AutoCodes – Generic – C128D

C128D Code - ABS Boost Pressure Sensor Raw Offset Error

Quick Answer

The Electronic Brake Control Module (EBCM) uses input from the boost pressure sensor for more accurate control during brake and vehicle stability enhancement system event. Common causes include Faulty Brake Pressure Modulator, Brake Pressure Modulator harness is open or shorted, Brake Pressure Modulator 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: C128D indicates ABS Boost Pressure Sensor Raw Offset Error.
Common causes: Common causes include Faulty Brake Pressure Modulator, Brake Pressure Modulator harness is open or shorted, Brake Pressure Modulator 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 1,479

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 03, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C128D Description

The Electronic Brake Control Module (EBCM) uses input from the boost pressure sensor for more accurate control during brake and vehicle stability enhancement system event. The boost pressure sensor is internal to the brake pressure modulator.

OBDII Code C128D - ABS Boost Pressure Sensor Raw Offset Error - AutoCodes.com — C128D Code - ABS Boost Pressure Sensor Raw Offset Error

What does this mean?

What are the Possible Causes of the DTC C128D?

Faulty Brake Pressure Modulator
Brake Pressure Modulator harness is open or shorted
Brake Pressure Modulator circuit poor electrical connection

How to Fix the DTC C128D?

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 C128D 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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Information for Specific Makes

C128D Buick — ABS Boost Pressure Sensor Raw Offset Error
C128D Cadillac — ABS Boost Pressure Sensor Raw Offset Error
C128D Chevrolet — ABS Boost Pressure Sensor Raw Offset Error
C128D GMC — ABS Boost Pressure Sensor Raw Offset Error

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 C128D Code

1. What does the OBDII code C128D mean?

C128D refers to an ABS Boost Pressure Sensor Raw Offset Error, indicating an issue with the boost pressure sensor used in the Anti-lock Braking System (ABS).

2. What are the common symptoms of code C128D?

Common symptoms include the ABS warning light illuminating, reduced or erratic ABS functionality, and in some cases, a spongy or unresponsive brake pedal.

3. What causes code C128D to trigger?

The most common causes include a faulty boost pressure sensor, wiring issues like damaged or corroded connectors, or a malfunction in the ABS control module.

4. Can I still drive my car with code C128D?

You can drive the car, but ABS functionality may be compromised, which could increase stopping distances or cause the brakes to behave unpredictably in emergency situations.

5. How can I diagnose code C128D?

Start by scanning for stored ABS codes, visually inspecting the boost pressure sensor and related wiring, and testing the sensorâ€™s output with a multimeter or diagnostic tool.

6. How do I fix code C128D?

Repairs may include replacing the boost pressure sensor, repairing or replacing damaged wiring or connectors, or reprogramming/updating the ABS control module.

7. How much does it cost to repair code C128D?

Repair costs vary but generally range from $150 to $400, depending on whether the sensor or ABS module needs replacement and labor costs in your area.

8. Can a low brake fluid level cause code C128D?

While low brake fluid isnâ€™t a direct cause, it can exacerbate ABS-related issues and should be checked if this code appears.

9. Does code C128D always require sensor replacement?

No, sometimes the issue can be resolved by fixing wiring problems, cleaning corroded connectors, or recalibrating the ABS system.

10. Can a generic OBDII scanner clear code C128D?

Most generic scanners can clear the code temporarily, but if the underlying issue isnâ€™t addressed, the code will return. Use a scanner capable of ABS diagnostics for better accuracy.