Removing the O2 sensor from the fuel system will cause some problems.
The most obvious problem will be very poor fuel economy.
The computer will put the car in to "limp" mode and it will run
very rich - resulting in poor fuel economy, exhaust problems, etc.

Your check engine light will come on and stay on if you unplug
the O2 sensor. I don't know about closing the circuit - I think
this would be challenging because the computer is looking
for a low voltage signal input from the O2 sensor.

I am also in an area where the emissions tests are not an issue,
but for your Volvo to run it's best I believe you will have to
put a good O2 sensor in there.

Good luck with it.

--
1990 240DL - 185K, 1994 850 Wagon - 140K, 1989 Ranger 235K