Hey i have a 97 civic dx, i bought an aftermarket header and there is only one spot for an 02 sensor and my obd2 has 2, o2 sensors , is it ok to run wthout the bottom one? what are the purpose of theses sensors? Any help is greatly appreciated.

 

There are a couple ways around using 2 O2 sensors. The first one is to just run one of them and leave the other one out. That will make your CEL go on and it wont turn off until you get that problem fixed.

There are two easy fixes that you can do to make sure it works right and you dont get a CEL.
The first is to get your ECU chipped with a program that eliminates the secondary O2 sensor. Easy enough.
The second way is a little more hands on. You can splice the wires from the secondary O2 sensor into the primary O2 sensors wires and run it like that. That way works fine too. I dont know of anyone that has had a problem doing it that way.

Later,
BR

 

I am going to go splice right now, i just need a temporary fix, i have drilled a hole and welded a nut on the header, but it's not a metric nut, i can't find one big enough, so i just got the closest standard nut and welded it on there, and very lightly tightened it and put some lic tite on it but, when i went out to test run a friend of mine's car, right when i shifted into second it popped out, but i'm gonna splice it in and see how it works, thanks.