C0221: Right Front Wheel Speed Sensor Circuit Open / Fault
ABS and traction control functionality may be disabled; standard braking still functions but with reduced safety on slippery surfaces
Overview
C0221 indicates a fault in the right front wheel speed sensor circuit, often due to sensor failure, wiring issues, or ABS module related faults
Common Symptoms
- ABS warning light illuminated
- Traction control warning light on
- Reduced ABS operation during heavy braking
- Potential wheel lock-up under hard braking
Most Common Causes
Sensor often fails due to environmental exposure, mechanical damage, or wear
Corrosion at connectors, broken wires, and harness flex points are common
Less common; requires deeper diagnostics to confirm
Wheel bearing play or broken teeth can cause incorrect speed readings
Diagnostic Steps
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Perform a visual inspection of the right front wheel speed sensor and its wiringExpected: No visible breaks, corrosion, or damaged connectorsInterpretation: Visible damage indicates likely sensor or wiring repair/replacement
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Check the wheel speed sensor resistance with a multimeterExpected: Resistance within manufacturer specification or similar to other wheel sensorsInterpretation: Out of range or open circuit confirms sensor fault
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Rotate the wheel and measure AC voltage signal from sensorExpected: AC voltage signal consistent with other wheel sensor outputsInterpretation: Significant deviation indicates sensor or tone ring issue
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Inspect the wheel hub tone ring for damage and wheel bearing playExpected: Tone ring teeth intact and no excessive hub playInterpretation: Damaged tone ring or hub play can mimic sensor failures
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Check wiring continuity back to ABS/EBCM moduleExpected: Continuous wiring with no shorts or opensInterpretation: Wiring faults identified here require repair
Repair Solutions
Cost varies by vehicle; OEM sensor recommended for reliability
Includes connectors and corrosion mitigation
Module replacement often requires programming
Recommended if hub play or tone ring damage is found
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Interpreting ABS warning light and assuming brake hydraulic failure instead of sensor circuit issue
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