OBD Guide
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C128B

ABS Master Cylinder Pressure Sensor Offset Error

C128B is an OBD-II diagnostic trouble code meaning: ABS Master Cylinder Pressure Sensor Offset Error. Common causes: master cylinder pressure sensor malfunction, damage to the sensor wiring harness. Estimated repair cost: $111–333.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$111–333 (est.)

Symptoms

  • ABS/ESP indicator is on
  • Incorrect operation of the ABS system
  • Reduced braking performance

Causes

  • Master cylinder pressure sensor malfunction
  • Damage to the sensor wiring harness
  • Corrosion or poor contact in the sensor connector
  • ABS module malfunction

How to Fix

  1. Check connections and sensor wiring harness
  2. Measure the resistance and voltage at the sensor
  3. Replace master cylinder pressure sensor if necessary
  4. Check the ABS module for errors

Related codes

C128AC128CC1290

FAQ

What does the C128B code mean?

C128B is an OBD-II diagnostic trouble code that indicates: ABS Master Cylinder Pressure Sensor Offset Error

What causes a C128B error code?

The most common causes of C128B include: Master cylinder pressure sensor malfunction; Damage to the sensor wiring harness; Corrosion or poor contact in the sensor connector; ABS module malfunction.

How do I fix a C128B diagnostic trouble code?

To fix C128B: Check connections and sensor wiring harness. Measure the resistance and voltage at the sensor. Replace master cylinder pressure sensor if necessary. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C128B?

Do not drive — repair immediately

How much does it cost to fix C128B?

The estimated repair cost for C128B is $111–333. Actual cost depends on your vehicle, location, and labor rates.

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