i have a IS 300 with a aftermarket catback exhaust from Greddy, a Ti-C, and i get a check engine lite because i got rid of that cat, its saying that i need a new O2 sensor it has been changed, and i changed it not 2 long ago. but now my check engine lite is on again but its not cause of the O2 sensor its tellin me now that my cat isnt flowing enuf air or arent clean or something i have no idea wat it is.. should i get a mid-pipe to get rid of the cat thats comin off the headers or just replace the stock cat??? any help or advice would be great..

 

Im not 100% on this, but maybe an o2 simulator would do the trick?

 

run a scanner through it and see which sensor it is...we have 4 bank 1 sensor 1 and 2, and bank 2 sensor 1 and 2

changing just the y-pipe will not help with the CEL, even after replacing the y u should not get a CEL

has to be another bad o2 sensor

 

i just changed the O2 sensor... and wen they hooked it up 2 the computer the o2 sensor didnt come up and it usually does if thats the problem.. wen the guy read it, it said that the air that is coming out my exhaust or from the cat thats still on there isnt clean or something... if that makes any sense??? im all confused and lost.... =(

 

if its not the sensor get the 02 simulator, that will solve it