WOMS
P code powertrain Medium severity

P1393 Glow Plug Circuit Low Input (Bank #2)

The OBD2 code P1393 indicates a low input signal from the glow plug circuit for bank #2, suggesting a potential issue with the glow plugs, wiring, or the engine control module (ECM) in that bank

Definition

The OBD2 code P1393 indicates a low input signal from the glow plug circuit for bank #2, suggesting a potential issue with the glow plugs, wiring, or the engine control module (ECM) in that bank

Common causes

  • Faulty glow plug
  • Open or shorted wiring in the glow plug circuit
  • Bad glow plug relay
  • Poor electrical connections
  • Faulty engine control module (ECM)
  • Corroded or damaged connectors
  • Blown fuse in the glow plug circuit

Common misdiagnoses

  • Faulty glow plugs
  • Bad glow plug relay
  • Wiring issues or shorts in the glow plug circuit
  • Faulty engine control module (ECM)
  • Incorrectly installed or damaged connectors
  • Fuel system issues
  • Injector problems
  • Air intake issues
  • Exhaust system restrictions
  • Sensor malfunctions (e.g., temperature sensors)

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 for the issue

  2. 2. Inspect the Glow Plugs

    Visual Inspection: Check the glow plugs for physical damage or corrosion

  3. 3. Resistance Test

    Use a multimeter to measure the resistance of each glow plug. A typical reading should be within the manufacturer's specifications (usually around 0.5 to 2 ohms). If any glow plug shows an open circuit (infinite resistance), it may need to be replaced

  4. 4. Check Glow Plug Relay

    Inspect the glow plug relay for proper operation. You can test the relay by applying power directly to it and checking if it activates

  5. 5. Ensure that the relay is receiving power from the battery and that the control signal from the ECM is functioning

  6. 6. Inspect Wiring and Connectors

    Check the wiring harness and connectors leading to the glow plugs and the relay for any signs of damage, corrosion, or loose connections

  7. 7. Look for frayed wires or broken connectors that could cause a poor connection

  8. 8. Test the Glow Plug Control Module (if applicable)

    Some vehicles have a dedicated glow plug control module. If your vehicle has one, check for proper operation and any fault codes related to it

  9. 9. Check Power and Ground

    Verify that the glow plugs are receiving the correct voltage. Use a multimeter to check for power at the glow plug terminals when the ignition is turned on

  10. 10. Ensure that the ground connections for the glow plugs are secure and free of corrosion

  11. 11. Inspect Engine Control Module (ECM)

    If all other components check out, there may be an issue with the ECM itself. Check for any software updates or reprogramming that may be needed

  12. 12. Clear Codes and Test Drive

    After performing 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. Consult Repair Manual

    Refer to the vehicle's service manual for specific diagnostic procedures and specifications related to the glow plug system

  14. 14. Seek Professional Help

    If you are unable to resolve the issue after these steps, it may be best to consult a professional mechanic or technician who has experience with diesel engines and OBD-II diagnostics. By following these steps, you should be able to identify and resolve the issue related to the P1393 code