GM Service Manual Online
For 1990-2009 cars only

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

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

IAT Sensor 2 Signal

P0097

P0098

P0098

P0098

IAT Sensor 2 Low Reference

--

P0098

P0098

P0098

Typical Scan Tool Data

IAT Sensor 2

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Ignition ON or Engine Running

Parameter Normal Range: -39 to +190°C (-38 to +374°F)

IAT Sensor 2 Signal

200°C (392°F)

-40°C (-40°F)

-40°C (-40°F)

IAT Sensor 2 Low Reference

--

-40°C (-40°F)

-40°C (-40°F)

Circuit/System Description

The intake air temperature (IAT) sensor 2 is a variable resistor. The IAT sensor 2 measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT signal 2 circuit, and a ground for the IAT sensor 2 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

P0097

    • DTC P0098 is not set.
    • The battery voltage is between 10-16 volts.
    • The ignition is ON for longer than 2 seconds.

P0098

    • DTCs P0097, P0112, and P0113 are not set.
    • The battery voltage is between 10-16 volts.
    • The ignition switch is ON for longer than 2 seconds.

Conditions for Setting the DTC

P0097

The ECM detects that the IAT sensor 2 signal voltage is less than 0.1 volt.

P0098

The ECM detects that the IAT sensor 2 signal voltage is more than 4.9 volts.

Action Taken When the DTC Sets

DTCs P0097 and P0098 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P0097 and P0098 are Type A DTCs.

Diagnostic Aids

Inspect for any recent engine mechanical repairs. An incorrectly installed IAT sensor 2 will cause this DTC to set.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component 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

Control Module References for scan tool information

Circuit/System Verification

Verify the integrity of the IAT sensor by inspecting for the following conditions:

    • Damaged components
    • Loose or improper installation

Circuit/System Testing

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

  1. Ignition OFF, disconnect the harness connector at the IAT sensor 2.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal 1 and ground.
  3. If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Ignition ON, verify the scan tool IAT Sensor 2 parameter is less than -39°C (-38°F).
  5. If greater than the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the ECM.
  6. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool IAT Sensor 2 parameter is greater than 190°C (374°F).
  7. If less than the specified range, test the signal circuit and low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  8. If all circuits test normal, replace the IAT sensor 2.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the IAT sensor 2.
  2. Measure the resistance between the signal terminal 2 and the low reference circuit terminal 1 at the sensor. Compare the value to the Temperature Vs Resistance table. Verify the resistance is within 5 percent of the specification. Refer to Temperature Versus Resistance.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Mass Airflow Sensor/Intake Air Temperature Sensor Replacement
    •  Control Module References for ECM replacement, setup, and programming