Ok. Let me start by saying I have a 08 g35x sedan. A couple months ago I installed fi cbe with 18" res. The car ran fine for a week. Then I had the rhfc installed. A day later I threw a code for bank 1 senser1. I then replaced that with a denso sensor. Again 2 days later the same code came on. I then had the mechanic switch sensors. So now the oem sensir is in bank 1 and the denso is in bank 2. 2 days later the same code for bank 1 sensor1 came again. I talked to tony a few times and he has been nothing but helpful. I never thought is was a bad cat, but if it was, he would have replaced it with no problem. So during this whole process it has been checked for leaks and 3 different places said Jo leaks. Yesterday I finally had the cats removed and the oem cats put back in, and guess what. I threw the same code within 1 hour of driving. Can anyone please help a brother out. I'm trying to get this right without shelling out slot more money. I took a look at the rhfc and they look normal. I'm thinking it was something during the install. Maybe when he used the torch. Idk. Im lost. Anyone with knowledge to this can you please point me in the right direction

 

Here is the deal. You had a leak. If u still have the oem sensor put both of them in the correct locations. Buy the Z1 gaskets. They are thicker. Also purchase the red hi temp gasket maker , sealer whatever it is called. I had the same set up but resonated test pipes from FI with their exhaust. After u do the above re torque everything after a few heat cycles. My code the same as yours went away. Some installers just don't do a good job. I did everything myself and zero issues.

 

Ok I took your advice, and had them reinstalled with the super thick z1 gaskets and permatex hI temp gasket maker. I'm a keep my fingers crossed and hopefully the ses light won't come back

 

I still have no codes with my FI Resonated test pipes. Hopefully this helps u because it solved my annoying problem..

 

I had this same stupid problem. The only solution I could think of was turning the code off with the Uprev tune.