I had my 2001 Dakota for about 45 minutes (bought used) when the check engine light came on. I reset it and it came back on showing the O2 sensors. Before I could get them ordered and replaced all 4 errored. I replaced both S2 but they didn't clear. Both S1 cleared. I posted here and found out that my 4.7 doesn't like anything but Bosch so I replaced both S2 and only B2S2 cleared. I swapped them to see if it was a bad sensor but B1S2 still errored. So do I have a wiring problem or a computer issue? What do I do next? I know you don't know the issue but what would be your guess or suggestion?

Thanks
Reid

 

What code are you getting?

 

You may have a bad cat. The downstream sensors are supposed to monitor the cat's efficiency, and make sure nobody removes them. If the sensor worked on one side but not the other, that leans towards a bad cat. I don't know if it will reach, but if the wiring will allow you to swap the left and right bank wiring, you can check the wiring by swapping them over. If the problem follows the wiring it's bad, if it follows the pipe it's the cat.

 

I had an aftermarket high flow cat on my dakota that the computer didn’t like. Idk if you have emission testing there but you can buy 2 spark plug non foulers for a Ford 302 drill one of them out to 27/64ths don’t quote me on that it needs to be big enough for the sensor to screw into it I’m thinking back over a decade on this one so that drill size may be wrong. Screw the drilled out one over the end of the rear o2 sensor then screw the non drilled one over that one and screw the whole thing into your exhaust. The sensor will get hot so it thinks it’s working but it will be out of the exhaust stream so it will think the cat is working. Works wonderful for a cat delete

 

From all the years of posts I've seen Dakota's don't like Bosch for anything.

I'd try another brand.