Diagnosis & Repair Procedure
- Visually inspect exhaust system for any leaks or damage. Repair as necessary. If exhaust system checks okay, check appropriate HO2S No. 2 wiring circuit. For DTC P0420, check for open or short in Red/Blue wire or Gray/Yellow wire between HO2S B1 S2 and PCM. See WIRING DIAGRAMS article. For DTC P0430, check for open or short in Red/Yellow wire or Gray/Yellow wire between HO2S B2 S2 and PCM. Repair wiring or replace HO2S as necessary. See REMOVAL, OVERHAUL & INSTALLATION article. If HO2S wiring checks okay, go to next step.
- Replace HO2S No. 2 on appropriate bank of engine (bank 1 for DTC P0420; bank 2 for DTC P0430). See REMOVAL, OVERHAUL & INSTALLATION article. Retest system. If problem returns, replace appropriate warm-up Three Way Converter (TWC). For DTC P0420, replace warm-up TWC on bank one. For DTC P0430, replace warm-up TWC on bank two. Retest system. If problem returns, replace PCM. See REMOVAL, OVERHAUL & INSTALLATION article. Retest system.