Normal2

I have owned a 2002 SC430 for more than 8 years. The engine light has always been on. To pass inspection, various codes have come on (mostly sensors or catalytic converter). Most of the time it has to do with emissions. A mechanic has always someone figured it out by resetting the code and replacing a small part here and there. I have brought the car in to the person who passed it last year. He has not been able to rectify the issue and it can't pass inspection. The code is 125. Any help would be very appreciated.