What Does C1139 Mean?
This code indicates the ABS control module has detected a missing tooth fault on the center (rear) wheel speed sensor tone ring. The tone ring is a toothed ring that the wheel speed sensor reads to determine rotational speed. A missing tooth creates an irregular signal pattern that the module identifies as a mechanical defect in the reluctor ring, distinct from an electrical sensor failure.
Safety Warning
ABS and traction control are likely disabled due to unreliable wheel speed data. Stopping distances may increase on slippery surfaces. Repair promptly.
Common Causes
40%
Cracked or broken tone ring with one or more teeth missing due to corrosion, metal fatigue, or impact damage
25%
Excessive rust or debris buildup on the tone ring teeth causing uneven air gap and simulating a missing tooth pattern
20%
Incorrect air gap between the wheel speed sensor and tone ring due to sensor displacement or bearing play
15%
Contaminated sensor tip with metallic debris adhering to the magnetic element, distorting the signal pattern
Diagnostic Steps
1
Step 1: Raise the vehicle and visually inspect the rear center tone ring for cracked, broken, or missing teeth. Rotate the wheel/axle slowly and examine every tooth around the full circumference.
2
Step 2: Clean the tone ring surface with a non-metallic brush to remove rust, debris, and metallic particles. Also clean the sensor tip of any metallic contamination.
3
Step 3: Measure the air gap between the sensor face and the tone ring teeth using a feeler gauge (typical spec 0.020-0.050 inches). Compare to manufacturer specification. Check for excessive bearing play that could affect the gap.
4
Step 4: Using an oscilloscope connected to the wheel speed sensor, slowly rotate the wheel and observe the waveform. A missing tooth will show as a wider gap in the otherwise regular pattern of voltage peaks.
5
Step 5: Replace the damaged tone ring (or hub assembly if the ring is integrated), clear codes, and test drive above 15 mph to verify consistent wheel speed readings.
Estimated Repair Cost
$150 - $500
Parts + labor, varies by vehicle and location
This code indicates the ABS control module has detected a missing tooth fault on the center (rear) wheel speed sensor tone ring. The tone ring is a toothed ring that the wheel speed sensor reads to determine rotational speed. A missing tooth creates an irregular signal pattern that the module identi...
The most common cause of C1139 (Wheel Speed Sensor Center Tone Ring Missing Tooth Fault) is: Cracked or broken tone ring with one or more teeth missing due to corrosion, metal fatigue, or impact damage
Typical repair costs for C1139 range from $150 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS and traction control are likely disabled due to unreliable wheel speed data. Stopping distances may increase on slippery surfaces. Repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1139 to identify the root cause.
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Quick Info
Category
Chassis
System
Anti-lock Brake System (ABS) / Traction Control System
Difficulty
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Manufacturer
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