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Engine-Codes – GMC – P1238 GMC

P1238 GMC Code - Injector 6 Output Circuit

Quick Answer

The P1238 GMC code specifically refers to an issue with the Injector 6 Output Circuit in the vehicle's engine. Common causes include Wiring issues: Damage or corrosion in the wiring harness connected to the injector circuit, Faulty fuel injector: A malfunctioning fuel injector can cause issues with fuel delivery, ECM failure: A defective engine control module may not be properly controlling the injector circuit. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1238 GMC indicates Injector 6 Output Circuit.
Common causes
Common causes include Wiring issues: Damage or corrosion in the wiring harness connected to the injector circuit, Faulty fuel injector: A malfunctioning fuel injector can cause issues with fuel delivery, ECM failure: A defective engine control module may not be properly controlling the injector circuit.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P1238 GMC Description

The P1238 GMC code specifically refers to an issue with the Injector 6 Output Circuit in the vehicle's engine. This code indicates that there is a problem with the electrical circuit that controls the fuel injector for cylinder 6. The fuel injector is responsible for delivering the precise amount of fuel into the combustion chamber for efficient and proper engine operation. When the injector circuit malfunctions, it can lead to issues with fuel delivery, which can impact the engine's performance and overall efficiency.

OBDII Code P1238 GMC - Injector 6 Output Circuit
P1238 GMC Code - Injector 6 Output Circuit

Common Causes of P1238 GMC

  1. Wiring issues: Damage or corrosion in the wiring harness connected to the injector circuit.
  2. Faulty fuel injector: A malfunctioning fuel injector can cause issues with fuel delivery.
  3. ECM failure: A defective engine control module may not be properly controlling the injector circuit.
  4. Electrical problems: Other electrical issues within the circuit, such as a short or open circuit.

Symptoms of P1238 GMC

  1. Rough idling: The engine may run unevenly or erratically at idle.
  2. Misfires: The engine may misfire, causing a noticeable lack of power or hesitation during acceleration.
  3. Reduced fuel efficiency: The vehicle may experience decreased fuel economy due to improper fuel delivery.
  4. Stalling: The engine may stall unexpectedly, especially at idle or low speeds.
  5. Check Engine Light: The Check Engine Light may illuminate on the dashboard to indicate a problem with the injector circuit.

How to Fix P1238 GMC

  1. Diagnostic scan: Use a diagnostic scanner to retrieve the specific trouble code and pinpoint the exact cause of the issue.
  2. Inspect wiring: Check the wiring harness for any damage, corrosion, or loose connections. Repair or replace as needed.
  3. Test fuel injector: Test the fuel injector for proper operation and replace if necessary.
  4. Check ECM: Inspect the engine control module for any signs of failure and replace if deemed faulty.
  5. Clear codes: Clear the trouble code from the ECM memory and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P1238 GMC

The typical repair costs for addressing a P1238 GMC code can vary depending on the specific cause of the issue. Generally, the cost of parts such as a new fuel injector or engine control module can range from $200 to $600, while labor costs can add another $100 to $300. Overall, the total repair cost for this issue may fall between $300 to $900. It's important to note that labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate.

What does this mean?

Tech Notes for P1238 GMC

If only 1 fuel injector Control circuit Diagnostic Trouble Code (DTC) is set, an open circuit or poor connection is the most likely cause. If groups of 4 fuel injector Control circuit DTCs are set, suspect a short to ground. Cylinder groups are 2, 3, 5, 8 or 1, 4, 6, 7. More than 4 fuel injector Control circuit DTCs set indicate short to voltage on fuel injector Control circuit is the most likely cause.



There is a factory service bulletin for the following models:



2004 GMC Sierra

2005 GMC Sierra

2004 GMC Topkick

2005 GMC Topkick

2004-2005 GMC Sierra, Topkick Factory Service Bulletin OBDII Code P1238

Need more information about the P1238 GMC code?

Need more information on how to fix the P1238 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1238 GMC code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1238 GMC Code

1. What are the common symptoms of OBDII code P1238 GMC (Injector 6 Output Circuit)?

- Common symptoms include engine misfires, rough idling, decreased fuel efficiency, and potentially stalling while driving.

2. What can cause the OBDII code P1238 GMC to trigger?

- The code may be triggered by issues such as a faulty fuel injector, a damaged injector wiring harness, or a problem with the engine control module (ECM).

3. How can I diagnose the cause of OBDII code P1238 GMC?

- Diagnosing the code typically involves checking the wiring harness and connector for damage, testing the fuel injector, and inspecting the ECM for any faults.

4. Is it safe to continue driving with OBDII code P1238 GMC present?

- It is not recommended to drive with this code present, as it can lead to engine performance issues and potentially cause further damage if left unaddressed.

5. Can I repair OBDII code P1238 GMC on my own?

- Depending on your level of automotive knowledge, you may be able to repair this code on your own by replacing the faulty fuel injector, repairing the wiring harness, or addressing any ECM issues.

6. Will clearing the OBDII code P1238 GMC make it go away permanently?

- Clearing the code without addressing the underlying issue will not make it go away permanently. It is important to diagnose and repair the root cause to prevent the code from reoccurring.

7. How much does it typically cost to fix OBDII code P1238 GMC at a repair shop?

- The cost of fixing this code can vary depending on the specific issue, but it may range from a few hundred to a few thousand dollars, including parts and labor.

8. Are there any preventive measures I can take to avoid OBDII code P1238 GMC in the future?

- Regular maintenance of your vehicle, such as keeping up with fuel injector cleaning and inspecting wiring harnesses for wear, can help prevent issues that may trigger this code.

9. Can OBDII code P1238 GMC affect the overall performance of my vehicle?

- Yes, this code can significantly impact the performance of your vehicle by causing engine misfires, reduced power, and other drivability issues.

10. How urgent is it to address OBDII code P1238 GMC once it appears?

- It is recommended to address this code as soon as possible to prevent further damage to the engine and ensure optimal performance of your vehicle.

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