Dealing with a P0672 code on your Duramax diesel engine can be frustrating and confusing. The most common reason for this code is a failed glow plug in cylinder two. Whether it’s faulty wiring, a bad control module, or simply the glow plug itself, solving this issue is essential to keep your engine running smoothly.
You’re not alone in facing this problem, and the good news is that there are several actionable steps to identify and fix the issue. From checking the glow plug circuit to examining wiring and connectors, this guide will help you get your Duramax back on the road.
Common Symptoms of the P0672 Code
The P0672 code on a Duramax engine can cause several noticeable issues including an illuminated check engine light, problems starting the engine in cold weather, and a decrease in power and acceleration. Knowing these symptoms can help you identify and address the problem quickly.
Check Engine Light and Error Messages
One of the first signs you might notice is an illuminated check engine light. This is a signal that your vehicle’s diagnostic system has detected an issue. The error message usually points to a problem with the glow plug circuit for cylinder 2.
An OBD-II scanner can confirm the P0672 code. It’s a good idea to get this checked as soon as possible to avoid further complications.
Issues with Cold Starts
A more specific symptom associated with the P0672 code is difficulty starting your engine, especially in cold weather. Glow plugs are essential for warming the engine and making it easier to start when temperatures drop.
If you find that your Duramax engine has a hard time starting or cranking slowly, this could be a sign of a faulty glow plug in cylinder 2 or problems in the glow plug circuit.
Reduction in Engine Power and Acceleration
Another sign of the P0672 code is a noticeable reduction in engine power when the engine is cold. You might experience poor acceleration and the engine may feel less responsive. This happens because the affected glow plug is not efficiently warming the engine, causing it to run less smoothly.
You may also notice rough idling or even white exhaust smoke. These symptoms can make driving uncomfortable and unsafe, and they indicate that the issue needs to be addressed promptly.
Causes of the P0672 Code
The P0672 code typically points to issues with the glow plug in cylinder two of your Duramax engine. These issues can stem from a few main sources including faulty glow plugs, electrical problems, or a malfunctioning glow plug control module.
Faulty Glow Plugs
A common cause of the P0672 code is a faulty glow plug. Glow plugs are essential for starting a diesel engine in cold weather. If the glow plug in cylinder two is damaged or worn out, it won’t provide enough heat to ignite the fuel. This fault can cause starting problems, especially in colder climates. Checking the glow plug’s condition and replacing it if necessary can often resolve this issue.
Wiring and Electrical Issues
Electrical issues with the glow plug control circuit can also trigger the P0672 code. This includes damaged wiring, poor connections, or short circuits. If the wiring harness is frayed or connectors are corroded, the circuit might not pass the necessary voltage to the glow plug. Ensuring all wires and connectors are intact and properly connected is key to avoiding these types of problems.
Problems with the Glow Plug Control Module
The glow plug control module is responsible for regulating the voltage to each glow plug. If this module is faulty, it may not send the correct signals, causing the P0672 code. Symptoms might include the engine light turning on or trouble starting the engine. It’s crucial to check the module for any signs of defects or failures and replace it if it’s not functioning correctly.
Inspecting these components will help you identify and fix the root cause of the P0672 code on your Duramax engine. Regular maintenance can prevent these issues from reoccurring, ensuring your vehicle starts smoothly, even in cold weather.
Step-by-Step Repair Guide
Fixing the P0672 code on your Duramax involves examining and possibly replacing the glow plugs, repairing any damaged wiring or connectors, and sometimes, replacing the glow plug control module. Here’s a detailed guide to help you through each step.
Replacing Faulty Glow Plugs
First, you’ll need to check the glow plugs for proper operation. Using a multimeter, measure the resistance of each glow plug. A healthy glow plug should show a resistance close to 1 ohm. If the resistance is higher, replace the glow plug.
To replace it, disconnect the battery first. Then, locate the faulty cylinder by following the P0672 code, which points to the #2 glow plug. Carefully remove the old glow plug using a plug socket and install the new one. Reconnect the battery and clear the code using a diagnostic tool.
