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

https://zaneznae304.lucialpiazzale.com/what-is-an-ecu-in-a-car-moving-beyond-guesswork-in-modern-repairs

Modern cars are basically rolling computer networks. When a warning light pops up, your basic code reader only gives you a surface-level glimpse. You need diagnostic software to talk directly to the individual ECUs and pull high-speed live data