I need help!!!!

[Protege_MP3_506]

My check engine light is on for "warm up catalyst below threshold" I got a brand new catalytic converter and the code came back on. I pulled out my o2 censors and one of them was black as night. I used to have a random multiple cylinder misfire code and i figure that its all the unburnt fuel from that. So i went to go see how much an 02 censor and it was close to $200. Is there any way i can just clean it and re-use it??? Is there anything else it could be?? My car will spit at me sometimes in my lower RPM's but my coils, plugs, and wires are all brand new too. Would the 02 cause that??? Thanks guys

[shane02pro5]

You can get the same 02 sensor only universal from the auto parts for like $70 you just have to splice it in. What was the actual code that was given?

[Protege_MP3_506]

I'm not sure of the actual number. I think it was like P0402 or something. It just read warm up catalyst below threshold