Re: iODB2 Engine Data Reader - Cheaper option
The data that you can get from the OBD socket depends on your car. My old Peugeot 206 only supports the basic diagnostic codes, and the current RPM.
That said, a £15 ODB to USB cable plus $5 for Torque is much cheaper than the £25 my local garage charge to check an engine warning light. And if it turns out to be something simple like a faulty O2 sensor, you can probably replace it yourself.