GM Service Manual Online
For 1990-2009 cars only

Circuit Description

This diagnostic monitors the signal of the intake air temperature (IAT) sensor. The IAT sensor is a variable resistor that measures the temperature of the intake air. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit. When the engine is stopped and enough time has passed, the temperature of the engine will equal the ambient air temperature. If the temperature of IAT sensor 2 is outside of the expected range after comparing the temperature readings of each sensor, this DTC sets.

The following table illustrates the difference between temperature, resistance, and voltage:

IAT

IAT Sensor Resistance

IAT Sensor Signal Voltage

Cold

High

High

Warm

Low

Low

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0096 Intake Air Temperature (IAT) Sensor 2 Performance

Conditions for Running the DTC

    • DTC P0097. P0098, P0112, P0113, P0116, P0117, P0118, and P0125 are not set.
    • The engine has been OFF for more than 6 consecutive hours.
    • The engine is started and idled for at least 10 seconds.
    • DTC P0096 runs once per drive cycle when the above conditions are met.

Conditions for Setting the DTC

The difference in temperature between the intake air temperature (IAT) sensor 2 and the engine coolant temperature (ECT) sensor is more than 26°C (79°F).

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

    • Use the Temperature vs Resistance table in order to test the IAT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in a driveability concern. If the engine has sat overnight, the engine coolant temperature and the intake air temperature values should display within a few degrees. If the temperatures are not within 3°C (5°F) of each other, refer to Temperature Versus Resistance - Intake Air Temperature Sensor .
    • An intermittent malfunction may be caused by a fault in the IAT sensor electrical circuit. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

  2. This step checks for a faulty IAT sensor.

  3. This step checks the integrity of the IAT sensor input circuit (5-volt reference).

  4. This step checks the integrity of the IAT sensor ground circuit.

Step

Action

Value(s)

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition, leaving the engine OFF.
  2. Install a scan tool.
  3. Let the engine cool to the ambient air temperature.
  4. Compare the intake air temperature (IAT) sensor 2 value with the ambient air temperature.

Is the IAT within the specified value of the ambient air temperature?

0°C-5°C (0°F-9°F)

Go to Step 3

Go to Step 4

3

Important: Observe the IAT sensor scan tool display continuously while performing the tests below.

  1. Disconnect the IAT sensor 2 electrical connector.
  2. Remove the IAT sensor 2 from the air cleaner assembly.
  3. Connect the IAT sensor electrical connector to the IAT sensor 2.
  4. Wrap a cool damp shop towel around the IAT sensor in order to lower the temperature while monitoring the IAT sensor parameter on the scan tool.
  5. Remove the cool shop towel and place a warm damp shop towel around the IAT sensor while monitoring the IAT sensor parameter on the scan tool.

Did the scan tool indicate a skip, jump, or a fixed value in the IAT sensor 2 display?

--

Go to Step 9

Go to Diagnostic Aids

4

  1. Disconnect the IAT sensor 2 electrical connector.
  2. Jumper the harness side of the IAT sensor 2 electrical connector with a fused jumper wire.

Does the IAT sensor 2 equal the specified value?

168°C (334°F)

Go to Step 9

Go to Step 5

5

  1. Remove the fused jumper wire.
  2. Disconnect the powertrain control module (PCM) electrical connector.
  3. Measure the resistance of the IAT sensor 2 input circuit from the sensor to the PCM with a DMM.

Is the resistance less than the specified value?

0.5 ohms

Go to Step 6

Go to Step 7

6

Measure the resistance of the IAT sensor 2 ground circuit from the sensor to the PCM with a DMM.

Is the resistance less than the specified value?

0.5 ohms

Go to Step 10

Go to Step 8

7

Repair the short to ground or high resistance in the IAT sensor input circuit between the PCM and the IAT sensor 2. Refer to Wiring Repairs .

Is the action complete?

--

Go to Step 11

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8

Repair the open circuit or high resistance in the IAT sensor 2 ground circuit between the PCM and the IAT sensor. Refer to Wiring Repairs .

Is the action complete?

--

Go to Step 11

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9

Replace the IAT sensor 2. Refer to Intake Air Temperature Sensor 2 Replacement .

Did you complete the replacement?

--

Go to Step 11

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10

  1. Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
  2. Perform the idle learn procedure. Refer to Idle Learn .

Did you complete the replacement?

--

Go to Step 11

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11

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or until the DTC P0096 diagnostic test has run.

Does the DTC run and pass?

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Go to Step 12

Go to Step 2

12

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

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Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK