Auto Systems and Repair: P0431 - OBD-II Trouble Code

OBD II Fault Code

  • OBD II P0431

Fault Code Definition
Code P0431 is triggered when the Bank 2 Warm Up Catalytic Converter's emissions reducing efficiency has fallen below the minimum allowable threshold. 

Symptoms

  • Check Engine Light will illuminate
  • In many cases, no abnormal symptoms may be noticed
  • In some cases, there may be a noticeable lack of engine power

Common Problems That Trigger the P0431 Code

  • Defective Warm Up Catalytic Converter
  • Engine misfires have damaged the Catalytic Converter

Common Misdiagnoses

  • Oxygen Sensor(s) are replaced when the real problem is a damaged Warm Up Catalyst
  • Warm Up Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
  • Warm Up Catalyst is replaced when a misfiring engine is the real problem