4x4Mon is a stand alone engine monitor for both 12V and 24V systems. It consists of a controller + display and it uses its own sensors for all it's measurements (it does not connect to a car computer via an OBD interface). The display can be either, a small screen mounted on a dashboard, OR a Bluetooth connected Android device with a 4x4Mon App (download via Google play), OR both simultaneously.
The same Android App is also used to configure all the sensors, alarms, relays outputs etc.