Engine-CodesGMC – P068F 2018 GMC Sierra

P068F 2018 GMC Sierra Code - Cylinder 8 Glow Plug Control Circuit High Voltage

Quick Answer

The diagnostic trouble code P068F for a 2018 GMC Sierra indicates an issue with the Cylinder 8 Glow Plug Control Circuit experiencing high voltage. Common causes include Faulty glow plug in cylinder 8, Wiring or connection issues in the glow plug control 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
P068F 2018 GMC Sierra indicates Cylinder 8 Glow Plug Control Circuit High Voltage.
Common causes
Common causes include Faulty glow plug in cylinder 8, Wiring or connection issues in the glow plug control 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 16, 2024
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Code P068F 2018 GMC Sierra Description

The diagnostic trouble code P068F for a 2018 GMC Sierra indicates an issue with the Cylinder 8 Glow Plug Control Circuit experiencing high voltage. Glow plugs are essential components in diesel engines that help with cold starts by heating the combustion chamber. When the control circuit for the glow plug in cylinder 8 is registering high voltage, it means that there is an electrical problem that needs to be addressed. This issue can lead to difficulties starting the engine, reduced fuel efficiency, and potential damage to the engine if left unresolved.

OBDII Code P068F 2018 GMC Sierra - Cylinder 8 Glow Plug Control Circuit High Voltage
P068F 2018 GMC Sierra Code - Cylinder 8 Glow Plug Control Circuit High Voltage

Common Causes of P068F 2018 GMC Sierra

  1. Faulty glow plug in cylinder 8.
  2. Wiring or connection issues in the glow plug control circuit.
  3. Defective glow plug control module.
  4. Corrosion or damage to the electrical connections.
  5. Issues with the engine control module (ECM).

Symptoms of P068F 2018 GMC Sierra

  1. Difficulty starting the engine, especially in cold weather.
  2. Rough idling or misfiring of the engine.
  3. Decreased fuel efficiency.
  4. Illumination of the Check Engine Light.
  5. Increased emissions.

How to Fix P068F 2018 GMC Sierra

  1. Begin by diagnosing the specific cause of the high voltage in the glow plug control circuit, using a diagnostic scanner to retrieve the trouble codes and pinpoint the issue.
  2. Inspect the wiring and connections in the glow plug control circuit for any damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Test the glow plug in cylinder 8 to determine if it is functioning properly. Replace if faulty.
  4. Check the glow plug control module for any defects and replace if needed.
  5. Clear the trouble codes from the ECM and test the vehicle to ensure that the issue has been resolved.

Cost to Fix P068F 2018 GMC Sierra

The cost of repairing a Cylinder 8 Glow Plug Control Circuit High Voltage issue in a 2018 GMC Sierra can vary depending on the specific cause of the problem. Typically, the cost of replacing a glow plug can range from $50 to $150 per plug, while a glow plug control module can cost between $100 and $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, including parts and labor. It's recommended to consult with a mechanic to get an accurate estimate based on the specific diagnosis and repair needed 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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