new Headers throwing a code

[Kevin Trick]

Please Help! Just put in new headers. I was able to put both o2 sensors in was working fine till I got on the Highway. now Check engine light is on.Is it because the second o2 is before the cat when it used to be after..HELP

[GScivic7]

why did you move the 02 sensor? Pull the code and post it on here

[superbluecivicsi]

you removed the o2 sensor from the cat when you put in the header?

[Kevin Trick]

The o2 sensor on the bottom of cat had to move to near the end of the headers, after the headers the new high flow cat is there. I can reset ecu but code comes back after awhile. But alas I dont have the tools to put the code. thx

[honda_luvr_2000]

count the number of times the LED blinks on the ECU, that's the code. also, again y would u move the O2 sensor in front of the cat? it HAS to be after the cat. even if it's a REAL hiflo cat. by real i mean it still is a cat and is higher flowing than stock, not just a straight pipe w/ a resonator. also, everytime u thro a code, the ECU records it, and E-check is gonna see it next time u go. (if u'r as unlucky as i am and HAVE to get E-checked) get enough of them built up and they'll fail u'r ass regardless. happened to my buddy w/ a 97 hatch

edit:
u could also roll over to AutoZone and have them pull the code for free.

[GScivic7]

How to pull ECU codes complete with listing of codes and how-to video

http://www.honda-tech.com/zerothread?id=682412

[Kevin Trick]

P0420 Catalyst System Efficiency Below Threshold,
Thats the code that Autozone told me, I guess this mean I have to drill a hole after the "high flow cat" then extend the wire on the O2 sensor the reach that point and I should be Good?
All I wanted to do was get just A liitle more power.

Thx

[GScivic7]

Yup sounds like it.

[superbluecivicsi]

my money says the hi flo will throw the cat again someday. when it happens, go get an o2 sim.

[Kevin Trick]

I think your right even if I move the o2 it will still throw a code.
Got any ideas?

Whats a o2 sim.
Perhaps getting one of those reprogramed ECU's?
THX

[Ricochet]

Originally Posted by Kevin Trick

I guess this mean I have to drill a hole after the "high flow cat" then extend the wire on the O2 sensor the reach that point and I should be Good?

Not so fast sparky. You have to buy a nut with threads fitting the sensor, and weld that into the hole.

[GrayV]

According to my mechanic, the catalytic converter provides about 1 pound of resistance and a higher heat reading on the o2 sensor when it is behind the cat. You need to have it moved to the rear of the cat to provide the correct reading so as to not throw out a code.
It worked on my 97 civic ex and I have not had a code since.
I know it sounds kinda lame, but the muffler shop cut the flanges of my cat and welded them on the opposite ends for $30 instead of plugging the hole and tapping a new one.

No more codes.

[superbluecivicsi]

i have yet to experience a carsound cat that will not throw a code.

[honda_luvr_2000]

yeah if it isn't a REAL cat then u'll still thro a code if u move the O2 sensor. the O2 sensor is checking the oxygen content by the heat level. if u have a resonator instead of a cat, then it's not gonna get hot enough for the O2 sensor to say everythings a.o.k. a cat burns off the NOx (x is a variable), CO, and CH. it has to reach a certain temp to do this and even higher to do it efficiently. the O2 sensor just reads the temp and that'll tell just how much the cat is doin. so if u have a resonator and not a real hi-flo cat, then u'r shit outta luck. if u don't know for sure. take it off and if u can see right thru it. it's not a cat.

edit:
one thing u could try, if u wanna keep u'r resonator "cat", is try wrapping the header w/ header wrap all the way back to the O2 sensor where it is right now. u might be able to keep enough heat in to trick it. just make sure u don't have a cheap header that will crack if wrapped, and get good wrap that doesn't let water thru. another option, the O2 simulator like was suggested by superblue.

[~ls/vtec~]

where can we get these 02 sims