Code 24, IAT Sensor Circuit, Open Or Shorted Circuit: Notes

Intake Air Temperature (IAT) sensor is a thermistor in series with a fixed resistor in ECM. IAT sensor measures temperature of air entering intake manifold. ECM applies 5 volts to IAT sensor. ECM monitors voltage across IAT sensor and converts it into temperature reading. When outside temperature is cold, IAT resistance is high.

When outside temperature is warm, IAT resistance is low. Therefore, when air temperature is cold, ECM will receive a high voltage input. When air temperature is warm, ECM will receive a low voltage input.

Code 24 will set if voltage input at ECM indicates either a very low or very high air temperature for at least .5 second.

1. Checks for open or short to ground in Yellow/Black wire between ECM and IAT sensor, and a faulty ECM.
2. Checks for open in Brown wire between ECM and IAT sensor, and a faulty ECM.
3. Determines if problem is a faulty IAT sensor or ECM.