2 new o2 and 2 codes? I would be double checking the splice job.
The only thing they both have in common is the heater power, and you would have a ton more codes if that was a prob.

To check the harness, you need to look at the wiring diags and check continuity pin to pin (o2 connector pin to ecu connector pin).
https://drive.google.com/file/d/0B_z...ew?usp=sharing

O2's are tough to check with just a voltmeter. Need something that graphs so you can see them switch.