A connected diagnostic system (CDS) for mobile assets that includes an onboard processing unit and a remote web-based platform that provides a remote view of an onboard display and/or Human Machine Interface (HMI) of the mobile asset. The onboard display and/or HMI can be the mobile asset's own onboard display or an onboard display can be included with the CDS. The onboard processing unit receives data from data sources onboard the mobile asset, such as onboard systems and onboard subsystems, and/or data sources remote from the mobile asset and displays the data on the onboard display, using wired communication channels, and on the remote web-based platform, using wireless communication channels. The onboard processing unit can also receive data from a data acquisition and recording system (DARS) for mobile assets that includes a data recorder.