Engine-CodesGMC – P068C 2018 GMC Sierra

P068C 2018 GMC Sierra Code - Cylinder 7 Glow Plug Control Circuit Low Voltage

Quick Answer

The diagnostic trouble code P068C for a 2018 GMC Sierra specifically refers to an issue with the Cylinder 7 Glow Plug Control Circuit experiencing low voltage. Common causes include Faulty glow plug in Cylinder 7, Wiring or connection issues in the glow plug control 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
P068C 2018 GMC Sierra indicates Cylinder 7 Glow Plug Control Circuit Low Voltage.
Common causes
Common causes include Faulty glow plug in Cylinder 7, Wiring or connection issues in the glow plug control 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 14, 2024
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Code P068C 2018 GMC Sierra Description

The diagnostic trouble code P068C for a 2018 GMC Sierra specifically refers to an issue with the Cylinder 7 Glow Plug Control Circuit experiencing low voltage. Glow plugs are essential components in diesel engines, as they help heat up the combustion chamber for easier cold starts. In this case, Cylinder 7's glow plug control circuit is not receiving the necessary voltage to operate effectively. This can lead to difficulties starting the engine, especially in cold weather, reduced engine performance, increased emissions, and potential damage to the engine over time.

OBDII Code P068C 2018 GMC Sierra - Cylinder 7 Glow Plug Control Circuit Low Voltage
P068C 2018 GMC Sierra Code - Cylinder 7 Glow Plug Control Circuit Low Voltage

Common Causes of P068C 2018 GMC Sierra

  1. Faulty glow plug in Cylinder 7.
  2. Wiring or connection issues in the glow plug control circuit.
  3. Malfunctioning glow plug control module.
  4. Electrical system issues, such as a blown fuse or relay.
  5. ECM (Engine Control Module) malfunction.

Symptoms of P068C 2018 GMC Sierra

  1. Difficulty starting the engine, especially in cold weather.
  2. Rough idling or misfires.
  3. Decreased fuel efficiency.
  4. Engine performance issues, such as lack of power or acceleration.
  5. Increased emissions output.

How to Fix P068C 2018 GMC Sierra

  1. Begin by conducting a visual inspection of the glow plug in Cylinder 7, checking for any signs of damage or wear.
  2. Test the glow plug control circuit for continuity and voltage using a multimeter to identify any wiring or connection issues.
  3. Inspect the glow plug control module for any signs of malfunction and replace if necessary.
  4. Check the electrical system components, such as fuses and relays, related to the glow plug control circuit and replace any faulty parts.
  5. If all components check out, consider testing or replacing the ECM if it is determined to be the source of the low voltage issue.

Cost to Fix P068C 2018 GMC Sierra

The typical repair costs for addressing a Cylinder 7 Glow Plug Control Circuit Low Voltage issue can vary depending on the specific cause of the problem. In general, the cost of replacing a glow plug can range from $50 to $150 per plug, while a glow plug control module replacement can cost between $150 and $300. Labor costs at auto repair shops typically range from $80 to $150 per hour, with the total repair bill potentially amounting to a few hundred dollars to over a thousand dollars, depending on the extent of the repairs needed. It is advisable to consult with a professional mechanic to get an accurate estimate based on the specific diagnosis and repair requirements for your 2018 GMC Sierra.

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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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