CEL Mystery

[00Civic]

i have had issues with o2 sensors before and shortly after my cat went bad. my primary threw a code for a year before the cat went bad. check the 2ndary o2 and on the hx the cat is on the header right? if that's the case you can convert it like a regular civic. i have no cat but my o2 is still plugged in with no CEL. it's a secret. i would def check the cat b/c on that model i think the cat is on the header and the 2nd o2 doesn't plug into the cat, i may have to get out my book for this one.

Yes, you're correct about the cat being on the header. I have been planning on converting it to like a regular civic, cause frankly, the cat/header thing is just ugly. Hopefully that'll do the trick when I get the whole setup.

[OldSchool87]

You took out the fuse for the check engine light? That will not work. You have to kill power to the ECU, that just kills power to the light. UN hooking the battery forces the ECU to reboot. The ECU stores codes on OBD2 cars. Once you reboot the ECU it searches for codes If it has a stored code it will pop the light on assuming the problem still exists.