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C1278 STEERING Wheel Angle 1and 2 Signal Faulted

The OBD2 code C1278 indicates a fault in the steering wheel angle sensor signals, specifically that the signals from the two sensors are not matching or are faulty

Definition

The OBD2 code C1278 indicates a fault in the steering wheel angle sensor signals, specifically that the signals from the two sensors are not matching or are faulty

Common causes

  • Faulty steering angle sensor
  • Poor electrical connections or wiring issues
  • Calibration issues
  • Malfunctioning power steering system
  • Software or firmware issues in the vehicle's control module
  • Physical damage to the steering angle sensor
  • Corrosion or dirt on sensor connectors

Common misdiagnoses

  • Faulty steering angle sensor
  • Wiring issues or shorts in the sensor circuit
  • Faulty power steering pump
  • Steering rack problems
  • Incorrect wheel alignment
  • ABS module issues
  • Faulty body control module (BCM)
  • Calibration errors after steering component replacement

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. Sometimes, multiple codes can provide more context for the issue

  2. 2. Inspect the Steering Wheel Angle Sensor

    Visual Inspection: Check the sensor for any visible damage, loose connections, or corrosion at the connectors

  3. 3. Wiring

    Inspect the wiring harness for any signs of wear, fraying, or disconnection

  4. 4. Check the Sensor Calibration

    Some vehicles require the steering angle sensor to be calibrated after certain repairs or replacements. Refer to the vehicle’s service manual for calibration procedures

  5. 5. Test the Sensor

    Use a multimeter to test the output voltage of the steering angle sensor. Compare the readings to the specifications in the service manual

  6. 6. If available, use a scan tool that can read live data to monitor the steering angle sensor's output while turning the steering wheel

  7. 7. Inspect the Steering Column

    Check for any mechanical issues in the steering column that could affect the sensor's operation, such as binding or misalignment

  8. 8. Check for Software Updates

    Some vehicles may require a software update for the electronic control unit (ECU) to properly interpret the signals from the steering angle sensor

  9. 9. Clear Codes and Test Drive

    After performing any repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  10. 10. Check Related Systems

    Investigate other systems that may be related to the steering angle sensor, such as the ABS (Anti-lock Braking System) or ESC (Electronic Stability Control), as they may share the same sensor or wiring

  11. 11. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the steering angle sensor for your specific vehicle make and model. Manufacturers may have issued guidance on common issues and fixes

  12. 12. Replace the Sensor (if necessary)

    If all other troubleshooting steps fail and the sensor is determined to be faulty, consider replacing the steering wheel angle sensor.1

  13. 13. Professional Diagnosis

    If you are unable to resolve the issue, it may be best to consult a professional mechanic or dealership for further diagnosis.Conclusion Always refer to the specific service manual for your vehicle for detailed procedures and specifications. Proper diagnosis is crucial to avoid unnecessary repairs and ensure the safety and functionality of the vehicle