Engine-CodesGMC – P066F 2017 GMC Sierra

P066F 2017 GMC Sierra Code - Cylinder 3 Glow Plug Control Circuit High Voltage

Quick Answer

The P066F diagnostic trouble code (DTC) for a 2017 GMC Sierra indicates an issue with the Cylinder 3 Glow Plug Control Circuit experiencing high voltage. Common causes include Malfunctioning glow plug control module, Faulty glow plug in Cylinder 3, Damaged wiring or connectors in the glow plug control circuit. 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 2017 GMC Sierra indicates Cylinder 3 Glow Plug Control Circuit High Voltage.
Common causes
Common causes include Malfunctioning glow plug control module, Faulty glow plug in Cylinder 3, Damaged wiring or connectors in the glow plug control circuit.
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 P066F 2017 GMC Sierra Description

The P066F diagnostic trouble code (DTC) for a 2017 GMC Sierra indicates an issue with the Cylinder 3 Glow Plug Control Circuit experiencing high voltage. Glow plugs are essential components in diesel engines, as they heat up the combustion chamber to facilitate cold starts. In this case, Cylinder 3's glow plug control circuit is detecting a voltage level that is higher than normal, which can lead to various performance issues.

OBDII Code P066F 2017 GMC Sierra - Cylinder 3 Glow Plug Control Circuit High Voltage
P066F 2017 GMC Sierra Code - Cylinder 3 Glow Plug Control Circuit High Voltage

Common Causes of P066F 2017 GMC Sierra

  1. Malfunctioning glow plug control module
  2. Faulty glow plug in Cylinder 3
  3. Damaged wiring or connectors in the glow plug control circuit
  4. Issues with the engine control module (ECM)
  5. Corrosion or poor connections in the electrical system

Symptoms of P066F 2017 GMC Sierra

  1. Difficulties starting the engine, especially in cold weather
  2. Rough idling or misfires
  3. Reduced fuel efficiency
  4. Increased emissions output
  5. Illumination of the check engine light on the dashboard

How to Fix P066F 2017 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 control module, glow plug, wiring, and connectors for any signs of damage or malfunction.
  3. Replace the faulty glow plug or control module as needed.
  4. Repair or replace any damaged wiring or connectors in the control circuit.
  5. Clear the DTC and reset the ECM to ensure the issue has been resolved.

Cost to Fix P066F 2017 GMC Sierra

The typical repair costs for addressing a P066F code in a 2017 GMC Sierra can vary depending on the specific cause of the issue. On average, replacing a glow plug control module or glow plug can range from $100 to $300, while addressing wiring or connector issues may cost between $50 and $150. Labor costs can add an additional $80 to $150 per hour, with the total repair bill potentially amounting to $200 to $500 or more. It's advisable to consult with a qualified mechanic or auto repair shop for an accurate estimate based on your vehicle's unique circumstances.

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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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