C128B 2014 GMC Sierra Code - ABS Master Cylinder Pressure Sensor Offset Error
Quick Answer
The Electronic Brake Control Module uses inputs from the Electronic Brake Control Brake Pedal Position Sensor to determine when the brake is applied and how much force is used. Common causes include Faulty Electronic Brake Control Module (EBCM), Electronic Brake Control Module harness is open or shorted, Electronic Brake 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
- C128B 2014 GMC Sierra indicates ABS Master Cylinder Pressure Sensor Offset Error.
- Common causes
- Common causes include Faulty Electronic Brake Control Module (EBCM), Electronic Brake Control Module harness is open or shorted, Electronic Brake 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 C128B 2014 GMC Sierra Description
Brake pressure sensor information is communicated from the Electronic Brake Control Module (EBCM) to the Hybrid Control Processor (HCP). This information is used to schedule regenerative braking and engine autostops.
The Diagnostic Trouble Code (DTC) will be set when the Engine Control Module (ECM) detects a corrupted data message from the Electronic Brake Control Module.
What are the Possible Causes of the DTC C128B 2014 GMC Sierra?
- Faulty Electronic Brake Control Module (EBCM)
- Electronic Brake Control Module harness is open or shorted
- Electronic Brake Control Module circuit poor electrical connection
- Faulty Starter/Generator Control Module
How to Fix the DTC C128B 2014 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 C128B 2014 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 C128B 2014 GMC Sierra Code
What does the OBDII code C128B mean on a 2014 GMC Sierra?
The C128B code indicates an "ABS Master Cylinder Pressure Sensor Offset Error," meaning the ABS module has detected an issue with the pressure sensor's calibration or signal.
What are the common symptoms of the C128B code?
Common symptoms include the ABS warning light turning on, reduced or disabled ABS functionality, and potential braking performance issues.
What causes the C128B code to appear?
This code is usually caused by a faulty master cylinder pressure sensor, wiring issues, a failed ABS module, or improper sensor calibration.
Can a dirty brake fluid system cause the C128B code?
Yes, contaminated or deteriorated brake fluid can affect the pressure sensor's performance and trigger the code.
How is the C128B code diagnosed?
A mechanic will use a scan tool to read the code, check live sensor data, inspect the master cylinder pressure sensor and its wiring, and perform a calibration test if needed.
Can I continue driving with the C128B code active?
Driving may be possible, but ABS functionality could be compromised, increasing the risk of reduced braking performance in emergencies.
How do you fix the C128B code?
Repairs may include replacing the master cylinder pressure sensor, repairing damaged wiring, recalibrating the sensor, or replacing the ABS module if necessary.
Does the C128B code require a brake fluid flush?
In some cases, a brake fluid flush may help if the fluid is contaminated, but this alone may not resolve the issue if the sensor or wiring is faulty.
Is recalibrating the master cylinder pressure sensor necessary for fixing the C128B code?
Yes, recalibration is often required after replacing the sensor or ABS module to ensure proper operation.
Can a weak battery cause the C128B code?
While uncommon, a weak or failing battery could potentially cause electrical issues that affect the ABS system, leading to this code.
Discuss the causes and fixes for C128B 2014 GMC Sierra OBDII Code
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