The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) 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 ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT signal circuit.

P0112

P0113

P0112

The IAT sensor is more than 148°C (298°F)  for more than 5 seconds.

P0113

The IAT sensor is less than -39°C (-38°F)  for more than 5 seconds.

DTCs P0112 and P0113 are Type B DTCs.

DTCs P0112 and P0113 are Type B DTCs.

If the engine is cold, then at ignition ON a properly functioning IAT sensor will gradually increase the scan tool IAT Sensor parameter. This is due to the heat that is generated by the MAF sensor heating elements.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. Engine running, observe the scan tool IAT Sensor parameter. The reading should be between -39 to +120°C (-38 to +248°F) depending on the current ambient temperature and the vehicle operating conditions.

Important: 

•	Perform this verification procedure only when the ignition has been OFF for 8 hours or more.

•	The IAT will begin to warm up as soon as the ignition key is turned ON

2. Ignition ON, observe the scan tool IAT Sensor and ECT Sensor parameters. The readings should be within 15°C (27°F) of each other and also the ambient temperature.
3. Engine running, observe the DTC information with a scan tool. DTCs P0112 or P0113 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 sufficient time for the control module to power down. Test for less than 5 ohms of resistance between the low reference circuit terminal D and ground.

⇒	If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify the scan tool IAT Sensor parameter is less than -39°C (-38°F).

⇒	If greater than the specified value, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the ECM.

Important: If a short to voltage is found on the IAT signal circuit, the 3A fuse in the jumper wire will open.

4. Install a 3A fused jumper wire between the signal circuit terminal E and a ground. Verify the scan tool IAT Sensor parameter is greater than 149°C (300°F).

⇒	If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test the MAF/IAT sensor. Refer to Component Testing.

Measure the resistance of the IAT sensor and compare the IAT sensor resistance to the values listed in the Temperature vs. Resistance table. Refer to Temperature Versus Resistance .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.