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
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
IAT Sensor Signal | P0112 | P0113 | P0113 | -- |
Low Reference | -- | P0113 | P0113 | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: Varies with ambient temperature. | |||
IAT Sensor Signal | 130°C (266°F), | 20°C (68°F) | 20°C (68°F) |
Low Reference | -- | 20°C (68°F) | -- |
Circuit Description
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The IAT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit.
The following table illustrates the difference between temperature, resistance, and voltage:
IAT | IAT Resistance | IAT Signal Voltage |
|---|---|---|
Cold | High | High |
Warm | Low | Low |
Conditions for Running the DTC
P0112
| • | DTC P0502 is not set. |
| • | The engine run time is more than 120 seconds. |
| • | The vehicle speed is greater than 50 km/h (31 mph). |
| • | This DTC runs continuously once the above conditions are met. |
P0113
| • | DTCs P0117, P0118, and P0502 are not set. |
| • | The engine run time is more than 120 seconds. |
| • | The engine coolant temperature is more than 70°C (158°F). |
| • | The calculated air flow is less than 15 g/s. |
| • | The vehicle speed is less than 25 km/h (16 mph). |
| • | This DTC runs continuously once the above conditions are met. |
Conditions for Setting the DTC
P0112
The ECM detects that the IAT sensor is more than 149°C (300°F) for more than 20 seconds.
P0113
The ECM detects that the IAT sensor parameter is less than -38°C (-36°F) for more than 120 seconds.
Action Taken When the DTC Sets
DTC P0112 and P0113 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTC P0112 and P0113 are Type B DTCs.
Diagnostic Aids
| • | If the vehicle has set overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F). |
| • | High resistance on either the IAT sensor signal circuit or the IAT sensor low reference circuit may not set a DTC. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
With the engine idling for 4 minutes, observe the DTC information with a scan tool. DTC P0112 or P0113 should not set.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector of the intake air temperature (IAT) sensor.
- Ignition ON, verify that the IAT sensor parameter is at -40°C (-40°F).
- Test for less than 0.5 volt between the low reference circuit of the IAT sensor and the negative terminal of the battery.
- Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the IAT sensor and the negative terminal of the battery.
- Install a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the IAT sensor and verify the IAT sensor parameter is greater than 128°C (262°F).
- If all circuits/connections test normal, test or replace the IAT sensor.
Important: The DTCs must be cleared or a temperature of 20°C (68°F) will be displayed on the scan tool.
| ⇒ | If greater than -40°C (-40°F), test the signal circuit of the IAT sensor for a short to ground. If the circuit/connections test normal, replace the engine control module (ECM). |
| ⇒ | If greater than 0.5 volt, test the low reference circuit of the IAT sensor for a short to voltage. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If greater than 5 ohms, test the low reference circuit of the IAT sensor for an open/high resistance. If the circuit/connections test normal, replace the ECM. |
Important: The DTCs must be cleared or a temperature of 20°C (68°F) will be displayed on the scan tool.
| ⇒ | If less than 128°C (262°F), test the signal circuit of the IAT sensor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM. |
Component Testing
- Ignition OFF, disconnect the harness connector of the intake air temperature (IAT) sensor.
- Test the IAT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance table and verify that the resistance is within 5 percent of the specification.
Important: A thermometer can be used to test the sensor off the vehicle.
| ⇒ | If the resistance vs. temperature is not within 5 percent, replace the IAT sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
