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Engine-Codes – GMC – P066F 2016 GMC Sierra

P066F 2016 GMC Sierra Code - Cylinder 3 Glow Plug Control Circuit High Voltage

Quick Answer

The diagnostic trouble code P066F for a 2016 GMC Sierra indicates an issue with the Cylinder 3 Glow Plug Control Circuit High Voltage. Common causes include Faulty glow plug in Cylinder 3, Wiring or connection issues in the glow plug control circuit, Corrosion or damage to the 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
P066F 2016 GMC Sierra indicates Cylinder 3 Glow Plug Control Circuit High Voltage.
Common causes
Common causes include Faulty glow plug in Cylinder 3, Wiring or connection issues in the glow plug control circuit, Corrosion or damage to the 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.
What is this?
Table of contents Created and updated by William Orellana on Sep 21, 2024
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Code P066F 2016 GMC Sierra Description

The diagnostic trouble code P066F for a 2016 GMC Sierra indicates an issue with the Cylinder 3 Glow Plug Control Circuit High Voltage. Glow plugs are essential components in diesel engines, as they heat the combustion chamber to facilitate cold starts. When the engine is cold, the glow plugs heat up to ensure proper ignition of the fuel-air mixture. The control circuit is responsible for regulating the voltage to the glow plug in Cylinder 3.

OBDII Code P066F 2016 GMC Sierra - Cylinder 3 Glow Plug Control Circuit High Voltage
P066F 2016 GMC Sierra Code - Cylinder 3 Glow Plug Control Circuit High Voltage

Common Causes of P066F 2016 GMC Sierra

  1. Faulty glow plug in Cylinder 3
  2. Wiring or connection issues in the glow plug control circuit
  3. Corrosion or damage to the glow plug control module
  4. Electrical issues such as a short circuit or high resistance in the circuit
  5. Engine control module (ECM) malfunction affecting the glow plug control circuit

Symptoms of P066F 2016 GMC Sierra

  1. Rough idling
  2. Decreased fuel efficiency
  3. Difficulty starting the vehicle, especially in cold weather
  4. Engine misfires
  5. Increased emissions

How to Fix P066F 2016 GMC Sierra

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

Cost to Fix P066F 2016 GMC Sierra

The typical repair costs for addressing a Cylinder 3 Glow Plug Control Circuit High Voltage issue in a 2016 GMC Sierra can range from $200 to $500, including parts and labor. However, it's important to note that actual costs can vary based on factors such as the location of the repair shop, the specific make and model of the vehicle, and the extent of the repairs needed. Diagnostic time and labor rates at auto repair shops typically range from $80 to $150 per hour. It's recommended to obtain quotes from local shops to get a more accurate estimate for this repair.

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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 P066F 2016 GMC Sierra Code

1. What does the OBDII code P066F mean on a 2016 GMC Sierra?

P066F indicates a high voltage issue in the glow plug control circuit for cylinder 3. This typically points to an electrical fault within the glow plug system.

2. What are the symptoms of a P066F code on a 2016 GMC Sierra?

Common symptoms include difficulty starting the engine in cold weather, illuminated check engine light, rough idling, and reduced fuel efficiency.

3. What causes the P066F code on a 2016 GMC Sierra?

The most common causes include a faulty glow plug for cylinder 3, damaged wiring or connectors in the glow plug circuit, or a malfunctioning glow plug control module.

4. Can I drive my 2016 GMC Sierra with a P066F code?

While the vehicle may still operate, driving with this code can lead to poor performance and harder starts in cold weather. It’s best to address the issue promptly to avoid further damage.

5. How do I diagnose the P066F code on my 2016 GMC Sierra?

Diagnosis involves checking the glow plug for cylinder 3, inspecting the wiring and connectors for damage, and testing the glow plug control module for proper operation.

6. How much does it cost to fix a P066F code on a 2016 GMC Sierra?

Repair costs vary, but replacing a single glow plug typically costs $50-$150, while fixing wiring or replacing the control module can cost $200-$500 or more.

7. Can a faulty glow plug alone trigger the P066F code on a 2016 GMC Sierra?

Yes, a faulty cylinder 3 glow plug can cause the circuit to register high voltage and trigger the P066F code.

8. How do I reset the P066F code after repairs on a 2016 GMC Sierra?

Use an OBDII scanner to clear the code after completing repairs. If the issue persists, the code will reappear.

9. What tools are needed to troubleshoot the P066F code on a 2016 GMC Sierra?

You’ll need an OBDII scanner, a multimeter to test voltage and continuity, and basic hand tools to inspect and replace components.

10. Can extreme weather conditions cause the P066F code on a 2016 GMC Sierra?

Cold weather can exacerbate glow plug issues and make symptoms more noticeable, but the code itself is typically caused by an underlying electrical fault.

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