AutoCodes – Cadillac – P129B Cadillac

P129B Cadillac 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 Cadillac 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 793

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

What does this mean?

What are the Possible Causes of the DTC P129B Cadillac?

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 Cadillac?

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 Cadillac 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 Cadillac code?

Need more information on how to fix the P129B Cadillac 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 P129B Cadillac Code

What does the OBDII code P129B mean for a Cadillac?

The OBDII code P129B indicates that the Fuel Pump Driver Control Module is detecting a low voltage condition in the fuel pump driver system.

What are the common symptoms associated with the P129B code?

Common symptoms include difficulty starting the vehicle, decreased engine performance, stalling, or the engine not running at all.

What could cause the P129B code to trigger?

Possible causes include a faulty fuel pump driver module, damaged wiring or connectors, a weak battery, or issues with the fuel pump itself.

How can I diagnose the P129B code?

You can start by checking the battery voltage and ensuring it's within the normal range, inspecting the wiring and connectors for damage, and testing the fuel pump driver module for proper operation.

What repairs are typically needed to fix the P129B code?

Repairs may involve replacing the fuel pump driver module, repairing damaged wiring or connectors, or replacing the fuel pump if it is found to be faulty.

Can I clear the P129B code without fixing the issue?

While you can clear the code using an OBDII scanner, it is important to address the underlying issue; otherwise, the code will likely return.

Is it safe to drive my Cadillac with the P129B code?

Driving with the P129B code can be risky, as it may lead to fuel delivery issues, which can cause the engine to stall or not start, so it's best to get it diagnosed and repaired promptly.

Are there any other OBDII codes that might be related to P129B?

Yes, related codes may include P0087 (fuel rail/system pressure too low) or P0230 (fuel pump primary circuit malfunction), which can indicate issues with the fuel system.

How much does it typically cost to repair issues related to the P129B code?

Repair costs can vary widely depending on the specific problem, but replacing the fuel pump driver module may range from $100 to $600, including parts and labor.