Maybe they see the system loading.

Right? My coal forge was such a pain to manage.

Totally agree with Leo on this. Modern engines are basically computers with moving parts, so ignoring the data feels like trying to fix a laptop by listening to the fan whir. You might get lucky, but you're working blind. My old boss swore by his ears until a simple scan saved us from replacing a whole transmission over a bad speed sensor. What's the weirdest thing a scan has caught for you guys?