P0674 Code: Cylinder 4 Glow Plug Circuit

Using an OBD-II scanner is a great way to identify what’s wrong with your vehicle. If you encounter the P0674 code, read this article to learn more about its causes, symptoms, and definition.

What Does the P0674 Code Mean?

Diagnostic trouble code (DTC) P0674 means “Cylinder 4 Glow Plug Circuit/Open.” The code is set when the powertrain control module (PCM) detects that the glow plug circuit in cylinder 4 has a malfunction.

Glow plugs are heating devices used to help diesel engines start, especially in cold temperatures. They’re pencil-shaped pieces of metal with a heating element at the tip.

Note: The definition of the P0674 code can be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P0674 Code?

A number of issues can cause the P0674 code to be stored. These include the following:

• Faulty glow plug in cylinder 4
• Circuit issues, such as a damaged wire or poor connection
• Faulty glow plug control module

What are the Common Symptoms of the P0674 Code?

Here are some of the common symptoms of the P0674 code:

• The engine won’t start
• Difficulty starting in cold weather
• Illuminated check engine light
• Engine producing less power while it’s cold

How to Diagnose the P0674 Code

Even though the code definition indicates that the glow plug could be the problem, this might not always be the case. You need to properly diagnose the issue before you can do any fixes, or else you might end up replacing a functioning component. You might need to visually inspect the glow plug and its wires. However, this can be difficult. You might need special tools and training to be able to properly do this job. We recommend consulting a trusted mechanic to diagnose the issue. 

You can also check out the video below to learn more about the diagnostic process:

How to Fix the P0674 Code

Since vehicle designs may vary, there isn’t a magic bullet to fix OBD-II trouble codes. If you’re not familiar with troubleshooting DTCs, then the best course of action is to leave the task to a trusted mechanic.

However, if you have the appropriate knowledge and hands-on experience with repairs, then the first step in properly fixing the P0674 code is getting an accurate diagnosis. After identifying the cause of the P0674 code, then you can start consulting online repair resources and guides for possible fixes.