p0380 Duramax

Cause and Solution to p0380 Duramax Code

The p0380 Duramax code is a common issue that many vehicle owners experience with their diesel-powered vehicles. This code specifically relates to the glow plug heater circuit, which is responsible for preheating the combustion chamber in order to facilitate cold starts and ensure smooth engine operation. When this circuit malfunctions, it can lead to various problems such as extended crank times, rough idling, and decreased fuel efficiency.

The below content is about the causes of the p0380 Duramax code and provides potential solutions to fix the issue. Understanding the root factors and applying appropriate remedies can restore the performance and reliability of diesel engines.

What is P0380 Code

p0380 Duramax
What is P0380 Code

The P0380 code is a diagnostic trouble code (DTC) that indicates an issue with the glow plug heater circuit in a diesel engine. When this code appears, it means that the powertrain control module (PCM) has detected a malfunction or abnormal voltage reading in the glow plug heater circuit. Glow plugs are crucial components of a diesel engine’s cold start system, as they heat up the combustion chambers to aid in starting the engine when it is cold outside. One common cause is a faulty glow plug itself, which may have burned out and needs to be replaced. 

If you own a vehicle, chances are you’ve encountered the dreaded check engine light at some point. It’s that ominous warning sign that something isn’t quite right under the hood. One common trouble code that may appear is P0380, which relates to glow plug/ heater circuit ‘A’. But what exactly does this code mean and how can you diagnose and fix the issue?

P0380 is a diagnostic trouble code related to the glow plug system in diesel engines. It indicates issues with the glow plugs or their circuits, which warm up the combustion chamber before starting the engine, especially in cold weather.

Symptoms of P0380 Code

The P0380 code is triggered when there are problems with the glow plugs. This code is associated with common symptoms:

  • Rough idle or misfiring can be caused by inadequate heat in the cylinder.
  • Excessive white smoke from the exhaust may indicate malfunctioning glow plugs.
  • Decreased power and acceleration could be due to incomplete combustion from faulty glow plugs.
  • Identifying and addressing these symptoms can prevent engine damage.
  • Difficulty starting in cold temperatures.
  • Rough idle, illuminated check engine light.
  • Inefficient combustion leads to reduced performance, acceleration, and increased exhaust emissions.

Addressing the issue is important to prevent further damage and restore proper engine functioning.

6 Causes of P0380 Code

The P0380 error code has six main factors that contribute to its occurrence, including faulty components and electrical problems. Thorough inspection and identification of the specific cause is crucial for effective resolution.

1. Faulty Glow Plugs

p0380 Duramax

Engines have one glow plug per cylinder, but these plugs can deteriorate over time. This can cause inefficient heating during cold starts and trigger the P0380 code on the OBD scanner. Duramax owners often experience issues with faulty glow plugs, which can lead to difficult starting, engine failure, decreased fuel efficiency, and increased emissions. It is recommended to consult a professional technician for accurate diagnosis and repairs to prevent further damage and costly repairs. Taking quick action is important to maintain vehicle performance and prolong the life of the Duramax engine.

2. Faulty Glow Plug Timer

A faulty glow plug timer can cause a P0380 error code by failing to control the glow plugs properly. This can cause difficulties in starting the engine, rough idling, reduced performance, and increased exhaust emissions. To fix the issue, the timer needs to be diagnosed and replaced.

3. Faulty Connector

The P0380 error code is triggered when the wiring connectors for the glow plugs are loose or damaged. This can cause starting difficulties, rough idling, and reduced engine performance. Inspect and repair or replace the faulty connectors to fix the issue.

4. Problems with the Glow Plug Control Module

p0380 Duramax

The glow plug control module controls the functions of the glow plug. A faulty module can cause voltage issues and trigger the P0380 code. The Glow Plug Control Module (GPCM) is important for diesel engines in cold weather conditions. It can cause problems, like the P0380 diagnostic trouble code (DTC), indicating a malfunction. This could be due to a faulty module or other components. The GPCM’s design and location make it difficult to access and maintain, increasing repair costs and time. Aftermarket solutions are claimed to be more durable and easier to install.

5. Electrical Issues

The P0380 error code can be caused by electrical issues, even if all glow plug components seem fine. Blown fuses or problems with the glow plug relay circuits can affect engine start-up, especially in cold weather. It is important to inspect and fix any electrical problems to resolve the error code and ensure the proper functioning of the glow plugs. Correct diagnosis and repair can restore engine performance and prevent future occurrences of the code.

6. PCM Malfunction

The Powertrain Control Module (PCM) manages engine components, including glow plugs. PCM malfunctions rarely cause the P0380 code. Other factors like faulty glow plugs are more common causes. 

Thorough inspections are needed to find the actual cause and apply the appropriate solution.

