Which wire goes to the computer from my oxygen sensor?

I have installed a used 328i exhaust system (stock BMW) onto my 320i BMW. Everything is fine except the oxygen sensor. The 'new' (328i) exhaust came with the two original oxygen sensors which were located in a different position - downstream from the catalytic converters. The original exhaust system had a single oxygen sensor in front (upstream towards the manifold)) of the catalytic converters. When installing the 'new' 328i exhaust system onto my car I blanked off one of the oxygen sensor ports with a screw-in plug and used the other port.

The wire on my original oxygen sensor was not long enough so I cut off a set of the wires from one of the oxygen sensors from the 'new' (328i) exhaust and used these wires to extend the wiring on the original oxygen sensor (as the plug was different).

My oxygen sensor has 4 wires - black, yellow, red and white.

According to info on one of the BMW forums the Siemens 4-wire Oxygen Sensor wires are as follows:
Yellow sensor signal (5v)
Black sensor ground
Red Heater +ve (12v)
White Heater -ve

Can you confirm that the yellow wire is the one that goes to the car's computer? This is important for me to know. If the yellow is NOT the one that goes to the car's computer, which one does?