SOLVED! After the dealer replaced the filler tube which didn't solve the PO2450 code, they replaced the connecting hose (FV6Z 9D333 C) ......engine light gone!
I have my 2015 Cmax H back to the dealer for the third time. They replaced everything associated with a PO2450 code...........the check engine light still comes on. Not sure what to do at this point.