P129C 2018 GMC Sierra Code - Fuel Pump Driver Control Module System Voltage High
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
- P129C 2018 GMC Sierra indicates Fuel Pump Driver Control Module System Voltage High.
- 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 P129C 2018 GMC Sierra Description
What are the Possible Causes of the DTC P129C 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 P129C 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 P129C 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 P129C 2018 GMC Sierra Code
1. What does the OBDII code P129C mean on a 2018 GMC Sierra?
P129C indicates that the Fuel Pump Driver Control Module (FPCM) has detected a system voltage that is too high, which can affect fuel delivery.
2. What are the common symptoms of P129C on a 2018 GMC Sierra?
Symptoms include poor engine performance, difficulty starting, reduced fuel efficiency, and in some cases, the vehicle may not start at all.
3. What causes the P129C code to appear on a 2018 GMC Sierra?
Common causes include a faulty Fuel Pump Driver Control Module, wiring issues such as damaged or corroded connections, or problems with the vehicle's charging system.
4. Can a faulty alternator cause the P129C code?
Yes, an overcharging alternator can lead to high system voltage, which may trigger the P129C code.
5. How do I diagnose the P129C code on my 2018 GMC Sierra?
Start by checking the battery voltage, alternator output, and wiring to the Fuel Pump Driver Control Module. Inspect for loose or corroded connections and test the module itself if necessary.
6. Is it safe to drive with the P129C code on my 2018 GMC Sierra?
Driving with this code is not recommended as it may lead to poor engine performance or potential damage to the fuel system components.
7. How can I fix the P129C code on my 2018 GMC Sierra?
Repairs may include replacing the Fuel Pump Driver Control Module, repairing or replacing damaged wiring, or addressing issues with the alternator or battery.
8. Can a dead or weak battery cause the P129C code?
While a weak battery typically causes low voltage issues, it’s essential to check the entire charging system, as related problems can indirectly contribute to high voltage readings.
9. How much does it cost to repair the P129C code on a 2018 GMC Sierra?
Repair costs vary but may range from $100 to $500 depending on whether the issue is with the Fuel Pump Driver Control Module, wiring, or alternator.
10. Will clearing the code fix the problem permanently?
No, clearing the code without addressing the root cause will only temporarily turn off the check engine light, and the code is likely to return.
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