P0671 Trouble Code: Meaning, Symptoms, Causes & Fixes

If you’re seeing a P0671 trouble code on your dash, you’re likely wondering what it means and how you can fix it.

This guide will thoroughly cover meaning, symptoms, causes, and solutions.

Having worked on numerous vehicles with this specific issue, I know the fixes that really work.

In this article, we’ll delve into why the P0671 code appears primarily in diesel engines and the typical symptoms drivers might notice. We’ll also discuss the best repair practices to resolve it.

Ready to get under the hood? Let’s start this engine.

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What Does P0671 Trouble Code Mean?

When your vehicle’s diagnostic system throws a P0671 trouble code, it’s specifically pointing to an issue with the electrical circuit of the glow plug in cylinder 1.

Glow plugs are essential for the proper starting and functioning of diesel engines, particularly in cold weather.

They heat the engine’s combustion chamber, ensuring that the diesel fuel ignites smoothly when the engine is cold. If one of these plugs fails, starting the engine can become a difficult task.

In practical terms, a P0671 code means that the powertrain control module (PCM) has detected a malfunction in the glow plug circuit of the first cylinder.

This could be due to the glow plug itself being faulty, or there could be an issue with the wiring or connectors leading to the glow plug.

This circuit includes the plug, the wiring that provides it power, and the grounding.

For diesel engine owners, recognizing this code is critical as it affects the vehicle’s ability to start and run efficiently.

Without a fully functional glow plug, the diesel fuel may not ignite properly, leading to rough idling, decreased power, higher emissions, and can increase the wear and tear on your engine due to incomplete combustion.

Understanding this code is particularly important in colder climates where diesel engines rely heavily on their glow plugs for efficient operation.

Delaying repairs can result in more significant issues, including damage to the engine from attempting to start without proper pre-heat, or the increased strain placed on the other glow plugs that must compensate for the failure of the first.

Fixing a P0671 code quickly ensures that your diesel engine continues to perform optimally, preventing the hassle of a vehicle that struggles to start on cold mornings and reducing the risk of broader engine problems.

P0671 Trouble Code Symptoms

If your vehicle is showing a P0671 trouble code, you might notice the following symptoms:

• Difficulty starting the engine, especially in cold weather
• Rough idling once the engine is running
• Decreased engine power
• Increased fuel consumption
• Excessive smoke from the exhaust, particularly at startup
• The “Check Engine” light is illuminated on the dashboard

P0671 Trouble Code Causes

The P0671 trouble code can be triggered by several issues, primarily related to the glow plug system:

• Faulty glow plug in cylinder 1
• Wiring issues in the glow plug circuit, such as shorts or disconnections
• Faulty glow plug relay or fuse
• Problems with the glow plug timer or controller
• Corrosion or poor connections at the glow plug terminal
• Damaged or corroded wiring harness

How To Fix A P0671 Trouble Code

Fixing a P0671 trouble code involves a few diagnostic steps to pinpoint the exact issue and the appropriate repairs. Here’s how to approach the resolution:

1. Visual Inspection

Start by inspecting the glow plug in cylinder 1. Look for any obvious signs of wear or damage. Check the wiring and connectors leading to the glow plug for any signs of disconnection, corrosion, or damage.

2. Testing the Glow Plug

Using a multimeter, measure the resistance of the glow plug. Compare the readings to the manufacturer’s specifications. A significant deviation indicates a faulty glow plug that needs replacement.

3. Check the Wiring and Connectors

Ensure all wiring and connectors in the glow plug circuit are intact and securely connected. Look for any signs of corrosion or damage, and repair or replace any faulty sections.

4. Glow Plug Relay and Fuse

Inspect the glow plug relay and fuse. A faulty relay or a blown fuse can prevent the glow plug from operating correctly. Test the relay with a multimeter and replace it if necessary. Similarly, replace any blown fuses.

5. Glow Plug Controller Testing

If your vehicle has a glow plug controller, it may need testing to ensure it’s functioning correctly. Refer to your vehicle’s service manual for specific testing procedures.

6. Replacing the Glow Plug

If the glow plug is defective, replace it. This is typically straightforward but varies by vehicle. Disconnect the battery, remove the connector and unscrew the old glow plug. Install the new plug, reconnect the connector, and reattach the battery.

7. Clear the Trouble Code

After repairs, clear the P0671 trouble code from the PCM using an OBD-II scan tool. Start the engine and let it run to ensure the issue is resolved and the code doesn’t reappear.

8. Final Checks

Run the engine to ensure it starts smoothly and operates correctly under various conditions. Check for the return of any symptoms and ensure the “Check Engine” light remains off.

Following these steps should successfully resolve the P0671 trouble code, restoring efficient operation to your diesel engine.

Conclusion

Now that you’ve learned what a P0671 trouble code means and how you can tackle it, you’re set to handle it confidently.

Have you experienced this issue with your diesel engine before?

Drop a comment below and share your experience or any additional tips you might have!