Error Code P0599: What It Means & What To Do?

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If the powertrain control module would detect an abnormally high voltage reading from the thermostat heater unit, then the P0599 error code would start triggering up.

The trouble code P0599 can be described as Thermostat Heater Control Circuit High. This diagnostic fault code is a generic powertrain code, which means that it would apply to the OBD-II equipped vehicles. The specific repair steps can vary as it depends upon the vehicle make and model.

What causes this problem with the Thermostat Heater Control Circuit High?

• There can be a loose or corroded connector on the thermostat
• The wiring harness between the computer and thermostat might be short or open
• Flaws in the motronic computer
• Leakage in the coolant
• The thermostat might start failing

1. Engine Coolant Temperature Sensor - The P0599 code can also arise due to some issues in Engine Coolant Temperature Sensor. So, it is advised to replace them as soon as possible.
2. Engine Control Module - Do you remember when was the last time you got your car engine control module checked up? A damaged engine control module can cause a lot of issues like displaying P0599 code.
3. Thermostat - Thermostat is an important car part which should never be neglected. May be there is some fault in it due to which P0599 code may start flashing.
4. Coolant or Antifreeze - Searching for Coolant or Antifreeze for your car? Don’t worry as we have solutions for all your problems.
5. Powertrain Control Module - Defective car Powertrain Control Module can be a major reason why P0599 code depicts. So, make sure to replace it online so that you don’t have to face any further issues.

Willing to know some common symptoms of OBD Trouble Code P0599? Your wish is our demand. Have a look at them below:

Common Symptoms

• The temperature gauge may read abnormally high
• Appearance of the check engine light

If you wish to correct this fault code, then you have to follow certain steps. Correcting a problem needs your careful attention. Here are some ways with the help of which you will be able to correct the OBD Code P0599:

• If there are some defects in the circuitry components, then they should be replaced
• The faulty thermostat should be replaced
• You can always replace or repair defective control housing
• Refill the low engine coolant
• The faulty powertrain control module should be replaced properly

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If you want to easily diagnose this fault code, then all you have to do is to follow the steps which are mentioned below:

Carefully remove and inspect the electrical connector. Remove any corrosion using baking soda or by scraping. Apply electro grease and confirm a tight connection. The coolant level in the radiator should be inspected properly. 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 require an infrared temperature probe and volt/ohmmeter. Carefully determine the temperature of the engine with the temperature probe. Start the engine and test the voltage on the motronic side of the harness as per the instructions. If it is within limits continue testing. If there was no voltage or it was out of range, replace the motronic unit

Compare the resistance on the thermostat side of the harness at the thermostat. If the resistance is out of range replace the thermostatic unit. If you find out that the tools are not readily available, take the vehicle to a good shop that has access to the necessary information

Common Mistakes When Diagnosing The P0599 Code

• A big mistake can be to replace the thermostat rather than checking the circuitry for malfunctioning electrical parts
• Many a time’s leaking engine coolant may cause wiring and other components to become corroded. Make sure to repair the source of the leak