P0112

DTC P0112

DTC DESCRIPTOR

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. Testing and Inspection






TYPICAL SCAN TOOL DATA

IAT Sensor Temperature:

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 control module 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 control module detects a high voltage on the IAT signal circuit. With lower sensor resistance, the control module detects a lower voltage on the IAT signal circuit.

CONDITIONS FOR RUNNING THE DTC

P0112
- DTCs P0116, P0117, P0118, P0502 (if applicable),P0503 (if applicable), P0608, P0609 are not set.
- The engine run time is more than 10 seconds.
- The vehicle speed sensor (VSS) indicates that vehicle speed is more than 40 km/h (25 mph).
- The engine coolant temperature (ECT) is less than 123°C (253°F).
- This diagnostic runs continuously when the above conditions are met.

P0112
- DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0502 (if applicable),P0503 (if applicable), P0608, P0609 are not set.
- The engine run time is more than 180 seconds.
- The VSS indicates that vehicle speed is less than 24 km/h (15 mph).
- The mass air flow (MAF) is less than 10 g/s.
- The ECT is more than 60°C (140°F).

CONDITIONS FOR SETTING THE DTC

P0112
The control module detects that the IAT sensor parameter is more than 130°C (266°F) for more than 18 seconds.

P0113
The control module detects that the IAT sensor parameter is less than -36°C (-33°F) for more than 110 seconds.

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.

DIAGNOSTIC AIDS
When the vehicle is at ambient temperature, the IAT sensor and the ECT sensor should be relatively close to each other. Refer to Temperature vs Resistance - Intake Air Temperature (IAT) Sensor.

CIRCUIT/SYSTEM TESTING
Always perform the Diagnostic System Check - Vehicle. Testing and Inspection

P0112
1. Observe the IAT sensor with a scan tool for 130°C (266°F).
2. Disconnect the MAF/IAT sensor. Observe the IAT sensor with a scan tool for -36°C (-33°F).
- If more than the specified temperature, test the signal circuit of the IAT sensor for a short to ground or a short to the IAT low reference circuit and repair as necessary. Test for an intermittent and for a poor connection at the control module. If all circuits test OK, replace the control module.
- If less than the specified temperature, test for an intermittent and for a poor connection at the IAT sensor. If the circuit tests OK, replace the MAF/IAT sensor.

P0113
1. Turn ON the ignition, with the engine OFF. Disconnect the MAF/IAT sensor. Connect a DMM between the signal circuit of the IAT sensor and a good ground. Measure for 5.2 volts.
- If more than 5.2 volts, test the signal circuit for a short to voltage.

IMPORTANT: The sensor may be damaged if the circuit is shorted to a voltage source.

2. Connect a 3-amp fused jumper wire between the signal circuit of the IAT sensor and the low reference circuit of the IAT sensor. Observe the IAT sensor parameter with a scan tool for 130°C (266°F).
- If more than 130°C (266°F), test the IAT signal circuit for a short to any 5-Volt reference circuit, or for an intermittent and for a poor connection at the IAT sensor. If the circuits test OK, replace the MAF/IAT sensor.
3. Connect a 3-amp fused jumper wire between the signal circuit of the IAT sensor and a good ground. Observe the IAT sensor parameter with a scan tool for 130°C (266°F).
- If more than 130°C (266°F), test the IAT sensor low reference circuit for high resistance or for an open. Test for an intermittent and for a poor connection at the control module. If the circuits test OK, replace the control module.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement
- Control Module References Verification Tests

REPAIR VERIFICATION
Diagnostic Repair Verification