I have a 2013 sierra 6.2 did a front mount turbo setup on it bent a rod so it got a forged rebuild. While the motor was out it i also installed a converter in it. Nothing electronic was replaced just unplugged for the motor rebuild then plugged back in. I know have the truck back on the road and the alcohol sensor is reading 64% even though i ran the tank completely empty and put premium gas in it. I even went to a different station today and it only changed to 62%. While i did the motor rebuild the truck sat for 3 months with no battery in it and it know has no cats so i unplugged the rear o2s and just left the SES checked with the codes set to 3. I'm wondering if anyone has ever seen this? Is it from the rear o2s or it just needs to do its thing for awhile im kinda lost truck only has 6k on it everything is brand new. Any help is greatly appreciated thanks