1998 Volvo S90 wiring/ecm integrity check?

[1998S90]

Hi all.

Background; p0130 code
Panlong PL-B02 Bluetooth scanner + Torque Pro app

02b1s1 voltage stays about 200mv
02b1s2 reads 0v (I've read that some pre-1999 Volvo will not report the b1s2 voltage via obdii?)

What should the reported voltage be with the o2 sensors unplugged? They stay the same plugged in or otherwise.

Can I use a 12v test light with a incandescent bulb to inject a signal into the ecu and validate wiring integrity?

Also, even after resetting the fault codes via obdii, and disconnecting the battery the Fuel Status seems locked into Open Loop, Sys Fail. Is there a way I can reset it to try going into closed loop again?

Thanks for any help, this is my first Volvo.

[vp965]

What's the mileage on the car? Has O2 sensor been replaced recently? Any other issues, general maintenance history of the car? In my case a new to me 1998 V90 had obviously been neglected for a period of time, used on short trips etc. The oxygen sensor went south, replacing it with a new Bosch one ($60 off ebay) took care of that little problem. Maybe a little more background information before getting into technical issues would help clarify things?