Re: PO406 Code
Hmmm.. interesting. Long explanation aside, this usually means that the ESIM (or current version thereof) failed to detect a pressure change in the Evaporative Emissions System. What it is looking for is for system pressure to go down in proportion to temperature. In a sealed system, a decrease in temp = proportional decrease in pressure. If the system is no longer sealed then pressure would remain steady (relatively).
My $0.02- have the code reset. It may never come back. If it does, then you might need to have someone test the sensor and/ or do a pressure test of the system to determine the leak. If anyone has been under the hood lately I would vheck the obvious vacuum lines and vacuum plugs to make sure they are in place and secure.