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Engine-Codes – GMC – P0598 GMC

P0598 GMC Code - Thermostat Heater Control Circuit Low

Quick Answer

The P0598 OBD-II code for GMC vehicles indicates a problem with the thermostat heater control circuit being lower than the expected value. Common causes include Faulty thermostat heater, Damaged wiring or connectors in the thermostat heater circuit, Malfunctioning engine coolant temperature sensor. 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
P0598 GMC indicates Thermostat Heater Control Circuit Low.
Common causes
Common causes include Faulty thermostat heater, Damaged wiring or connectors in the thermostat heater circuit, Malfunctioning engine coolant temperature sensor.
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 12, 2024
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Code P0598 GMC Description

The P0598 OBD-II code for GMC vehicles indicates a problem with the thermostat heater control circuit being lower than the expected value. The thermostat heater is responsible for regulating the engine coolant temperature by controlling the flow of coolant through the engine. When the thermostat heater control circuit is low, it means that the engine may not reach its optimum operating temperature, leading to poor fuel efficiency, increased emissions, and potential damage to engine components.

OBDII Code P0598 GMC - Thermostat Heater Control Circuit Low
P0598 GMC Code - Thermostat Heater Control Circuit Low

Common Causes of P0598 GMC

  1. Faulty thermostat heater
  2. Damaged wiring or connectors in the thermostat heater circuit
  3. Malfunctioning engine coolant temperature sensor
  4. Problem with the engine control module (ECM)
  5. Low coolant level or air pockets in the cooling system

Symptoms of P0598 GMC

  1. Check engine light illuminated on the dashboard
  2. Engine running too cold or too hot
  3. Poor fuel economy
  4. Decreased power output
  5. Potential overheating of the engine

How to Fix P0598 GMC

  1. Begin by performing a visual inspection of the thermostat heater circuit, wiring, and connectors. Repair or replace any damaged components.
  2. Test the thermostat heater for proper operation using a multimeter. Replace the thermostat heater if it fails the test.
  3. Check the engine coolant temperature sensor for correct readings. Replace if necessary.
  4. Test the engine control module (ECM) for any faults or programming issues. Reset or replace the ECM if needed.
  5. Refill the cooling system with the appropriate coolant mixture and bleed out any air pockets to ensure proper operation.

Cost to Fix P0598 GMC

The cost of repairing a P0598 GMC code can vary depending on the specific cause of the issue. In general, the cost of parts such as a thermostat heater, engine coolant temperature sensor, or engine control module can range from $50 to $200. Labor costs may range from $100 to $300, depending on the shop's hourly rates and the complexity of the repair. It's best to consult with a professional mechanic to get an accurate estimate based on the vehicle's make and model.

What does this mean?

Tech Notes for P0598 GMC

The engine coolant thermostat heater has a mechanical fail-safe in case of an electrical condition with the engine coolant thermostat heater. The mechanical thermostat will open at approximately 104°C (220°F). The mechanical thermostat will cycle from approximately 104°C (220°F) to approximately 98°C (208°F). The heater is part of the thermostat. The engine coolant thermostat heater and the thermostat housing are serviced as an assembly.

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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 P0598 GMC Code

1. What are the common symptoms of OBDII code P0598 in a GMC vehicle?

- Common symptoms include engine overheating, decreased fuel efficiency, and the vehicle's temperature gauge showing lower than normal temperatures.

2. What can cause the OBDII code P0598 (Thermostat Heater Control Circuit Low) in a GMC?

- The code P0598 can be caused by a faulty thermostat heater control circuit, a malfunctioning thermostat, wiring issues, or a defective engine control module (ECM).

3. How serious is the OBDII code P0598 in a GMC vehicle?

- The code P0598 should be addressed promptly as it can lead to engine overheating, which may cause serious damage to the engine if left unresolved.

4. Can I continue driving my GMC with the OBDII code P0598?

- It is not recommended to continue driving with the code P0598 present, as it can result in overheating and potential engine damage. It's best to address the issue as soon as possible.

5. How can I diagnose the OBDII code P0598 in my GMC?

- Diagnosing the code P0598 typically involves using an OBDII scanner to retrieve the code, checking the thermostat heater control circuit for continuity, inspecting wiring for damage, and testing the thermostat's functionality.

6. What are some DIY repair tips for fixing the OBDII code P0598 in a GMC?

- DIY repair tips may include checking and repairing any damaged wiring, replacing the thermostat if faulty, and ensuring proper connection of the thermostat heater control circuit.

7. Will resetting the OBDII code P0598 in my GMC make it go away permanently?

- Resetting the code may temporarily clear the check engine light, but if the underlying issue causing the code is not fixed, the code is likely to reappear.

8. How much does it cost to repair the OBDII code P0598 in a GMC at a mechanic?

- The cost of repairing the code P0598 can vary depending on the root cause of the issue, but it may range from $150 to $400 at a mechanic, including parts and labor.

9. Can the OBDII code P0598 in a GMC be a false alarm?

- While it's possible for a code to be triggered erroneously, it's important to properly diagnose and address the issue to prevent potential engine damage associated with overheating.

10. Are there any preventive measures to avoid the OBDII code P0598 in a GMC?

- Regular maintenance, such as checking and replacing the thermostat as recommended by the manufacturer, can help prevent issues that may lead to the code P0598.

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