A year or so ago I had this code on my 95 850 (NA, not turbo) at about 100000 miles. I reset the code, but it came back after about 3 months. I ordered the sensor at a PepBoys store and the one that came was a Bosch unit which was identical looking. It had a pigtail (wire assembly) about 20 inches long that plugged into the corresponding connector. I did not have to disturb the rear sensor or its wiring. I had to do the job from under the car. The connector retainer was quite tight so it was hard to take off the old one. The only caution would be to secure the connector and wiring so it will not touch the exhaust anywhere or snag on anything while you are driving along. No further codes have appeared.