Read and clear fault codes (DTCs) from every electronic control unit (ECU) in the car, including the engine (DME), transmission (EGS), airbag, and ABS.
Monitor "live" values such as coolant temperature, mass air flow, fuel trim, and sensor voltages.
Perform "bidirectional" tests, such as manually turning on the radiator fan, fuel pump, or individual fuel injectors to verify they are working.
