C0066 DTC: Right Front Wheel Speed Sensor Circuit Low
What Does C0066 Mean?
Diagnostic Trouble Code (DTC) C0066 indicates that the ABS control module has detected a lower-than-expected voltage or signal level in the right front wheel speed sensor circuit. This usually results from a short-to-ground condition, excessive circuit resistance, damaged wiring, or a faulty wheel speed sensor. The incorrect signal can affect the operation of the Anti-lock Braking System (ABS), Traction Control System (TCS), and Electronic Stability Control (ESC).
Symptoms
- ABS warning light illuminated.
- Traction Control (TCS) warning light ON.
- Electronic Stability Control (ESC) warning.
- ABS disabled during hard braking.
- Traction Control unavailable.
- Incorrect wheel speed shown in live data.
- Cruise control may be disabled on some vehicles.
- Additional ABS DTCs stored.
Common Causes
- Faulty right front wheel speed sensor.
- Short-to-ground in the sensor circuit.
- Damaged or pinched wiring harness.
- Loose or corroded electrical connector.
- Excessive resistance in the circuit.
- Damaged tone ring (reluctor ring).
- Wheel bearing wear causing improper sensor alignment.
- Faulty ABS control module (rare).
Typical Diagnostic Flow
How to Diagnose C0066
- Read ABS fault codes using a professional scan tool.
- Monitor live wheel speed data during a road test.
- Compare the right front wheel speed with the other wheels.
- Inspect the sensor wiring for damage or short circuits.
- Check the connector for corrosion or loose terminals.
- Measure sensor resistance and circuit voltage.
- Inspect the tone ring and wheel bearing.
- Repair or replace faulty components as needed.
Typical Values
- All wheel speed sensors should display nearly identical speeds.
- Circuit voltage should remain within manufacturer specifications.
- Actual values vary depending on vehicle make and model.
Estimated Repair Cost
- Wheel speed sensor replacement: $70–250
- Wiring repair: $50–200
- Connector replacement: $30–120
- Tone ring replacement: $80–300
- Wheel bearing replacement: $150–500
- ABS control module replacement: $400–1,200
Related DTCs
- C0065
- C0067
- C0068
- C0069
- C0070
Frequently Asked Questions
Can I drive with C0066?
Yes. The vehicle can usually be driven safely, but the ABS, Traction Control, and Stability Control systems may not function properly until the fault is repaired.
What is the most common cause of C0066?
The most common causes are a faulty right front wheel speed sensor, damaged wiring, short-to-ground, corroded connectors, or a damaged tone ring.
Will clearing the DTC permanently fix C0066?
No. Clearing the code only removes it temporarily. If the underlying electrical fault remains, the ABS control module will detect the problem again during the next drive cycle.