P0674 Fault Code

Cylinder 4 Glow Plug Circuit

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

The P0674 fault code indicates a problem with the glow plug circuit specifically related to cylinder 4 in diesel engines. This code triggers when the Engine Control Module (ECM) detects a malfunction in the electrical circuitry that controls the glow plug for cylinder 4.

• The glow plugs are crucial for starting a diesel engine, especially in cold temperatures, by preheating the combustion chamber.
• Cylinder 4's glow plug circuit issue can lead to poor engine performance, difficult starting, and increased emissions.

What are the symptoms of the P0674 code?

When the P0674 code is present, you might experience the following symptoms:

• Difficulty starting the engine, especially in colder weather conditions.
• Increased engine cranking time before starting.
• Rough idling or misfire during operation, specifically associated with cylinder 4.
• Higher emissions due to incomplete combustion or unburnt fuel.
• Illuminated check engine light (CEL) on the dashboard.

What causes the P0674 code?

Several factors can lead to the P0674 fault code:

• A faulty glow plug in cylinder 4 that cannot heat properly.
• Damaged wiring or connectors that supply power to cylinder 4's glow plug.
• A malfunctioning glow plug control module that may fail to send the correct signals.
• Issues with the power supply or fuses related to the glow plug system.

How to fix P0674?

To resolve the P0674 fault code, consider the following troubleshooting steps:

• Inspect the glow plug in cylinder 4 for wear or damage; replace if necessary.
• Check all wiring and connectors leading to the glow plug for damage or corrosion and repair or replace as needed.
• Test the glow plug control module to ensure it is functioning correctly; replace if faulty.
• Assess the power supply and fuses to ensure that they are intact and supplying the required voltage.