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

WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Bank No. 1 refers to bank which includes cylinder No. 1. Bank No. 2 refers to bank without cylinder No. 1. Heated oxygen sensor No. 1 refers to sensor closest to engine block. Heated oxygen sensor No. 2 refers to sensor farthest away from engine block.