WOMS
P code powertrain Medium severity

P0596 Thermostat Control Circuit Range/Performance Problem

The OBD2 code P0596 indicates that there is a problem with the thermostat control circuit, specifically that the thermostat is not operating within the expected range or performance parameters

Definition

The OBD2 code P0596 indicates that there is a problem with the thermostat control circuit, specifically that the thermostat is not operating within the expected range or performance parameters

Common causes

  • Faulty thermostat
  • Wiring issues or damaged connectors
  • Failed engine control module (ECM)
  • Incorrect coolant level
  • Faulty coolant temperature sensor
  • Stuck open thermostat
  • Poor electrical connections

Common misdiagnoses

  • Faulty thermostat
  • Coolant temperature sensor issues
  • Engine control module (ECM) problems
  • Wiring or connector issues
  • Low coolant levels
  • Radiator problems
  • Water pump failure
  • Air pockets in the cooling system

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 Thermostat

    Visual Inspection: Check the thermostat for any visible signs of damage or leaks

  3. 3. Operation Check

    Ensure that the thermostat opens and closes properly. You can do this by monitoring the engine temperature as it warms up. The thermostat should open at the specified temperature

  4. 4. Examine the Wiring and Connectors

    Inspect the wiring and connectors associated with the thermostat and the engine control module (ECM). Look for frayed wires, corrosion, or loose connections that could affect the circuit

  5. 5. Test the Thermostat

    If the thermostat is suspected to be faulty, it can be tested by removing it and placing it in a pot of water on the stove. Use a thermometer to monitor the water temperature. The thermostat should open at its specified temperature (usually marked on the thermostat)

  6. 6. Check Coolant Levels

    Ensure that the coolant level is adequate. Low coolant levels can affect the thermostat's operation and lead to incorrect readings

  7. 7. Inspect the Engine Coolant Temperature (ECT) Sensor

    The ECT sensor provides temperature data to the ECM. If this sensor is faulty, it may cause incorrect readings and trigger the P0596 code. Test the ECT sensor for proper operation and replace it if necessary

  8. 8. Check for Coolant Flow Issues

    Ensure that there are no blockages in the cooling system that could prevent proper coolant flow. This includes checking the radiator, hoses, and water pump

  9. 9. Examine the Engine Control Module (ECM)

    In rare cases, the ECM itself may be faulty. If all other components check out, consider having the ECM tested or reprogrammed

  10. 10. 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

  11. 11. Consult a Professional

    If the issue persists after performing these steps, it may be best to consult a professional mechanic for further diagnosis and repair. By following these troubleshooting steps, you can identify and resolve the underlying issue causing the P0596 code