There are events stored in the ECM memory that are not DTCs, but will cause one if the occur too frequently, for example misfires. Also, some components depend on codes set by others... For example, when my LPFP and fuel control module failed all I got was a communication code (not DTC and won't light a CEL) about bad information from the fuel pumps to the ECM, and a low fuel rail pressure code from the sensor on the HPFP. Point is there may be indications that don't set DTCs. Even at that the FCM failure wasn't diagnosed until it died during the test drive for the LPFP. My MyCal saw these so surely Torque, etc will.
