The intake air temperature (IAT) sensor 2 is a variable resistor. The IAT sensor 2 measures the temperature of the air at the engine intake manifold. The engine control module (ECM) supplies 5 volts to the IAT sensor 2 signal circuit, and a ground for the IAT sensor 2 low reference circuit. When the IAT sensor 2 is cold, the sensor resistance is high. When the intake manifold air temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the IAT sensor 2 signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT sensor  2 signal circuit. The ECM monitors the IAT sensor 2 and the IAT sensor 1 signal voltages for a voltage that is not within a calibrated range of each other.

At start-up, after a 10 hour engine soak time, the IAT sensor 2 temperature is more than 15°C (27°F) higher or lower than the IAT sensor 1.

DTC P2199 is a type B DTC.

DTC P2199 is a type B DTC.

1. A slight to moderate resistance in either signal or low reference circuit, can widen the spread between the two IAT sensors, and cause this DTC to set.
2. An IAT sensor that is skewed lower at various ambient temperatures, due to more resistance than is normal, can widen the spread between the two sensors and cause this DTC to set. Measure and record the resistance of the IAT sensor 1 and IAT sensor 2 at various ambient temperatures, and then compare those measurements to the Temperature vs. Resistance Table. Refer to Temperature Versus Resistance .
3. Inspect IAT sensor 1 and sensor 2 terminals, for corrosion or a poor connection.
4. If the ignition has been OFF for more than 10 hours, then determine which IAT sensor is skewed by comparing ECT, IAT sensor 1, and IAT sensor 2 parameters with a scan tool.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Definition

Scan Tool Reference

Important: Perform this verification procedure only if the ignition has been OFF for 8 hours or more.

1. If DTCs P0112, P0113, P0097, or P0098 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
2. Ignition ON, observe the scan tool IAT Sensor, IAT Sensor 2, and ECT Sensor parameters. The readings should be within 8°C (15°F) of each other and also the ambient temperature.
3. Engine running, observe the DTC information with a scan tool. DTC P2199 should not set.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
2. Ignition OFF, allow at least 60 seconds for the ECM to power down.
3. Test for less than 5 ohms of resistance between the low reference circuit terminal 1 and ground.

⇒	If greater than the specified range, test the low reference circuit for high resistance. If the circuit tests normal, replace the ECM.

4. Ignition OFF, disconnect the harness connector at the intake air temperature (IAT) sensor 2.
5. Test for less than 5 ohms of resistance between the low reference circuit terminal B and ground.

⇒	If greater than the specified range, test the low reference circuit for high resistance. If the circuit tests normal, replace the ECM.

6. Ignition OFF, disconnect the harness connector at the ECM.
7. Test for less than 5 ohms of resistance between the IAT sensor 1 signal circuit terminal 2 and the corresponding ECM connector C1 terminal 42.

⇒	If greater than specified range, repair the high resistance on the signal circuit.

8. Test for less than 5 ohms of resistance between the IAT sensor 2 signal circuit terminal A and the corresponding ECM connector C1 terminal 65.

⇒	If greater than the specified range, repair the high resistance on the signal circuit.

9. If all circuits test normal, test the IAT sensor 1 and the IAT sensor 2. Refer to Component Testing.

1. Compare the resistance of the IAT sensor 2 sensor to the temperature vs resistance table.

⇒	If the difference is more than 9 percent, replace the IAT sensor 2.

2. Compare the resistance of the IAT sensor 1 to the temperature vs resistance.

⇒	If the difference is more than 9 percent, replace the MAF/IAT sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.