Need solution for o2 sensor, upgrading to header/exhaust with no cat

drummer_jb

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10+ Year Member
My exhaust has rusted through and fell to the ground for the 2nd time in a few months in 2 different spots, and upon research I found that many 96-00 exhaust manifolds crack:bs:, therefore I am buying an aftermarket header and exhaust system for my 2000 civic HX to fix my current and any future common problems with exhaust.

In the dx/cx/lx/hx models, the exhaust manifold has the catalytic converter built right into it, before the downpipe. there are 2 o2 sensors, one in the exhaust manifold before the cat, and one at the end of the cat.

With the aftermarket header, it is basically upgrading it into an ex/si header with no catalytic converter built in. In those models the cat is after the downpipe under the center console area, and then goes to the mid pipe, s pipe, and muffler. My new exhaust comes with a test pipe in place of a real catalytic converter. I do not need or want a cat, my state does not test for them. But I know I need to buy an o2 sensor wiring extension for the 2nd o2 sensor to reach all the way down to the test pipe bung under the car.

My question is, if I do that and simply plug in my o2 into the test pipe (high flow cat) bung, won't it will throw a check engine light code for having no catalytic converter because the temperatures will read the same and possibly run badly or in "limp mode?" How do I get around this exactly? I have seen there are o2 defoulers for $30 that are 90 degree right angle design, screw into the test pipe bung, and then o2 sensor screws into that. Will that fix the CEL code? Any suggestions? What is the best way to go here? I dont need a cat and dont want to pay for one either:jerkit:.
Sorry for the essay, but I figured its better to explain exactly what i know and what i need to know.
I need a solution ASAP so I can order my s*** and get them on my car because I am borrowing a vehicle in the meantime and need to return it as soon as my car is fixed.
 

CO671

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Weld a bung then use the spark plug non fouler trick
 


drummer_jb

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5+ Year Member
10+ Year Member
Weld a bung then use the spark plug non fouler trick
I thought I would just use the non fouler trick too, there is already a bung on it luckily. But someone else said they didn't think it would work bcuz the hx 5-wire sensor is very sensitive??
Should I try a non fouler trick and if that doesn't work buy a dummy o2 sensor? Guess that would work.

I also read about another issue... on 99-00 civics, apparently there is a bad o2 sensor positioning on most aftermarket headers, from ebay no-names to DC sports. I have read a whole lot of forums where ppl who bought an aftermarket header stated that their o2 bung was on the wrong side, or made the o2 sensor rub on the axle?? Anyone had/not had this problem with o2 sensors positioning/rubbing with an aftermarket header?
 


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