Engine-CodesGMC – P0674 2014 GMC Sierra

P0674 2014 GMC Sierra Code - Cylinder 4 Glow Plug Circuit Fault

Quick Answer

The diagnostic trouble code P0674 in a 2014 GMC Sierra indicates a fault in the glow plug circuit for cylinder 4. Common causes include Faulty glow plug in cylinder 4, Damaged wiring harness or connectors, 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
P0674 2014 GMC Sierra indicates Cylinder 4 Glow Plug Circuit Fault.
Common causes
Common causes include Faulty glow plug in cylinder 4, Damaged wiring harness or connectors, 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 15, 2024
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Code P0674 2014 GMC Sierra Description

The diagnostic trouble code P0674 in a 2014 GMC Sierra indicates a fault in the glow plug circuit for cylinder 4. Glow plugs are essential components in diesel engines that help with cold starts by heating the air in the combustion chamber. When the engine is cold, the glow plugs warm up to ensure proper ignition of the fuel. In the case of cylinder 4, if the glow plug circuit is not functioning correctly, it can lead to issues with starting the engine, reduced performance, increased emissions, and potential damage to the engine over time.

OBDII Code P0674 2014 GMC Sierra - Cylinder 4 Glow Plug Circuit Fault
P0674 2014 GMC Sierra Code - Cylinder 4 Glow Plug Circuit Fault

Common Causes of P0674 2014 GMC Sierra

  1. Faulty glow plug in cylinder 4.
  2. Damaged wiring harness or connectors.
  3. Malfunctioning glow plug control module.
  4. Corrosion or poor connections in the circuit.
  5. Electrical issues such as short circuits or open circuits.

Symptoms of P0674 2014 GMC Sierra

  1. Check Engine Light illuminated on the dashboard.
  2. Difficulty starting the engine, especially in cold weather.
  3. Reduced fuel efficiency.
  4. Rough idling or engine misfires.
  5. Increased emissions.

How to Fix P0674 2014 GMC Sierra

  1. Begin by diagnosing the specific cause of the glow plug circuit fault using a diagnostic scanner to pinpoint the issue.
  2. Inspect the glow plug in cylinder 4 for proper operation and replace if necessary.
  3. Check the wiring harnesses and connectors for any damage or corrosion, repairing or replacing them as needed.
  4. Test the glow plug control module for functionality and replace if it is faulty.
  5. Clear the trouble code from the vehicle's computer after completing the repairs and test the vehicle to ensure the issue is resolved.

Cost to Fix P0674 2014 GMC Sierra

The typical repair costs for addressing a cylinder 4 glow plug circuit fault in a 2014 GMC Sierra can vary depending on the specific cause of the issue. Generally, the cost of replacing a glow plug can range from $50 to $150 per plug, while the cost of a control module can be around $100 to $300. Labor costs at auto repair shops can range from $80 to $150 per hour. Overall, the total repair cost for this issue could range from $200 to $600 or more, depending on the extent of the repairs needed. It is advisable to consult with a professional mechanic for a more accurate cost estimate based on the specific diagnosis and repair requirements for your vehicle.

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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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