Circuit Description

The intake air temperature (IAT) sensor 1 is a variable resistor. The IAT sensor 1 has a signal circuit and a low reference circuit. The IAT sensor 1 measures the temperature of the air entering the induction system. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an excessively low IAT signal voltage, indicating a high temperature, DTC P0112 sets.