How to Fix the P0672 DTC Code on Duramax (Expert Insights)

P0672 is a standard trouble code. When a vehicle’s onboard diagnostics system detects a malfunction, it generates this trouble code. It’s a brief message that explains what needs to be fixed so that your vehicle remains operational and safe.

On a Duramax, the code P0672 indicates that something in the glow plug circuit is malfunctioning, resulting in the glow plug on cylinder two failing to heat up and the engine failing to start.

When the code appears, you should immediately take the necessary steps.  Don’t worry if you’re unsure what to do if this code appears. In this article, we’ll go over the details of the P0672 code on Duramax and tell you how to fix it.

How to Fix the P0672 DTC Code on Duramax

What Does Code P0672 Mean On Duramax?

As previously stated, the code P0672 indicates a malfunction in the glow plug circuit, resulting in the glow plug on cylinder two failing to heat up. As a result, the engine fails to start.

The Duramax gets cold in the winter, especially in the cylinder head, which prevents high temperatures from being created by piston lift and air compression.

This lack of heat prevents the engine from starting. The purpose of the glow plug is to increase the compression heat in the cylinder, allowing the fuel to ignite spontaneously.

Breakdown of the code P0672

  • P = Powertrain, the system of components that propel your car forward (engine, gearbox, and transmission).
  • 0 = a generic number derived from the SAE standard.
  • 6 = Glow Plug
  • 72 = Specific fault index (In our case, this denotes a malfunctioning glow plug circuit).

How Serious Is the P0672 Code on Duramax?

The code does not automatically indicate that the engine will not start. However, if the problem persists, it may result in a loss of power and acceleration.

Another fact is that the Duramax has eight cylinders and thus eight glow plugs. It is unlikely that all of them will become faulty. Even if one or two glow plugs are faulty, the engine will start.

However, it is recommended that you do not spend too much time replacing a faulty plug. Also, avoid cold environments if you have a bad glow plug.

What Are the Symptoms of the P0672 Code on Duramax?

The most common symptom is that you will receive a code or that your engine light will illuminate. More severe symptoms depend on how many plugs have failed. The more the plugs fail, the more symptoms you’ll notice. The following is a list of them.

  • The cylinder head’s temperature will be lower
  • Difficulties with acceleration
  • The engine’s performance isn’t up to par
  • During acceleration, the motor may oscillate
  • Engine power is insufficient
  • The pre-heat light may stay on
  • Difficulty in starting engine

What Causes P0868 Code on Duramax?

A variety of factors can cause P0672 codes on Duramax. The failure of the glow plug in cylinder two is, however, the most common cause.  Other causes are:

  • The glow plug circuit is open.
  • The glow plug circuit has a short circuit.
  • Damaged wiring connector
  • The control module for glow plugs is defective.

How To Fix The P0672 Code On Duramax?

The most common fix for this error code is to replace the plug or possibly the fuse. However, you must first diagnose the system and determine the specific cause of the code.

You’ll need a scanner to get the code, erase it, and see if you can get it again after fixing the problem. To check the resistance, you’ll need a digital Volt-meter.

Diagnostic Steps:

Step 1: Check the resistance of the No. 2 cylinder glow plug.

Before we start the procedure, change the Volt-ohmmeter to ohms. After that, as usual, just place the black wire and red wire on the appropriate position.

Red wire should be on the terminal of the plug. Check the estimated range limit.  if the range is too high, replace the plug.

Step 2: Examine the glow plug wire’s resistance to the relay bar.

Check the resistance of the glow plug wire to the relay bar at this point. A resistance of less than 1 ohm is preferable.  The wire must be replaced if the resistance exceeds the specification.

Step 3: Test the wire of the second glow plug

The technician connects the red lead on the wire to the glow plug inside and the black lead to the ground. The wire must be replaced if the resistance is higher than the specification.

Final Step: Clear the Code

You must clear the code after identifying the problem and taking the necessary steps. Connect the OBD scanner to the OBD port of your car. Make sure the key is in position with the engine turned off.

Common Fixes:

Fixes for this error code are fairly common. You may need to repair or replace any corroded, damaged, or lose wiring, connectors, or harnesses.  If the issue is a blown fuse or a bent spin in the connectors, another solution is to replace them.

The most important replacement is the glow plug replacement for cylinder number 2. It’s also possible that the plug relay needs to be replaced. Either the necessary part needs to be replaced or repaired, that’s all.

How Much Does It Cost To Fix The Duramax P0672 Code?

Because there are numerous causes for the code to appear, the mechanic must perform a diagnostic to determine the exact cause. The average cost for the diagnosis is anywhere between $100 and $200.

On the other hand, you must pay for glue plug replacement. The cost of a new glow plug is estimated to be between $30 and $50. Make sure a warranty covers the repair.

As you can see, the cost depends on multiple factors. The cost of mechanics differs depending on the mechanic. The cost of the plug also varies depending on the quality and brand of the plug.

Can You Drive Your Duramax with a P0672 Code?

As long as one glow plug is damaged, you can drive Duramax with code P0672. I recommend not going if two or more Glue plugs are damaged, as the engine could be severely damaged.

In addition, when multiple plugs are damaged, you may fail to start the engine. However, if only one plug fails, it may take several tries to start the engine.

It is a good idea to replace the old plug with the new one as soon as possible. And when you’ve got a code, try not to go into the cold environment too much.


Fixing the code necessitates specific skills and tools which you may not have. So it can be challenging to fix the code on your own. You can always look for the best mechanic.

There’s no need to be concerned. If the fault code appears, don’t freak out. It is a common problem among those of us who own automobiles. If you can afford the replacement cost, the problem can be solved quickly.

We hope you found our guide useful. At least you know what to do next. However, you can expand your search and learn more about this error code by broadening your search.

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