Engine-CodesChevrolet – P0678 Chevrolet

P0678 Chevrolet Code - Cylinder 8 Glow Plug Circuit Fault

Quick Answer

The P0678 diagnostic trouble code (DTC) for Chevrolet vehicles indicates a fault in the glow plug circuit of cylinder 8. Common causes include Defective glow plug in cylinder 8, Damaged wiring or connectors in 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
P0678 Chevrolet indicates Cylinder 8 Glow Plug Circuit Fault.
Common causes
Common causes include Defective glow plug in cylinder 8, Damaged wiring or connectors in 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 26, 2024
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Code P0678 Chevrolet Description

The P0678 diagnostic trouble code (DTC) for Chevrolet vehicles indicates a fault in the glow plug circuit of cylinder 8. Glow plugs are essential components in diesel engines that help with cold starting by heating the combustion chamber. When the engine is cold, the glow plugs heat up to ensure proper ignition of the fuel-air mixture. In the case of cylinder 8, a malfunction in the glow plug circuit can lead to difficulties starting the engine, rough idling, decreased fuel efficiency, and potentially even engine misfires.

OBDII Code P0678 Chevrolet - Cylinder 8 Glow Plug Circuit Fault
P0678 Chevrolet Code - Cylinder 8 Glow Plug Circuit Fault

Common Causes of P0678 Chevrolet

  1. Defective glow plug in cylinder 8.
  2. Damaged wiring or connectors in the glow plug circuit.
  3. Malfunctioning glow plug control module.
  4. Issues with the engine's computer system.
  5. Corrosion or poor connections in the glow plug circuit.

Symptoms of P0678 Chevrolet

  1. Difficulty starting the engine, especially in cold weather.
  2. Rough idling or engine vibrations.
  3. Decreased fuel efficiency.
  4. Engine misfires.
  5. Illumination of the check engine light on the dashboard.

How to Fix P0678 Chevrolet

  1. Diagnose the specific cause of the glow plug circuit fault using a scan tool.
  2. Inspect the glow plug in cylinder 8 for proper operation and replace if necessary.
  3. Check the wiring and connectors in the glow plug circuit for damage or corrosion and repair as needed.
  4. Test the glow plug control module and replace if found to be faulty.
  5. Clear the DTC from the vehicle's computer system and test the vehicle to ensure the issue has been resolved.

Cost to Fix P0678 Chevrolet

The typical repair costs for addressing a cylinder 8 glow plug circuit fault in a Chevrolet vehicle can range from $200 to $500, including parts and labor. However, actual costs may vary depending on the specific diagnosis time, labor rates, and the price of replacement parts at the auto repair shop. It is advisable to consult with a trusted mechanic or service center to obtain a more accurate estimate based on the vehicle's make and model, as well as the extent of the repairs required.

Tech Notes for P0678 Chevrolet









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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.

Frequently Asked Questions about P0678 Chevrolet Code

1. What are the common symptoms of OBDII code P0678 in a Chevrolet related to the cylinder 8 glow plug circuit fault?

- Common symptoms include hard starting, rough idling, misfires, reduced engine power, and the illumination of the check engine light.

2. What are the possible causes of the cylinder 8 glow plug circuit fault (P0678) in a Chevrolet?

- Potential causes may include a faulty glow plug in cylinder 8, damaged wiring or connectors in the glow plug circuit, or a malfunctioning glow plug control module.

3. How can I diagnose the cylinder 8 glow plug circuit fault in my Chevrolet triggering code P0678?

- Diagnosis typically involves checking the resistance of the glow plug, inspecting the wiring and connectors for damage, and testing the glow plug control module for proper operation.

4. Can I drive my Chevrolet with OBDII code P0678 related to the cylinder 8 glow plug circuit fault?

- It is not recommended to drive the vehicle with this fault, as it can lead to performance issues and potential damage to the engine over time. It is advisable to address the issue promptly.

5. Are there any safety concerns associated with OBDII code P0678 in a Chevrolet due to the cylinder 8 glow plug circuit fault?

- While not a direct safety risk, driving with this fault can impact the vehicle's performance and fuel efficiency, potentially leaving you stranded if the issue worsens.

6. How much does it typically cost to repair the cylinder 8 glow plug circuit fault triggering OBDII code P0678 in a Chevrolet?

- The cost of repair can vary depending on the exact cause of the fault, but it may range from $100 to $300 for parts and labor.

7. Can I replace the glow plug in cylinder 8 myself to address OBDII code P0678 in my Chevrolet?

- If you have the necessary tools and mechanical skills, replacing the glow plug in cylinder 8 can be done as a DIY repair. However, it is important to follow proper procedures to avoid causing additional damage.

8. Will resetting the check engine light clear OBDII code P0678 related to the cylinder 8 glow plug circuit fault in my Chevrolet?

- Resetting the check engine light will clear the code temporarily, but if the underlying issue is not addressed, the code is likely to reappear once the vehicle is driven and the system performs its self-diagnostic checks.

9. Is it possible for a loose connection to cause OBDII code P0678 related to the cylinder 8 glow plug circuit fault in a Chevrolet?

- Yes, a loose or poor connection in the glow plug circuit can lead to the fault code P0678. It is important to check for and secure any loose connections during diagnosis and repair.

10. How long does it typically take to repair the cylinder 8 glow plug circuit fault causing OBDII code P0678 in a Chevrolet?

- The repair time can vary based on the exact cause of the fault and the technician's experience. In general, the repair may take anywhere from 1 to 3 hours to complete.

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