Modern cars are basically rolling computer networks. When a warning light pops...

https://www.red-bookmarks.win/basic-obd-readers-barely-scratch-the-surface-of-today-s-vehicles-modern-cars

Modern cars are basically rolling computer networks. When a warning light pops up, your basic code reader only gives you a surface-level hint. To actually fix the car, you need diagnostic software that talks to every ECU and tracks live data streams