I think there is some test routine that gets stuck trying to run over and over when it doesn't see the rear O2's. I'm not sure of the cause but even with stock DFCO settings it was happening. It only started when I removed the rear O2's which I only did because on the Camaro's, the ARH headers don't have a 5th bung for the wideband like the Corvette Systems do. Once I used User Defined Parameters to change some tables, that are not exposed by HPTuners, the issue stopped.