Does the guage light up at all? or does it just stay dark?

stays dark..

brand new???

if so.. wiring is wrong.. you are not making connection somewhere to power or ground.

yes either your grounds are bad or your power wires are not hooked up right. I would go back and double check your wiring and use a test light on where ever you hooked them up for to power to make sure those are even power wires your hooking them up into

hooked up to the battery, grounded to the same spot as the battery

i mean two red wires on right are power, two blacks on left are ground, and white goes to ecu pin #4.

Maybe it's wired wrong as far as the gauge, not too sure on that one. I noticed that you said it's in the front O2 sensor spot. I think it explains in the instructions that a separate bung needs to be welded on, around, 32 inches downstream of the turbo and before the CAT, I believe. The wideband O2 sensor is placed in that bung. If this is not done the wideband readings will be incorrect. I think there is a video for install on AEM's website if it's not in the manual.

thank you for the thought. but... a second bung does not HAVE TO be welded in place.. and you actually get a better reading on A/F ratio with the sensor in the front o2 spot.. that why (and im not sure about previous versions) dsm link v3 has a sim for the factory o2 sensor. so its not needed. ill stay updated after i try a few different things tomorrow. bought a pigtail for my fuse box inside the car, maybe ill have luck with that

Ok I'm stumped... Maybe the gauge itself is bad or something happened to it while it was in my trunk.. LoL