If you only want it to display O2, and not connect to anything, you only need power and ground. The white wire is a 0-5v linear output, the blue is serial output. You only use the latter two if your going to connect to your tuning device, Megasquirt in my case.
So if you have red and black wired, check for a good ground, and good switched power. Also where is the WB sensor located?
2004 Ion Redline (stock)
1995 Saturn SW1 (boosted)
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