UPDATE:

So I traced the stock wiring up the harness. One heater wire turns brown with a purple tracer and runs to the computer. The other one, black, goes to ground. The ground is good and the circuit is good from the computer connector through the sensor to ground (2-2.5 ohm). Does this condemn the computer? Does this absolutely mean I need a new computer? Should I try just running the wire from the computer through a resistor to ground? Maybe my meter says it's all good but under a load something happens?

I'm just trying not to buy a new computer for a non-essential issue. Thanks everyone!

 

FIXED!
After 3 sensors and some wiring repairs, the code has not returned. The factory ground was intermittent. And 2 replacement sensors had 2-3 ohms on the heater side. The third had 9 ohms, so I guess it heats up more. I also lengthened the sensor harness to better route it away from the headers.

Thanks everyone for your help.