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P0112



DTC P0112

DTC DESCRIPTORS

DTC P0112
Intake Air Temperature (IAT) Sensor Circuit Low Voltage

DTC P0113
Intake Air Temperature (IAT) Sensor Circuit High Voltage

DIAGNOSTIC FAULT INFORMATION






IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

TYPICAL SCAN TOOL DATA

IAT Sensor:






CIRCUIT/SYSTEM DESCRIPTION
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.

CONDITIONS FOR RUNNING THE DTC
- The engine is running.
- DTC P0112 and P0113 run continuously.

CONDITIONS FOR SETTING THE DTC

P0112
The IAT Sensor parameter is more than 148°C (299°F) for more than one second. This is equal to less than 0.10 volt on the IAT signal circuit as measured by the ECM.

P0113
The IAT Sensor parameter is less than -39°C (-38°F) for more than one second. This is equal to more than 4.8 volts on the IAT signal circuit as measured by the ECM.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

CIRCUIT/SYSTEM VERIFICATION

IMPORTANT: If you cannot duplicate the condition, 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.

If the ignition has been OFF for eight hours or more, the IAT and engine coolant temperature (ECT), should be within 6°C (11°F) of each other and also the ambient temperature.

CIRCUIT/SYSTEM TESTING

P0112
With the ignition ON, the engine OFF, and the IAT sensor harness disconnected, observe the IAT Sensor parameter with a scan tool for a value of less than -39°C (-38°F).
- If the IAT Sensor parameter is less than -39°C (-38°F), replace the IAT sensor.
- If the IAT sensor parameter is more than -39°C (-38°F), test the IAT sensor signal circuit for a short to ground, low reference, or faulty ECM.

P0113
1. With the ignition ON, the engine OFF, and the IAT sensor harness disconnected, use a DMM and measure for a voltage range of 4.8-5.1 volts between the IAT signal circuit and a good ground.
- If the voltage is more than 5.1 volts, test the IAT signal circuit for a short to voltage.
- If the voltage is less than 4.8 volts, test the IAT signal circuit for an open, high resistance, or a faulty ECM.
2. Measure the voltage between the IAT low reference circuit and the IAT signal circuit.
- If the voltage is less than 4.8 volts, test the IAT low reference circuit for an open, high resistance, or a faulty ECM.
3. With the ignition ON, the engine OFF, and the IAT sensor harness disconnected, observe the scan tool IAT temperature parameter for a value of less than -39°C (-38°F).
4. With a 3-amp fused jumper wire connected between the signal and low reference circuits, observe the scan tool IAT temperature parameter for a value of more than 148°C (299°F).
- If the temperature is more than 148°C (299°F), test the IAT signal circuit for a short to a 5-volt reference circuit.
5. If the IAT sensor circuits test normal, replace the IAT sensor.

COMPONENT TESTING
Compare the IAT sensor resistance to the values listed in the Temperature vs. Resistance table. Refer to Temperature vs Resistance (ECT Sensor) Temperature vs Resistance (IAT Sensor) Temperature vs Resistance (IAT 2 Sensor) Temperature vs Resistance (Fuel Temperature).
- If the resistance is not within the range listed in the Temperature vs. Resistance table, replace the IAT sensor.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement
- Powertrain Control Module Programming and Setup for ECM replacement, setup, and programming
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