Circuit Description

WARNING: This page is about a different car, the 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

The mass air flow (MAF) and the intake air temperature (IAT) sensor 1 are an integrated sensor. The IAT sensor 1 is a variable resistor that measures the temperature of the air entering the induction system. The powertrain control module (PCM) supplies 5 volts to the IAT sensor 1 signal circuit and a ground for the IAT sensor 1 low reference circuit. When the sensor is cold, the resistance is greater. This results in a greater voltage on the signal circuit that is interpreted by the PCM as a colder IAT. As the sensor becomes warmer, the resistance decreases. This results in a lesser voltage on the IAT signal circuit that is interpreted by the PCM as a warmer IAT. If the PCM detects an IAT sensor 1 signal voltage that is not within a calibrated range of the IAT sensor 2 signal voltage, DTC P0111 sets.