So, i just got done getting my high-flow catalytic converter installed, and i have a CEL on in my car.
I do not have the error codes on me, but when i got it checked out at auto zone, they said it was a cataltylic low efficiency, which he said either means that my car's o2 sensor is dead, or that because its a high-flow converter, then it needs a o2 simulator/ eliminator.

now, my questions is, does anyone know where i can get one of those o2 simulators/elminators for my car?

it's an '00 Neon ES

 

i am having the exact same problem! i have an 03 neon, and first took out my cat, that's when the code started comin on. Then, i installed a high flow Cat with a magnaflow exhaust, and am still having that same problem. The code should be P0420 "catalyst low efficiency". I have reset my ecu countless times and still get this error code.I would love it if someone could solve our problem as I'm sure that not everyone that puts an exhaust or high flow Cat on their car has this code come up. The closest thing i got was neonRT saying that it is either a bad cat or 02 sensor. Not exactly sure what it is but i would personally like to solve the problem without using the o2 sensor simulator. but here is a link to one that i found, i have another link but am not home right now will post later. SOMEONE PLEASE HELP US OUT LOL, THAT DAMN CODE IS ANNOYING!!!!!! http://www.voodooboost.com/performan.../O2_Simulator/

 

ya that o2 simulator works perfect... install that and your codes will leave. i did it with my car.

 

just drill out a spark plug defouler screw it in between the pipe in the senser and problem solved for under $5

 

is there anyway for fix it without using the simulator or drilling holes? if you do install the simulator, do you still get codes if something goes wrong with the exhaust? or is it just gonna read like everything is clear even when it's not?

 

I will pull of my down/ cat and do little write up for you guys about the defouler trick

 

do the spark plug nonfouler trick. like tooslow said. get 2 14mm spark plug nonfoulers (they come in a pack of two) and you have to drill out one of them so the 02 sensor fits in it. possible 3/8 bit im not sure i;m doing this off the top of my head and then just screw them into the bung and your set. and no the 02 simulator does not work