Toyota fault code p0420 4runner o2 P0171 sensor p0174 p0170 bank oxygen lean system too fuel code trim dtc ecu constantly
P0420 fixed with replacing o2 and a/f sensors - Toyota 4Runner Forum
Toyota Fault Code P0171
P0420 fixed with replacing o2 and a/f sensors Toyota p0420 exhaust code system fault converter catalytic bank p0171 sensor schematic vehicle below threshold efficiency systems where location catalyst