95 prizm o2 sensor/cel questions...

[Tomtomtom]

Well, I've been searching the interweb for weeks now to no avail... So, hopefully you guys can help.

Got a 95 prizm, 4afe, and the flex-pipe on the downpipe rusted away 6 months ago, effectively making it sound like a v8 with less low-end power than a scooter. And I found that getting an OEM replacement wouldn't be cheap, so I went with an aftermarket no-name Ebay header(which turned out to be a good deal; nice welds, 2.0"...)

Anyway, I went to pull the 2nd o2 sensor off to take it to autozone to match it up with a sparkplug antifouler and bung(got a buddy who can weld it for me) to trick the computer and whatnot... It wasn't the threaded type, looks just like the upstream o2 but smaller...AND IT WAS MISSING THE NUTS holding it on, but still sitting in place... I was baffled. Perhaps the previous owner planned on working on the downpipe and got sidetracked...

So, I pulled it off, disconnected it, and started it up expecting to see a check engine light...and there was nothing(but it does sound like a harley when I hit the gas of course since I have 2 exhaust leaks now).

Ok, now I have a few questions... Is the cel disabled? And, if so, is it possible to re-enable it? And, if I install this header, straight-piping the cat, and leaving the 2nd o2 sensor disconnected, will it affect the computer and fuel/air ratio in a noticeable way?

I'm planning on goin down to get the codes pulled(which I'm assuming there will be at least 1) but don't want to do some extra fabrication unless it is 100% necessary...

[speedy25]

The 02 sensors ARE necessary. It will trigger a CEL eventually. You found out there are two styles- thread in and bolt on. Pick the one that works easiest for you.

-SP