p0031 code questions

[4wheeln2]

I have an '04 outback limited. I recently had the head gaskets done by the dealer. Soon after, the p0031 code showed up (like within 10 miles of the dealership). I replaced the o2 sensor with a generic one, then one from a dealership bought off the web (it had the wrong connector). I carefully soldered and heat-shrinked the connections of the 2nd o2 sensor (came in a subaru box) and it still is throwing the p0031 code. I am beginning to think the 02 sensor is not at fault, but may be wiring or relays. Any ideas would be helpful. I took it back to the dealer, but they had experienced some network probs and could pull and erase the code, but could not use any of the realtime data to delve deeper into a solution (so to speak). The tech was a little puzzled and didn't seem to have any answers. Am trying to sell this car, so I would not like to throw money at it unless I am sure of a solution! Any ideas or FSM troubleshooting tips? I am fairly handy and have a digital VOM and tools. Thanks in advance!

[Fairtax4me]

Heater circuit. Check the pins in the wire harness connector for 12V when the ignition is on. I think it's pin 3 is the 12v feed for the heater. I don't recall if the heater grounds back through the harness or not. I know there is an FSM for the 04 Legacy floating around the "interwebz" here somewhere. Some searching might dig it up and you can check out the diagnostic procedure in the OBD2 file of the Troubleshooting section.

[tuckeroo]

i know this sounds strange but may want to try the a/c relay...it has worked for some and not on others(we have an "05 that has a gremlin we can't find)...the relay is not too exspensive