Please help me..I need to know the wire thats inside that gray insulation(ignore the black and pink wires thats connected to it for now). There's a white inner wire and a gray outer wire. Right now that white wire is connected to the oxygen sensor #2 and the gray wire is grounded. I don't what the previous owner did but the o2 sensor connectors are gone. It's makes me wonder if my o2 sensor is connected properly..thanks.

1992 Es300

 

I think what the PO did was to connect some univeral O2 sensors into the "Check Connector" box. The O2 sensor were connected to the ECU and also to the Check connection box. The Check connection box should have O2 sensor 1 on terminal 4 and O2 sensor 2 on terminal 15. The Check connection box is used to gain access to signals without having to tap into the wire bus. The colors of the wires for the O2 sensors are white for one sensor 1 and Red/Blue for sensor two. Brown is connected to ground.