OBD Codes

B0079

Horn Relay Circuit Malfunction

Moderateelectrical

About B0079

The B0079 code indicates that the body control module has detected a horn relay circuit malfunction condition. This relates to the vehicle's body electrical systems, which control comfort, convenience, and safety features. When this code is stored, the affected system or component may not operate correctly, potentially impacting safety or comfort features. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: Interior lights staying on or not working. Instrument cluster warning lights erratic. Power window inoperative on one or more doors. Climate control not responding to inputs. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Faulty SRS/airbag control module. Short circuit in wiring. Water intrusion into electrical connectors. Failed window/lock/seat motor. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Connect an OBD-II scanner and read all stored body control module trouble codes. Inspect the affected circuit fuse and relay; replace if blown or faulty. Check the wiring harness and connectors for damage, corrosion, or loose pins. Test circuit voltage and ground with a multimeter at the affected component. Verify battery voltage is within specification (12.4V+ engine off). If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Body (B) collection on OBD Codes. We provide comprehensive, up-to-date information to help you find solutions quickly.

Quick Answer

Is it safe to drive with the airbag light on?

Driving with the airbag warning light on means the SRS system may not deploy in a crash, which significantly increases injury risk. Have the system inspected as soon as possible.

Overview

The B0079 code indicates that the body control module has detected a horn relay circuit malfunction condition. This relates to the vehicle's body electrical systems, which control comfort, convenience, and safety features. When this code is stored, the affected system or component may not operate correctly, potentially impacting safety or comfort features.

Symptoms

  • Interior lights staying on or not working
  • Instrument cluster warning lights erratic
  • Power window inoperative on one or more doors
  • Climate control not responding to inputs

Common Causes

  • Faulty SRS/airbag control module
  • Short circuit in wiring
  • Water intrusion into electrical connectors
  • Failed window/lock/seat motor

Diagnosis Steps

  1. 1Connect an OBD-II scanner and read all stored body control module trouble codes
  2. 2Inspect the affected circuit fuse and relay; replace if blown or faulty
  3. 3Check the wiring harness and connectors for damage, corrosion, or loose pins
  4. 4Test circuit voltage and ground with a multimeter at the affected component
  5. 5Verify battery voltage is within specification (12.4V+ engine off)

Estimated Repair Cost

$75$800

Cost varies by vehicle, location, and repair shop. Includes parts and labor.

Commonly Affected Vehicles

Toyota CamryHonda AccordMazda CX-5Hyundai Sonata

Related Codes

More Electrical Codes

Frequently Asked Questions

Driving with the airbag warning light on means the SRS system may not deploy in a crash, which significantly increases injury risk. Have the system inspected as soon as possible.