3.2volts on first O2 with p0420 code?

#1
2008 Corolla with 136k miles. PO said he swapped a hollowed out cat system with one from a junk car. Just got it yesterday, and I hooked up my OTC scanner with live data. The code is p0420, the first sensor reads ~3.2V steady and the second O2 reads between .1 and .9 but changes very quickly. The first O2 is plugged in, but I didn't do much more troubleshooting on it yet. Is 3.2V right or should I look at a wire issue?
 
#2
as an update, it appears the 3.2v is from the air/fuel sensor and that voltage should be OK. Now I'm not sure if the second O2 is supposed to fluctuate or be more steady?
 
#3
Hi, I have exactly the same problem and I posted my question in feb but I had no help. Did you get the answer to your question? Please let me know.
Also Nero
 
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