Struggling with the P0671 code on your Duramax diesel truck can be frustrating. The P0671 code indicates a problem with the glow plug in cylinder #1. This issue can cause your check engine light to turn on and affect your truck’s performance. By understanding what this code means and how to fix it, you can get your truck back on the road smoothly. Keep reading to learn how to tackle this issue effectively.
Common Symptoms of a P0671 Code
When your Duramax engine shows a P0671 code, there are a few symptoms you might notice.
First, you will likely see the Check Engine Light (CEL) on your dashboard. This is one of the earliest signs that something is wrong.
You might also experience a misfire, especially when starting the engine. Misfires can cause your truck to run roughly.
In cold weather, the engine might struggle even more. White smoke coming from the exhaust is another symptom that often appears in the morning or when it’s cold outside.
Here is a quick list of common symptoms:
| Symptom | Description |
|---|---|
| Check Engine Light | Light on dashboard indicating an issue |
| Misfire | Engine running roughly or sputtering |
| White Smoke | Smoke from exhaust, often in cold weather |
Potential Causes of the P0671 Code
The P0671 code in Duramax engines usually indicates an issue with the glow plug in Cylinder #1 or its related components. Key areas to inspect include the glow plug itself, circuitry, control module, relay issues, and environmental factors like corrosion.
Glow Plug Failure Causes
A common reason for the P0671 code is a faulty glow plug. Glow plugs can wear out, become damaged, or fail over time.
When a glow plug is damaged or malfunctioning, it can cause your engine to have difficulty starting, especially in cold weather. If the glow plug in Cylinder #1 has gone bad, the voltage reading may be low, indicating a problem. You might also find that the resistance is not within the expected range, signaling a need for replacement.
Circuitry Issues
Electrical problems in the glow plug circuit can also trigger the P0671 code. Open or short circuits can prevent proper functioning.
Shorted wires or connections might lead to inconsistent or no power reaching the glow plug. Voltage readings may drop or fluctuate if there’s an issue with the wiring, causing the check engine light to activate. In some cases, damaged wires or loose connections can be the root cause. Checking for continuity and ensuring all connections are secure is essential for diagnosis.
Control Module and Relay Problems
The glow plug control module and the glow plug relay are crucial for proper operation. A malfunctioning control module can send incorrect signals to the glow plug, leading to the P0671 code.
If the module malfunctions, it might not provide the correct commands, causing Cylinder #1’s glow plug to fail. Similarly, if the relay is faulty, it can prevent the proper current from reaching the glow plug. Testing the relay for voltage reading discrepancies or resistance issues often helps identify problems.
Environmental Factors and Corrosion
Environmental conditions can also affect the glow plug system. Corrosion is a frequent culprit, especially in areas where rust can form due to moisture.
Rusted connectors and corroded wiring can interrupt the electrical flow. If you live in a region with high humidity or salty air, regular inspection for rust and corrosion is essential. Corrosion can lead to a short or open circuit, both of which can trigger the P0671 code. Checking and cleaning connections can help maintain the functionality of your glow plug system.
Step-by-Step Glow Plug Replacement
Replacing a glow plug in your Duramax diesel engine can seem daunting, but with careful steps, you can get it done. Here’s how to prepare, remove the faulty glow plug, install a new one, and test the system afterward.
Preparing for Replacement
Before starting, gather all necessary tools: a ratchet and socket set, extension bars, and replacement glow plugs. Ensure your vehicle is on a flat surface and has cooled down to avoid burns. Disconnect the battery to prevent any electrical short circuits.
Locate the cylinders. The glow plugs for Cylinders #1, 3, 5, and 7 are along the passenger side, under the fenders. Removing the vehicle fenders might be required for better access.
Removing the Faulty Glow Plug
Once prepared, start by carefully disconnecting the glow plug control module from the faulty glow plug. Use your ratchet and socket set to remove the old glow plug. Be sure to keep track of any screws or bolts you take out to avoid misplacing them.
Sometimes, glow plugs can be stuck. If so, use penetrating oil and allow it to sit for a few minutes. Turn the ratchet slowly to prevent breaking the plug inside the cylinder head.
Installing the New Glow Plug
After the faulty glow plug is out, compare it with the new one to ensure it’s the correct type. Insert the new glow plug into the socket carefully. Tighten it with your hand first, then use the ratchet to secure it snugly. Avoid overtightening, as this can damage the plug or the threads.
Reconnect the glow plug control module to the new glow plug. Double-check all connections and ensure nothing is loose.
Testing Post-Replacement
Reconnect the vehicle battery. Start the engine and check if the check engine light turns off. It’s essential to make sure that the new glow plug is functioning correctly. If the light remains on, there may be other issues, such as problems with the glow plug relay or the glow plug control module.
Monitor the vehicle over the next few days to ensure the issue is resolved. If any problems persist, further diagnostics or professional help might be necessary.
By following these steps, you can replace a faulty glow plug in your Duramax diesel engine efficiently.
Tips and Advice for Handling a P0671 Code
When dealing with a P0671 code on your Duramax, it’s crucial to stay calm and methodical. Here are some tips and advice to guide you through the process:
Identify the Faulty Glow Plug:
- The P0671 code indicates an issue with glow plug #1.
- To locate it, you’ll need to access the passenger side of the engine.
Check Glow Plug Resistance:
- Use a multimeter to measure the resistance of the glow plug.
- The typical resistance should be between 0.5 to 2 ohms. If it’s outside this range, the glow plug is likely faulty.
Disassemble the Fenders:
- You might need to remove the vehicle fenders to access the glow plugs.
- Be careful when taking things apart to avoid any additional damage.
Clean and Lubricate the Area:
- Before removing the glow plug, clean the threads and apply lubrication.
- This helps prevent the threads from getting damaged and makes removal easier.
Slow and Steady Removal:
- Use a 6-point deep socket to slowly and gently loosen the glow plug.
- If it resists, try tightening it slightly before attempting to loosen it again. This back-and-forth motion can help ease it out.
Consider Professional Help:
- If you’re not confident in handling the repair yourself, seeking assistance from a trusted mechanic or dealer is a good option. They have the tools and expertise to handle these issues efficiently.
