Engine-Codes.com
Engine-Codes – GMC – P066C 2018 GMC Sierra

P066C 2018 GMC Sierra Code - Cylinder 2 Glow Plug Control Circuit Low Voltage

Quick Answer

The diagnostic trouble code P066C for a 2018 GMC Sierra indicates an issue with the Cylinder 2 Glow Plug Control Circuit experiencing low voltage. Common causes include Faulty glow plug in Cylinder 2, Defective glow plug control module, Wiring issues such as corrosion or breaks. 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 2018 GMC Sierra indicates Cylinder 2 Glow Plug Control Circuit Low Voltage.
Common causes
Common causes include Faulty glow plug in Cylinder 2, Defective glow plug control module, Wiring issues such as corrosion or breaks.
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 18, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P066C 2018 GMC Sierra Description

The diagnostic trouble code P066C for a 2018 GMC Sierra indicates an issue with the Cylinder 2 Glow Plug Control Circuit experiencing low voltage. Glow plugs are essential components in diesel engines, especially during cold starts, as they heat up the combustion chamber to facilitate ignition. The glow plug control module regulates the voltage supplied to the glow plugs, ensuring they reach the necessary temperature for efficient combustion.

OBDII Code P066C 2018 GMC Sierra - Cylinder 2 Glow Plug Control Circuit Low Voltage
P066C 2018 GMC Sierra Code - Cylinder 2 Glow Plug Control Circuit Low Voltage

Common Causes of P066C 2018 GMC Sierra

  1. Faulty glow plug in Cylinder 2
  2. Defective glow plug control module
  3. Wiring issues such as corrosion or breaks
  4. Malfunctioning engine control module (ECM)
  5. Poor electrical connections

Symptoms of P066C 2018 GMC Sierra

  1. Hard starting or extended cranking time
  2. Rough idle or misfires
  3. Decreased engine performance
  4. Increased fuel consumption
  5. Illumination of the check engine light

How to Fix P066C 2018 GMC Sierra

  1. Begin by diagnosing the specific cause of the low voltage in the Cylinder 2 glow plug circuit using a diagnostic scanner to pinpoint the exact issue.
  2. Inspect the glow plug in Cylinder 2 for functionality and replace if necessary.
  3. Check the glow plug control module for proper operation and replace if faulty.
  4. Inspect the wiring harness for any damage, corrosion, or loose connections, repairing or replacing as needed.
  5. Clear the diagnostic trouble codes, reset the ECM, and test the vehicle to ensure the issue has been resolved.

Cost to Fix P066C 2018 GMC Sierra

The typical repair costs for addressing a Cylinder 2 Glow Plug Control Circuit Low Voltage issue can vary depending on the specific cause of the problem. On average, the cost of replacing a glow plug can range from $50 to $150 per plug, while a glow plug control module replacement can cost between $150 to $300. Labor costs at auto repair shops typically range from $80 to $150 per hour, with additional charges for diagnostic time and any necessary parts. It is advisable to consult with a trusted mechanic or dealership for a more accurate estimate based on your vehicle's make and model, as well as the local labor rates.

Need more information about the P066C 2018 GMC Sierra code?

Need more information on how to fix the P066C 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P066C 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P066C 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P066C on a 2018 GMC Sierra related to the Cylinder 2 Glow Plug Control Circuit Low Voltage?

The common symptoms may include rough idling, decreased engine performance, and an illuminated check engine light.

2. What are the possible causes of OBDII code P066C in a 2018 GMC Sierra, indicating an issue with the Cylinder 2 Glow Plug Control Circuit Low Voltage?

Possible causes may include a faulty glow plug, damaged wiring or connectors in the glow plug circuit, or a malfunctioning glow plug control module.

3. How can I diagnose the issue related to OBDII code P066C in my 2018 GMC Sierra's Cylinder 2 Glow Plug Control Circuit Low Voltage?

Diagnosis typically involves inspecting the glow plug, checking the wiring and connectors for damage, and testing the glow plug control module for proper functioning.

4. Can driving with OBDII code P066C in a 2018 GMC Sierra, signaling a problem with the Cylinder 2 Glow Plug Control Circuit Low Voltage, cause further damage to the vehicle?

Continuing to drive with this issue may lead to decreased fuel efficiency, potential engine misfires, and further damage to the glow plug system.

5. How can I repair OBDII code P066C on a 2018 GMC Sierra associated with the Cylinder 2 Glow Plug Control Circuit Low Voltage?

Repair methods may include replacing the faulty glow plug, repairing or replacing damaged wiring or connectors, or installing a new glow plug control module.

6. Is it possible to clear the OBDII code P066C on a 2018 GMC Sierra without addressing the underlying issue with the Cylinder 2 Glow Plug Control Circuit Low Voltage?

Clearing the code without fixing the problem may temporarily turn off the check engine light, but the issue will persist and likely trigger the code again.

7. Are there any preventive measures to avoid encountering OBDII code P066C in a 2018 GMC Sierra related to the Cylinder 2 Glow Plug Control Circuit Low Voltage?

Regular maintenance checks, including inspecting the glow plug system and related components, can help prevent issues leading to this trouble code.

8. How long does it typically take to repair OBDII code P066C on a 2018 GMC Sierra associated with the Cylinder 2 Glow Plug Control Circuit Low Voltage?

The repair time can vary depending on the exact cause of the issue and the availability of parts, but it may take a few hours to a full day for a professional mechanic to address the problem.

9. Can a DIY enthusiast with basic automotive knowledge fix OBDII code P066C in a 2018 GMC Sierra related to the Cylinder 2 Glow Plug Control Circuit Low Voltage?

While some aspects of the repair may be tackled by DIY enthusiasts, diagnosing and fixing electrical issues like those related to glow plug circuits may require specialized tools and expertise.

10. How much does it cost to repair OBDII code P066C on a 2018 GMC Sierra, signaling an issue with the Cylinder 2 Glow Plug Control Circuit Low Voltage?

The cost of repair can vary based on the specific components that need replacement or repair, with potential expenses ranging from a few hundred to over a thousand dollars, including parts and labor.

Discuss the causes and fixes for P066C 2018 GMC Sierra OBDII Code

Submit a New Comment

Code P066C 2018 GMC Sierra comments

No comments found for this page.