Ok I searched around and couldn't get a clear answer, so here's my question:
I installed an aftermarket header onto my '97 civic cx. As soon as I started the engine, the CEL popped up. The O2 wire was already extended. I took it to Autozone and they said my O2 sensor is out. DUH. Why did it go out? I have a spare O2 but I don't want to risk toasting it until I know. Thanks in advance guys.

 

The O2 sensor is fine, you removed the CAT. All the second O2 sensor does is monitor the the Cat's efficency, so if the cat is not there any more the sensor thinks there is a problem with it. Search around a bit you will be able to find an O2 sensor simulator. Or just convert to OBDI.

 

how did u no he removed the cat he didnt say that... is that cat out???

 

Seriously?! There's nothing wrong with it? Someone told me that since it's throwin the cel on the o2, it will affect my air/fuel ratio and I'll lose gas mileage. Is this true? Im going on a trip that's a total of 10 hours in drive time so Im trying to make sure the car is in tip top shape.

 

I am a noob. My mechanic friend installed it for me. Basically he completely removed my stock header and replaced it with the after market one.

 

My friend told me the cat is built into my header? If so that explains it.

 

what exhaust do you have? where is the second o2? if the code is sensor 2 related you'll be fine, if you can stand the cel on constantly. or get a cat and put it after the header and modify your exhaust to fit. it's not complicated.

 

I still have my stock exhaust. The secondary is, correct me if Im wrong, on the bottom where the header connects to the exhaust.

 

do u have a hole there?? what kind of header do u have

 

not anymore. was the header you got for an ex civic? if so sensor 1 would be at the bottom of the header, before the cat. sensor 2 would be after the cat. it's hard to find a streetable header for a non ex civic. if you think about it honda was trying to cram sensor 1/cat/sensor 2 all in one exhaust manifold/header. so like i said...get an ex cat, or high flow, and put it after header. you'll need a o2 sensor bung after the cat for the 2nd o2, and modify exhaust accordingly.

 

Damn... I think it was neuspeed not sure. Im kinda confused. Im getting told 2 different things at once. Friend says my year civics have the cat built into the stock header and my o2 is fine. Some one else says its just the o2 that needs to be replaced. I knowfor sure its not an ex header. and yes there is a hole on the bottom of the header.

 

get an o2 simulator off ebay or something. or build your own. you will have to put it on the rear o2 sensor so that the engine senses less voltage. Or convert it to obd1 and your set.

 

Thanks guys, your quick response is extremely appreciated. I will try the O2 simulator and see what happens. Thanks again everyone.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by del_slow420 &raquo;</TD></TR><TR><TD CLASS="quote">how did u no he removed the cat he didnt say that... </TD></TR></TABLE>

I'm just that good

 

So let me get this straight. The cat was built into my header. By removing the header I remove the cat which is the cause of the cel. So now I have to either convert to obd1 or buy/make an o2 simulator. Is there a faq on how to build one yourself?

 

coulndt you just run an EX cat under the car????

 

i dunno....i tried to unplug the battery but it did not work.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kiddcarbuff &raquo;</TD></TR><TR><TD CLASS="quote">coulndt you just run an EX cat under the car????</TD></TR></TABLE>

this is what i've been saying. get a catalytic converter or simulator...problem solved. most likely the header you have is not designed for your car, and you will have to modify.

 

the header takes away the cat from your car. the thing under your car is a resonator. You need to change the ecu to OBD-1 through a conversion harness, ot just get an o2 sensor simulator, which i am selling, with instructions.