Got a 97 XLE Camry with V6 2 months ago with 95k miles- P0420 code popped up 2 weeks later Replaced rear 02 sensor after cat with a Bosch - code still shows up. Had dealer do diagnostics, said my aftermarket sensor had to go, cat convertor was aftermarket and bad and upstream stock O2 sensor by firewall was bad. Will replace that with OEM next. Questions- anyone have bad luck with aftermarket cat convertors or O2 sensors? Which cat convertor can I weld in or should I buy a complete aftermarket y tube for $300? Do those $12 MIL eliminators that you hook up to the rear sensors work?