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 Descriptor

DTC P0111 00: Intake Air Temperature (IAT) Sensor Performance
DTC P0112 00: Intake Air Temperature (IAT) Sensor Circuit Low Voltage
DTC P0113 00: Intake Air Temperature (IAT) Sensor Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to voltage | Signal Performance
--- | --- | --- | --- | --- | ---
IAT Sensor Signal | P0112 00, P0114 00 | P0113 00, P0114 00 | P0113 00, P0114 00 | P0113 00, P0114 00 | P0111 00, P0114 00
Low Reference | -- | P0113 00, P0114 00 | P0113 00, P0114 00 | P0113 00, P0114 00 | P0111 00, P0114 00

### Typical Scan Tool Data

#### IAT Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: The ignition is ON, or the engine is running Parameter Normal Range: Varies with ambient temperature
IAT Sensor Signal | 129°C (264°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 is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 V to the IAT signal circuit, and a ground for the IAT low reference circuit.

### Conditions for Running the DTC

#### P0111 00

• | DTCs P0501 00, P0116 00, P0117 00, P0118 00, P0119 00, P0112 00, P0113 00, P0114 00, P0107 00 or P0108 00 are not set

• | The engine run time is greater than 10 min.

#### P0112 00 and P0113 00

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

• | The battery voltage is greater than 9 V.

### Conditions for Setting the DTC

#### P0111 00

The ECM detects that the IAT deviates less than 1.5°C (35°F) since engine start.

#### P0112 00

The ECM detects that the IAT sensor voltage is less than 0.15 V for greater than 0.1 s.

#### P0113 00

The ECM detects that the IAT sensor voltage is more than 4.85 V for greater than 0.1 s.

### Action Taken When the DTC Sets

DTCs P0111 00, P0112 00 and P0113 00 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0111 00, P0112 00 and P0113 00 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Air Intake System Description

#### 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

### Circuit/System Verification

1. Engine running, observe the scan tool Intake Air Temperature parameter. The reading should be between -38 to +149°C (-38 to +300°F) depending on the current ambient temperature and the vehicle operating conditions.
2. 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 data.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B66 Intake Air Temperature (IAT) Sensor.
2. Ignition OFF for 90 s, test for less than 5 Ω between the low reference circuit terminal B 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 K20 Engine Control Module (ECM).

3. Ignition ON, verify the scan tool IAT is colder than -39°C (-38°F).

⇒ | If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Install a 3 A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool IAT Sensor is greater than 149°C (300°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 K20 Engine Control Module (ECM).

5. If all circuits test normal, test or replace the B66 Intake Air Temperature (IAT) Sensor.

### Component Testing

#### Static Test

Measure and record the resistance of the B66 Intake Air Temperature (IAT) Sensor at various ambient temperatures, then compare those measurements to the Temperature Versus Resistance table.

### Repair Instructions

Perform the Diagnostic Repair Verification

• | Intake Air Temperature Sensor Replacement

• | Engine Control Module Replacement