P129B 2018 GMC Sierra 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 2018 GMC Sierra 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.
Code P129B 2018 GMC Sierra Description
What are the Possible Causes of the DTC P129B 2018 GMC Sierra?
- 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 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 P129B 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.
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Frequently Asked Questions about P129B 2018 GMC Sierra Code
1. What does the OBDII code P129B mean on a 2018 GMC Sierra?
P129B indicates that the Fuel Pump Driver Control Module (FPCM) is detecting a system voltage that is lower than the expected range.
2. What are the common symptoms of a P129B code?
Symptoms may include engine hesitation, reduced power, stalling, difficulty starting, or an illuminated check engine light.
3. What can cause the P129B code to appear on a 2018 GMC Sierra?
Possible causes include a failing Fuel Pump Driver Control Module, poor electrical connections, a faulty fuel pump, corroded wiring, or a weak vehicle battery.
4. Can a weak battery trigger the P129B code?
Yes, a weak or failing battery can cause low system voltage, potentially triggering the P129B code.
5. How do I diagnose the P129B code?
Start by checking the battery voltage, inspecting wiring and connectors for damage or corrosion, and testing the Fuel Pump Driver Control Module with a scan tool.
6. Is it safe to drive with a P129B code?
Driving with a P129B code is not recommended, as it may lead to poor engine performance or stalling, increasing the risk of an accident.
7. How do I fix the P129B code on my GMC Sierra?
Repairs may include replacing the Fuel Pump Driver Control Module, repairing damaged wiring or connectors, cleaning corroded terminals, or replacing the battery.
8. Can a failing alternator cause the P129B code?
Yes, a failing alternator can lead to low system voltage, which may trigger the P129B code.
9. Does the fuel pump need to be replaced for a P129B code?
Not always. The fuel pump should only be replaced if it is confirmed to be the root cause after thorough diagnostics.
10. How much does it typically cost to repair a P129B code?
Repair costs vary depending on the cause but can range from $100 for basic wiring repairs to $500 or more for module or fuel pump replacement.
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