Cummins ISB4.5 CM2150 Fault Code: 693 PID: 351 SPN: 1172 FMI: 2 Turbocharger 1 Compressor Intake Temperature – Data Erratic, Intermittent, or Incorrect.

Circuit Description
The turbocharger compressor intake temperature sensor is a variable resistor sensor and is used to measure the temperature of the air entering the compressor intake of the turbocharger. The engine control module (ECM) supplies 5 volts to the compressor intake temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the air temperature.

Component Location
Some engines use a combination ambient air temperature/pressure sensor located in the OEM intake air plumbing rather than a turbocharger compressor intake temperature sensor. Refer to the engine wiring diagram to determine which sensor this application uses.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes
The ECM detects that the compressor intake temperature reading is too high or too low for the engine operating conditions.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails. A default value for the compressor intake temperature reading is used.

Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Possible Causes
-Stuck in-range compressor intake temperature sensor
-High resistance in the compressor intake temperature sensor signal or return lines.