Buick Regal: DTC P0097, P0098, or P0099

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 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

IAT Sensor 2

Typical Scan Tool Data

IAT Sensor 2

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 ºC (ºF).

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 ºC (ºF) 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

IAT Sensor 1 - Temperature, Resistance, Voltage Table

IAT Sensor 2 - Temperature, Frequency Table

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.
• Where P0099 is used, the DTC runs continuously within the enabling conditions.

Conditions for Setting the DTCs

P0097

NOTE: The scan tool display range is between -40 and +150ºC (-40 and +302ºF).

The ECM detects that the IAT sensor 2 signal is less than 13 Hz, colder than -60ºC (-76ºF), for greater than 5 s.

P0098

The ECM detects that the IAT sensor 2 signal is greater than 390 Hz, warmer than 150ºC (302ºF), for greater than 5 s.

P0099

Where P0099 used, 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 - North America and Korea.
• DTCs P0097, P0098, and P0099 are Type C DTCs - Except North America and Korea.
• The ECM commands the cooling fans ON.

Conditions for Clearing the MIL/DTC

• DTCs P0097, P0098, and P0099 are Type B DTCs - North America and Korea.
• DTCs P0097, P0098, and P0099 are Type C DTCs - Except North America and Korea.

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.
• 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; -40ºC (-40ºF), and there are also Humidity Sensor DTCs, check for a circuit problem.

Reference Information

Schematic Reference

Engine Controls Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Powertrain Component Views

Powertrain Component Views

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-38522-A Variable Signal Generator

For equivalent regional tools, refer to Special Tools (diagnostic tools) and Special Tools (Mechanical Tools).

Circuit/System Verification

1. Ignition ON.

2. Verify that DTC P0641, P0651, P0697, P06A3, or P06D2 is not set.

• If any of the DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

• Go to next step: If none of the DTCs are set

NOTE: To minimize the effects of residual engine heat and sensor internal heating elements, perform Steps 3 and 4 of this verification procedure only if the ignition has been OFF for 8 hours or more.

3. Ignition ON.

4. Verify the following scan tool parameters are within 30ºC (54ºF) of each other.

• Start-Up IAT Sensor 1
• IAT Sensor 2
• IAT Sensor 3; where equipped
• If not within 30ºC (54ºF)

Refer to Circuit/System Testing.

• Go to next step: If within 30ºC (54ºF)

5. Engine idling, verify the following scan tool parameters are between: between -38 and +149ºC (-36 and +300ºF).

• IAT Sensor 1
• IAT Sensor 2
• IAT Sensor 3; where equipped
• If not between: -38 and +149ºC (-36 and +300ºF)

Refer to Circuit/System Testing.

• Go to next step: If between: -38 and +149ºC (-36 and +300ºF)

6. 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.

7. Verify the DTC does not set.

• If the DTC sets

Refer to Circuit/System Testing.

• Go to next step: If the DTC does not set

8. All OK

Circuit/System Testing

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, and all vehicle systems OFF, it may take up to 2 min. for all vehicle systems to power down. Disconnect the harness connector at the B75C Multifunction Intake Air sensor.

2. Test for less than 2 Ω between the low reference circuit terminal 3 and ground.

• If 2 Ω or greater

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
   • If 2 Ω or greater, repair the open or high resistance in the circuit.
   • If less than 2 Ω replace the K20 Engine Control Module.

• Go to next step: If less than 2 Ω

3. Ignition OFF, all vehicle systems OFF, test for less than 2 Ω between the ground circuit terminal 7 and ground.

• If 2 Ω or greater

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 Ω in the ground circuit end to end.
   • If 2 Ω or greater, repair the open or high resistance in the circuit.
   • If less than 2 Ω, repair the open/high resistance in the ground connection.

• Go to next step: If less than 2 Ω

4. Ignition ON, verify that a test lamp illuminates between the ignition 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 Ω in the ignition voltage circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, 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 circuit, replace as necessary.

• Go to next step: If a test lamp illuminates

5. Ignition ON, test for 4.8 - 5.2 V between the intake air temperature sensor 2 signal circuit terminal 8 and ground.

• If less than 4.8 V

1. Ignition OFF, disconnect the 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.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, 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 harness connector at the K20 Engine Control Module.
2. Ignition ON, 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.

• Go to next step: If between 4.8 - 5.2 V

6. Determine if EL-38522-A Variable Signal Generator or equivalent is available.

• EL-38522-A, Variable Signal Generator; or equivalent is not available

1. Test or replace the B75C Multifunction Intake Air sensor.
2. 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.
3. Verify the DTC does not set.

• If the DTC sets

Replace the K20 Engine Control Module.

• Go to next step: If no DTCs set

4. All OK.

• Go to next step: EL-38522-A, Variable Signal Generator; or equivalent is available

7. Ignition OFF, connect the leads of the EL-38522-A Variable Signal Generator as follows:

• Red lead to the signal circuit terminal 8 at the harness connector
• Black leads to ground
• Battery voltage supply lead to B+

8. Set the EL-38522-A Variable Signal Generator to the following specifications.

• Signal switch to 5 V
• Duty Cycle switch to 50 % (Normal)
• Frequency switch to 30 Hz

9. Ignition ON, verify the scan tool IAT Sensor 2 parameter is between 28 - 32 Hz.

• If not between 28 - 32 Hz

Replace the K20 Engine Control Module.

• Go to next step: If between 28 - 32 Hz

10. Test or replace the B75C Multifunction Intake Air sensor.

Component Testing

Multifunction Intake Air Sensor

1. Test the IAT Sensor 2 by varying the sensor temperature while monitoring the air temperature with a thermometer. Compare the readings with the scan tool IAT Sensor 2 parameter. The values should be within 5%.

• If not within the specified range

Replace the B75C Multifunction Intake Air Sensor.

• Go to next step: If within the specified range

2. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Mass Airflow Sensor with Intake Air Temperature Sensor Replacement for multifunction intake air sensor replacement
• Control Module References for engine control module replacement, programming, and setup.

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