2001 2dr 2wd auto w/116,000 miles

A few months back, I replaced my cracked exhaust manifold. I tried to recover and reuse the original o2 sensor, but it was a lost cause. I got a sensor failure code. Anyway, I bought two new universal o2 sensors (denso's, I believe) and put them in. The new sensors seem to work fine (no more p0134 at least), but I have a heater circuit code for both sensors (P0135 & P0140). If I understand it correctly, the heater circuit only heats the sensors up so that they start working sooner. In other words, there shouldn't be any adverse effects, right? The problem is that I need to get it inspected.

Anyway, what could be the cause of the heater circuit failure? I checked all fuses, and those are ok. Could it be the way they are wired? There were two black wires for the heater circuit, but polarity doesn't matter, right? Could it be that my universal o2 sensors don't play well with my KIA? I think I remember reading something about using an in line resistor to get them to work. I just hate to pay $100+ bucks to get sensors that heat up better. I saved the rear sensor, so I'll just put it back in, if I need to.

Thanks for the help,
Kris