WOMS
P code powertrain Medium severity

P1397 System Voltage Out Of Self Test Range

The OBD2 code P1397 indicates that the system voltage is outside the expected range during the self-test process, suggesting a potential issue with the vehicle's electrical system or battery

Definition

The OBD2 code P1397 indicates that the system voltage is outside the expected range during the self-test process, suggesting a potential issue with the vehicle's electrical system or battery

Common causes

  • Faulty battery
  • Bad alternator
  • Poor electrical connections
  • Damaged wiring or harness
  • Faulty PCM (Powertrain Control Module)
  • Corroded terminals
  • Grounding issues
  • Voltage regulator malfunction

Common misdiagnoses

  • Faulty battery
  • Bad alternator
  • Poor ground connections
  • Faulty voltage regulator
  • Wiring issues
  • Defective engine control module (ECM)
  • Sensor malfunctions (e.g., camshaft or crankshaft position sensors)
  • Corroded connectors or terminals

Troubleshooting steps

  1. 1. Check Battery Voltage

  2. 2. Use a multimeter to measure the battery voltage. It should be around 12.6 volts when the engine is off and between 13.7 to 14.7 volts when the engine is running. If the voltage is too low, consider charging or replacing the battery

  3. 3. Inspect Battery Connections

  4. 4. Ensure that the battery terminals are clean, tight, and free of corrosion. Loose or corroded connections can lead to poor electrical performance

  5. 5. Examine the Alternator

  6. 6. Check the alternator output to ensure it is charging the battery properly. A faulty alternator can cause low voltage issues. You can test the alternator output with a multimeter or have it tested at an auto parts store

  7. 7. Inspect Fuses and Relays

  8. 8. Check the fuses and relays related to the engine control module and charging system. Replace any blown fuses or faulty relays

  9. 9. Check Wiring and Connectors

  10. 10. Inspect the wiring and connectors related to the battery, alternator, and ECM for any signs of damage, fraying, or loose connections. Repair or replace any damaged components

  11. 11. Test the ECM

  12. 12. If all other components are functioning correctly, the ECM itself may be faulty. Use a scan tool to check for any other codes that may indicate ECM issues. If necessary, consult a professional for further diagnosis

  13. 13. Clear Codes and Test Drive

  14. 14. After performing the above checks and repairs, clear the trouble codes using an OBD-II scanner and take the vehicle for a test drive to see if the code reappears

  15. 15. Check for Parasitic Draw

  16. 16. If the battery is draining quickly, check for parasitic draw by measuring the current draw from the battery with the vehicle off. A draw greater than 50 milliamps may indicate a problem

  17. 17. Consult a Professional

  18. 18. If you are unable to identify or resolve the issue after these steps, it may be best to consult a professional mechanic or technician for further diagnosis. By following these troubleshooting steps, you should be able to identify the cause of the P1397 code and take appropriate action to resolve the issue