Showing no codes, driving on freeway and vehicle just started coasting. There was no warning of any malfunction. Any ideas as to cause?

Hello, naturally you should check to ensure you have full, clean transmission fluid in the transmission. Beyond that, there could be an internal transmission failure that has rendered it unable to engage a forward gear. You could also have an electronic transmission concern. A diagnostic tool with the ability to monitor the operation of vehicle components can be used by a trained technician to evaluate transmission electronic operation.