P0098
DTC P0097, P0098, or P0099
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 P0097
- Intake Air Temperature (IAT) Sensor 2 Circuit Low Voltage
DTC P0098
- Intake Air Temperature (IAT) Sensor 2 Circuit High Voltage
DTC P0099
- Intake Air Temperature (IAT) Sensor 2 Circuit Intermittent
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The intake air temperature (IAT) sensor 1 is a variable resistor that measures the temperature of the air in the sensor bore. The engine control module (ECM) supplies 5 V to the IAT sensor 1 signal circuit and a ground for the IAT sensor 1 low reference circuit. The signal varies with inlet air temperature and is displayed by the scan tool as °C (°F).
The IAT sensor 2 produces a frequency signal based on the inlet air temperature very close to the humidity sensor within the sensor bore. The signal varies with inlet air temperature and is displayed by the scan tool as °C (°F) and Hertz (Hz). The ECM applies 5 V to the circuit. The signal circuit is shared by the IAT sensor 2 and the humidity sensor. Ignition voltage and ground circuits are also supplied to the multifunction intake air sensor's internal circuits for these sensors:
* IAT sensor 2
* Humidity sensor
* Mass Air Flow (MAF) sensor
The multifunction intake air sensor houses the following:
* IAT sensor 1
* IAT sensor 2
* Humidity sensor
* MAF sensor
* BARO pressure sensor
Conditions for Running the DTCs
P0097, P0098, and P0099
* The ignition is ON, or the engine is running.
* The Ignition 1 voltage is at least 11 V.
* The DTCs run continuously within the enabling conditions.
Conditions for Setting the DTCs
P0097
Note: The scan tool display range is between -40 and +150°C (-40 and +302°F).
The ECM detects that the IAT sensor 2 signal is less than13 Hz, colder than -60°C (-76°F), for greater than 5 s.
P0098
The ECM detects that the IAT sensor 2 signal is greater than 390 Hz, warmer than 150°C (302°F), for greater than 5 s.
P0099
The ECM detects that the IAT sensor 2 signal is intermittent or has abruptly changed for longer than 5 s.
Action Taken When the DTC Sets
* DTCs P0097, P0098, and P0099 are Type B DTCs.
* The ECM commands the cooling fans ON.
Conditions for Clearing the MIL/DTC
DTCs P0097, P0098, and P0099 are Type B DTCs.
Diagnostic Aids
* With the ignition ON, the engine OFF, if the engine is cold, a properly functioning IAT sensor 2 will gradually increase the scan tool IAT Sensor 2 parameter. This is due to the heat that is generated by the MAF sensor heating elements.
* Inspect the multifunction intake air sensor terminals for corrosion.
* The humidity sensor and the IAT sensor 2 signals are sent to the ECM on the same circuit. If the IAT Sensor 2 parameter displays the values: 10 Hz; -40°C (-40°F), and there are also Humidity Sensor DTCs, check for a circuit problem.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector Views
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 Control Module References for scan tool information
Special Tools
* J 38522 Variable Speed Generator
* For equivalent regional tools, refer to Special Tools (Diagnostic Tools) Tools and Equipment.
Circuit/System Verification
Note: Perform Step 1 of this verification procedure only if the ignition has been OFF for 8 hours or more.
1. Ignition ON, observe the following scan tool parameters. The readings should be within 25°C (45°F) of each other.
* Start-Up IAT Sensor 1
* IAT Sensor 2
* Start-Up ECT
2. Engine running, observe the scan tool IAT Sensor 1 and IAT Sensor 2 parameters. Depending on the current ambient temperature and the vehicle operating conditions, the readings should be between:
* -38 and +149°C (-36 and +300°F) for IAT sensor 1
* -38 and +149°C (-36 and +300°F) for IAT sensor 2
3. 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.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B75C multifunction intake air sensor.
2. Ignition OFF, all vehicle systems OFF, test for less than 5 ohm between the ground circuit terminal 7 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
• If the circuit tests normal and the fuse is open, test all the components connected to the circuit and repair or replace as necessary.
4. Ignition ON, test for 4.8-5.2 V between the IAT sensor 2 signal circuit terminal 8 and ground.
• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
Note: If the signal circuit is shorted to a voltage the ECM or the sensor may be damaged.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. Ignition OFF, connect the red lead of the J 38522 to the signal circuit terminal 8 at the harness connector. Connect the battery voltage supply to B+, and the black lead to ground.
6. Set the J 38522 to the following specifications.
* Signal switch to 5 V
* Duty Cycle switch to 50 % (Normal)
* Frequency switch to 30 Hz
7. Ignition ON, observe the scan tool IAT Sensor 2 parameter. The scan tool parameter should be between 28-32 Hz.
• If the parameter is not within the specified range, replace the K20 ECM.
8. If all circuits test normal, test or replace the B75C multifunction intake air sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement Service and Repair for multifunction intake air sensor replacement.
* Control Module References Control Module References for engine control module replacement, programming, and setup.