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 P0095 03: Intake Air Temperature (IAT) Sensor 2 Circuit Voltage Below Threshold
DTC P0095 07: Intake Air Temperature (IAT) Sensor 2 Circuit Voltage Above Threshold
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 | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
IAT Sensor Signal | P0095 03, P0097 | P0095 07, P0098 | P0095 07, P0098* | P0110
Low Reference | -- | P0095 07, P0098 | P0095 07, P0098* | P0110
* Internal ECM or sensor damage may occur if the circuit is shorted to B+

### Circuit Description

The intake air temperature (IAT) sensor 2 is an integral part of the turbocharger pressure sensor. The IAT sensor is a variable resistor that measures the temperature of the intake air. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit.

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

IAT | IAT Resistance | IAT Signal Voltage
--- | --- | ---
Cold | High | High
Warm | Low | Low

### Conditions for Running the DTC

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

• | The DTCs run continuously once the above conditions are met.

### Conditions for Setting the DTC

#### P0095 03, P0097

The ECM detects that the IAT sensor 2 is less than 160 mV for greater than 0.5 seconds.

#### P0095 07, P0098

The ECM detects that the IAT sensor 2 parameter is greater than 4.9 volts for greater than 0.5 seconds.

### Action Taken When the DTC Sets

DTCs P0095, P0097, and P0098 are Type B DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P0095, P0097, and P0098 are Type B DTCs.

### Diagnostic Aids

• | If the engine has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F).

• | High resistance on either the IAT sensor signal circuit or the IAT sensor low reference circuit could set a DTC.

### 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

1. Ignition On, observe the DTC information with a scan tool. DTCs P0095, P0097, or P0098 should not set.
2. 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. Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the turbocharger pressure sensor.
2. Test for less than 5 ohms of resistance between the low reference circuit terminal 4 and ground.

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

3. Install the MAIN fuse. Ignition ON, test for 4.8-5.2 volts between the IAT signal circuit terminal 3 and ground.

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

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. If all circuits test normal, test or replace the turbocharger pressure sensor.

### Component Testing

Measure and record the resistance between the IAT signal circuit terminal 3 and the low reference circuit terminal 4 at various ambient temperatures. Compare those measurements to the Temperature Versus Resistance table and verify that the resistance is within 5 percent of the specification.

⇒ | If not within the specified range, replace the turbocharger pressure sensor

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Turbocharger Pressure Sensor Replacement

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