OBD Guide

C004B

Brake Fluid Level Sensor/Switch Circuit/Open

C004B is an OBD-II diagnostic trouble code meaning: Brake Fluid Level Sensor/Switch Circuit/Open. Common causes: broken or damaged sensor wires, malfunction of the brake fluid level sensor. Estimated repair cost: $17–56.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$17–56 (est.)

Symptoms

  • Low brake fluid indicator light is on
  • False warnings on the dashboard
  • Malfunction of the ABS or ESP system (in some cases)

Causes

  • Broken or damaged sensor wires
  • Malfunction of the brake fluid level sensor
  • Poor contact in the sensor connector
  • Low brake fluid level

How to Fix

  1. Check the brake fluid level in the reservoir
  2. Inspect the sensor wires and connectors for damage
  3. Test the sensor with a multimeter
  4. Replace the sensor or repair damaged wires
  5. Reset the error with an OBD-II scanner

Related codes

Error C004B by Vehicle Brand

FAQ

What does the C004B code mean?

C004B is an OBD-II diagnostic trouble code that indicates: Brake Fluid Level Sensor/Switch Circuit/Open

What causes a C004B error code?

The most common causes of C004B include: Broken or damaged sensor wires; Malfunction of the brake fluid level sensor; Poor contact in the sensor connector; Low brake fluid level.

How do I fix a C004B diagnostic trouble code?

To fix C004B: Check the brake fluid level in the reservoir. Inspect the sensor wires and connectors for damage. Test the sensor with a multimeter. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C004B?

Limited driving only, diagnose soon

How much does it cost to fix C004B?

The estimated repair cost for C004B is $17–56. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat