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Engine-Codes – Generic – P0677

P0677 Code - Cylinder 7 Glow Plug Circuit Fault

Quick Answer

The diagnostic trouble code P0677 indicates a fault in the glow plug circuit of cylinder 7 in a diesel engine. Common causes include Failed glow plug in cylinder 7, 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
P0677 indicates Cylinder 7 Glow Plug Circuit Fault.
Common causes
Common causes include Failed glow plug in cylinder 7, 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.
What is this?
Table of contents Created and updated by William Orellana on Sep 22, 2024
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Code P0677 Description

The diagnostic trouble code P0677 indicates a fault in the glow plug circuit of cylinder 7 in a diesel engine. Glow plugs are essential components in diesel engines, especially during cold starts, as they heat the combustion chamber to facilitate ignition. When the engine is cold, the glow plugs warm up to ensure proper combustion of the air-fuel mixture. If the glow plug circuit in cylinder 7 is malfunctioning, it can lead to difficulties starting the engine, reduced fuel efficiency, increased emissions, and potential engine misfires.

OBDII Code P0677 - Cylinder 7 Glow Plug Circuit Fault
P0677 Code - Cylinder 7 Glow Plug Circuit Fault

Common Causes of P0677

  1. Failed glow plug in cylinder 7.
  2. Damaged wiring or connectors in the glow plug circuit.
  3. Malfunctioning glow plug control module.
  4. Faulty engine control module (ECM).
  5. Corrosion or carbon buildup affecting the glow plug operation.

Symptoms of P0677

  1. Difficulty starting the engine, especially in cold weather.
  2. Rough idling or engine misfires.
  3. Decreased fuel efficiency.
  4. Illumination of the check engine light.
  5. Increased exhaust emissions.

How to Fix P0677

  1. Begin by diagnosing the specific cause of the fault code using a diagnostic scanner to pinpoint the issue in the glow plug circuit of cylinder 7.
  2. Inspect the glow plug in cylinder 7 for proper operation and replace it if necessary.
  3. Check the wiring and connectors in the glow plug circuit for any damage or corrosion, repairing or replacing as needed.
  4. Test the glow plug control module and the engine control module for proper functioning, replacing them if they are found to be faulty.
  5. Clear the fault code from the ECM's memory and test the vehicle to ensure that the issue has been resolved.

Cost to Fix P0677

The typical repair costs for addressing a cylinder 7 glow plug circuit fault can vary depending on the specific cause of the issue and the vehicle's make and model. Generally, the cost of replacing a single glow plug can range from $50 to $150, while the replacement of a glow plug control module or engine control module can cost between $200 and $500 each. Labor costs at auto repair shops typically range from $80 to $150 per hour, and the total repair cost can add up to several hundred dollars. It is advisable to consult with a professional mechanic to get an accurate estimate based on the specific circumstances of the vehicle in question.

What does this mean?

Tech Notes for P0677

















User Submitted Video

When is the Code Detected?

The Engine Control Module (ECM) has detected a fault in the cylinder #7 glow plug circuit

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Code P0677 Information for Specific Makes

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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