Recently my CEL came on and it was the o2 sensor heater circuit, so I took off the heat shield and my manifold was craaaaacked as hell, right down the middle. I'll post a pic after class. So I looked at how much a new OEM exhaust costs, and I got 220 ish at AutoZone. I looked at aftermarket for like 5 minutes, and I was thinking about this:
http://www.protuninglab.com/hds-hc88.html

I don't know if that thing at the end of the y-pipe is an o2 sensor bung for the upstream sensor, or if its for anything. Do I even need the upstream sensor? I'm trying to keep as low emissions as possible for as long as I have this y7 motor. Thanks for any help!

EDIT: almost forgot: 99 civic lx sedan, stock powertrain.

 

If you get that manifold, you'll have to convert your entire exhaust to an EX style. The reason your stock manifold is so expensive is the integrated catalytic converter. There's no getting around that.

 

The Y7 stock manifold includes a cat. An aftermarket header will not include a cat and you'll need to add a cat...as well as an exhaust from an EX model. Then you'll need to lengthen your secondary O2 wires.

Yes, you need a primary O2 sensor. That's how the ECU determines fuel amounts. You cannot properly run without a primary.

The heater circuit being bad likely means you need to change the sensor. Buy a Denso or NTK sensor. Pick one of those two. Buy a direct plug in.

To keep it simple:
-buy a new manifold/cat combo for a Y7 (or a good used one).
-buy a Denso/NTK direct fit primary O2 sensor.

 

Alrighty, I figured. Lesson learned, I forgot there was a cat in there. I'll probly just have to buy new... Oh well! Thanks guys!

 

Or you can comb thru the marketplace. There might be some kid taking off a manifold for some ebay jdm header.

 

Lol I would do that normally, but this is one of those cases where id like the security of a brand new part. Plus, lifetime warranty at AZ. So, I'm now down $248, so that's one more delay for the new apartment.