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 operating.

• | 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

• | Engine Control Module Connector End Views

• | Engine Controls 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

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

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. DTCs P0095, P0097, or P0098 should not set.

### 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/connections test normal, replace the engine control module (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/connections test normal, replace the ECM.

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

4. If all circuits/connections 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