AutoCodes – Generic – C12B3

C12B3 Code - ABS Master Cylinder Pressure Sensor Circuit Short To Battery

Quick Answer

The Electronic Brake Control Module (EBCM) uses input from the master cylinder pressure sensor for more accurate control during a 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: C12B3 indicates ABS Master Cylinder Pressure Sensor Circuit Short To Battery.
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 1,390

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 04, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C12B3 Description

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

OBDII Code C12B3 - ABS Master Cylinder Pressure Sensor Circuit Short To Battery - AutoCodes.com — C12B3 Code - ABS Master Cylinder Pressure Sensor Circuit Short To Battery

What does this mean?

What are the Possible Causes of the DTC C12B3?

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

How to Fix the DTC C12B3?

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 C12B3 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 C12B3 code?

Need more information on how to fix the C12B3 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C12B3 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

C12B3 Buick — ABS Master Cylinder Pressure Sensor Circuit Short To Battery
C12B3 Cadillac — ABS Master Cylinder Pressure Sensor Circuit Short To Battery
C12B3 Chevrolet — ABS Master Cylinder Pressure Sensor Circuit Short To Battery
C12B3 GMC — ABS Master Cylinder Pressure Sensor Circuit Short To Battery

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 C12B3 Code

1. What does the OBDII code C12B3 mean?

C12B3 indicates a problem with the ABS master cylinder pressure sensor circuit, specifically a short to the battery, which may disrupt proper brake system operation.

2. What are the common symptoms of code C12B3?

Symptoms may include the ABS warning light illuminating, reduced or intermittent ABS functionality, and potentially erratic brake pedal behavior.

3. What causes the C12B3 code to appear?

Common causes include damaged wiring or connectors in the ABS pressure sensor circuit, a faulty master cylinder pressure sensor, or internal ABS module failure.

4. Can I drive with the C12B3 code active?

While it may be possible to drive, it is not recommended, as the ABS system may not function properly, increasing the risk of skidding during hard braking.

5. How do I diagnose the C12B3 code?

Start by inspecting the wiring and connectors for damage, test the master cylinder pressure sensor with a multimeter, and check for proper voltage and ground at the sensor.

6. What tools are needed to fix the C12B3 code?

Tools may include a multimeter, OBDII scanner, wiring diagrams, and basic hand tools to inspect and repair the circuit or replace components.

7. How do I fix the C12B3 code?

Repairs may involve replacing a faulty master cylinder pressure sensor, repairing damaged wiring or connectors, or replacing the ABS module if itâ€™s defective.

8. How much does it cost to fix the C12B3 code?

Repairs can vary, but replacing the master cylinder pressure sensor typically costs $150-$300, while ABS module replacement can exceed $1,000.

9. Will clearing the code solve the issue?

Clearing the code without addressing the underlying issue will likely result in the code returning and the ABS system remaining impaired.

10. Can a failing alternator cause the C12B3 code?

While unlikely, electrical system issues like a failing alternator can contribute to voltage irregularities, potentially exacerbating circuit problems.