The Intake Air Temperature (IAT) sensor is located in the fresh air duct to the throttle body. The Intake Air Temperature (IAT) sensor is a thermistor. The VCM uses the IAT to monitor the temperature of the air entering the throttle body. The VCM applies 5 volts to the sensor on the 5 volt reference circuit. When the air is cool, the resistance in the sensor will read high, and the VCM will sense a high voltage signal. If the air is warm, the sensor resistance will read low, and the VCM will sense a low voltage signal. The DTC P1111 is a type D DTC.

The following conditions will set the DTC:

The VCM stores the DTC in History if the VCM detects an intermittent problem.

The VCM turns OFF the MIL after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (the coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle) or the scan tool clearing feature has been used.

A scan tool indicates the temperature of the ambient air entering the throttle body. The air temperature should read very close to the temperature of the outside air. The air temperature should rise gradually as the engine warms up and the underhood temperature increases. If the DTC P1111 is set, the problem is intermittent. Check for poor connections at the VCM and IAT sensor by wiggling the connector gently and monitoring the IAT temperature or IAT voltage on the scan tool. If the voltage waivers, repair the connector that caused the waiver. Also, a sensor may become skewed or mis-scaled. The Temperature vs. Resistance Value Table will help to detect a skewed sensor. Refer to Temperature vs Resistance .