2003 toyota corolla Had a p0420 on my corolla, and have a scan tool with 3 color emissions status and it was yellow. Check exhaust system ,ok , hooked up scan tool and upstream o2 changed alot, down stream was steady, ok . Changed upstream o2 with new bocsh unit 99.00 $, reset pcm...
TOYOTA(GR)4Runner2000- AVENSIS2003-2011 CAMRY (JPP/SED)2000-2001 CAMRY (AUSTRALIA)2002-2006 CAMRY/AURION/HV(ARL)2006-2017 CAMRY/HYBRID2017- CAMRY/HYBRID (ASIA)2006- COASTER FUELCELL2021-2022 COROLLA SED/WG2000-2014 COROLLA (MEXICO)2019- ...