bad o2 sensor or cats?

[Duckdestroyer]

OK so last weekend I had the code p0430 come up.
A couple weeks ago my exhaust rotted off at the cross over pipe, and had to remove my cat half of the exhaust to pound the studs out, to bolt on the new cross over pipe. as I pounded the studs out I noticed white powder and pepper looking stuff falling out of the pipes of the cats. I didn't think anything of it till now. I removed my o2 sensor on the driver side cat to find flakes of stuff in the fins of the sensor. I can't get the passenger side sensor out as of now. I figure its the same, so my question for you guys is. Did I F up my cats and now there clogged From when I pounded out the studs. Or will o2 sensors fix the problem. Any advise or test will be greatly appreciated. Also my mpg has dropped greatly, anything else you guys need to know I'll try to answer the best I can
Thanks

 

[BirchyBoy]

I had the P0430 code for a while. Changed my O2 sensor and it went away but came back within 200 miles. I had a new Magnaflow cat installed and it hasn't come back since.

My rig is a '99 with 175k on it. You're welcome to try the sensor, but my money is on the cat.

 

[SunlitComet]

Sorry but if you have cat efficiency codes like you do you need to replace them. And when you do also use new sensors on them for the best treatment of them by the pcm.

 

[Duckdestroyer]

Can I do this with the dummy sensor things on the down stream ones?
http://www.jegs.com/webapp/wcs/stor...ctId=348964&storeId=10001&sType=&pgGrp=search

 

[SunlitComet]

No!, you can still get codes and the pcm will not be able to fine tune the A/F ratio to make the cats function the best they can. Use the cats and all four sensors. You do know that those pipes you listed are already part of the stock cat system right?

 

[Duckdestroyer]

OK thought I would try and yes I know. But I do not have a welder so thought I would try them. But thank you I guess now the question is what brand should I get. I don't know anything about cats?

 

[SunlitComet]

Magnaflow makes a cat assembly. Complete with the crossover pipes. Same model will fit 2 or 4dr vehicles. They sell individual cats as well. In either case Cali or non-Cali versions.