Engine-CodesGMC – P0673 2018 GMC Sierra

P0673 2018 GMC Sierra Code - Cylinder 3 Glow Plug Circuit Fault

Quick Answer

The P0673 diagnostic trouble code (DTC) specifically relates to a fault in the glow plug circuit of cylinder 3 in a 2018 GMC Sierra. Common causes include Faulty glow plug in cylinder 3, Damaged wiring harness connecting the glow plug circuit, 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
P0673 2018 GMC Sierra indicates Cylinder 3 Glow Plug Circuit Fault.
Common causes
Common causes include Faulty glow plug in cylinder 3, Damaged wiring harness connecting the glow plug circuit, 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 16, 2024
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Code P0673 2018 GMC Sierra Description

The P0673 diagnostic trouble code (DTC) specifically relates to a fault in the glow plug circuit of cylinder 3 in a 2018 GMC Sierra. Glow plugs are essential components in diesel engines, as they help 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 this case, a fault in the glow plug circuit of cylinder 3 indicates that there is an issue with the electrical system responsible for activating the glow plug in that specific cylinder.

OBDII Code P0673 2018 GMC Sierra - Cylinder 3 Glow Plug Circuit Fault
P0673 2018 GMC Sierra Code - Cylinder 3 Glow Plug Circuit Fault

Common Causes of P0673 2018 GMC Sierra

  1. Faulty glow plug in cylinder 3.
  2. Damaged wiring harness connecting the glow plug circuit.
  3. Malfunctioning glow plug control module.
  4. Issues with the engine control unit communication.
  5. Corrosion or poor connections in the glow plug circuit.

Symptoms of P0673 2018 GMC Sierra

  1. Difficulty starting the engine, especially in cold weather.
  2. Rough idling or engine misfires.
  3. Decreased fuel efficiency.
  4. Engine stalling or hesitation during acceleration.
  5. Illumination of the check engine light.

How to Fix P0673 2018 GMC Sierra

  1. Begin by diagnosing the specific cause of the fault by using a scan tool to read the DTC and perform electrical tests on the glow plug circuit.
  2. Inspect the glow plug in cylinder 3 to determine if it is functioning properly. Replace the glow plug if necessary.
  3. Check the wiring harness for any damage or corrosion. Repair or replace any faulty wiring.
  4. Test the glow plug control module for proper operation. Replace if found to be malfunctioning.
  5. Clear the DTC from the ECU memory and test the vehicle to ensure that the issue has been resolved.

Cost to Fix P0673 2018 GMC Sierra

The typical repair costs for addressing a cylinder 3 glow plug circuit fault in a 2018 GMC Sierra can range from $200 to $500, including parts and labor. However, it's important to note that the actual cost can vary depending on the specific diagnosis time, labor rates, and the price of parts at different auto repair shops. Rates may also differ based on the location, the vehicle's make and model, and the type of engine. It's recommended to check with local auto repair shops 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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