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 P0114: Intake Air Temperature (IAT) Sensor Circuit Intermittent

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
IAT Sensor Signal | P0112 | P0113 | P0113 | P0114
Low Reference | -- | P0113 | P0113 | P0114

### Typical Scan Tool Data

#### IAT Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine operating in Closed Loop Parameter Normal Range: Varies with ambient temperature
IAT Sensor Signal | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F)*
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)*
* Internal ECM or sensor damage may occur if the circuit is shorted to B+.

### Circuit Description

The intake air temperature (IAT) sensor is an integral part of the mass air flow (MAF) sensor. The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The IAT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT 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 engine is running.

• | The DTC runs continuously once the above condition is met.

### Conditions for Setting the DTC

The ECM detects that the IAT sensor signal varies greater than 10°C (18°F) between each consecutive sample for greater than 20 seconds.

### Action Taken When the DTC Sets

DTC P0114 is a Type B DTC.

### Conditions for Clearing the MIL/DTC

DTC P0114 is a Type B 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. Engine idling, observe the diagnostic trouble code (DTC) information with a scan tool. DTCs P0112 or P0113 should not be set.

⇒ | If a DTC is set, refer to DTC P0112 or P0113 for further diagnosis.

2. Engine idling, observe the scan tool IAT Sensor parameter while moving the related wiring harness and harness connectors. The reading should not change abruptly.

⇒ | If the reading changes abruptly, repair the wiring harness or the harness connectors.

3. If all circuits test normal, test or replace the MAF/IAT sensor.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.

Note: A thermometer can be used to test the sensor off the vehicle.

2. Test the IAT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with 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 MAF/IAT sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Mass Airflow Sensor with Intake Air Temperature Sensor Replacement

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