Rustin:4-dontknow:This one has me baffled? The O2 is the only thing I could think of?:thk:
LB7 LLY and LBZ Duramaxs don't have O2 sensors.
Are you running stock tuning?
Cause most of the times they will throw an EGR Insufficient flow code when you improve exhaust flow. Also might want to clean the MAP sensor.