When I reset it and it came back on between 40 and 150 miles later, I knew it was times to change the sensor. No degrade in fuel economy.
So I got the Bosch sensor for my ’97 850 T5 (T=turbo) from one of my sponsors, Bosch part #15062. It was around $90. I didn’t want to fiddle with the Bosch universal sensor, although some here have used that with success and thus saved money.
It’s an easy job to change rear oxygen sensor, really. No exotic tools necessary. I did my front sensor years ago without the fancy socket, and it went ok. Be safe under the car.
Welcome to Volvo news, help and DIY fixes. We feature the Volvo Repair Database, the best Volvo Forum, and an awesome monthly Volvo newsletter. Joining is always free!