2006 GS300 P0420, Rotten egg smell
 

Hey guys, so I had a p0420 light on for about 2 months before parking by car over the winter in November 2017. I pulled my car back out just last week (July 2018) and had code for p0158 (Bank 2 Sensor 2) and 2 misfires this time. I changed the o2 sensor for bank 2 sensor 2 and got the spark plugs changed aswell and after an hour the light came back on, this time for p0420 with misfire codes all gone. Since purchasing my car about 2 years ago Ive always gotten a rotten egg smell at high rpms so Im wondering if my catalytic converter has gone bad or should I continue to inspect the o2 sensors?

It's probably your catalytic converters going bad.

There's quite a few threads in this subforum about hte issue. You might want to do a search and cross reference to see how people have resolved the issue (FWIW, an OEM catalytic converter's EXPENSIVE, so try to go aftermarket and find an exhaust shop to weld on your new one)