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 PCM. IAT sensor measures temperature of air entering intake manifold. PCM applies 5 volts to IAT sensor. PCM 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, PCM will receive a high voltage input. When air temperature is warm, PCM will receive a low voltage input.

Code 24 will set if voltage input at PCM 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 PCM and IAT sensor, and a faulty PCM.
2. Checks for open in Brown wire between PCM and IAT sensor, and a faulty PCM.
3. Determines if problem is a faulty IAT sensor or PCM.