Since we have a new car (VW Golf 5 GT) which has an OBD2 connector, I was curious what it can do. So I bought myself an el cheapo ELM327 Bluetooth adapter and connect to it via Torque Pro and low and behold, it works and the data it can see and display looks good and matches what either the car dashboard shows or what is common sense.
It’s quite fun to watch the parameters as they change: gas pedal, oil temperature, turbo boost pressure. No real purpose, but technically interesting.
Once an error occurs, it’ll get more interesting: without diagnostic tool all you get is an “yellow motor error” light. Not much you can do here than go to a car repair shop. With software like Torque and OBD2 data, you possibly get the sensor which is either broken or shows bad data.