Engine-CodesGMC – P068D 2018 GMC Sierra

P068D 2018 GMC Sierra Code - Cylinder 7 Glow Plug Control Circuit High Voltage

Quick Answer

The P068D diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the cylinder 7 glow plug control circuit experiencing high voltage. Common causes include Faulty glow plug in cylinder 7, Wiring or connection issues in the glow plug control circuit, ECM malfunction or software glitch. 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
P068D 2018 GMC Sierra indicates Cylinder 7 Glow Plug Control Circuit High Voltage.
Common causes
Common causes include Faulty glow plug in cylinder 7, Wiring or connection issues in the glow plug control circuit, ECM malfunction or software glitch.
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 18, 2024
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Code P068D 2018 GMC Sierra Description

The P068D diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the cylinder 7 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 engine control module (ECM) detects high voltage in the glow plug control circuit for cylinder 7, it signifies an issue with the glow plug system's operation.

OBDII Code P068D 2018 GMC Sierra - Cylinder 7 Glow Plug Control Circuit High Voltage
P068D 2018 GMC Sierra Code - Cylinder 7 Glow Plug Control Circuit High Voltage

Common Causes of P068D 2018 GMC Sierra

  1. Faulty glow plug in cylinder 7
  2. Wiring or connection issues in the glow plug control circuit
  3. ECM malfunction or software glitch
  4. Corrosion or damage to the glow plug control module
  5. Electrical issues such as a short circuit or high resistance in the circuit

Symptoms of P068D 2018 GMC Sierra

  1. Rough idling or misfiring engine
  2. Difficulty starting the engine, especially in cold weather
  3. Decreased fuel efficiency
  4. Illumination of the check engine light
  5. Engine performance issues, such as lack of power or acceleration

How to Fix P068D 2018 GMC Sierra

  1. Begin by conducting a thorough inspection of the glow plug in cylinder 7, checking for any signs of damage or malfunction. Replace the glow plug if necessary.
  2. Inspect the wiring and connections in the glow plug control circuit for any damage, corrosion, or loose connections. Repair or replace any faulty components.
  3. Use a diagnostic tool to scan the ECM for any stored fault codes and to reset the system after repairs have been made.
  4. Test the glow plug control circuit to ensure that the voltage is within the specified range. Make adjustments as needed to correct any high voltage issues.
  5. Clear the DTC and test the vehicle to ensure that the issue has been resolved and that the engine starts and runs smoothly.

Cost to Fix P068D 2018 GMC Sierra

The typical repair costs for addressing a P068D code in a 2018 GMC Sierra can vary depending on the specific cause of the issue. Generally, replacing a glow plug can range from $50 to $150 per plug, while addressing wiring or connection issues may cost between $100 to $300. Labor costs can add an additional $80 to $150 per hour, and the total repair cost can range from $200 to $500 or more. It's important to note that these estimates are approximate, and actual costs can vary based on factors such as location, vehicle make and model, and the extent of the repairs needed. It's recommended to consult with a qualified mechanic or repair shop for a more accurate cost 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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