Engine-CodesGMC – P066C 2014 GMC Sierra

P066C 2014 GMC Sierra Code - Cylinder 2 Glow Plug Control Circuit Low Voltage

Quick Answer

The P066C diagnostic trouble code (DTC) for a 2014 GMC Sierra refers to an issue with the Cylinder 2 Glow Plug Control Circuit experiencing low voltage. Common causes include Faulty glow plug in Cylinder 2, Wiring issues or a poor connection in the glow plug control circuit, Malfunctioning glow plug control module. 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
P066C 2014 GMC Sierra indicates Cylinder 2 Glow Plug Control Circuit Low Voltage.
Common causes
Common causes include Faulty glow plug in Cylinder 2, Wiring issues or a poor connection in the glow plug control circuit, Malfunctioning glow plug control module.
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 17, 2024
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Code P066C 2014 GMC Sierra Description

The P066C diagnostic trouble code (DTC) for a 2014 GMC Sierra refers to an issue with the Cylinder 2 Glow Plug Control Circuit experiencing low voltage. Glow plugs are essential components in diesel engines that help with cold starts by heating the combustion chamber to aid in ignition. When the engine is cold, the glow plug control module sends a signal to the glow plugs to heat up. In the case of Cylinder 2, the control circuit is not receiving enough voltage, which can lead to difficulties starting the engine, decreased fuel efficiency, rough idling, and potential engine misfires.

OBDII Code P066C 2014 GMC Sierra - Cylinder 2 Glow Plug Control Circuit Low Voltage
P066C 2014 GMC Sierra Code - Cylinder 2 Glow Plug Control Circuit Low Voltage

Common Causes of P066C 2014 GMC Sierra

  1. Faulty glow plug in Cylinder 2.
  2. Wiring issues or a poor connection in the glow plug control circuit.
  3. Malfunctioning glow plug control module.
  4. Electrical system problems, such as a blown fuse or a short circuit.
  5. Corrosion or damage to the glow plug components.

Symptoms of P066C 2014 GMC Sierra

  1. Difficulty starting the engine, especially in cold weather.
  2. Reduced fuel efficiency.
  3. Rough idling or engine misfires.
  4. Illumination of the Check Engine Light.
  5. Decreased engine performance.

How to Fix P066C 2014 GMC Sierra

  1. Begin by diagnosing the specific cause of the low voltage issue in the Cylinder 2 glow plug control circuit using a diagnostic scanner.
  2. Inspect the glow plug in Cylinder 2 to determine if it is faulty and needs replacement.
  3. Check the wiring and connections in the glow plug control circuit for any damage or corrosion, repairing or replacing as necessary.
  4. Test the glow plug control module to ensure it is functioning correctly, replacing it if needed.
  5. Clear the DTC from the vehicle's computer and test the vehicle to verify that the issue has been resolved.

Cost to Fix P066C 2014 GMC Sierra

The cost of repairing a Cylinder 2 Glow Plug Control Circuit Low Voltage issue can vary depending on the specific cause of the problem and the labor rates in your area. On average, the cost of replacing a glow plug can range from $50 to $150 per plug, while the cost of a glow plug control module can range from $100 to $300. Labor costs can add an additional $100 to $200, depending on the complexity of the repair. Overall, you can expect to pay anywhere from $200 to $600 for parts and labor to address this issue. It's recommended to obtain quotes from local auto repair shops to get a more accurate estimate based on your vehicle's make and model.

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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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