P0380 Duramax: Fixing P0380 Engine Code

How to Fix P0380 Duramax [A Complete 6 Steps Guide]

P0380 Duramax

If you’re a proud owner of a Duramax diesel engine, chances are you’ve come across the dreaded P0380 error code at some point. This code specifically relates to the glow plug heater circuit, which is responsible for ensuring that your engine starts smoothly, especially in colder temperatures. Dealing with this issue can be frustrating and time-consuming, but fear not! In this comprehensive guide, Six simple steps are discussed to fix the P0380 Duramax error code and get your engine running flawlessly once again. So let’s dive in and unravel the mysteries behind this pesky problem!

  • Start by checking the glow plug fuse to ensure it is not blown.
  • Inspect the glow plug relay to see if it is functioning properly.
  • Test the glow plug module to determine if it is faulty.
  • Check the wiring harness for any damage or loose connections.
  • Use a multimeter to test the resistance of the glow plugs.
  • If necessary, replace any faulty glow plugs or repair any damaged wiring.

Following these steps will help you fix the P0380 Duramax error code related to the glow plugs. To rectify the P0380 Duramax error code, adhere to the instructions provided below:

1. Perform a Visual Inspection

To diagnose and address the P0380 error code related to a faulty glow plug timer, visually inspect the glow plugs, connectors, and wiring for damage or wear. Check for loose connections or corrosion. Take appropriate action to repair or replace faulty components. A thorough visual inspection can pinpoint the problem and ensure the proper functioning of the glow plug timer.

2. Check Glow Plug Resistance

To check glow plug resistance, use a digital multimeter, ensuring the engine is cool. Remove each plug’s connector and measure the resistance value. Compare with manufacturer’s specs and replace any faulty plugs. This ensures optimal performance and smooth engine starting, especially in cold conditions.

3. Check the Glow Plug Voltage

To check the glow plug voltage, use a multimeter to check the module and individual plug voltage. Voltage should be within the specified range. Direct tests can be done by applying 12 volts to each terminal and grounding the body for 2 to 4 seconds. A healthy plug will become red hot, indicating proper function. If there is no red glow or faint glow, the plug is faulty and needs replacement. These tests allow for accurate assessment and necessary steps to address issues for smooth engine start-ups and optimal performance.

4. Check the Glow Plug Control Module

To troubleshoot and address potential issues with the glow plug control module, it is important to thoroughly inspect it. If you suspect a fault, replace it. Diagnosing the problem requires advanced scanner tools like the OBD-II scanner. Take the vehicle to a reputable repair shop with the necessary equipment and expertise to get an accurate diagnosis. Seeking professional assistance ensures a precise diagnosis and proper resolution for optimal engine performance.

5. Inspect the PCM

If the P0380 code persists after checking other potential causes, focus on the vehicle’s PCM. Bring it to an experienced mechanic as PCM issues can be expensive to fix. The PCM regulates engine operations and its failure can cause performance problems and trigger error codes like P0380. Inspecting and diagnosing the PCM is important for smooth vehicle function.

6. Reset the Error Code

To reset the P0380 error code, you can use a diagnostic scanner or disconnect the negative battery cable for 10 seconds. After resetting, check for warning lights and monitor the glow plug’s performance during engine start-up.

Preventive Measures for P0380 Code

To prevent the P0380 code and maintain the glow plug, You need to:

  • Use high-quality fuel.
  • Use good-quality glow plugs.
  • Avoid frequent cold starts.
  • Park in a warmer place or use block heaters, and warm up the combustion chamber before driving.
  • Inspect and clean wiring harness and glow plug connections regularly.

Following these instructions ensures proper functioning and avoids the P0380 error code. Also, Regular maintenance is essential for troubleshooting.

P0380 Duramax: Preventive Measures for P0380 Code

Final Thoughts

The p0380 Duramax code is a common issue that many Duramax owners may encounter. It can be resolved easily and at a relatively low cost.  It is important to address this problem promptly to avoid any further damage to the vehicle’s engine. By understanding the potential causes and symptoms of this code, owners can take appropriate action and seek professional assistance if necessary. Regular maintenance, such as cleaning or replacing glow plugs, can also help prevent future occurrences of the p0380 code.

Remember, keeping your Duramax engine in good condition is vital for its performance and longevity, so don’t hesitate to address any issues that may arise. Take care of your vehicle and enjoy years of reliable driving with your Duramax engine!


What causes the P0380 code?

The P0380 code in a Duramax engine is triggered by issues with the glow plug heater circuit. This can be caused by faulty glow plugs, a malfunctioning control module, or damaged wiring. Inspect glow plugs, control module, and wiring for issues.

How do I fix error code P0380?

Error code P0380 is a common issue in Duramax engines, indicating a problem with the glow plug circuit. To fix it, check the wiring, inspect glow plugs, and test the relay. If the issue persists, consult a professional mechanic for further diagnosis and guidance. Proper troubleshooting can resolve the error code efficiently.

What causes glow plug relay failure?

Duramax owners can avoid glow plug relay failure caused by wear and tear, voltage spikes, and environmental factors. Regular maintenance and wiring modifications are essential.

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