ScanTool.net OBD-II Software for ElmScan is free software that allows you to  use your computer and an inexpensive hardware interface to read information  from your car's computer. Current version allows you to read trouble codes and  see their descriptions, clear the codes and turn off the "Check Engine" light,  and display real-time sensor data such as RPM, Engine Load, Vehicle Speed,  Coolant Temperature, and Timing Advance.