ensure a tight fit
Measure sensor resistance -- should read 1000-2500 ohms typically
Use scan tool live data to compare rear wheel speeds while driving
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.