Engine-CodesGMC – P0668 2014 GMC Sierra

P0668 2014 GMC Sierra Code - Control Module Temperature Sensor Circuit Low Voltage

Quick Answer

The P0668 diagnostic trouble code (DTC) for a 2014 GMC Sierra indicates that there is a low voltage condition detected in the control module temperature sensor circuit. Common causes include Faulty Temperature Sensor: The temperature sensor itself may be malfunctioning, providing incorrect voltage readings to the ECM, Wiring Issues: Damaged or corroded wiring in the temperature sensor circuit can cause a low voltage condition, Poor Electrical Connection: Loose or poor electrical connections at the sensor or ECM can lead to voltage discrepancies. 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
P0668 2014 GMC Sierra indicates Control Module Temperature Sensor Circuit Low Voltage.
Common causes
Common causes include Faulty Temperature Sensor: The temperature sensor itself may be malfunctioning, providing incorrect voltage readings to the ECM, Wiring Issues: Damaged or corroded wiring in the temperature sensor circuit can cause a low voltage condition, Poor Electrical Connection: Loose or poor electrical connections at the sensor or ECM can lead to voltage discrepancies.
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.
Table of contents Created and updated by William Orellana on Sep 15, 2024
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Code P0668 2014 GMC Sierra Description

The P0668 diagnostic trouble code (DTC) for a 2014 GMC Sierra indicates that there is a low voltage condition detected in the control module temperature sensor circuit. In this case, the Engine Control Module (ECM) is not receiving the expected voltage signal from the temperature sensor, which is responsible for monitoring the temperature of the control module. This can lead to various issues with the vehicle's performance and overall operation.

OBDII Code P0668 2014 GMC Sierra - Control Module Temperature Sensor Circuit Low Voltage
P0668 2014 GMC Sierra Code - Control Module Temperature Sensor Circuit Low Voltage

Common Causes of P0668 2014 GMC Sierra

  1. Faulty Temperature Sensor: The temperature sensor itself may be malfunctioning, providing incorrect voltage readings to the ECM.
  2. Wiring Issues: Damaged or corroded wiring in the temperature sensor circuit can cause a low voltage condition.
  3. Poor Electrical Connection: Loose or poor electrical connections at the sensor or ECM can lead to voltage discrepancies.
  4. ECM Malfunction: A malfunctioning ECM may not be able to properly interpret the voltage signals from the temperature sensor.
  5. Environmental Factors: Extreme temperatures or exposure to moisture can also affect the performance of the temperature sensor circuit.

Symptoms of P0668 2014 GMC Sierra

  1. Check Engine Light: The most common symptom associated with the P0668 code is the illumination of the check engine light on the dashboard.
  2. Reduced Engine Performance: The vehicle may experience a decrease in power and acceleration due to incorrect engine adjustments.
  3. Poor Fuel Efficiency: A malfunctioning temperature sensor circuit can lead to inefficient fuel delivery, resulting in decreased fuel economy.
  4. Rough Idle: The engine may idle erratically or rough due to incorrect temperature readings affecting fuel mixture.
  5. Stalling: In severe cases, the vehicle may stall or have difficulty starting due to the control module temperature sensor circuit issue.

How to Fix P0668 2014 GMC Sierra

  1. Diagnose the Issue: Use a scan tool to retrieve the DTC and perform a thorough inspection of the control module temperature sensor circuit.
  2. Check Wiring and Connections: Inspect the wiring harness and connectors for any damage, corrosion, or loose connections. Repair or replace as needed.
  3. Test the Temperature Sensor: Test the temperature sensor using a multimeter to ensure it is providing the correct voltage readings. Replace if faulty.
  4. Clear DTC and Test Drive: Clear the DTC from the ECM memory and test drive the vehicle to ensure the issue has been resolved.
  5. Monitor Operation: Monitor the vehicle's performance and check for any recurring issues related to the control module temperature sensor circuit.

Cost to Fix P0668 2014 GMC Sierra

The typical repair costs for addressing a P0668 code on a 2014 GMC Sierra can vary depending on the specific cause of the issue. In general, the cost of parts such as a new temperature sensor and any necessary wiring repairs can range from $50 to $200. Labor costs at an auto repair shop can range from $100 to $300, depending on the shop's hourly rates and the complexity of the repair. It's important to note that diagnostic time and labor rates can vary, so it's advisable to check with local auto repair shops for a more accurate estimate based on your location and vehicle.

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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.

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