DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1) & DTC P0430: Catalyst System Efficiency Below Threshold (Bank 2): Notes

2004 Toyota Matrix XR, FWD, StandardSECTION Notes
WARNING: This page is about a different car, the 2003 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Bank No. 1 is also know as right bank (RH). Air/Fuel (A/F) sensor refers to sensor closest to engine block. Heated oxygen sensor No. 2 refers to sensor farthest away from engine block.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.