DTC P2199: Description

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

The DTC P2199 Intake Air Temperature (IAT) Sensor 1/2 Correlation diagnostic compares the IAT sensor 1 input with the IAT sensor 2 input. There are 2 IAT sensors on the 3.5L engine. IAT sensor 1 is located in the intake air duct and IAT sensor 2 is located in the intake manifold. The IAT sensor is a thermistor. A thermistor is a resistor whose value varies with temperature. The IAT sensors resistance is high when the coolant temperature is cold, and the IAT sensors resistance is low when the coolant temperature is warm. The IAT sensor is wired in series with a fixed resistor in the powertrain control module (PCM). The PCM applies 5 volts to the IAT sensor. The PCM monitors the voltage across the IAT sensor and converts the voltage into a temperature reading. The PCM expects the output of the 2 IAT sensors to follow the same linear path. If the 2 sensors report conflicting information to the PCM, a DTC P2199 can set.

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

DTC P2199

IAT	IAT Resistance	IAT Signal Voltage
Cold	High	High
Warm	Low	Low