Engine-CodesGMC – P129F GMC

P129F GMC Code - Fuel Pump Driver Control Module Fuel Pump Speed Signal Incorrect

Quick Answer

The P129F diagnostic trouble code (DTC) for GMC vehicles indicates a problem with the Fuel Pump Driver Control Module (FPDM) related to the fuel pump speed signal being incorrect. Common causes include Malfunctioning Fuel Pump Driver Control Module, Faulty wiring or connections, Defective fuel pump. 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
P129F GMC indicates Fuel Pump Driver Control Module Fuel Pump Speed Signal Incorrect.
Common causes
Common causes include Malfunctioning Fuel Pump Driver Control Module, Faulty wiring or connections, Defective fuel pump.
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.
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P129F GMC Description

The P129F diagnostic trouble code (DTC) for GMC vehicles indicates a problem with the Fuel Pump Driver Control Module (FPDM) related to the fuel pump speed signal being incorrect. The FPDM is responsible for controlling the fuel pump's operation, ensuring that the correct amount of fuel is delivered to the engine at all times. In this case, the code signifies that the signal being sent by the FPDM regarding the fuel pump speed is not within the expected parameters.

OBDII Code P129F GMC - Fuel Pump Driver Control Module Fuel Pump Speed Signal Incorrect
P129F GMC Code - Fuel Pump Driver Control Module Fuel Pump Speed Signal Incorrect

Common Causes of P129F GMC

  1. Malfunctioning Fuel Pump Driver Control Module
  2. Faulty wiring or connections
  3. Defective fuel pump
  4. Issues with the fuel pump speed sensor
  5. Electrical system problems

Symptoms of P129F GMC

  1. Engine stalling or hesitation
  2. Rough idling or misfiring
  3. Difficulty starting the vehicle
  4. Decreased fuel efficiency
  5. Check Engine Light illuminated

How to Fix P129F GMC

  1. Diagnose the issue by connecting a scan tool to retrieve the specific DTC and related data.
  2. Inspect the wiring and connections associated with the fuel pump driver control module.
  3. Test the fuel pump speed sensor for proper operation.
  4. Replace the faulty FPDM or fuel pump as necessary.
  5. Clear the DTC and perform a test drive to ensure the issue has been resolved.

Cost to Fix P129F GMC

The typical repair costs for addressing a P129F code can vary depending on the extent of the issue and the necessary repairs. In general, replacing the Fuel Pump Driver Control Module or the fuel pump itself can range from $200 to $600, including parts and labor. Additional costs may be incurred for diagnostic testing, wiring repairs, or sensor replacements. It's important to consider the specific rates of auto repair shops in your area to obtain a more accurate estimate for this repair.

Tech Notes for P129F GMC

A factory service bulletin for the 2019-2020 Chevrolet Silverado 2500/3500 and GMC Sierra 2500/3500 recommends replacing the Fuel Pump Driver Control Module for vehicles with Loss of power, stalling, and the P129F engine code.

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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 P129F GMC Code

1. What are the common symptoms of OBDII code P129F in a GMC vehicle?

- Common symptoms include rough engine idle, poor acceleration, stalling, and the vehicle going into "limp mode."

2. What are the potential causes of OBDII code P129F in a GMC vehicle?

- The code P129F can be triggered by a faulty fuel pump driver control module, issues with the fuel pump speed signal, wiring problems, or a malfunctioning fuel pump.

3. How can I diagnose OBDII code P129F in my GMC vehicle?

- Diagnosis typically involves using a scan tool to read the code, checking the fuel pump driver control module, inspecting the wiring for damage, and testing the fuel pump speed signal.

4. Can I still drive my GMC vehicle with OBDII code P129F present?

- It is not recommended to drive the vehicle with code P129F present, as it can lead to poor engine performance and potential safety hazards.

5. How can I repair OBDII code P129F in my GMC vehicle?

- Repairing this code may involve replacing the fuel pump driver control module, repairing or replacing damaged wiring, or replacing the fuel pump if necessary.

6. Is it safe to reset the OBDII code P129F in my GMC vehicle using a scan tool?

- While resetting the code may temporarily turn off the check engine light, it is important to address the underlying issue causing the code to prevent further problems.

7. Will OBDII code P129F in a GMC vehicle affect fuel efficiency?

- Yes, code P129F can lead to decreased fuel efficiency due to improper fuel pump operation affecting the engine's performance.

8. Can a DIY enthusiast fix OBDII code P129F in a GMC vehicle?

- Depending on the root cause, some DIY enthusiasts may be able to address the issue by following repair guides and using the necessary tools.

9. How much does it cost to repair OBDII code P129F in a GMC vehicle at a repair shop?

- The cost of repairs for code P129F can vary based on the specific issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

10. Are there any preventive measures to avoid OBDII code P129F in a GMC vehicle?

- Regular maintenance, such as checking the fuel system components, keeping the fuel pump clean, and addressing any fuel system issues promptly, can help prevent code P129F from occurring.

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