RobZ

I have these codes and did a search,but its seems to me there might be different solutions to this problem.Its either a bad cat,bad or lazy o2.About for months ago I installed some Magnaflow High flow cats on my previous off-road y pipe to pass inspection.Which I passed with no problems.However now these codes pop up.I replaced the top o2 bank 1 sensor went away for awhile,but came back after a week or two.This cats have about 4 months of use and seems like my right side cat is ok.What should I do?

Ive picked up a scanner to check out the millivolts on the o2's what should I look for?

NiceTry

iTrader: (1)

Those codes are catalyst inefficiency codes if i remember correct, you need to have them deleted. No high flow cat is going to work as well as your factory one, so your car thinks you have bad factory cats.

02Z28LS1

iTrader: (2)

yep, those are definitely catalytic converter codes....i have one on my passenger side cat right now (PO430).

you have 4 options:

1) replace the cats with stock replacements and lose some flow,
2) use O2 simulators to simulate good cats (hard to find nowadays, and may still have problems later on)
3) get the codes tuned out in the PCM, or
4) do this to trick the O2 sensors into thinking the cats are good.

RobZ

Appreciate all the info....Funny reseted the codes and after some miles they haven't come back on.I have a feeling they might come back tho.Thanks again.