I wound up purchasing a Denso 234-5701 for about $200. It's an exact replacement (5 wires). I spent about 90 minutes trying to get at the connector. Removed the air box, etc. But you just can't get to it. You need to be under the car, and I believe remove the skid plate. So I just spliced the wires ...

I got the CEL and found P0030 (O2 sensor) on my 2005 Volvo XC90 T6, 46,000 miles. I can get to the sensor from the engine compartment. However the wires disappear after the first 12" of wire. It is difficult to find where they go - there's hoses / pipes / etc, can't see, can't get your hand in ...