[NiftySVX]

The only culprits could be wiring, sensor, and control unit. It usually works by measuring current to the heater circuit, and if the current is too high or too low it will set the DTC. If you did not use an sensor from a subaru box or the correct sensor for you may want to do so this time. I have seen this many times on toyotas. The computer is picky about the sensors and if they aren't of high quality they likely won't be able to please the computer. Oxygen sensors are in my top ten list of parts to never get aftermarket. Keep in mind that over the counter retail subaru parts carry a 12 month warranty.