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?