I just installed 4-2-1 headers on my 98 honda civic lx, and the first thing is: since the install, my "check engine" light has been on...could this be becasue i havent installed the catalylic converter behind the headers yet???

and the second question is: When i install the catalylic converter behind the 2nd half of the headers will i have to place one of the O2 sensors on it, or can i keep both O2 sensors on the headers???

 

If you don't have both of your o2 sensors hooked up, that's gonna be your CEL. Whatisthe code it'sthrowing?

 

yes

no, not unless you like check engine lights

 

what is the CEL and i dont know its throwing i havent put a computer to it yet....and wat happens if the O2 sensor cant reach the catalylic converter, cuz its hardly reachin the 2nd half of the headers

 

you will have to extend the wires.

 

You may have broken one of the O2 sensors when you removed it from the original headers. If you smack them right they break, I did it.

 

I've heard you should unhook your battery for 20 minutes after you install headers or any exhaust as it resets the computer.... Not sure if this will do anything. If the O2 aren't hooked up, it's going to throw codes

 

seriously, there should be a sticky for "6th Gen DX Header Installation FAQ". I wrote this

As you may or may not know, 6th Gen (96-00)DX's have the catalytic converter right in the exhaust manifold/header. If you look at yours, you'll see a big bulge in it. Thats the cat. So when you put a header on, you're removing the cat as well. This is illegal in alot of states and also bad for the enviroment. To fix this, you need to get a new cat. You can a high-flow cat from Magnaflow or Randomstech that will give you a few horses but still keep you emissions legal. Just search around the internet for "Universal Magnaflow High-Flow Catalytic Converter". If you buy the kind youget welded into your exhaust: Once your header is on, bring the new high-flow cat to a muffler shop and they'll weld it in somewhere in the exhaust. Thats taken care of. If you go the route of getting a high-flow cat that bolts on, you will have to bolt it to the end of the header, cut part of the midpipe out, then weld a custom flange on the end of the midpipe. This makes it convenient if you ever want to replace the cat/get a catback exhaust. As a sidenote, a catback exhaust from an EX of the same year as your DX will bolt right up the cat (once its bolted onto the header) and the length will fit perfectly.

For header installation, its just bolted to the block and then to the rest of the exhaust. Unscrew both o2 sensors and then unbolt it from the block, then from the midpipe. Install the header the opposite way. The first o2 sensor in the engine bay should fit length-wise perfectly. The second one however poses another big problem for DX owners. Yes, its possible to splice the wires and extend them, but this is not recommend and theres something that fixes it automatically. An o2 simulator. These are either wired into the 4 wires of the secondary o2 sensor or its something you screw into the 2nd bung of your header and then the original sensor screws into it. Since the 2nd sensor is still in the header (and the cat is after the header),it thinks the cat isnt doing it's job at all, so you get a Check Engine Light. Both of the simulators trick your ECU into thinking the catalytic converter is working perfectly. You can find the one that is wired into the sensor at www.o2simulator.com and they are about $25 (get the universal kind).

I nominate that as a sticky since theres alot of questions asked about it (i wrote that myself btw)