Circuit Description: Notes

The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit. The PCM monitors the mutual performance of the IAT and the engine coolant temperature (ECT) signals. The PCM monitors the warm up and cool down behavior of the sensors, after a vehicle driven at operating temperature is shut down. If the PCM detects that the IAT is not with in a predetermined range of ECT after a long soak, or the IAT and ECT are not within a range of each other, as compared to a previous cold start, this DTC sets.

The following table illustrates the difference between temperature, resistance, and voltage: