R_G:
I would say Bank 2 is the downstream sensor, the one that's after the catalyst. That's if you are driving a 4 banger. Not sure about the Duratecs though.
Don't say that anymore, becauze on a 4cyl you only have two O2 sensors, the upstream and the downstream. You can't speak about bank on a 4cyl. 
Nic.
Contour 99 MTX V6 fully loaded, stock with 110000km. Illuminated sunroof switch. About to do the mystique rear dome light conversion with eyeball dome light.
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