OBD 2 Readers can show you various pieces of information that aren't available on the standard dash.
- Transmission temperature
- Scangauge supports, not sure about Kiwi
- Miles per Gallon (MPG)
- More accurate Water Temperature
- The dash gauge is really a dumb sensor
- Trip data, like average MPG or top speed, average speed.
- Read trouble Codes
- Find out why the engine light is on
- Aftermarket stereo harnesses, on some models, can destroy or be incompatible with OBD Readers.
- Solution is to cut the K line so that power is not sent over the line (traditionally the power is sent to extend powered antennae)
- Article for more details