Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
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
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. 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 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). |
| • | 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 MAF 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
| • | DTCs P0112 and P0113 are Type B DTCs. |
| • | DTCs P1111 and P1112 are Type C DTCs. |
Conditions for Clearing the DTC
| • | DTCs P0112 and P0113 are Type B DTCs. |
| • | DTCs P1111 and P1112 are Type C DTCs. |
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 Verification
If the ignition has been OFF for 8 hours or more, the IAT and the ECT, should be within 15°C (27°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 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), then 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, replace the control module. |
| ⇒ | If less than -36°C (-33°F), replace the MAF/IAT sensor. |
| ⇒ | If the IAT signal circuit tests normal, the replace the control module. |
P0113 or P1111
- Turn ON the ignition, with the engine OFF.
- Disconnect the 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 and a good ground.
Important: The sensor may be damaged if the circuit is shorted to a voltage source.
| ⇒ | If voltage is less than 4.9 volts, test the IAT sensor signal circuit for high resistance or an open circuit. |
| ⇒ | If 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 a high resistance or an open circuit. If the circuit tests normal, replace the control module. |
| ⇒ | If all circuits test OK, then replace the IAT sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
