2002 Sentra GXE Header Installation

[quetzal50]

i want to install a header.the problem i see is relocating the 2 oxygen sensors after the pre-cat. I was wondering how to go about these sensors so i don't have a check engine light. i know that these 2 sensors aren't required for the vehicle to run properly as the other two oxygen sensors in the header take care of the A/F mixture but the other ones are just for the pre-cat. Any Thoughts?

[centralcoaster33]

I think you're getting some of the details mixed up. Check out your existing exhaust system. Look at it in the FSM (see the link). Off of the top of my head, I'd say you have two O2 sensors, a primary (typically in the header, before the primary cat) and a secondary (typically after the primary cat) and maybe two or so cats. The header will likely delete one, the pre-cat. The header should have a bung for the O2 sensor. The second O2 sensor might need to be moved out of the path of the exhaust a bit to get it to read properly. Your computer uses both to adjust your A/F ratio.

http://www.nicoclub.com/FSM/Sentra/2002/