i just installed a dc sports 4-1 type r header on a 2000 si a few days ago and the cel came on. it says its the primary o2 sensor. i was wondering would putting the header on cause the problem with the o2 sensor or did my o2 sensor just happen to crap out on me when i put it on? i ran open header for like a day and a half until i could get the header to line up with the stock cat (temporary fix, bolt pattern on flanges didnt line up correctly) im going to be buying a high flow cat in a few days. Just needing peoples input on the o2 sensor. Thanks

 

bump

 

I am not real fimilar with the SI but if you ran it open header and your o2 sensor was mounted in the pipe that was not connected to your header than yeah it will throw a code becuase it your o2 sensor was not getting a true reading from your exhaust system....

your computer has Parameters for what your o2 sensor should be seeing.... and if your o2 sensor is not picking up anything in your exhaust and your computer thinks it should be it will set a DTC......

this is the most logical problem i can think of..... so i would clear the code and hook your exhaust up right and see if it comes back before replaceing the o2 sensor.... but then agian if you have 100k miles on a stock sensor it may not hurt to replace it.... they do go bad over time...
just my .2 cents.....

kev

 

well did you connect the primary O2 sensor?
or did you just leave it off?

 

well the thing is i got everything mounted back up correctly after running with an open header and the cel went off after like 2 1/2 days of driving with it on... then like 12 hours later it came back on. everything was connectly up correctly i'll have to check the plug of the o2 sensor again. any other suggestions? if i have to get a new o2 sensor where would be the best place and around how much would it cost? thanks again

 

any parts shop will have the o2 if obd2 uses a 4wire (not sure if they do) its around 80 bucks usu

 

i have run into the same problem a while back on my old em1
and its one of two things either it comes on because it didnt
adjust to the headers yet..so i reset the light and it was fine
or another issue ive had was that its probably your stock o2
sensor so its like 8-9 years old and all that extra air coming
through from the header burnt it out and ive replaced it and
it was fine..hope this helps.

 

if it was the original sensor than its possible that handling it (switching it over to the new header) could have damaged it in some way.

Hondafab19 is wrong though there wouldnt be much extra air coming through (if any) and it wouldnt damage the sensor something else would have had to have happened to it.

 

then what is the point of a header if no extra air is coming through???

 

the same amount of exhaust fumes will come through the header. a well designed header has a better width and bend profile to allow the fumes to flow in a more desirable manner to free up some power

 

well thanks for clearing that up for me...

 

ok well i just reset my ecu again and im waiting for this damn snow to clear so i can go drive and see if it comes back on... if it does it looks like im going to go get a new o2 sensor thanks for your help