DTC Descriptors
DTC P0112: Intake Air Temperature (IAT) Sensor Circuit Low VoltageDTC P0113: Intake Air Temperature (IAT) Sensor Circuit High Voltage
DTC P1111: Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage
DTC P1112: Intake Air Temperature (IAT) Sensor Circuit Intermittent 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°C to +120°C (-38°F 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. 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. If the control module detects an excessively low IAT signal voltage, indicating a high temperature, DTC P0112 sets. If the control module detects an excessively high IAT signal voltage, indicating a low temperature, DTC P0113 sets. If the control module detects an intermittent high IAT signal voltage, indicating a low temperature, DTC P1111 sets. If the control module detects an intermittent low IAT signal voltage, indicating a high temperature, DTC P1112 sets.
Conditions for Running the DTC
P0112
| • | DTCs P0116, P0117, P0118, P0125, P0128, P0502, P0503 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 121°C (250°F). |
| • | The diagnostic runs continuously when the above conditions are met. |
P0113
| • | DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0125, P0128, P0502, P0503 are not set. |
| • | The engine run time is more than 180 seconds. |
| • | The vehicle speed sensor (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 engine coolant temperature (ECT) is more than 60°C (140°F). |
| • | The diagnostic runs continuously when the above conditions are met. |
P1111
| • | DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0125, P0128, P0502, P0503 are not set. |
| • | The engine run time is more than 180 seconds. |
| • | The ECT sensor parameter is more than 60°C (140°F). |
| • | The vehicle speed is less than 24 km/h (15 mph). |
| • | The mass air flow is less than 10 g/s. |
| • | The diagnostic runs continuously when the above conditions are met. |
P1112
| • | DTCs P0116, P0117, P0118, P0125, P0128, P0502, P0503 are not set. |
| • | The engine run time is more than 10 seconds. |
| • | The ECT sensor parameter is less than 121°C (250°F). |
| • | The VSS indicates that vehicle speed is more than 40 km/h (25 mph). |
| • | The diagnostic runs continuously when the above conditions are met. |
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.
P1111
The control module detects that the IAT sensor parameter is less than -36°C (-33°F) intermittently for more than 100 seconds.
P1112
The control module detects that the IAT sensor parameter is more than 130°C (266°F) intermittently for more than 16 seconds.
Action Taken When the DTC Sets
P0112 and P0113
| • | 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. |
P1112 and P1111
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The MIL will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
P0112 or P0113
| • | The control module turns OFF the 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. |
DTC P1112 or P1111
| • | 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 non-emission related diagnostic. |
| • | Clear 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 Versus Resistance .
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Circuit/System Testing
Always perform the Diagnostic System Check - Vehicle .
P0112 or P1112
- Turn ON the ignition, with the engine OFF.
- Disconnect the MAF/IAT sensor. Observe the IAT sensor with a scan tool for -36°C (-33°F).
| • | If more than -36°C (-33°F), 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. If all circuits test normal, then replace the control module. |
| • | If less than -36°C (-33°F), replace the MAF/IAT sensor. |
| • | If IAT signal circuit tests normal, then replace the control module. |
Important: The sensor may be damaged if the circuit is shorted to a voltage source.
P0113 or P1111
- Turn ON the ignition, with the engine OFF.
- Disconnect the MAF/IAT sensor.
- Measure for 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 less than 5 ohms of resistance between the IAT low reference circuit and a good ground.
| ⇒ | If the voltage is less than 4.9 volts, test the IAT sensor signal circuit for 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, or any 5-volt reference. |
| ⇒ | If the IAT sensor signal circuit tests normal, and the voltage is still not within the proper range, then replace the control module. |
| ⇒ | If the resistance is more than 5 ohms, test the low reference circuit for high resistance or an open circuit. If the circuit tests normal, replace the control module. |
| ⇒ | If all circuits test normal, then replace the IAT sensor. |
Repair Instructions
Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Repair Verification
