A method 'isEngineOn' should be implemented in 'application_t' class.
This method should return a boolean and determine the engine state using the engine speed (got with a UBS/UBD2 request).

This method should be used to check engine state before sending a diagnostic request ('subscribe_unsubscribe_diagnostic_messages' function in 'low-can-cb.cpp' file), and rise a warning when a diagnostic request is send when the engine is off.