Contour Enthusiasts Group Archives Forums General General O2 Sensor Locations and CEL

I think I have this right, but I'd like some reassurance.

A Duratec V6 has an oxygen sensor in each manifold before the pre-cat and one after the pre-cats but before the main cat. Is that all, or is there a fourth one?

I have a CEL so I went to Autozone. The guy told me it was the second sensor in bank 1 that was going out. Is that the sensor in the y-pipe? Is bank 1 the manifold between the engine and the firewall? BTW, this CEL came on 10 minutes after installing a new y-pipe.

Thanks for your help.