Originally Posted by PlumCrazyDaytona
I would recommend just replacing the 02 sensor. For $20 its cheaper than the cat!
I appreciate your suggestion but I don't think that is going to work since I did the earlier experiment where I swapped the oxygen sensors from one side to the other and the problem remained on the same side so that proves that the oxygen sensor is not the problem
Since I know now that bank 1 on the v6 is on the passenger side I took a closer look at it. I banged on it with my fist and I heard some rattling It sounded small like it has some pebbles in there so probably a small chunk broke off in any case that's not good sign and that is probably the cause of the p0420
I repeated the experiment I did on the other side on bank one this time where I had the oxygen sensor wrapped in aluminum foil and than wrapped with buss wire
The experiment worked for a while The waveform was holding steady at about 067 volts So I took it out for a run around the block only about 1 mile or 2 so I can run it at 55mph so the monitors would start running since I erased the code
When I got back I noticed the waveform was around 0.12 volts and was steady for a few seconds then it jumped up and started going up and down although somewhat erratically so I thought maybe the foil fell off
but after I took the oxygen sensor out I noticed the buss wire turned yellow and at the tip where I just twisted the foil it looked like the foil melted so it was only sensing through the small hole at the tip of the sensor and that was still enough to make a big jump on the waveform
I could probably make a better cover to fool the sensor in case I don't find anything else but there is no reason at this point since the cat is more likely the suspect now with the rattling noise
If it was just carbon buildup I would have attempted to clean it with something but if it's breaking up there is no use in cleaning it
So now I have to look around for a new cat
Any opinions as to what type is best ? OEM or after market ? Any particular brand ?