Diagnostic Trouble Code
P0597
Thermostat Heater Control Circuit Open
Technical Description P0597
Thermostat Heater Control Circuit Open
What Does This Mean P0597?
This is a generic powertrain diagnostic trouble code (DTC), which means it covers all makes/models, 1996-newer. However, specific troubleshooting steps will vary depending on the vehicle.
The codes P0597, P0598 and P0599 all refer to an electronically controlled engine thermostat. They are generic codes, meaning they pertain to all vehicles using this type of thermostatic control, however, only a small number of manufacturers employ this type of system. Therefore, this trouble code article is basically identical for all three codes.
The P0597 engine code indicate a fault has occurred with this system where the control voltage is nonexistent. For the most part, German manufactured vehicles such as BMW, Mercedes, Audi, Mini, Volkswagen, Opel and Jaguar use this system.
The electronically controlled thermostat consists of various temperature and load sensors, a computer program and the control housing with a built-in thermostat.
By controlling the coolant flow or engine temperature electronically, part throttle increases fuel economy and reduces emissions, whereas reducing the temperature under load increases power.
The codes P0597, P0598 and P0599 all refer to an electronically controlled engine thermostat. They are generic codes, meaning they pertain to all vehicles using this type of thermostatic control, however, only a small number of manufacturers employ this type of system. Therefore, this trouble code article is basically identical for all three codes.
The P0597 engine code indicate a fault has occurred with this system where the control voltage is nonexistent. For the most part, German manufactured vehicles such as BMW, Mercedes, Audi, Mini, Volkswagen, Opel and Jaguar use this system.
The electronically controlled thermostat consists of various temperature and load sensors, a computer program and the control housing with a built-in thermostat.
By controlling the coolant flow or engine temperature electronically, part throttle increases fuel economy and reduces emissions, whereas reducing the temperature under load increases power.
Symptoms P0597
1
The check engine light will illuminate and one of the above codes will be set
2
The temperature gauge may read abnormally high if the thermostat failed in the partially closed position, conversely, it will read lower than normal if the thermostat failed in the full open position
Possible Causes P0597
1
A loose or corroded connector on the thermostat
2
A coolant leak will cause the code to set
3
The thermostat itself has failed
4
A short or open has occurred in the wiring harness between the computer and thermostat
5
The Motronic computer has failed
Solutions & Repair Steps P0597
• Remove and inspect the electrical connector. Remove any corrosion using baking soda or by scraping. Apply electro grease and confirm a tight connection.
• Inspect the coolant level in the radiator. Low levels of coolant will set a code by causing the electronic thermostat to overheat.
• Remove the electrical connector and check the resistance values on the thermostat. For this procedure you will need a service manual or the necessary information found online.
This information needs to include the identification of the pins and their location, color of the wires, pin values in volts at specific temperatures and resistances. These values and flow of diagnosis varies from manufacturer to manufacturer and with engine size.
You will also need an infrared temperature probe and volt/ohmmeter.
• Inspect the coolant level in the radiator. Low levels of coolant will set a code by causing the electronic thermostat to overheat.
• Remove the electrical connector and check the resistance values on the thermostat. For this procedure you will need a service manual or the necessary information found online.
This information needs to include the identification of the pins and their location, color of the wires, pin values in volts at specific temperatures and resistances. These values and flow of diagnosis varies from manufacturer to manufacturer and with engine size.
You will also need an infrared temperature probe and volt/ohmmeter.