I am having difficulty finding the upstream O2 sensor for the S90/960, only the downstream/rear one for some reason. However, IPD who are pretty good at identifying the parts and what uses them lists the sensor as not suitable for a V/S70: https://www.ipdusa.com/products/23968/Oxygen-Sensor-960-S90-...

Vent it to atmosphere and put a vacuum cap on the air intake hose. It won't cause a lean condition.

I’ll be in Korea in a couple of weeks. Give me the part numbers you need and I’ll see if I can drag them in.

Use Volvo parts online to get part numbers