its from ur cat being hollowed. the o2 is trying to check the cats efficiency and its of course not good. i suggest getting one of those o2 simulation things, put ur cat back, go with an obd1 ecu.civicleo said:Ok, so recently I just put exhaust on my '98 Ex. I hollowed the cat., piped the rest 2 1/4", and have a silver bullet muffler. I also have 4-2-1 header, but my prob. is that my Down Stream O2 sensor is causing my check engine light to come on. I keep resetting it, but after a couple of days, it comes right back on. Is there anyway I can bypass this, or do something to keep the check engine light from coming on. Thanks!
clearing it wont do anything because once ur car runs thru the drive cycles the code will come back along with the light