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P0185 Fuel Temperature Sensor B Circuit Malfunction

The OBD2 code P0185 indicates a malfunction in the fuel temperature sensor B circuit, which measures the temperature of the fuel in the system

Definition

The OBD2 code P0185 indicates a malfunction in the fuel temperature sensor B circuit, which measures the temperature of the fuel in the system

Common causes

  • Faulty fuel temperature sensor
  • Wiring issues (shorts, opens, or corrosion)
  • Poor electrical connections
  • Faulty engine control module (ECM)
  • Incorrect sensor calibration
  • Fuel system contamination
  • Damaged or frayed wiring harness
  • Faulty fuel pump or fuel system components

Common misdiagnoses

  • Faulty fuel temperature sensor
  • Wiring issues or short circuits
  • Fuel pump problems
  • Engine control module (ECM) issues
  • Fuel pressure regulator malfunction
  • Injector problems
  • Other sensor malfunctions (e.g., coolant temperature sensor)

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 more context and help identify related issues

  2. 2. Inspect the Fuel Temperature Sensor

    Locate the fuel temperature sensor (often referred to as Sensor B) and visually inspect it for any signs of damage, corrosion, or loose connections

  3. 3. Ensure that the sensor is properly connected to the wiring harness

  4. 4. Test the Sensor

    Use a multimeter to test the resistance of the fuel temperature sensor. Compare the readings to the specifications provided in the vehicle’s service manual

  5. 5. If the resistance is outside the specified range, the sensor may be faulty and should be replaced

  6. 6. Check the Wiring and Connectors

    Inspect the wiring harness and connectors leading to the fuel temperature sensor for any signs of wear, fraying, or damage

  7. 7. Look for any short circuits, open circuits, or poor connections that could affect the sensor's operation

  8. 8. Check the Fuel Temperature Sensor Circuit

    Use a multimeter to check for proper voltage and ground at the sensor connector. Ensure that the sensor is receiving the correct voltage from the engine control module (ECM)

  9. 9. If the voltage is not within specifications, trace the circuit back to the ECM to identify any issues

  10. 10. Inspect the ECM

    If the sensor and wiring appear to be in good condition, the issue may lie within the engine control module itself. Check for any software updates or known issues related to the ECM

  11. 11. In some cases, reprogramming or replacing the ECM may be necessary

  12. 12. Clear the Codes and Test Drive

    After performing repairs or replacements, clear the trouble codes using the OBD-II scanner

  13. 13. Take the vehicle for a test drive to see if the code reappears. Monitor the fuel temperature readings to ensure they are within normal operating ranges

  14. 14. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the fuel temperature sensor or the specific vehicle model. Manufacturers may have issued guidance on common issues and fixes

  15. 15. Seek Professional Help

    If you are unable to resolve the issue after following these steps, it may be best to consult a professional mechanic or technician who has experience with your specific vehicle make and model. By following these troubleshooting steps, you should be able to identify and address the cause of the P0185 code effectively