Here is the story i got my Berk`s HFC`s finally installed. Driver side O2 sensor got broken while install but i order new one. I were driving for 5 days with out sensor so my check engine light came on after 4th day. Then i put new sensor in and i got little computer called scaungauge so i reset the light. Next morning im driving to work and the CEL came back on. Anyone have idea what it could be? Another question about HFC when the installer were putting them in he asked me about any instructions because there are 2 holes on each cat to put O2 sensor. He wasnt sure about which hole to use so he put into the one that bigger maybe that is the case?
Please any advice.

 

Pull the code with your scan gauge and look it up. That'd give you a definitive answer on the problem

 

The other 2 holes are for an exhaust gas temp sensor (EGT) if you ever want to add one or if someone needs to tap in while tuning.

 

alrite problem is solved. Had to reset CEL twice and now its all good.
Thanks guys