The Input Air Temperature sensor (IAT) has the function of measuring the temperature of the air entering through the motor. It is important to know the value of the air temperature, taking into account that the greater the intake air, the higher the combustion temperatures will be. The high combustion temperatures are the result of increased nitrogen oxide emissions.
So that these high temperatures do not cause combustion temperatures, it is necessary that the intake air pipe is clean, since in this way the engine can in a certain sense breathe air that does not look like the engine compartment. The IAT sensor (Intake Air Temperature) uses a thermistor that has a reference signal of 5 volts from the Power Train Control Module (PCM) and also a ground.
Generally, when the air temperature is low, the resistance increases. And if, on the other hand, the air temperature is high, the resistance drops. This variation in resistance makes the 5 volt reference of the PCM (Powertrain Control Module) change and in this way, information is given to the PCM about the incoming air temperature. If the Powertrain Control Module (PCM) observes that the temperature of the incoming air is above the expected level, when it is possible that the engine temperature is low, the DTC code P0112 OBD2 is established.