OBD Guide

C1A4B

Stop Light Relay Circuit

C1A4B is an OBD-II diagnostic trouble code meaning: Stop Light Relay Circuit. Common causes: faulty brake light relay, open or short circuit in wiring harness. Estimated repair cost: $11–56.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$11–56 (est.)

Symptoms

  • Brake lights don't work
  • The malfunction indicator on the dashboard is on
  • Error C1A4B in the control unit memory

Causes

  • Faulty brake light relay
  • Open or short circuit in wiring harness
  • Problems with contacts in the circuit
  • Control unit malfunction

How to Fix

  1. Check the operation of the brake lights
  2. Check brake light relay
  3. Inspect the wiring harness for damage
  4. Check the contacts in the circuit
  5. If necessary, replace the relay or repair the wiring

Related codes

FAQ

What does the C1A4B code mean?

C1A4B is an OBD-II diagnostic trouble code that indicates: Stop Light Relay Circuit

What causes a C1A4B error code?

The most common causes of C1A4B include: Faulty brake light relay; Open or short circuit in wiring harness; Problems with contacts in the circuit; Control unit malfunction.

How do I fix a C1A4B diagnostic trouble code?

To fix C1A4B: Check the operation of the brake lights. Check brake light relay. Inspect the wiring harness for damage. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C1A4B?

Limited driving only, diagnose soon

How much does it cost to fix C1A4B?

The estimated repair cost for C1A4B is $11–56. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat