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

https://wiki-mixer.win/index.php/Reading_Codes_vs._Running_Tests:_Why_Your_Code_Reader_is_Lying_to_You

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