OBD Guide

C122D

Active Brake Booster Control Circuit

C122D is an OBD-II diagnostic trouble code meaning: Active Brake Booster Control Circuit. Common causes: open or short circuit in wiring harness, faulty booster solenoid valve. Estimated repair cost: $56–167.

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

Symptoms

  • Increased brake pedal travel
  • Hard brake pedal
  • The brake system fault light is on
  • Reduced braking performance

Causes

  • Open or short circuit in wiring harness
  • Faulty booster solenoid valve
  • Problems with the brake system control unit
  • Low brake fluid level
  • Brake pedal sensor malfunction

How to Fix

  1. Check the brake fluid level
  2. Inspect the wiring harness for damage
  3. Check the amplifier solenoid valves
  4. Read additional fault codes
  5. Test the brake system control unit

Related codes

FAQ

What does the C122D code mean?

C122D is an OBD-II diagnostic trouble code that indicates: Active Brake Booster Control Circuit

What causes a C122D error code?

The most common causes of C122D include: Open or short circuit in wiring harness; Faulty booster solenoid valve; Problems with the brake system control unit; Low brake fluid level.

How do I fix a C122D diagnostic trouble code?

To fix C122D: Check the brake fluid level. Inspect the wiring harness for damage. Check the amplifier solenoid valves. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C122D?

Limited driving only, diagnose soon

How much does it cost to fix C122D?

The estimated repair cost for C122D is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat