OBD Guide

C0138

Base Brake System Pressure Circuit/Sensor Low

C0138 is an OBD-II diagnostic trouble code meaning: Base Brake System Pressure Circuit/Sensor Low. Common causes: brake pressure sensor malfunction, wiring harness damage. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • The brake system fault indicator is on
  • Deterioration of ABS and ESP performance
  • Unusual behavior of the brake pedal

Causes

  • Brake pressure sensor malfunction
  • Wiring harness damage
  • Short circuit in the circuit
  • Sensor connection problems
  • Brake ECU malfunction

How to Fix

  1. Check the connection of the pressure sensor and the condition of the connector
  2. Check the integrity of the wiring harness
  3. Check resistance and voltage at pressure sensor
  4. If necessary, replace the pressure sensor
  5. Check the operation of the brake system after repair

Related codes

Error C0138 by Vehicle Brand

FAQ

What does the C0138 code mean?

C0138 is an OBD-II diagnostic trouble code that indicates: Base Brake System Pressure Circuit/Sensor Low

What causes a C0138 error code?

The most common causes of C0138 include: Brake pressure sensor malfunction; Wiring harness damage; Short circuit in the circuit; Sensor connection problems.

How do I fix a C0138 diagnostic trouble code?

To fix C0138: Check the connection of the pressure sensor and the condition of the connector. Check the integrity of the wiring harness. Check resistance and voltage at pressure sensor. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C0138?

Limited driving only, diagnose soon

How much does it cost to fix C0138?

The estimated repair cost for C0138 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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