WOMS
P code powertrain Medium severity

P0597 Thermostat Control Circuit Low Input

The OBD2 code P0597 indicates that the engine control module (ECM) has detected a low input signal from the thermostat control circuit, which may suggest a malfunction in the thermostat or its associated wiring

Definition

The OBD2 code P0597 indicates that the engine control module (ECM) has detected a low input signal from the thermostat control circuit, which may suggest a malfunction in the thermostat or its associated wiring

Common causes

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

Common misdiagnoses

  • Faulty thermostat
  • Bad coolant temperature sensor
  • Wiring issues or shorts in the circuit
  • Engine control module (ECM) failure
  • Low coolant level
  • Faulty radiator fan
  • Incorrectly installed thermostat

Troubleshooting steps

  1. 1. Check for Additional Codes

    Before proceeding, check for any other related trouble codes that may provide more context to the issue

  2. 2. Inspect the Thermostat

  3. 3. Ensure that the thermostat is functioning properly. A stuck-open thermostat can cause the engine to run cooler than normal, which may trigger this code

  4. 4. If the thermostat is faulty, replace it

  5. 5. Examine Wiring and Connectors

  6. 6. Inspect the wiring and connectors related to the thermostat for any signs of damage, corrosion, or loose connections

  7. 7. Repair or replace any damaged wiring or connectors

  8. 8. Test the Thermostat Sensor

  9. 9. If the vehicle has a separate thermostat sensor, test its resistance with a multimeter. Compare the readings to the specifications in the vehicle’s service manual

  10. 10. If the sensor is out of specification, replace it

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

  12. 12. Ensure that the ECM is functioning correctly. If there are issues with the ECM, it may not be able to process the input from the thermostat correctly

  13. 13. In some cases, a software update may be required

  14. 14. Inspect the Cooling System

  15. 15. Check the coolant level and ensure there are no leaks in the cooling system. Low coolant levels can affect thermostat operation

  16. 16. Make sure the cooling system is functioning properly, including the water pump and radiator

  17. 17. Clear the Codes and Test Drive

  18. 18. After performing any repairs, clear the trouble codes using an OBD-II scanner

  19. 19. Take the vehicle for a test drive to see if the code returns

  20. 20. Consult a Professional

  21. 21. If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic for further diagnosis. By following these steps, you should be able to identify and resolve the issue related to the P0597 code