Fixing Wiring and Connector Issues
Damaged wiring or connectors can also trigger the P0672 code. Start by visually inspecting the wiring harness for any signs of wear, corrosion, or damage. Pay special attention to the connectors as well.
If you find any damaged wires, you’ll need to repair or replace them. Cut out the damaged section and use butt connectors or solder to splice new wire in. Crimp or solder the connections securely and wrap them with heat-shrink tubing or electrical tape. Ensure that the connectors are clean and securely attached to avoid future issues.
Glow Plug Control Module Replacement
If replacing the glow plugs and fixing wiring issues doesn’t clear the P0672 code, the problem might be with the glow plug control module. This module controls the operation of the glow plugs and can fail over time.
To replace the module, locate it in the engine bay, usually near the glow plugs. Disconnect the battery and then remove any mounting screws or bolts holding the module in place. Disconnect the wiring harness from the old module and connect it to the new one before mounting it back. Reconnect the battery and clear the code with a diagnostic scanner to ensure the new module is working correctly.
By following these steps, you should be able to address the P0672 code on your Duramax effectively and get your engine running smoothly again.
Maintaining Your Duramax’s Glow Plug System
To keep your Duramax engine running smoothly, proper care of the glow plug system is essential. This involves regular checks and understanding how the glow plug timer and relay system function.
Regular Check-Ups and Preventative Care
Regular check-ups are crucial for identifying any issues with your glow plugs before they become major problems. Start by inspecting the glow plugs for any signs of wear or damage. Look out for corrosion or deposits on the tips, which can affect performance.
Using a multimeter, test the resistance of each glow plug. A typical resistance should be less than 1 ohm. If it exceeds this, the plug needs replacing. Ensure your wiring harness is in good condition by visually inspecting it and using a multimeter.
Maintaining proper battery health is also important. Weak or faulty batteries can lead to poor glow plug performance. Regularly clean and check battery connections to ensure they are secure and corrosion-free.
Understanding the Glow Plug Timer and Relay System
The glow plug timer and relay system are vital parts of your engine’s starting process. The glow plug timer controls how long the glow plugs are activated, which is important for starting a cold engine.
The relay distributes power to the glow plugs. If your engine is hard to start, it could be due to a faulty relay. You can test the relay by checking for power delivery to the glow plugs when the ignition is on.
During colder temperatures, the timer may need to stay on longer to heat the glow plugs thoroughly. Always monitor how your system responds in different conditions to prevent cold start issues.
Regularly testing and understanding these components will help you maintain your Duramax’s glow plug system effectively.
Costs and Warranty Considerations
When dealing with the P0672 code on your Duramax, you should consider both costs and warranty issues.
Replacement Costs
- Glow Plug: A single glow plug can cost between $20-$50.
- Labor: Repairing or replacing the glow plug might cost around $80-$150 in labor.
- Additional Parts: Wiring or harness repairs could add extra costs if needed.
Warranty Coverage
- Manufacturer Warranty: Check if your vehicle is still under the manufacturer’s warranty. Typically, warranties cover major engine parts and can last up to five years or 60,000 miles.
- Extended Warranty: If you have an extended warranty, such plans might also cover glow plugs and associated labor costs.
Do-it-Yourself (DIY) vs. Professional Repair
- DIY: Fixing the glow plug yourself can save money but requires proper tools and knowledge.
- Professional Repair: Professional repairs are more expensive but ensure the job is done correctly, possibly saving you future costs.
Warranty Impact
- Using Non-OEM Parts: If you use non-original parts, your warranty might be voided.
- Proper Documentation: Keep records of all repairs and part purchases to maintain your warranty coverage.
Common Costs Breakdown
| Item | Cost |
|---|---|
| Glow Plug | $20 – $50 |
| Labor | $80 – $150 |
| Additional Parts | Varies |
Understanding these costs and warranty considerations can help you make informed choices about repairing the P0672 code on your Duramax.
