I have had luck doing this recently to a 92 240, with no advers affects, and it turned my check engine light off. I don't know if this application works for you, but I used a bosch sensor from a 89 Mustang 5.0. This car actually has four sensors, the only difrence being wire lenth. Do be sure to soder conections. A weak signal will result in check engine light. Also shrink wrap to keep our water. Good luck

Tony, make sure there isn't a problem that is causing your O2 sensor to go bad. Otherwise you are only treating the symptom.

Good luck.

I haven't done this yet but there are universal O2 sensors available from auto parts stores that you just splice into the existing wiring. I would get a Bosch sensor, I think they are the original supplier.

Steps:

1. remove old sensor and disconnect from wire harness.

2. cut and splice (crip connector and solder is a nearly permanent connection) new sensor and old wire harness connector (the part from the old sensor).

3. heat shrink around the splice.

4. install new sensor and connect to harness

I am sure there are sensors from production vehicles that also fit. Then you get the vehicle side harness/o2 sensor from a junk yard and splice that into the Volvo's O2 side harness connector and you have a plug-n-play application.