I just received this fault along with a few others while sitting in the car (not driving but ready).
The following messages were displayed: Visit Dealer, I-Key System Fault, and When parked apply parking brake.
The following warning lights were displayed: Vehicle Dynamic Control (VDC) warning light, BRAKE system warning light (yellow), and Electric shift control system warning light.
I turned the car off, waited a few minutes, and turned the car back on. After the "reboot" the I-Key System Fault remained but other faults were not displayed.
Dealers are closed on Sundays but if anyone has any ideas let me know.