Got an 03 gt with and magnaflow system without Cats. I just had a new one put in because of damage to the old one. The rear O2 were shot for some reason. So I got new ones and bought the MILs from steeda. Now the trick is I bought the left side from my work( Checker Auto) the other I had to get from ford purple connector side. The O2 were installed correctly and all that stuff. I now have 2 codes vs the previous 4 without O2s. As follows: Bank 1 sensor 2 heater circuit malfunction. Pending code: Bank 2 sensor 2 heater circuit malfunction. Bank 2 is the ford sensor which might not have a problem. Steeda said there product shouldn't be a fault. I the Checker part crap and cause both codes to trip or is it the MILs? I am going to UTI and just took electronics, go figure I don't know what I am doing. Please help if you got a trick. Thank you