Engine-CodesGMC – P0677 2017 GMC Sierra

P0677 2017 GMC Sierra Code - Cylinder 7 Glow Plug Circuit Fault

Quick Answer

The diagnostic trouble code P0677 for a 2017 GMC Sierra indicates a fault in the glow plug circuit for cylinder 7. Common causes include Faulty glow plug in cylinder 7, Damaged wiring or connectors in the glow plug circuit, Defective 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
P0677 2017 GMC Sierra indicates Cylinder 7 Glow Plug Circuit Fault.
Common causes
Common causes include Faulty glow plug in cylinder 7, Damaged wiring or connectors in the glow plug circuit, Defective 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 P0677 2017 GMC Sierra Description

The diagnostic trouble code P0677 for a 2017 GMC Sierra indicates a fault in the glow plug circuit for cylinder 7. 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. In the case of cylinder 7, a malfunction in the glow plug circuit can lead to difficulties starting the engine, rough idling, decreased fuel efficiency, and increased emissions.

OBDII Code P0677 2017 GMC Sierra - Cylinder 7 Glow Plug Circuit Fault
P0677 2017 GMC Sierra Code - Cylinder 7 Glow Plug Circuit Fault

Common Causes of P0677 2017 GMC Sierra

  1. Faulty glow plug in cylinder 7.
  2. Damaged wiring or connectors in the glow plug circuit.
  3. Defective glow plug control module.
  4. Issues with the engine's computer system.
  5. Corrosion or poor connections in the glow plug circuit.

Symptoms of P0677 2017 GMC Sierra

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

How to Fix P0677 2017 GMC Sierra

  1. Begin by diagnosing the specific cause of the fault code using a diagnostic scanner to pinpoint the issue.
  2. Inspect the glow plug in cylinder 7 to determine if it is faulty or damaged.
  3. Check the wiring and connectors in the glow plug circuit for any signs of damage or corrosion.
  4. Test the glow plug control module to ensure it is functioning correctly.
  5. Replace any faulty components, such as the glow plug, wiring, connectors, or control module, and clear the fault code from the vehicle's computer system.

Cost to Fix P0677 2017 GMC Sierra

The typical repair costs for addressing a cylinder 7 glow plug circuit fault in a 2017 GMC Sierra can range from $150 to $400, including parts and labor. However, it's important to note that specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Most auto repair shops charge between $80 and $150 per hour for labor, but rates may be higher in metropolitan areas or at dealerships, while independent shops often offer lower rates. It's recommended to inquire about local rates for a more accurate estimate.

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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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