Quote Originally Posted by antus View Post
pcmhammers checksum tests are enough, if it says its ok, its ok.
Thanks pal, I went ahead and flashed in the 12212156 so, it’s running great! Only issue I’m having is a PO171 and PO174 code. This never showed up prior to the OS swap, could it possibly be a different O2 sensor type/pin out? I swapped this OS into a 99 Silverado 4x4 1500