a diesel engine has a control system that processes certain data to develop data values for one or more temperature - dependent variables , such as injection control pressure , that affect engine starting and ensuing warm - up . the control system also processes data for detecting a temperature differential in the engine indicative of a block heater having been used to heat the engine prior to cranking . upon detection of such temperature differential , the control system selects a temperature data source from multiple available temperature data sources , namely engine coolant temperature ect , engine oil temperature eot , and charge air temperature ait , and processes temperature data from the selected source with additional data to develop data values for one or more of the temperature - dependent variables .