Gone are the days when you could fix every car with a wrench and a test light....
https://charlie-wiki.win/index.php/Why_Does_My_Check_Engine_Light_Need_a_Professional_Scan_Tool_Now%3F
Gone are the days when you could fix every car with a wrench and a test light. Today’s vehicles are networks of interacting ECUs that control everything from your fuel trim to your door locks