Purchased the Bosch universal O2 sensor.  The problem is that even though the sensors came with a color coding chart for matching up wire colors, none of the chart color schemes exactly match mine!
I have 1 gray, 1 blue, and 2 black wires.  If anyone out there has changed these, can you tell me the right match?

Thanks for any help on this.

i had the same problem and i dont like to cut wires so i took it back and bought the oem one it cost alot more but easy to do.   

Well I found the match.  If anyone ever uses the Bosch universal sensors, just follow the chart with the blue wire.  It will make sense when you see the chart.  All is running well now.