AutoCodes – GMC – P129E 2018 GMC Sierra

P129E 2018 GMC Sierra Code - Fuel Pump Driver Control Module Signal Message Counter Incorrect

Quick Answer

The Fuel Pump Power Control Module is constantly sending serial data messages to the Engine Control Module (ECM) regarding the operating state of the fuel pump power control system. Common causes include Faulty Fuel Pump Power Control Module, Fuel Pump Power Control Module harness is open or shorted, Fuel Pump Power Control Module circuit poor electrical connection. 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: P129E 2018 GMC Sierra indicates Fuel Pump Driver Control Module Signal Message Counter Incorrect.
Common causes: Common causes include Faulty Fuel Pump Power Control Module, Fuel Pump Power Control Module harness is open or shorted, Fuel Pump Power Control Module circuit poor electrical connection.
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.

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Code Popularity 156

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 27, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P129E 2018 GMC Sierra Description

The Fuel Pump Power Control Module is constantly sending serial data messages to the Engine Control Module (ECM) regarding the operating state of the fuel pump power control system. These messages are sent in a continuously repeating series of rolling counts with associated password protect samples and each count/sample is assigned a value. When the ECM determines that too many of the counts/samples contain an error value, the ECM sets the Diagnostic Trouble Code (DTC) P129E.

OBDII Code P129E 2018 GMC Sierra - Fuel Pump Driver Control Module Signal Message Counter Incorrect - AutoCodes.com — P129E 2018 GMC Sierra Code - Fuel Pump Driver Control Module Signal Message Counter Incorrect

What does this mean?

What are the Possible Causes of the DTC P129E 2018 GMC Sierra?

Faulty Fuel Pump Power Control Module
Fuel Pump Power Control Module harness is open or shorted
Fuel Pump Power Control Module circuit poor electrical connection

How to Fix the DTC P129E 2018 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P129E 2018 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P129E 2018 GMC Sierra code?

Need more information on how to fix the P129E 2018 GMC Sierra code? Get Access to Factory Service Manuals

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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 P129E 2018 GMC Sierra Code

1. What does the OBDII code P129E mean for a 2018 GMC Sierra?

P129E indicates that the Fuel Pump Driver Control Module (FPCM) is detecting an incorrect signal message counter, suggesting a communication issue.

2. What are the common symptoms of code P129E in a 2018 GMC Sierra?

Symptoms may include difficulty starting the engine, rough idling, decreased fuel efficiency, or the Check Engine Light illuminating.

3. What causes the P129E code to appear on a 2018 GMC Sierra?

Common causes include a faulty Fuel Pump Driver Control Module, wiring or connector issues, or a software glitch in the module.

4. Can I drive my 2018 GMC Sierra with the P129E code?

Itâ€™s not recommended to drive with this code for an extended period, as it may lead to fuel delivery issues and engine performance problems.

5. How do I diagnose the P129E code on a 2018 GMC Sierra?

Diagnosis involves checking the FPCM wiring and connectors for damage, scanning for module communication errors, and testing the module's voltage and ground connections.

6. How do I fix the P129E code on my 2018 GMC Sierra?

Repairs may include replacing the Fuel Pump Driver Control Module, repairing damaged wiring or connectors, or updating the moduleâ€™s software.

7. Is the P129E code a common issue with the 2018 GMC Sierra?

While not extremely common, it can occur due to module degradation or wiring issues over time.

8. What tools are needed to troubleshoot the P129E code?

Youâ€™ll need an OBDII scanner, a multimeter for electrical testing, and potentially access to the vehicleâ€™s service manual for wiring diagrams.

9. How much does it cost to fix the P129E code on a 2018 GMC Sierra?

Repair costs can vary, ranging from $100 to $600, depending on whether the issue is wiring-related or if the FPCM needs replacement.

10. Can a software update resolve the P129E code on a 2018 GMC Sierra?

In some cases, a software update for the Fuel Pump Driver Control Module may resolve the issue if the incorrect message counter is due to a programming glitch.