AutoCodes – GMC – P128F 2015 GMC Sierra

P128F 2015 GMC Sierra Code - Fuel Rail Pressure Sensors 1 and 2 Signals Message Counter Incorrect

Quick Answer

The fuel rail pressure sensor transmits fuel pressure and temperature information by serial data. Common causes include Faulty Fuel Rail Pressure Sensor, Fuel Rail Pressure Sensor harness is open or shorted, Fuel Rail Pressure Sensor 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: P128F 2015 GMC Sierra indicates Fuel Rail Pressure Sensors 1 and 2 Signals Message Counter Incorrect.
Common causes: Common causes include Faulty Fuel Rail Pressure Sensor, Fuel Rail Pressure Sensor harness is open or shorted, Fuel Rail Pressure Sensor 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 555

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 Sep 27, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P128F 2015 GMC Sierra Description

The fuel rail pressure sensor transmits fuel pressure and temperature information by serial data. The fuel rail pressure sensor internal microprocessor allows 4 separate sensor outputs from one 3 wire sensor. The Engine Control Module (ECM) supplies the fuel rail pressure sensor with a 5 V reference circuit, a low reference circuit, and an asynchronous signal/serial data circuit. The asynchronous signal means communication is only going from the fuel rail pressure sensor to the ECM. The ECM decodes the serial data signal into separate voltages which are displayed on a scan tool as the voltage inputs from the Fuel Temperature Sensor, Fuel Rail Pressure Sensor and Fuel Rail Pressure Sensor 2.

OBDII Code P128F 2015 GMC Sierra - Fuel Rail Pressure Sensors 1 and 2 Signals Message Counter Incorrect - AutoCodes.com — P128F 2015 GMC Sierra Code - Fuel Rail Pressure Sensors 1 and 2 Signals Message Counter Incorrect

What does this mean?

What are the Possible Causes of the DTC P128F 2015 GMC Sierra?

Faulty Fuel Rail Pressure Sensor
Fuel Rail Pressure Sensor harness is open or shorted
Fuel Rail Pressure Sensor circuit poor electrical connection

How to Fix the DTC P128F 2015 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 P128F 2015 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 P128F 2015 GMC Sierra code?

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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 P128F 2015 GMC Sierra Code

1. What does the OBDII code P128F mean on a 2015 GMC Sierra?

P128F indicates that the Fuel Rail Pressure Sensors 1 and 2 are sending signals with an incorrect message counter, suggesting a communication or correlation issue between the sensors.

2. What are the common symptoms of P128F on a 2015 GMC Sierra?

Symptoms may include a check engine light, reduced engine performance, rough idling, difficulty starting, or poor fuel efficiency.

3. What causes the P128F code to appear on a GMC Sierra?

The most common causes include faulty fuel rail pressure sensors, wiring issues such as damaged or corroded connections, or a malfunctioning ECM (engine control module).

4. Can I drive my 2015 GMC Sierra with the P128F code?

Driving with this code is not recommended, as it can lead to poor engine performance or potential damage if the fuel pressure is not regulated correctly.

5. How do I diagnose the P128F code on my GMC Sierra?

Start by using an OBDII scanner to confirm the code, then inspect the fuel rail pressure sensors, wiring, and connectors for damage. If no visible issues are found, test the sensors' output and communication with the ECM.

6. How do I fix the P128F code on a 2015 GMC Sierra?

Repairs may include replacing faulty fuel rail pressure sensors, repairing damaged wiring or connectors, or reprogramming or replacing the ECM if necessary.

7. How much does it cost to fix the P128F code on a GMC Sierra?

Repair costs can vary, but replacing a fuel rail pressure sensor typically ranges from $150 to $350, including parts and labor. ECM repairs or replacements could be significantly higher.

8. Can a dirty fuel system cause the P128F code?

While a dirty fuel system is not a direct cause of this code, it can lead to fuel pressure irregularities that might exacerbate sensor issues.

9. Do I need to replace both fuel rail pressure sensors for the P128F code?

Not necessarily. Only replace the sensor that is faulty after diagnosing the issue. However, if both sensors are old or showing signs of wear, replacing them together may be a good preventive measure.

10. Will resetting the check engine light fix the P128F code?

Resetting the light will not fix the underlying issue. The code will likely return unless the root cause, such as a faulty sensor or wiring problem, is properly addressed.