i have a 99 civic and my check engine light says its either the O2
sensor or the CAT, i replaced the O2 and it still says its one of the
2, a new O2 sensor for mine was $180 and did nothing. a new CAT for
mine would be $500 plus, if your CAT is still under waranty take
advantage of that and save alot of money, i mean it cant hurt can it?
wish i could get a new CAT haha, but i think its just the aftermarket
headers screwin up the O2