Diagnostic Instructions

DTC Descriptors

DTC P0112: Intake Air Temperature (IAT) Sensor Circuit Low Voltage

DTC 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, P0112	P0113	--
Low Reference	--	P0113	P0113	--

Typical Scan Tool Data

IAT Sensor

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running Parameter Normal Range: Varies with ambient temperature
IAT Sensor Signal	150°C (302°F)	-40°C (-40°F)	-40°C (-40°F)*
Low Reference	--	-40°C (-40°F)	-40°C (-40°F)*
*Internal ECM or sensor damage may occur if the circuit is shorted to B+

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 engine control module (ECM) supplies 5V to the IAT signal circuit, and a ground for the IAT low reference circuit.

Conditions for Running the DTC

P0112

P0113

Conditions for Setting the DTC

P0112

The ECM detects that the IAT sensor parameter is warmer than 149°C (300°F) for greater than 5 seconds.

P0113

The ECM detects that the IAT sensor parameter is colder than -39°C (-38°F) for greater than 5 seconds.

Action Taken When the DTC Sets

DTCs P0112 and P0113 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P0112 and P0113 are Type B DTCs.

Diagnostic Aids

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition OFF for 8 hours or greater.
2. Ignition ON, observe the scan tool IAT and ECT sensor parameters. The ECT, IAT, and ambient temperatures should be within 15°C (27°F) of each other.
3. Engine running, observe the scan tool IAT Sensor parameter. The reading should be between -39 to +120°C (-38 to +248°F), depending on the current ambient temperature and the vehicle operating conditions.

Circuit/System Testing

Note: All modules must be powered down or misdiagnosis may result.

1. Ignition OFF, disconnect the scan tool and wait 60 seconds to ensure all modules are powered down.
2. Ignition OFF, disconnect the harness connector at the IAT sensor.
3. Ignition OFF for 90 seconds, test for less than 5 Ω between the low reference circuit terminal E and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

4. Ignition ON, verify the scan tool IAT parameter is colder than -39°C (-38°F).

⇒	If warmer than the specified range, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the signal circuit terminal D and a good ground. Verify the scan tool IAT parameter is warmer than 149°C (300°F).

⇒	If colder than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, test or replace the IAT sensor.

Component Testing

Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the Temperature Versus Resistance table.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.