Check engine light (Front O2) after going back to stock

Due to various reasons I had decided not to play tuning anymore a couple years ago and flashed my JDM LGT back to essentially a stock map with the exception of my corrections made to the MAF sensor readings to account for changes in airflow from my intake system.

 

Recently I have decided to return my car to stock and swapped out the intake and TMIC. However I have long lost my Tactrix cable so I was unable to flash my rom back to stock. Since the MAF corrections I made in the map was minor, I thought it would be alright to just leave it.

 

I had switched back to the stock intake and TMIC for around a week and everything went fine and yesterday I had finally came around to switch the exhaust system back to stock from the down-pipe down.

 

After converting the exhaust back to stock I started getting the check engine light and every time I tried to reset it, it would come back after 5-10 mins (it would come on regardless whether I am driving or just letting the car sit on idle). Diagnostics from the garage showed the front O2 sensor going bad.

 

Could it be my MAF settings that is throwing off the ECU calculations making think the O2 sensor is going bad or did the O2 sensor really got damaged while swapping the exhaust? If it was due to my previous MAF corrections, shouldn't it should up while I converted the intake back to stock rather than the exhaust?

 

Thank you.

Forgot to mention, I have lost my tactrix cable so I am unable to flash my ROM back to stock.