Brought the car to the dealership today to get some tranny fluid change and few minor maintenances and had them see if they could fix my check engine lights, well i got P0130,P0141 (both being O2 Sensors) and P0748 i think from my B&M shiftkit or so they said, thing is i changed both o2 sensors a few months back but the codes never cleared so i'm thinking that they were actually going to fix the o2 sensor codes rather then just delete them for $90 that i could have done at autozone for free which im kinda pissed about. I had the codes throwing before i changed my full exhaust/header could it be this causing it now. (note both the exhaust and the header are street legal and i have a cat also legal) anyone got any ideas on the o2 problems because im scared that even though the sensors are new the computers still reading that there f$&%*d and possibly taking away from my gas milage, oh and after they deleted the codes they all came back 5 min later any help on this situation would be greatly appreciated, thanks