P0676 Duramax: Underlying Causes And What You Can Do To Solve It - Auto Master X (2024)

The P0676 Duramax error code is nothing new in the car world but what does it mean? In short, this code entails that the glow plug box of your car has reached the end of its life span.

The code is a sign of many technical issues, such as the plug circuit not functioning or issues with the wiring, which might cause a little burning.

Here we’ll go into depth about what causes this code and what steps you can take to remedy it. Once you go through this article, you should have a broader, if not then a general, understanding of the P0676 Duramax code.

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Causes And Solution Of P0676 Duramax Problems

From the 2006 Duramax p0676 to the 2012 Duramax p0676, the causes for this error code remain the same.

The following will define the causes and introduce ways to figure out what’s actually causing this code to appear to do this. You may need a DVOM device and OBD scanner.

Check out the following table on the error code

Damaged Wire connectorsEngine unable to start
Faulty plug moduleEngine low on power
Shorted plug circuitStalling car acceleration
Faulty cylinder plugColder cylinder temperature

Now, let’s get more in-depth about this error code.

Wire Connection

When it comes to dealing with electronic errors, the simplest thing to do is to check whether the wires are all connected properly. Open up your relay to see the wires that connect to your glow plug.

Use your digital meter to measure the resistance by placing it on the first buss bar wire. If the meter shows a resistance that is greater than 2, then congratulations, you just found the problem.

Solution: You’ll now need to get new wires to connect to the glow plug, and the issue should resolve. Reconnecting loose wires should also fix the problem. Connect your scanner to the OBD port after checking for any more loose wires and clear the code.

Module Malfunction

Most diesel-run cars will have a control module that contains all the glow plugs. This can make it more challenging for you to see when one of your glow plugs goes terrible.

So what do you do in this situation? One way to identify a faulty plug is if there’s white smoke along with a burning smell.

Solution: If only one or two glow plugs have gone bad, then the plugs are faulty, but if more have degraded, the issue lies with your glow plug module. This means you might have to install a new glow plug control module.

A faulty module will cause your engine to start slow in warmer temperatures, and the engine will fail entirely when it gets colder.

Plug Short Circuit

Glow plugs have tips connected to a combustion chamber that heats up the fuel when the temperature is low. This heating procedure helps to start up the car, but it can have the opposite effect.

A glow plug that has short-circuited will be unable to heat up the mixture in the combustion chamber and might end up burning out the controls for the glow plug.

Also Read: P1093 Duramax Error Code And Their Solutions

Solution: You might hear a sizzling sound when a plug has short-circuited and this means that the wire connecting to the plug is also burning up.

To fix this issue, have a new circuit installed as fast as you can. You might need to change wires damaged by the sizzling plugs too.

Broken Cylinder

A p0676 Duramax lmm may also occur when the ECU detects an issue with the sixth cylinder of your engine. The glow plug that has exceeded its range of mileage may malfunction, causing a problem with the cylinder.

This might happen even before it completed its 100,000-mile lifespan. When you get the error code it could mean a few things, mainly that your cylinder has been damaged.

Solution: These cylinders are needed to be in perfect shape as they help to start up your car when the engine gets cold or if the weather reads a low temperature.

Not fixing these cylinders will keep the engine from heating up. A quick trip to the mechanic will be enough to repair them unless you need to buy new ones.

These are some of the few ways to fix the error code, and even though you can fix it, it isn’t something you should be taken lightly.

There might be severe damage to the engine, so you should take your car to your mechanic as fast as possible.

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Frequently Asked Questions (FAQs)

What does the engine code P0676 mean?

This means that your engine will be unable to start in some weather conditions. The engine won’t be able to heat up by itself, and if it does, it might take some time. The most common cause for this error is usually a faulty glow plug.

How Do I Fix Code P0676?

Check your wires and look for a loose or broken connection. Make sure that your plugs are without any damage every once in a while. Have it serviced regularly or have a mechanic look at it often.

Where is the number 6 glow plug on Duramax?

