OBD Guide

U302B

Ignition Output Accessory/On/Start

U302B is an OBD-II diagnostic trouble code meaning: Ignition Output Accessory/On/Start. Common causes: faulty ignition relay, blown fuse. Estimated repair cost: $6–56.

Severity
⚠️ Medium
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$6–56 (est.)

Symptoms

  • Engine won't start
  • Problems turning on the ignition
  • Unstable operation of electrical equipment
  • Check Engine Light Is On
  • The car may suddenly stall

Causes

  • Faulty ignition relay
  • Blown fuse
  • Wiring harness damage
  • Ignition switch malfunction
  • Problems with the engine control unit

How to Fix

  1. Check and replace fuses
  2. Diagnose the ignition relay
  3. Check wiring integrity
  4. Test the ignition switch
  5. Scan the control unit for other errors

Related codes

Error U302B by Vehicle Brand

FAQ

What does the U302B code mean?

U302B is an OBD-II diagnostic trouble code that indicates: Ignition Output Accessory/On/Start

What causes a U302B error code?

The most common causes of U302B include: Faulty ignition relay; Blown fuse; Wiring harness damage; Ignition switch malfunction.

How do I fix a U302B diagnostic trouble code?

To fix U302B: Check and replace fuses. Diagnose the ignition relay. Check wiring integrity. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U302B?

Do not drive — repair immediately

How much does it cost to fix U302B?

The estimated repair cost for U302B is $6–56. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat