General Maintenance & Repairs - precat 02 sensor needed?

i have a 97 v6 and i have an 02 sensors on each manifold and i have one more on the after the y pipe before the cat and one after the cat. is the one right before the cat needed or can i remove it to install my wide-band there. thanks.

All parts on a car are "needed." If you unplug the pre-cat sensor, you will be very disappointed...

i was thinking the 02 sensors on each manifold where controlling af ratio and the pre and post cat sensors monitored the catalytic to see if it was working. but if the pcm needs these readings that means i would have to install a bung. :( i don't care about a check engine light im getting a tune real soon but if the pcm needs these readings for air fuel ratio then ill keep it and install a bung.

you need the pre-cat O2, but can delete the post-cat (SES code for a bad cat)

Yes you need the precat the post cat just makes sure the cat is working properly as you stated

i was thinking the 02 sensors on each manifold where controlling af ratio and the pre and post cat sensors monitored the catalytic to see if it was working. but if the pcm needs these readings that means i would have to install a bung. :( i don't care about a check engine light im getting a tune real soon but if the pcm needs these readings for air fuel ratio then ill keep it and install a bung.

Right. You need that pre-cat for the fuel/air calculations.

The post-cat is not as dominant, but the factory service manual does state that it is used for some air/fuel calculations. So, if you can get away with deleting it given your state's emissions laws, you should probably make sure your PCM is happy with the delete method.

ok guys thanks, a bung is going on next week.