Currently working on a customer's 2018 Silverado 5.3. Customer requested turning off AFM. I read the ECM, toggled the AFM option, and cal flashed. Right at the end I got the $06FF error. Doing some reading, I saw many folks reference B9999, but that is not in this file. Truck has not been touched supposedly. What is the fix for this? I sent support a message but haven't heard back yet. Any help is appreciated.