WOMS
C code chassis Medium severity

C1855 Acceleration Position Sensor Conflict

The OBD2 code C1855 indicates a conflict or discrepancy between the signals from the acceleration position sensor and the expected values, suggesting a malfunction in the sensor or its circuit

Definition

The OBD2 code C1855 indicates a conflict or discrepancy between the signals from the acceleration position sensor and the expected values, suggesting a malfunction in the sensor or its circuit

Common causes

  • Faulty acceleration position sensor
  • Wiring issues or damaged connectors
  • Poor electrical connections
  • Malfunctioning throttle body
  • Software or calibration issues in the engine control module (ECM)
  • Mechanical binding in the throttle linkage
  • Interference from other sensors or systems

Common misdiagnoses

  • Throttle Position Sensor (TPS) issues
  • Accelerator Pedal Position Sensor (APPS) failure
  • Wiring or connector problems
  • Engine control module (ECM) faults
  • Vacuum leaks
  • Fuel delivery issues
  • Transmission problems
  • Other sensor conflicts or failures

Troubleshooting steps

  1. 1. Check for Additional Codes

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

  2. 2. Inspect the Acceleration Position Sensor

  3. 3. Locate the acceleration position sensor (often part of the throttle body assembly)

  4. 4. Check for physical damage, corrosion, or loose connections at the sensor and its wiring harness

  5. 5. Test the Sensor

  6. 6. Use a multimeter to test the sensor's resistance and voltage output according to the manufacturer's specifications

  7. 7. Compare the readings to the expected values in the service manual

  8. 8. Check Wiring and Connectors

  9. 9. Inspect the wiring harness for any signs of wear, fraying, or damage

  10. 10. Ensure that all connectors are secure and free of corrosion

  11. 11. Inspect the Throttle Body

  12. 12. If the acceleration position sensor is integrated into the throttle body, check the throttle body for cleanliness and proper operation

  13. 13. Clean the throttle body if necessary, as carbon buildup can affect sensor readings

  14. 14. Check for Ground Issues

  15. 15. Ensure that the sensor has a good ground connection. A poor ground can lead to erratic sensor readings

  16. 16. Look for Software Updates

  17. 17. Check if there are any software updates available for the vehicle's engine control module (ECM) that may address known issues with the acceleration position sensor

  18. 18. Perform a Reset

  19. 19. After addressing any issues found, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  20. 20. Consult Technical Service Bulletins (TSBs)

  21. 21. Look for any TSBs related to the specific make and model of the vehicle that may provide additional guidance on resolving the C1855 code

  22. 22. Seek Professional Help

  23. 23. If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle and its systems. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the C1855 code