Modern cars are basically rolling computer networks. When a check engine light...

https://johnathankvdj950.wpsuo.com/why-modern-repair-shops-can-no-longer-survive-on-basic-diagnostics

Modern cars are basically rolling computer networks. When a check engine light pops up, your basic code reader only gives you a surface-level hint. It can't talk to the dozens of ECUs running your transmission, brakes, or steering