Cefiro RB20E O2 sensor

[gwsallen]

I got my Cefiro few months ago running on RB20E without O2 exhaust sensor connected. I read a thread from other forum saying that the O2 sensor should measure around 0.39V to 0.49V at idle. The problem is I use digital multi meter to get the reading from the O2 sensor, read 0V. So I assume the O2 sensor is out. But there is no wire connected to it currently. I do not see any wire nearby daggling or hanging around empty nearby the O2 sensor. Can I tap direct from ECU and which one? Any one here have RB20E ECU pin-outs diagram? My fuel consumption is at about 13.75L / 100km.

Any help, thanks in advance.