Modern vehicles are rolling networks where dozens of ECUs constantly talk to...

https://www.pop-bookmarks.win/if-you-re-still-relying-on-a-basic-code-reader-you-re-only-seeing-half-the

Modern vehicles are rolling networks where dozens of ECUs constantly talk to each other. A basic OBD reader only scratches the surface by pulling generic codes, which leaves you guessing why a fault actually happened