P128B 2017 GMC Sierra Code - Fuel Rail Pressure Sensor 2 Internal Performance
Quick Answer
The Engine Control Module (ECM) uses the Fuel Rail Pressure (FRP) sensor to constantly adjust the high-pressure fuel pump's feed rate so that the ideal pressure is permanently maintained in the high-pressure section (between the high-pressure fuel pump and the injectors) by means of closed-loop control. Common causes include Low or no fuel, Faulty Fuel Rail Pressure (FRP) Sensor, Fuel Rail Pressure harness is open or shorted. 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
- P128B 2017 GMC Sierra indicates Fuel Rail Pressure Sensor 2 Internal Performance.
- Common causes
- Common causes include Low or no fuel, Faulty Fuel Rail Pressure (FRP) Sensor, Fuel Rail Pressure harness is open or shorted.
- 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 P128B 2017 GMC Sierra Description
What are the Possible Causes of the DTC P128B 2017 GMC Sierra?
- Low or no fuel
- Faulty Fuel Rail Pressure (FRP) Sensor
- Fuel Rail Pressure harness is open or shorted
- Fuel Rail Pressure circuit poor electrical connection
- Faulty Fuel Pump
How to Fix the DTC P128B 2017 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 P128B 2017 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 P128B 2017 GMC Sierra code?
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Frequently Asked Questions about P128B 2017 GMC Sierra Code
1. What does the OBDII code P128B mean on a 2017 GMC Sierra?
P128B indicates an issue with the Fuel Rail Pressure Sensor 2, specifically an internal performance problem where the sensor is not operating within its expected range.
2. What are the symptoms of code P128B in a 2017 GMC Sierra?
Common symptoms include poor engine performance, difficulty starting, reduced fuel efficiency, stalling, and the illumination of the check engine light.
3. What causes the P128B code to appear?
This code can be triggered by a faulty fuel rail pressure sensor, wiring or connector issues, fuel delivery problems, or, less commonly, a malfunctioning powertrain control module (PCM).
4. Can I drive my 2017 GMC Sierra with the P128B code?
While the vehicle may still be drivable, continuing to drive with this code could lead to reduced performance or further damage to the fuel system. It’s best to address the issue promptly.
5. How is the P128B code diagnosed?
A mechanic will use a scan tool to confirm the code, inspect the fuel rail pressure sensor and its wiring, and may perform fuel pressure tests to identify any irregularities.
6. How do I fix the P128B code on my 2017 GMC Sierra?
Repairs may include replacing the fuel rail pressure sensor, repairing or replacing damaged wiring, cleaning corroded connectors, or addressing fuel system issues like a failing fuel pump.
7. How much does it cost to repair the P128B code?
Repair costs vary, but replacing the fuel rail pressure sensor typically ranges from $200 to $400, including parts and labor. Additional repairs may increase costs.
8. Can a dirty fuel filter cause the P128B code?
While a dirty fuel filter is not a direct cause, it can lead to fuel delivery problems, which may indirectly affect fuel rail pressure and trigger this code.
9. Does the P128B code require replacing the PCM?
Replacing the PCM is rarely needed for this code. It’s typically caused by sensor or wiring issues, and the PCM should only be replaced after all other possibilities are ruled out.
10. How can I prevent the P128B code from occurring again?
Regular maintenance, such as inspecting fuel system components, replacing the fuel filter as recommended, and ensuring connectors and wiring are in good condition, can help prevent this issue.
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