DTC P0112 or P0113. GMC Truck Sierra

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra - 2WD 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC P0112 or P0113

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 provide an overview of each diagnostic category.

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 1 Signal	P0112	P0113	P0113	P0113
IAT Low Reference	--	--	--	--

Typical Scan Tool Data

IAT Sensor 1

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON or Engine Running Parameter Normal Range -39 to +120°C (-38 to +248°F)
IAT Sensor 1 Signal	149°C (300°F)	-40°C (-40°F)	-40°C (-40°F)*
IAT Low Reference	--	--	*
*Internal ECM or sensor damage may occur if the circuit is shared to B+

The intake air temperature (IAT) sensor 1 is a variable resistor. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) 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 ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT signal circuit.

Conditions for Running the DTC

•	The engine is running.

•	DTC P0112 and P0113 run continuously.

Conditions for Setting the DTC

P0112

The IAT Sensor parameter is warmer than 148°C (299°F) for greater than 1 second. This is equal to or less than 0.10 volt on the IAT signal circuit as measured by the ECM.

P0113

The IAT Sensor parameter is colder than -39°C (-38°F) for greater than 1 second. This is equal to greater than 4.8 volts on the IAT signal circuit as measured by the ECM.

Action Taken When the DTC Sets

•	DTC P0112 and P0113 are Type B DTCs.

•	Diesel particulate filter (DPF) regeneration is inhibited.

Conditions for Clearing the DTC

DTC P0112 and P0113 are Type B DTCs.

Diagnostic Aids

•	With the ignition ON and the engine OFF, if the engine is cold, a properly functioning IAT sensor will gradually increase the scan tool IAT Sensor parameter. This is due to the heat that is generated by the mass air flow (MAF) sensor heating elements.

•	Depending on the ambient temperature, an IAT sensor signal circuit or low reference circuit that is shorted to the MAF sensor signal circuit can cause a DTC P0113 to set. This condition can cause a rapid fluctuation in the IAT Sensor parameter.

•	An IAT low reference circuit that is open can cause the IAT Sensor parameter response to be sluggish. This condition may not necessarily set a DTC.

•	An IAT sensor signal circuit that is shorted to the MAF sensor ignition circuit can cause a DTC P0113 to set.

•	Verify that any electrical aftermarket devices are properly connected and grounded. Refer to Checking Aftermarket Accessories.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

•	Engine Controls Connector End Views

•	Engine Control Module Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

•	Scan Tool Data List

•	Scan Tool Data Definitions

Circuit/System Verification

Engine running, observe the scan tool IAT Sensor 1 parameter. The reading should be between -38 to +148°C (-36 to +298°F) depending on the current ambient temperature and the vehicle operating conditions.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Ignition OFF, disconnect the harness connector at the mass air flow MAF/IAT sensor.
Ignition OFF and scan tool disconnected for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal 4 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.

Ignition OFF and scan tool disconnected for 90 seconds, test for less than 5 ohms of resistance between the MAF sensor low reference circuit terminal 2 and ground.

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

Ignition ON, verify the scan tool IAT Sensor 1 parameter is less than -39°C (-38°F).

⇒	If warmer than the specified range, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the ECM.

Install a 3A fused jumper wire between the signal circuit terminal 5 and a ground. Verify the scan tool IAT Sensor 1 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.

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

Component Testing

Measure and record the resistance between the signal terminal 5 and the low reference circuit terminal 4 at the IAT sensor. Compare the value to the Temperature Vs Resistance table. Refer to Temperature Versus Resistance.

Repair Instructions

•	Mass Airflow Sensor/Intake Air Temperature Sensor Replacement

•	Control Module References for ECM replacement, setup, and programming

Repair Verification

Install any components or connectors that have been removed or replaced during diagnosis.
Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
Clear the DTCs.
Turn OFF the ignition for 90 seconds.
Duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.
Perform the Diesel Particulate Filter (DPF) Service Regeneration.