Engine-Codes - Generic - P0599

P0599 Code - Thermostat Heater Control Circuit High

- Code Popularity: 55,218 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
Table of contents
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What are the Possible Causes of the DTC P0599?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Failed Engine Cooling Thermostat
  • Engine Cooling Thermostat harness is open or shorted
  • Engine Cooling Thermostat circuit poor electrical connection

Code Tech Notes

If there are not coolant system leaks, replaced the thermostat to fix the problem.

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How to Fix the DTC P0599?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0599 code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

When is the Code Detected?

The P0599 is triggered when there is an open or short thermostat heather control circuit.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

What Does the P0599 Code Mean?

The Engine Control Module (ECM) controls the Pulse Width Modulated (PWM) thermostat. The engine coolant thermostat heater controls coolant flow and regulates the engine operating temperature. The ECM supplies 12 V to the thermostat. The ECM controls the engine coolant thermostat heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

P0599 Code - Thermostat Heater Control Circuit High

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Code P0599 Information for Specific Makes

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