Hi-flow Race Cat

[Tadek]

is the afr is 14.7:1 before the cat, that's perfect combustion. the cat burns some fuel, but there is still the same amount of air in the system. comes out of the cat at 20:1. (all figures pulled out of jerk, but it's a good example)

*truth be told, o2 sensors react off the hydrocarbons and give a reading off of that... more HC, more energy, higher reading (richer). less HC's, less energy, lower reading (leaner) where is that gonna be that isn't in the pipe? pat even put his next to his turbo, the thing doesn't keep warm. trust me.

Hmm, I think I have to disagree on that. I have never heard of any O2 sensor that reacts to hydrocarbons. O2 sensors react to O2 concentration, or better said, the difference in O2 concentration on both sides of the sensor ceramics.

[Zappo]

How old is your front sensor? Also, are you sure the problem is even with the sensors or any part of the exhaust system? Just because you get that error doesn't mean it is what is says it is. I have gotten this error before with a race cat, but it was due to an overly rich running condition at WOT. If you are running rich, the cat isn't going to compensate for it very well.

[stinky240]

Both sensors are new and code P0422 started immediately after new cat was installed.

I guess it could be a coincident?

[TheMan5952]

A spark plug non-fouler is something I've seen/heard of people using. Might wanna give one a shot.

[stinky240]

Do you know where I can get one?

[TheMan5952]

most auto parts stores should have them, goto Autozone or NAPA and see if they have them, if not you can get them online.