i took out the distributor to get to the bottom hose on my honda civic n the O2 sensor, but when i'm done with fixing everything and install everything back together, the check engine light came on and remain on... my question is, why did that happen? what do I need to do to fix it? Everything seems find except for the unexpected check engine light... For the sake of this question, I don't want to take it to the mechcanic becuz i think i can do it myself since I mess with it. I just need infomation to fix it...