Hi Accord pros, I've installed an OBX 4-2-1 headers into my 4 cyl 2000 Accord for over two years now, but it finally gave me the engine check light. I'm not sure where to start to trouble shoot the problem. I'm pretty sure that it's the header... I'm getting some of carbon builds up on the sparkplugs' tip.

Could it be that the catalytic converter have gone bad?
Or O2 sensor gone nuts?

I have the check light on for over a year now, the light do accationally went off but it only off for like a day. Other than that the car runs flawlessly.

check the o2 sensor, it could have a heater circuit failure..

Go to my album for pictures from haynes manual to find out how to read trouble codes-> http://www.imagestation.com/album/?id=4288023469

Get a scanner. I use The Mentor from MAC tools. They only cost 4k. You can get a snap on scanner for $1300.00. Just because there is a check engine light doesnt meen its a O2 sensor. It can be a million things.