How to Fix the P0673 Code on Duramax (The Expert Approach)

A Duramax SUV or truck comes with a very strong engine of more horsepower and torque. And you must have hoped that this beast engine would not have any power startup issue in any situation. Right?

Unfortunately, that might happen if you have any p0673 issues in your Duramax truck. This error code indicates a  mismatch in voltage reading in the glow plug of the Duramax cylinder.

Don’t worry. Just follow our article, and you should get all your queries answered. In this article, we are here to provide you with a summary of the P0673 code and will instruct you to solve this issue.

How to Fix the P0673 Code on Duramax

What Does The P0673 Code Mean On Duramax?

P0673 on Duramax is an on-board diagnostic trouble code that indicates issues with cylinder number three glow plug circuits. When the powertrain control module or PCM detects any mismatch in voltage reading in the glow plug of cylinder number three of a Duramax engine, it gives a p0673 error code.

Glow plugs are parts that are used to heat the engine cylinders to a certain level to burn the diesel in the engine and start the engine. When glow plugs fail to heat up to a certain level, it can cause the Duramax engine startup problem and can damage glow plugs in cylinder 3.


  • P = Powertrain, the system of components that propels your car forward (Here, circuit for cylinder 3 glow plug).
  • 0 = a generic number derived from the SAE standard
  • 6 = Computer Auxiliary Output
  • 73 = Specific fault index (In this case, this indicates a mismatch in voltage reading in the glow plug)

How Serious Is The P0673 Code On Your Duramax?

At first look, it might look like a normal problem. That is, it does the simple work of heating the Duramax engine. But there are plenty of problems that you might face if you get a p0673 code. The following are the results of the p0673 error code.

Misfiring engine:

With a glow plug malfunction, one of the first problems in the Duramax engine is a misfire. It is due to a lack of heat needed for diesel combustion.

Weakened Performance:

P0673 leads to inadequate heat for the ignition of the fuel. And it results in the lower acceleration of the Duramax trucks.  

Decrease in power:

It is another major problem caused by inadequate heat to burn the diesel in the combustion. Besides, it decreases engine horsepower.

Hard starting:

In cold weather, when the engine is colder than usual, a damaged glow plug will never be able to generate the required cylinder pressure.

What Causes The P0673 Code On A Duramax?

Different triggers may cause the code P0673. We will now note some common reasons to cause this error code on your Duramax.

  • Excessive heat

The main reason for a p0673 problem on Duramax is the excessive amount of heat generated in the plug area or high voltages that are reaching the glow plug. In both cases, it will result in a mismatch in the heat amount specified by the manufacturer and cause engine start issues.

  • Faulty wiring

The controller might bring high voltage issues which can worsen the situation. And if there is faulty wiring in the controller, the glow plug will receive a constant amount of power all the time. Plus, it causes premature burnout of the glow plug.

  • Use of gasoline

Besides, leaking the fuel or gasoline in the engine can also cause glow plug damage. It may bring a heat buildup in the pre-chamber.

How To Fix The P0673 Code On Duramax?

Trouble code p0673 on Duramax can be solved by yourself or by taking the car to an auto workshop. But as it can be fixed with a DIY or do-it-yourself try, it is recommended to fix the p0673 issue by yourself. Following are the two most common DIY methods to solve the error p0673.

Method A: The Glow Plugs

The following are the three steps to test and change a glow plug to fix the error code p0673 of your car engine.

  • Remove the glow plugs

The glow plug is located on top of cylinder number three. Carefully remove the glow plug from the engine. 

  • Test the glow plugs

Use a Multimeter to precede a test on the glow plugs. Read the result of the Multi-meter display. A resistance of fewer than 6 ohms of glow plug in the meter usually means the plug is good. Now you have to repeat the whole thing for all other glow plugs.

  • Change the glow plugs

In case of the failure of glow plugs, you had better have the entire set replaced. 

Method B: The glow plug control module

It is a two steps method to solve the p0673 problem from your Duramax engine.

  • Inspect the glow plug control module (PCM)

The glow plug control module is directly connected to the control unit of a Duramax engine. First, remove the glow plug control module carefully from the vehicle and visually inspect the module to make sure that it has not been contaminated or damaged by a leak from any other engine components.

Check the glow plug control module itself and its electrical connections for any damages; replace the glow plug control module if the damages are found.

  • Replace the glow plug control module

Changing your glow plug control module or glow plug is very easy.  Try to replace it after every 60 miles or 95 thousand kilometers. 

These are the two most common and practical DIY methods that can be used to solve the p0673 problem without taking your Duramax truck to the auto workshop. And after following this method, all the problems related to p0673 also will be solved.

Other Symptoms Of Getting P0673 On Duramax

If your Duramax has one glow plug failure, its symptoms might not be notable, and the Duramax engine can start normally. But in the cold season, you can get the following symptoms

  • Code sent from engine management computer (PCM) to your phone
  • The engine will face difficulty starting or may not start at all in cold weather
  • The engine may have difficulty starting if it is sitting for a long time
  • Lack of power generation until the engine heats up sufficiently
  • Problem in acceleration

How Much Does P0673 Cost To Get Fixed On Duramax?

The p0673 problem can be solved with a minimum cost if you try to solve the problem with the DIY method. With the DIY methods mentioned above, you can replace your glow plugs and solve the issue with just $9.25. The overall process requires only purchasing the new glow plugs, and there is no other cost.  

Can You Drive Your Duramax With Code P0673?

Yes, you can drive your Duramax diesel vehicles with the p0673 issue. But the actual answer to this question depends on the severity of glow plug damage. If your car has multiple glow plug damage, then it means the severity is high, and it requires solving the issue immediately.

And if your automobile has single glow plug damage, then you might not face too many problems immediately starting your car. But it is strongly recommended to solve the p0673 problem without any delay because of safety reasons.


P0673 problem is one of the most common automobile start-up problems that you derive from glow plug damage issues. Yet these glow plugs are related to the major problem of a car starting.

Plus, it affects fuel efficiency, and if you do not fix this problem, your Duramax performance will decrease over time. So it is recommended not to delay this issue and to solve the error code p0673 immediately.

Follow the recommended procedures accordingly. And if you find any difficulties, please feel free to take professional help.

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