WOMS
P code powertrain Medium severity

P0659 Sensor Reference Voltage ""C"" Circuit Low

The OBD2 code P0659 indicates that there is a low voltage detected in the Sensor Reference Voltage "C" circuit, which typically means that the power supply to a sensor or component is insufficient or there is a fault in...

Definition

The OBD2 code P0659 indicates that there is a low voltage detected in the Sensor Reference Voltage "C" circuit, which typically means that the power supply to a sensor or component is insufficient or there is a fault in the circuit

Common causes

  • Faulty sensor
  • Damaged wiring or connectors
  • Short circuit in the circuit
  • Open circuit in the circuit
  • Faulty engine control module (ECM)
  • Poor ground connection
  • Corroded connectors

Common misdiagnoses

  • Faulty sensor
  • Wiring issues
  • Bad ground connection
  • Powertrain control module (PCM) failure
  • Short circuit in the harness
  • Open circuit in the harness
  • Other sensor malfunctions
  • Corroded connectors

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide additional context for the issue

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors associated with the sensor that is linked to the reference voltage circuit. Look for

  3. 3. Damaged, frayed, or corroded wires

  4. 4. Loose or corroded connectors

  5. 5. Signs of short circuits or open circuits

  6. 6. Test the Sensor

    Identify the specific sensor associated with the reference voltage "C" circuit. Common sensors that may be involved include

  7. 7. Throttle position sensor (TPS)

  8. 8. Mass air flow sensor (MAF)

  9. 9. Oxygen sensors (O2)

  10. 10. Test the sensor according to the manufacturer's specifications to ensure it is functioning correctly

  11. 11. Check Reference Voltage

    Use a multimeter to measure the reference voltage at the sensor connector. The expected voltage is typically around 5 volts, but refer to the vehicle's service manual for the exact specification

  12. 12. If the voltage is low or absent, trace the circuit back to the ECM to identify any breaks or shorts

  13. 13. Inspect the ECM

    If the wiring and sensor are functioning correctly, the issue may lie within the ECM itself. Check for

  14. 14. Signs of water damage or corrosion

  15. 15. Loose connections at the ECM

  16. 16. If necessary, consult a professional to test the ECM

  17. 17. Check Ground Connections

    Ensure that all ground connections related to the sensor and ECM are secure and free of corrosion. Poor ground connections can lead to voltage issues

  18. 18. Clear Codes and Test Drive

    After performing repairs or adjustments, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  19. 19. Consult a Professional

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has access to advanced diagnostic tools and equipment.Additional Tips: - Always refer to the vehicle's service manual for specific wiring diagrams and specifications. - Take safety precautions when working on electrical systems, including disconnecting the battery when necessary. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0659 code