OBD Guide

C004C

Brake Booster Motor A Position Sensor Exceeded Learning Limit

C004C is an OBD-II diagnostic trouble code meaning: Brake Booster Motor A Position Sensor Exceeded Learning Limit. Common causes: position sensor malfunction, open or short circuit in wiring harness. Estimated repair cost: $167–444.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$167–444 (est.)

Symptoms

  • Hard brake pedal
  • CHECK lamp lights up
  • Reduced braking performance
  • Rattling sounds from vacuum amplifier

Causes

  • Position sensor malfunction
  • Open or short circuit in wiring harness
  • Oxidation of sensor connector contacts
  • Mechanical wear of the vacuum booster
  • Software failure in the brake system control unit

How to Fix

  1. Diagnostics of the sensor and wiring harness with a multimeter
  2. Checking connections for oxidation
  3. Replacing the position sensor if necessary
  4. Adaptation of a new part via a scanner
  5. Replacing the vacuum booster in case of mechanical damage

Related codes

Error C004C by Vehicle Brand

FAQ

What does the C004C code mean?

C004C is an OBD-II diagnostic trouble code that indicates: Brake Booster Motor A Position Sensor Exceeded Learning Limit

What causes a C004C error code?

The most common causes of C004C include: Position sensor malfunction; Open or short circuit in wiring harness; Oxidation of sensor connector contacts; Mechanical wear of the vacuum booster.

How do I fix a C004C diagnostic trouble code?

To fix C004C: Diagnostics of the sensor and wiring harness with a multimeter. Checking connections for oxidation. Replacing the position sensor if necessary. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C004C?

Limited driving only, diagnose soon

How much does it cost to fix C004C?

The estimated repair cost for C004C is $167–444. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat