The OBD II engine ECU diagnostics tool is a helpful device that connects to your car's OBD2 engine management system using a cheap Bluetooth ELM/OBD adapter. It provides real-time information about your car's performance, including engine fault codes, sensor data, and more. The tool can export map/track log files to Google Earth KML/CSV and has a customizable dashboard with theme support. It can also help you fix your car and keep car repair costs down. The free/basic version lets you get a feel for the application and find out if it works with your vehicle/obd2 adapter combination, while the paid version has more features and supports more vehicles and ECU types.

The paid version of the OBD II engine ECU diagnostics tool has more features, including horsepower, torque, 0-60, quarter-mile tests, graph data, map/track views, and no adverts. It also has better ABS/knock sensor support, transmission temperature support for some makes of car/trucks (GM/Ford, etc.), and turbo boost on many more vehicles (including VW). The tool works on vehicles made by Ford, GM/Vauxhall/Opel, Chrysler, Mercedes, Volkswagen, Audi, Jaguar, Citroen, Peugeot, Skoda, Kia, Mazda, Lexus, Daewoo, Renault, Mitsubishi, Nissan, Honda, Hyundai, BMW, Toyota, Seat, Dodge, Jeep, Pontiac, Subaru, and many more vehicle makes, European, US, Far East, etc. Some vehicle ECUs may support more/less features than others.

Please note that any reports of hanging or freezing after quitting the app are due to a bug in the HTC Evo 4G and Galaxy Tab, which can be triggered by using the Pandora/Vlingo/Aldiko Bluetooth enabled apps. Disabling Pandora's new Bluetooth settings fixes the problem, but HTC/Samsung need to release a fix. The pro version supports USB ELM adapters that use 'Prolific' or 'FTDI' chips. A freeze/hang workaround has been found and is available in the full version in the General Preferences settings.

Overall, the OBD II engine ECU diagnostics tool is a useful device that provides real-time information about your car's performance and helps keep car repair costs down. The paid version has more features and supports more vehicles and ECU types, making it a worthwhile investment for car enthusiasts and mechanics alike. However, users should be aware of the bug in the HTC Evo 4G and Galaxy Tab and take steps to avoid it.