Well my car has been sitting for a few monthes with just the regular start up and idle with a few revs just to keep things moving while my 10 bolt was out. Now that I've started breaking in my new 9 inch I got a SES light. It was P0135 02 sensor bank 1 sensor 1. Well the 02s are new less thank 1k on them and its bad. I also just put a e cutout on the car could the change in exhaust flow have caused the 02 the crap out or is getting a premature failure just one of those things that happens from time to time. They're factory replacement bosch from Advance. Thanks

 

i had somewhat the same problem a while back. have you tried putting spacers on them? that worked for mine.