FWIW: There are a few GM TIS bulletins out there about failures of 'in car' J2534 flash loads, and them failing in process. So I imagine it's a case by case type deal, but they nail ya in labor either way. It is truly amazing how much money GM has milked out of a closed technology that is going on 3 decades old, and is still alleged to be closed to the public, even after accepting public revenue.