I've come up with s modification of the O2 sensor that will eliminate the p0420 code. It is undetectable and plugs in just like a factory one would. This is not some electronic crap or some extenders that stick out 4 inches which will not pass if found. I can modify your o2 sensor or sell you a modified one. This is nowhere on the net so save your time. Ive invented this modification and know it works. For testing or offroad use only.