For 1990-2009 cars

### 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

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
IAT Sensor 2 Signal | P0097, P0099 | P0098, P0099 | P0098, P0099 | P0098, P0099 | P2199
Low Reference | -- | P0098, P0099 | P0098, P0099 | P0098, P0099 | P2199

### Typical Scan Tool Data

#### IAT Sensor 2

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine Running Parameter Normal Range: Varies with ambient temperature
IAT Sensor 2 Signal | 143°C (289°F) | -40°C (-40°F) | -40°C (-40°F)
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)

### Circuit/System Description

The intake air temperature (IAT) sensor 2 is integrated with the intake air pressure and temperature sensor. The IAT sensor 2 is a variable resistor that measures the temperature of the air after the turbocharger and the charge air cooler, and before it enters the engine intake manifold. The engine control module (ECM) supplies 5V to the IAT sensor 2 signal circuit and a ground for the low reference circuit.

### Conditions for Running the DTC

#### P0097

• | The ignition is ON or the engine is running.

• | This DTC runs continuously within the enabling conditions.

#### P0098

• | The engine is running.

• | This DTC runs continuously within the enabling conditions.

#### P0099

• | The ignition is ON or the engine is running.

• | This DTC runs continuously within the enabling conditions.

### Conditions for Setting the DTC

#### P0097

The ECM detects that the IAT sensor 2 is warmer than 140°C (284°F) for greater than 15 seconds at idle.

#### P0098

The ECM detects that the IAT sensor 2 is colder than -39°C (-38°F) for greater than 15 seconds at idle.

#### P0099

The ECM detects that the IAT sensor 2 signal is intermittent or has abruptly changed for greater than 4 seconds.

### Action Taken When the DTC Sets

DTCs P0097, P0098, P0099 are Type B DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P0097, P0098, P0099 are Type B DTCs.

### Diagnostic Aids

Depending on the output from the turbocharger, an IAT sensor 2 signal circuit that is shorted to the intake air pressure signal circuit may cause the IAT Sensor 2 parameter response to be erratic or become stuck at a given value.

### 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

• | If the ignition has been OFF for 8 hours or greater, the IAT sensor, the IAT sensor 2, and the engine coolant temperature (ECT) sensor should be within 9°C (16°F) of each other. Ignition ON, observe the scan tool IAT Sensor, IAT Sensor 2 and the ECT Sensor parameters. Compare those sensor parameters to each other to determine if the condition is current.

• | Engine running, observe the scan tool IAT Sensor 2 parameter. The reading should be between -39 to +130°C (-38 to +266°F) depending on the current ambient temperature and the vehicle operating conditions.

• | Operate the vehicle within the Conditions for Running the DTC to verify 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. Verify that debris is not blocking the airflow through the charge air cooler (CAC).
2. Ignition OFF for 90 seconds, disconnect the harness connector at the intake air pressure and temperature sensor.
3. Test for less than 5 Ω between the low reference circuit terminal 1 or A and ground.

⇒ | If greater than the specified range, 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 colder than -39°C (-38°F).

⇒ | If warmer than the specified range, test the signal circuit terminal 2 or B for a short to ground. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the signal circuit terminal 2 or B and ground. Verify the scan tool IAT Sensor 2 parameter is warmer than 142°C (288°F).

⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal replace the ECM.

6. If the circuits test normal, test or replace the intake air pressure and temperature sensor.

### Component Testing

Measure and record the resistance of the IAT sensor 2 at various ambient temperatures, then compare those measurements to the Temperature Versus Resistance.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Intake Air Pressure and Temperature Sensor Replacement

• | Control Module References for ECM replacement, setup, and programming