WOMS
P code powertrain Medium severity

P0155 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

The OBD2 code P0155 indicates a malfunction in the heater circuit of the oxygen sensor located on Bank 2, Sensor 1, which can affect the sensor's ability to reach optimal operating temperature

Definition

The OBD2 code P0155 indicates a malfunction in the heater circuit of the oxygen sensor located on Bank 2, Sensor 1, which can affect the sensor's ability to reach optimal operating temperature

Common causes

  • Faulty oxygen sensor
  • Damaged wiring or connectors
  • Blown fuse
  • Short circuit in the heater circuit
  • Open circuit in the heater circuit
  • Poor ground connection
  • Engine control module (ECM) issues

Common misdiagnoses

  • Faulty oxygen sensor
  • Wiring issues or shorts in the sensor circuit
  • Exhaust leaks
  • Engine control module (ECM) problems
  • Fuel system issues (e.g., rich or lean conditions)
  • Incorrectly installed or damaged exhaust components
  • Other sensor malfunctions (e.g., upstream sensors)

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. This can help identify if there are other issues that need to be addressed

  2. 2. Visual Inspection

    Inspect the wiring and connectors leading to the oxygen sensor for any signs of damage, corrosion, or loose connections

  3. 3. Look for frayed wires, broken connectors, or any signs of wear that could affect the sensor's operation

  4. 4. Test the Oxygen Sensor

    Use a multimeter to check the resistance of the heater element in the oxygen sensor. The resistance should typically be within the manufacturer's specified range (usually around 10-30 ohms, but check the specific vehicle's service manual)

  5. 5. If the resistance is out of range, the sensor may need to be replaced

  6. 6. Check the Heater Circuit

    With the ignition on (engine off), use a multimeter to check for voltage at the oxygen sensor heater circuit connector. You should see battery voltage (typically around 12V)

  7. 7. If there is no voltage, trace the wiring back to the engine control module (ECM) to find any breaks or shorts

  8. 8. Inspect the Ground Connection

    Ensure that the oxygen sensor has a good ground connection. A poor ground can cause the heater circuit to malfunction

  9. 9. Check the ground wire for continuity and ensure it is securely connected

  10. 10. Check the Engine Control Module (ECM)

    If all other components check out, the issue may lie with the ECM itself. Ensure that the ECM is functioning properly and is not sending incorrect signals to the oxygen sensor

  11. 11. Replace the Oxygen Sensor

    If the sensor is determined to be faulty after testing, replace it with a new one. Make sure to use a quality replacement part that meets OEM specifications

  12. 12. Clear the Codes and Test Drive

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

  13. 13. Monitor for Recurrence

    After the test drive, recheck for any codes. If the P0155 code does not return, the issue is likely resolved. If it does return, further diagnosis may be needed.Additional Tips: - Always refer to the vehicle's service manual for specific testing procedures and specifications. - If you're not comfortable performing these steps, consider seeking help from a professional mechanic. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0155 code