oseise

I would appreciate any tech help. I Have a 2000 honda Accord LX 4 cyl, auto. The Primary O2 sensor was located at the top of the headers and the secondary after the catalyst. I replaced the headers with one from Arospeed which only has an opening down below before the catalyst.I had also replaced the catalyst with an OBX hi-flo catalyst. I now have just the opening at the bottom of the headers before the catalyst and 2 O2 sensors. I tried attaching the one O2 sensor from the catalyst in that opening leaving the one that was at the top of the headers which is the primary not in use. This is causing my check engine light to stay on. Can I please get som help on what needs to be done. Will I need to lengthen the primary sensor in the top and actually make that one reach all the way down to the opening at the bottom of the header before the catalyst. But then now the secondary sensor will not be in use because there will be no where to place that one. Will that cause my engine light to go off. I would appreciate any help from the more experienced.

Accordlxcpe97

I am not an expert but you might be able to drill a hole and weld a nut to the hole of proper size in order to connect your second O2 sensor. Sometime this works, sometimes it does not. I had a similar situation in which I replaced my cat with a test pipe and tried putting the O2 sensor in the test pipe. ODBII does not like that very much. Needless to say I had to put my cat back on and sold it to my cousin that has an ODBI Accord. It worked for him since he does not have a sensor at the cat.

oseise

Guys,
Thanks so much for the help. Excuse me for my ignorance. What is OBDI or OBD II? So, the primary sensor should be installed with an extension to where the heads come together. Then I guess I should remove the high flow cat and replace my stock cat to be able to reinsert the secondary O2 sensor. Is that correct?

oseise

I am going to order the extension and thanks for taking the time to answer and explain things to me. You have been a great help. I have gotten responses at other sites and they were either not as informative or judgemental and the parts I have purchased instead of helping me understand the problem. Thank you to both who have commented and assisted me a great deal. Obviously this website has a much more mature and experienced crowd who takes the time to help us individuals just starting out! Thank you!!

Accordlxcpe97

ODBII is up to 99 models I beleive. ODBIII for 2000 and up. I am not exactly sure on the break there but I do know that ODBIII exists.