808Bill

I see some advertised as pre or post cat and others with no description at all.
Is there a difference in the sensors themselves or just wire length?

rechtien

They are different. The wire colors are different, slightly different lengths. The pre cats wires are black, post cat blue. Different part numbers. From one side to the other the pre/post at the same.

I used the oem pre and I think Bosch post and seem to be working fine. Just changed mine this summer.