Modern cars are basically networks of rolling computers. When a dashboard light...

https://wiki-square.win/index.php/Demystifying_Manufacturer_Diagnostic_Protocols:_Why_Your_Shop_Needs_More_Than_an_OBD_Reader

Modern cars are basically networks of rolling computers. When a dashboard light pops on, a cheap code reader only shows you a vague surface fault. To actually fix the car, you need software that talks to every ECU and tracks live data streams