P0112
DTC P0112 or P0113
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides 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
Typical Scan Tool Data
Circuit/System Description
The intake air temperature (IAT) sensor 1 and the humidity sensor are integrated within the humidity/intake air sensor body and share the same signal circuit. The IAT sensor 1 signal is displayed by the scan tool as Hertz (Hz) and °C (°F). The engine control module (ECM) supplies 5 V to the signal circuit. Ignition voltage and ground circuits are also supplied to the sensor.
The table below shows the relationship between temperature and the IAT Sensor 1 parameters.
Conditions for Running the DTCs
P0112 and P0113
* The engine run time is greater than 1 s.
* The DTCs run continuously when the above conditions are met.
Conditions for Setting the DTCs
P0112
The ECM detects that the IAT sensor 1 signal is warmer than 149°C (300°F) for greater than 5 s.
Note: The scan tool display range is between -40 and +150°C (-40 and +302°F).
P0113
The ECM detects that the IAT sensor 1 signal is colder than -60°C (-76°F) for greater than 5 s.
Action Taken When the DTCs Set
* DTCs P0112, and P0113 are Type B DTCs.
* The ECM commands the cooling fans ON.
Conditions for Clearing the DTCs
DTCs P0112, and P0113 are Type B DTCs.
Diagnostic Aids
* The following 2 functions of the (8 Pin) Multifunction Intake Air Sensor (IAT sensor 1) are used by the ECM:
- Intake Air Humidity
- Intake Air Temperature (IAT sensor 1)
* The (8 Pin) Multifunction Intake Air Sensor (IAT sensor 1) is placed in the air stream ahead of the (5 Pin) Mass Air Flow/Intake Air Temperature Sensor (IAT sensor 2). They are both mounted to the air cleaner cover.
* The Intake Air Humidity sensor and the IAT sensor 1 signals are sent to the ECM on the same circuit. If the Intake Air Humidity parameter displays the value: 0 %, and there are also IAT sensor 1 DTCs, check for a circuit problem.
* With the ignition ON, the engine OFF; if the engine is cold, a properly functioning IAT sensor 1 will gradually increase the scan tool IAT Sensor 1 parameter. This is due to the heat that is generated by the sensor heating element.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
* J-23738-A - Vacuum Pump
* For equivalent regional tools, refer to Special Tools Tools and Equipment.
Circuit/System Verification
Note:
* To minimize the effects of residual engine heat and sensor internal heating elements, perform Steps 1 and 2 of this verification procedure only if the ignition has been OFF for 8 hours or more.
* The vehicle sitting in direct sun light or having the block heater ON will skew the results.
1. Ignition ON.
2. Verify the following scan tool parameters are within 25°C (45°F) of each other.
* Start-Up IAT Sensor 1
* IAT Sensor 2
* Start-Up ECT
• If not within 25°C (45°F)
Refer to Circuit/System Testing.
• If within 25°C (45°F)
3. Engine idling.
4. Verify the following scan tool parameters are within the specified ranges.
* IAT Sensor 1; -39 to +145°C (-38 to +293°F)
* IAT Sensor 1; 45 to 302 Hz
* Intake Air Humidity; 5 to 95%
* IAT Sensor 2; -38 to +148°C (-36 to +298°F)
• If not within the specified ranges
Refer to Circuit System Testing.
• If within the specified ranges
5. Engine idling.
6. Verify the IAT Sensor 1 and IAT Sensor 2 Sensor parameters are between -38 and +149°C (-36 and +300°F).
• If not between -38 and +149°C (-36 and +300°F)
Refer to Circuit/System Testing.
• If Between -38 and +149°C (-36 and +300°F)
7. Operate the vehicle within the conditions for running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
8. Verify the DTCs do not set.
• If any of the DTCs set
Refer to Circuit/System Testing.
• If none of the DTCs set
9. All OK
Circuit/System Testing
Note:
* You must perform the Circuit/System Verification before proceeding with the Circuit/System Testing.
* You must perform the Diagnostic Repair Verification after completing the Circuit/System Testing.
1. Ignition OFF, disconnect the harness connector at the (8 Pin) B75C Multifunction Intake Air Sensor (IAT sensor 1).
2. Test for less than 2 ohms between the ground circuit terminal 7 and ground.
• If 2 ohms or greater
1. Ignition OFF, disconnect the appropriate engine ground connector.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open or high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 2 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between the ignition voltage circuit terminal 5 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp and remove the fuse for the ignition voltage circuit.
2. Test for less than 2 ohms in the ignition voltage circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the test lamp and remove the fuse for the ignition voltage circuit.
2. Test for infinite resistance between the ignition voltage circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, test all components connected to the ignition voltage circuit and replace as necessary.
• If the test lamp illuminates
5. Test for 4.8-5.2 V between the signal circuit terminal 8 and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the X3 harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.
• If greater than 5.2 V
Note: If the signal circuit is shorted to a voltage the engine control module or the sensor may be damaged.
1. Ignition OFF, disconnect the X3 harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 Engine Control Module.
• If between 4.8-5.2 V
6. Ignition OFF, connect the leads of the J 38522 - Variable Signal Generator as follows:
* Red lead to the signal circuit terminal 8 at the harness connector
* Black lead to ground
* Battery voltage supply lead to B+
7. Set the J 38522 - Variable Signal Generator to the following specifications.
* Signal switch to 5 V
* Duty Cycle switch to 50 % (Normal)
* Frequency switch to 30 Hz
8. Ignition ON, verify the scan tool IAT Sensor 1 parameter is between 28-32 Hz.
• If not between 28-32 Hz
Replace the K20 Engine Control Module.
• If between 28-32 Hz
9. Test or replace the (8 Pin) B75C Multifunction Intake Air Sensor (IAT sensor 1).
Component Testing
Mass Air Flow/Multifunction Intake Air Sensor (IAT Sensor 1)
* Test the IAT Sensor 1 by varying the sensor temperature while monitoring the air temperature with a thermometer. Compare the readings with the scan tool IAT Sensor 1 parameter. The values should be within 5%.
• If not within the specified range, replace the (8 Pin) B75C Multifunction Intake Air Sensor (IAT Sensor 1).
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (5 Pin) Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (5 Pin)Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (8 Pin) Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (8 Pin)
for (8 Pin) Multifunction Intake Air Sensor (IAT Sensor 1) replacement
* Perform the scan tool Diesel Particulate Filter (DPF) Regeneration Enable Diesel Particulate Filter (DPF) Regeneration Enable procedure if the scan tool DPF Soot Mass is less than 30 g. If the scan tool DPF Soot Mass is greater than 30 g, perform the Diesel Particulate Filter (DPF) Service Regeneration Diesel Particulate Filter (DPF) Service Regeneration.
* Control Module References Control Module References for Engine Control Module replacement, programming, and setup