I just got a call from my mechanic who's installing my AEM UEGO widband O2 sensor and guage. Everything is installed except he doesn't know where the white wire connects to. For those of you who've installed this before could you please let me know so I can call and tell him? I'm starting to question my mechanics knowledge...this seems to be an easy install with directions and everything and he still cant figure it out. He said he called AEM and left a message but they never called him back. BTW its going in my 06 STI.

Thanks guys.

Just connect the red and black wires, the power and ground. The white wire in question is an analog output(0-5V), and the blue is a serial output. Unless you have use for the outputs, do not worry about them.
-Adam

I just installed my AEM UEGO on my 02 WRX. I connected the power(red) and black(ground) wires already and have the serial output(blue) and analog output(white) unconnected to anything.

What are they for and what would require their use? I'm guessing the gauge works fine the way it is now. On cold startup with a manifold leak it reads nasty lean, but with a little throttle blip it reads richer.