What causes P0430 Catalyst System Efficiency Below Threshold (Bank 2)

[Cobra4B]

Came on tonight..... I cleared it and it hasn't come back... I have Kooks LT headers w/ hi-flo cats an no tuning... last time I dyno'd it it was 11.5:1 up top but nothing bad. I've had them for almost a year now w/o any codes.

Any ideas?

[mjustmike]

I have a similiar setup and get that along with an 0420. I was told that it is the computer thinking the cats are not functioning correctly but in fact the hi flo's are too free flowing. Mine usually pop up after a nice romp thru the gears then stop and set at idle for a few minutes, blink on goes the light. And this happens after tuning. I have an early set of the Random Tech's, they are supposed to have resolved the issue with later production. Hope this little info helps some.

[Cobra4B]

Hmmm... it's wierd that the car has been completely fine for a year w/o issues and now throws a code. If it keeps comming up I'll look into it. Coudl I have an 02 sensor acting up from something?