AutoCodes – Buick – P129B Buick

P129B Buick Code - Fuel Pump Driver Control Module System Voltage Low

Quick Answer

The Fuel Pump Power Control Module monitors the battery positive voltage circuit to verify the voltage is within the normal operating range. Common causes include Faulty Fuel Pump Driver Control Module, Fuel Pump Driver Control Module harness is open or shorted, Fuel Pump Driver 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: P129B Buick indicates Fuel Pump Driver Control Module System Voltage Low.
Common causes: Common causes include Faulty Fuel Pump Driver Control Module, Fuel Pump Driver Control Module harness is open or shorted, Fuel Pump Driver 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 680

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 Jul 04, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P129B Buick Description

The Fuel Pump Power Control Module monitors the battery positive voltage circuit to verify the voltage is within the normal operating range. The Diagnostic Trouble Code (DTC) will be set when the Fuel Pump Power Control Module detects the battery positive voltage is less than 7 V for 1 s.

OBDII Code P129B Buick - Fuel Pump Driver Control Module System Voltage Low - AutoCodes.com — P129B Buick Code - Fuel Pump Driver Control Module System Voltage Low

What does this mean?

What are the Possible Causes of the DTC P129B Buick?

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

How to Fix the DTC P129B Buick?

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 P129B Buick 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 P129B Buick code?

Need more information on how to fix the P129B Buick code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P129B Buick 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 P129B Buick Code

1. What does the OBDII code P129B mean on a Buick?

Code P129B indicates that the Fuel Pump Driver Control Module (FPCM) is detecting a voltage level that is lower than expected.

2. What are the common symptoms of P129B on a Buick?

Symptoms may include difficulty starting the engine, reduced engine performance, stalling, or the check engine light being illuminated.

3. What causes the P129B code to appear?

Potential causes include a faulty Fuel Pump Driver Control Module, corroded or damaged wiring, a weak fuel pump, or a failing battery or alternator.

4. Can a low battery cause the P129B code?

Yes, a weak or failing battery can cause low voltage in the Fuel Pump Driver Control Module system, triggering the P129B code.

5. How is the P129B code diagnosed?

A mechanic will typically use a scan tool to confirm the code, check the wiring and connectors for damage, test the battery and alternator, and inspect the fuel pump and FPCM for proper operation.

6. Can I drive my Buick with a P129B code?

It is not recommended to drive with this code, as it can lead to fuel delivery issues and potentially cause the engine to stall or run poorly.

7. How do I fix the P129B code on my Buick?

Repairs may include replacing the Fuel Pump Driver Control Module, repairing or replacing damaged wiring, charging or replacing the battery, or addressing alternator issues.

8. How much does it cost to repair a P129B code on a Buick?

Repair costs can vary widely. Replacing the Fuel Pump Driver Control Module may cost $300-$600, while wiring repairs or battery replacements may be less expensive.

9. Can a dirty fuel pump or fuel filter cause the P129B code?

While not a direct cause, a clogged fuel filter or failing fuel pump can strain the fuel system and potentially contribute to low voltage issues.

10. Is the P129B code specific to Buick vehicles?

No, the P129B code can appear on other vehicles, but the diagnostic and repair process may vary depending on the make and model. Always refer to your vehicleâ€™s service manual.