In order to search which wire goes to the ECU, your best friend to help is a multimeter. Disconnect the ECU plug and place one probe of multimeter on the designated pin (pin found on the manual) - get a long wire in order to test the loose wires as the distance from the loose wires/plug to the ECU plug is great and the multimeter probes are short.
Only this way you will know which cable is specific to the ECU pin. Don't try to guess things as wrong pins to wrong probes might burn the ECU.
No, that is not the problem. (or that method still is not the solution)
I shall explain why.
We have wires from ECU plug to lambda probe socket (harness side)
Then we have wires from Lambda probe socket to lambda probe body (sensor side)
These two sides are connected by the socket. (other socket is for the heating element, and does not connect to the ECU)
Your method determines the harness side socket-to-ECU pin identification.
Actually, it is identified using the wiring diagram.
The problem is identifying the sensor side wires.
Sensor side has 1 black and 1 white wire.
My question is, sensor side white wire connects to green or black wire of the harness?
I cannot identify, since the harness side socket was removed from wires. Pictures would explain this better.