P0678 Fault Code

Cylinder 8 Glow Plug Circuit

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0678 fault code relates to the glow plug circuit for cylinder 8 in diesel engines. It indicates an issue with the heating element that helps start the engine in cold conditions. Proper function of the glow plug is essential for optimal engine performance and emissions control.

What are the symptoms of the P0678 code?

Symptoms that may occur alongside the P0678 code include:

• Difficulty starting the engine, especially in cold weather
• Increased exhaust emissions
• Rough or uneven engine idle
• A noticeable drop in fuel efficiency

What causes the P0678 code?

Common causes of the P0678 code include:

• A faulty glow plug for cylinder 8
• Issues with the wiring harness connected to the glow plug
• A malfunctioning glow plug relay
• Problems with the engine control module (ECM) that governs the glow plug operation

How to fix P0678?

To address the P0678 fault code, consider the following steps:

• Inspect and test the glow plug for cylinder 8, replacing it if defective
• Check the wiring harness and connections for damage or corrosion
• Test the glow plug relay and replace if malfunctioning
• Run a diagnostic check on the ECM and update or replace if necessary
• Clear the fault code and retest the system to ensure the issue is resolved