Modern vehicles are basically computers on wheels. When a check engine light...

https://alpha-wiki.win/index.php/The_Professional_Workflow:_What_a_Real_Diagnostic_Session_Actually_Looks_Like

Modern vehicles are basically computers on wheels. When a check engine light pops on, a basic code reader only gives you a surface-level hint. You need diagnostic software to talk to every ECU and view live data streams in real time