Ok i have a catted ZZP downpipe that i installed the C.E.L light is on its the P0240 code I think. My question is would a defouler help me pass emissions.????? Or do i have to install my stock DP back on.

 

Sure it's not P0420?That ones not enough catalyst I think.

 

ya P0420 due to catalytic converter

 

I had to put a defouler on my zzp one too and it does not come on no more..
Give your car like a week with the defouler on it and it should erase the code from the system cause the dummy light wont come back on and try to pass it..It should pass then!!

 

I got the one from Modern performance..
Vibrant Oxygen Sensor Defouler

 

Get a tune that deletes the downstream O2 sensor.... Emmissions will be none the wiser