OBD Codes List

Diagnostic reference · U3031

U3031

Ignition Output Off

System
Network communication (U code)
Lamp
Check Engine Light
Category
Network Communications

What it means

U3031 means Ignition Output Off.

Check these first

  • A fault in the ignition output off circuit
  • A failed module that will not release the ignition output
  • A short holding the ignition output circuit live
  • A component that stays powered after key off

What to do next

  1. Read ignition output off status on a scan tool
  2. Test the ignition output circuit for a short
  3. Inspect the ignition output wiring and connector
  4. Verify the output drops when the key is off
  5. Repair the circuit or replace the module if the output stays live
  6. Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.