AutoCodes – GMC – P0597 GMC

P0597 GMC Code - Thermostat Heater Control Circuit Open

Quick Answer

The Engine Control Module (ECM) controls the Pulse Width Modulated (PWM) thermostat. Common causes include Failed Engine Cooling Thermostat Heater, Engine Cooling Thermostat Heater harness is open or shorted, Engine Cooling Thermostat Heater circuit poor electrical connection. 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: P0597 GMC indicates Thermostat Heater Control Circuit Open.
Common causes: Common causes include Failed Engine Cooling Thermostat Heater, Engine Cooling Thermostat Heater harness is open or shorted, Engine Cooling Thermostat Heater circuit poor electrical connection.
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.

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Code Popularity 3,512

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 27, 2024

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0597 GMC Description

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. The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 15 s.

OBDII Code P0597 GMC - Thermostat Heater Control Circuit Open - AutoCodes.com — P0597 GMC Code - Thermostat Heater Control Circuit Open

What does this mean?

What are the Possible Causes of the DTC P0597 GMC?

Failed Engine Cooling Thermostat Heater
Engine Cooling Thermostat Heater harness is open or shorted
Engine Cooling Thermostat Heater circuit poor electrical connection

How to Fix the DTC P0597 GMC?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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 104Â°C (220Â°F). The mechanical thermostat will cycle from approximately 104Â°C (220Â°F) to approximately 98Â°C (208Â°F). The heater is part of the thermostat. The engine coolant thermostat heater and the thermostat housing are serviced as an assembly.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0597 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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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 P0597 GMC Code

1. What are the common symptoms of OBDII code P0597 in a GMC vehicle?

- Common symptoms include engine overheating, fluctuating engine temperature gauge readings, poor fuel economy, and potential heater malfunctions.

2. What does the OBDII code P0597 in a GMC indicate?

- The code P0597 indicates a problem with the thermostat heater control circuit being open, preventing the thermostat from regulating engine temperature efficiently.

3. What are the possible causes of the P0597 code in a GMC vehicle?

- Common causes of the P0597 code include a faulty thermostat, damaged wiring or connectors in the heater circuit, a malfunctioning thermostat heater control module, or a blown fuse related to the circuit.

4. How can I diagnose the P0597 code in my GMC vehicle?

- Diagnosing the P0597 code involves checking the thermostat heater circuit for continuity, inspecting wiring and connectors for damage, testing the thermostat heater control module, and verifying the fuse related to the circuit.

5. Can I continue driving my GMC vehicle with the P0597 code present?

- It is not recommended to drive your vehicle with the P0597 code, as it can lead to engine overheating and potential damage. It is best to address the issue promptly to prevent further problems.

6. How can I repair the P0597 code in my GMC vehicle?

- Repairing the P0597 code typically involves replacing a faulty thermostat, repairing damaged wiring or connectors, replacing the thermostat heater control module if needed, and ensuring the circuit is functioning properly.

7. Is it possible to reset the OBDII code P0597 in a GMC without fixing the issue?

- While you can clear the code using an OBDII scanner, it is not recommended to do so without addressing the underlying problem. The code is likely to reappear if the issue is not resolved.

8. Will the P0597 code affect my GMC's performance?

- Yes, the P0597 code can affect your GMC's performance by causing engine overheating, reduced fuel efficiency, and potential heater malfunctions. It is essential to address the issue promptly.

9. How much does it typically cost to repair the P0597 code in a GMC?

- The cost of repairing the P0597 code can vary depending on the underlying issue, parts needed for replacement, and labor costs. It is advisable to consult a mechanic for an accurate estimate.

10. Can I prevent the OBDII code P0597 from occurring in my GMC?

- Regular maintenance, such as checking and replacing the thermostat as needed, inspecting wiring for damage, and addressing any cooling system issues promptly, can help prevent the occurrence of the P0597 code in your GMC.