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Engine-Codes – Generic – P0599

P0599 Code - Thermostat Heater Control Circuit High

Quick Answer

The OBD-II code P0599 indicates a problem with the thermostat heater control circuit being too high. Common causes include Faulty thermostat heater, Wiring issues in the thermostat heater circuit, Corrosion or poor connection in the thermostat heater circuit. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0599 indicates Thermostat Heater Control Circuit High.
Common causes
Common causes include Faulty thermostat heater, Wiring issues in the thermostat heater circuit, Corrosion or poor connection in the thermostat heater circuit.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P0599 Description

The OBD-II code P0599 indicates a problem with the thermostat heater control circuit being too high. In modern vehicles, the thermostat is responsible for regulating the engine's temperature by controlling the flow of coolant. The thermostat heater control circuit is a component that helps maintain the proper temperature of the engine by heating the thermostat when necessary.

OBDII Code P0599 - Thermostat Heater Control Circuit High
P0599 Code - Thermostat Heater Control Circuit High

Common Causes of P0599

  1. Faulty thermostat heater.
  2. Wiring issues in the thermostat heater circuit.
  3. Corrosion or poor connection in the thermostat heater circuit.
  4. Defective Engine Control Module.
  5. Coolant temperature sensor malfunction.

Symptoms of P0599

  1. Engine overheating or running hotter than usual.
  2. Poor fuel efficiency.
  3. Decreased engine performance.
  4. Check Engine Light illuminated on the dashboard.
  5. Heater not working properly in the vehicle.

How to Fix P0599

  1. Begin by conducting a visual inspection of the thermostat heater and its wiring to check for any visible damage or corrosion.
  2. Use a multimeter to test the thermostat heater circuit for proper voltage and resistance values.
  3. If the thermostat heater is faulty, replace it with a new one following the manufacturer's guidelines.
  4. Check the wiring and connections in the thermostat heater circuit, repairing or replacing any damaged components.
  5. Clear the trouble codes from the ECM using an OBD-II scanner and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0599

The cost of repairing a P0599 code can vary depending on the specific cause of the issue and the labor rates at the repair shop. On average, the parts required for this repair, such as a new thermostat heater, can range from $50 to $200. The labor cost for diagnosing and repairing the issue can add an additional $100 to $300 to the total bill. It's important to note that prices may vary based on the vehicle make and model, as well as the location of the repair shop. It is recommended to consult with a trusted mechanic to get an accurate estimate for the repair.

What does this mean?

Tech Notes for P0599

If there are no coolant system leaks, replace the thermostat to fix the problem.

Need more information about the P0599 code?

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Code P0599 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0599 Code

1. What are common symptoms of OBDII code P0599 (Thermostat Heater Control Circuit High)?

- Common symptoms include the engine overheating, the temperature gauge showing incorrect readings, and a possible decrease in fuel efficiency.

2. What can cause the OBDII code P0599 to trigger?

- The code P0599 is typically triggered by a malfunction in the thermostat heater control circuit, which may be caused by a faulty thermostat, damaged wiring, or a defective thermostat heater.

3. How serious is the OBDII code P0599 (Thermostat Heater Control Circuit High)?

- While the code itself may not cause immediate harm to the engine, it can lead to engine overheating if not addressed promptly, potentially causing more severe damage.

4. How can I diagnose the OBDII code P0599?

- Diagnosing the OBDII code P0599 involves using an OBDII scanner to read the code, checking the thermostat and its wiring for any visible damage, and testing the thermostat heater for proper functionality.

5. Is it safe to continue driving with the OBDII code P0599 present?

- It is not recommended to continue driving with the OBDII code P0599 present, as it can lead to engine overheating and potential damage if the thermostat heater control circuit issue is not resolved.

6. Can I repair the thermostat heater control circuit issue myself?

- Depending on your experience and knowledge, you may be able to repair the thermostat heater control circuit issue yourself by replacing the faulty thermostat, repairing damaged wiring, or fixing the thermostat heater.

7. How much does it typically cost to repair the OBDII code P0599?

- The cost of repairing the OBDII code P0599 can vary depending on the underlying cause of the issue, but it may range from around $100 to $300 for parts and labor.

8. Are there any preventive measures to avoid the OBDII code P0599 in the future?

- To prevent the OBDII code P0599 from occurring in the future, it is recommended to perform regular maintenance on the cooling system, including checking the thermostat and its components for any signs of wear or damage.

9. Will clearing the OBDII code P0599 make it go away permanently?

- Clearing the OBDII code P0599 without addressing the underlying issue will not make it go away permanently. The issue causing the code to trigger needs to be identified and repaired to prevent it from reoccurring.

10. Can the OBDII code P0599 affect my vehicle's performance?

- Yes, the OBDII code P0599 can affect your vehicle's performance by causing engine overheating, incorrect temperature readings, and reduced fuel efficiency if not resolved in a timely manner.

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