XC90 O2 Sensor Fault

I had a similar issue with my XC90. Same symptoms – check engine light and increased fuel consumption. Have you checked the air-fuel ratio? An aged oxygen sensor can cause that.

When you say "aged oxygen sensor", are we talking about the sensor itself being faulty, or just a connection issue? And did your error code specifically point to the O2 sensor, or was it more generic?

In my case, the error code specified the oxygen sensor. Considering your mileage, it may be more than just a loose connection. I advise you visit a workshop.

Appreciate the insight! Shop confirmed a faulty O2 sensor. Cost me 95€, but at least the light's gone and the fuel consumption is back to normal!