The no.6 glow plug is usually on the driver’s side. Depending on left or right-handed steering, the location may vary. It’s the 3 plugs on the driver’s side.


Maintaining a car can be quite a big headache. P0676 Duramax is one of the many problems that could lead to an even bigger issue. Hopefully, this information brings some use to you and helps you keep your car in shape.

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P0676 Duramax: Underlying Causes And What You Can Do To Solve It - Auto Master X (2024)


What is code P0676 on LBZ Duramax? ›

What Does the P0676 Code Mean? Diagnostic trouble code (DTC) P0676 stands for “Cylinder #6 Glow Plug Circuit/Open.” Some diesel engines use glow plugs to warm up the combustion chamber before starting the engine.

How to test glow plug control module? ›

If your glow plugs are all working correctly, move onto your glow plug control module. Start by checking the battery voltage to the glow plug control module, a voltage drop of over a half volt (or more) means your control module should be replaced.

What happens if the glow plug relay is not working? ›

Although designed to operate between 850 to 1,100 degrees centigrade, when the electrical current to the glow plug is held too long, because of a faulty relay and/or controller, it can lead to overheating, which will cause the glow plug to swell, split or burst and result in immediate failure.

How do I know if my glow plugs are bad in Duramax? ›

Six signs it's time to replace your glow plugs
  1. Hard starting. A hard starting engine is the most common indicator of damaged glow plugs. ...
  2. Engine misfiring. ...
  3. Rough idling. ...
  4. Decreased fuel efficiency. ...
  5. White smoke. ...
  6. Black smoke.
Jan 29, 2020

How do I know which glow plug is bad? ›

Any glow plugs that does not light the test light is bad. Alternate methods – Use an ohmmeter – (Again, disconnect all wires from each glow plug to prevent parallel paths.) Measure resistance between ground the terminal of each glow plug. Any glow plug that indicates infinity or more than a few ohms is bad.

How do you test a diesel glow plug? ›

The Process Of Testing Glow Plugs
  1. Diagnostic inspection. Any proper engine inspection must start with a thorough check-up. ...
  2. Use an infrared thermometer. ...
  3. Prepare your multimeter. ...
  4. Test battery voltage. ...
  5. Remove glow plug connectors. ...
  6. Connect the multimeter to your glow plugs. ...
  7. Evaluate the reading when testing glow plugs.
Nov 18, 2023

What happens when your glow plug control module goes bad? ›

Possible symptoms of a faulty glow plug control unit or glow plug relay include: glow plugs not receiving power, glow plugs not staying on or the glow plug relay clicking rapidly.

How do you start a diesel with bad glow plugs? ›

Crank for 5 seconds, then wait 5 seconds, then again crank 5 seconds, then wait 5 seconds. Continue with this cranking pattern and the engine should start after the forth or so try.

How do you test glow plugs without taking them out? ›

Connect one multimeter test lead to a ground on the engine (preferably near the glow plug). Connect the other lead to the (power supply) terminal on the top of the glow plug. Read the result off the multimeter display. Note that a resistance of less than 6Ω usually means the glow plug is 'good'.

What causes glow plugs to break? ›

Common reasons why glow plugs fail include:

Excessive carbon build up in your pre chambers. Folds and dents on the rod of the glow plug. Snapped or damaged tip of the glow plug. Excessive heat reaching the glow plug.

What does cylinder glow plug circuit open mean? ›

DTC P0673 stands for “Cylinder 3 Glow Plug Circuit Open” This code is logged when the PCM detects that the glow plug is unable to heat up. It is commonly caused by malfunctioning glow plugs, glow plug control plug module failure, and damaged wiring connectors.

What does cylinder 7 glow plug circuit open mean? ›

OBD-II Code Hard or no start in cold weather is defined as a Cylinder 7 Glow Plug Circuit/Open. The Glow Plug is used on diesel engines to preheat the cylinder before the engine is started. If the engine control module (PCM) detects the glow plug for cylinder seven is not operating properly, the PCM will set code P0677 ...

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