DTC Descriptors
DTC P0112: Intake Air Temperature (IAT) Sensor Circuit Low VoltageDTC 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.
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
IAT Sensor Signal | P0112 | P0113 | P0113 | P0113 | -- |
Low Reference | -- | P0113 | P0113 | P0113 | -- |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
IAT Sensor Signal | -39 to +120°C (-38 to +248°F) | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -- | -40°C (-40°F) | -40°C (-40°F) |
Circuit/System Description
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit.
Conditions for Running the DTC
P0112
| • | DTCs P0116, P0117, P0118, P0125, P0128, P0502, P0503 are not set. |
| • | The engine is running for more than 10 seconds. |
| • | The vehicle speed sensor (VSS) indicates a vehicle speed of more than 0 km/h (0 mph). |
| • | The engine coolant temperature (ECT) is less than 150°C (302°F). |
| • | This DTC runs continuously within the enabling conditions. |
P0113
| • | DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0125, P0128, P0502, P0503 are not set. |
| • | The engine is running for more than 10 seconds. |
| • | The VSS indicates a vehicle speed of more than 0 km/h (0 mph). |
| • | The ECT is more than 50°C (122°F). |
| • | This DTC runs continuously within the enabling conditions. |
Conditions for Setting the DTC
P0112
The ECM detects that the IAT is more than 149°C (300°F) for more than 5 seconds.
P0113
The ECM detects that the IAT is less than -39°C (-38°F) for more than 5 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. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
If the ignition has been OFF for 8 hours or more, the IAT and the ECT, should be within 6°C (11°F) of each other and also the ambient temperature. Turn ON the ignition, with the engine OFF, and use a scan tool to observe the IAT and ECT parameters.
Circuit/System Testing
P0112
- Turn ON the ignition, with the engine OFF.
- Disconnect the IAT sensor.
- Observe the IAT Sensor parameter with a scan tool.
| ⇒ | If the IAT Sensor parameter is less than -39°C (-38°F), then replace the IAT sensor. |
| ⇒ | If the IAT Sensor parameter is more than 149°C (300°F), then test the IAT sensor signal circuit for a short to ground. |
| ⇒ | If the IAT sensor signal circuit tests normal, replace the ECM. |
P0113
- Turn ON the ignition, with the engine OFF.
- Disconnect the IAT sensor.
- Measure for the proper range of 4.9-5.2 volts between the IAT sensor signal circuit and a good ground with a DMM.
- Turn OFF the ignition, and all electrical accessories. Allow sufficient time for all of the control modules to power down before taking a resistance measurement.
- Measure for a proper value of less than 5 ohms of resistance between the IAT low reference circuit and a good ground.
- Turn ON the ignition, with the engine OFF.
- Observe the IAT Sensor parameter while connecting and disconnecting a 3-amp fused jumper wire between the IAT sensor signal and low reference circuits. This should cause the IAT Sensor parameter to toggle between the upper and lower temperature limits.
| ⇒ | If the voltage is less than 4.9 volts, test the IAT sensor signal circuit for a high resistance or an open circuit. |
| ⇒ | If the voltage is more than 5.2 volts, test the IAT sensor signal circuit for a short to voltage. |
| ⇒ | If the IAT sensor signal circuit tests normal, replace the ECM. |
| ⇒ | If the resistance is more than 5 ohms, test the low reference circuit for a high resistance, or an open circuit. If the circuit tests normal, replace the ECM. |
| ⇒ | If the IAT Sensor parameter does not toggle, replace the ECM. |
| ⇒ | If the IAT Sensor parameter does toggle, then test the IAT sensor signal circuit for a short to another 5-volt reference circuit. |
| ⇒ | If the IAT sensor signal circuit is not shorted to another 5-volt reference circuit, then replace the IAT sensor. |
Component Testing
Measure and record the resistance of the IAT sensor at various ambient temperatures, and then compare those measurements to the Temperature vs Resistance Table. Refer to Temperature Versus Resistance .
Repair Instructions
Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
