DTC P0420 Or P0430: Catalyst System Efficiency Below Threshold: Notes

WARNING: This page is about a different car, the 2000 Lexus GS 400. 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 furthest away from engine block.