Alert Code General Information
A Diagnostic Trouble Code (DTC) is an alphanumeric identifier for a fault condition identified by the On Board Diagnostic System (SAE j1930 v003). Tesla's diagnostic process does not generally rely on DTCs, however, and instead relies on event based troubleshooting via "alerts".
An alert is how the electronic control unit (ECU) denotes and records an event of interest. This can include faults, abnormal behavior, normal behavior, a particular use case (shift with foot off brake, driving with door open, etc.), and many other events. The key distinction is that Tesla alerts are event based troubleshooting as opposed to fault condition based troubleshooting.
Alerts can also trigger behaviors and/or messages on the User Interface (UI) to communicate with the driver in special circumstances where Tesla wants the driver to perform an action as a result of the event. For example, if the vehicle detects that the hood is unlatched, it can alert the driver that the hood is unlatched in addition to a traditional telltale. The UI may display a telltale, make a sound, change the UI, or display a message, depending on the UI behavior associated with the alert (if any).