ok...i recently changed my o2 sensor,the one on the mainifold, hoping i'll get the stupid light off. i changed it, noticed better gas mileage but the light still goes on after i reset it and the same code pops up...49...49...49. it just annoys the hell out of me, so can someone please tell me how to fix this.
could it be the other o2 sensor thats gone bad????
o2 sensor
SO that means you have one in before the cat and one after the cat, I just assumed you have a S13... anyways, which one did you replace? the one before the cat or the one after? Usually the one before the cat goes out first but if the 49 code says it's the O2 sensors then I guess you'll have to replace both if you haven't already done so.
I don't have my FSM handy, but if the second O2 sensor is throwing the code, it's either faulty or your catalytic converter has gone out. The second sensor is only used for diagnostic purposes, it verifies that the catlytic converter is working properly. If it's seeing the same input as the first sensor, then it throws a code because the cat isn't doing it's job.