Things have gotten pretty complex. The old OBD1 started out without a scanner. Just jump the ALDL and count the service engine light flashes. I remember when we got our first OTC code reader. We thought it was hot stuff!
I was at the chrysler dealer as this efi was just spooling up, the diagnostic computer was the size of a toolbox, had to roll it up to cars, just like a scope. And detailed repairs on the sbec itself.
Back the i was thinking how great this was going to become. I have seriously lost interest in the computer controlled cars as of late. They are all diagnostic nightmares.