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 P2199: Intake Air Temperature (IAT) Sensor 1-2 Correlation

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
IAT Sensor Signal | P0112, P0114 | P0113, P0114 | P0113, P0114 | P0113, P0114 | P0114, P2199
Low Reference | -- | P0113, P0114 | P0113, P0114 | P0113, P0114 | P0114, P2199
IAT Sensor 2 Signal | P0097, P0099 | P0098, P0099 | P0098, P0099 | P0098, P0099 | P0096, P0099, P2199
Low Reference | -- | P0098, P0099 | P0098, P0099 | P0098, P0099 | P0096, P0099, P2199

### Typical Scan Tool Data

#### IAT Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine running Parameter Normal Range: -39 to +120°C (-38 to +248°F)
IAT Sensor Signal | 143°C (289°F) | -40°C (-40°F) | -40°C (-40°F)
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)

#### IAT Sensor 2

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine running Parameter Normal Range: -39 to +140°C (-38 to +284°F)
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 is integrated with the mass air flow (MAF) sensor. The IAT sensor is a variable resistor that measures the temperature of the air when it first enters the induction system. This sensor is also used to calculate ambient air temperature. The engine control module (ECM) supplies 5 volts to the IAT sensor signal circuit and supplies a ground to the low reference circuit.

• | The intake air temperature (IAT) sensor 2 is integrated with the boost pressure 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 5 volts to the IAT sensor 2 signal circuit and supplies a ground to the low reference circuit.

### Conditions for Running the DTC

• | The engine is running.

• | The MAF is between 9-50 g/s.

• | The vehicle speed is greater than 71 km/h (44 mph).

• | The boost pressure to barometric (BARO) pressure ratio is less than 1.4.

• | The above conditions must be met for greater than 20 seconds.

• | This DTC runs continuously within the enabling conditions.

### Conditions for Setting the DTC

The ECM detects that the difference in range between the IAT and the IAT sensor 2 either plus or minus is greater than 20°C (36°F) for greater than 4 seconds continuously or 50 seconds cumulative.

### Action Taken When the DTC Sets

DTC P2199 is a Type B DTC.

### Conditions for Clearing the MIL/DTC

DTC P2199 is a Type B DTC.

### Diagnostic Aids

• | Depending on the ambient temperature, an IAT sensor signal circuit that is shorted to the MAF sensor signal circuit can cause either a rapid fluctuation in the IAT Sensor parameter or cause it to become stuck at a given value.

• | An IAT low reference circuit that is open can cause the IAT Sensor parameter response to be sluggish.

• | An IAT sensor 2 signal circuit that is shorted to the boost pressure sensor signal circuit may cause the IAT Sensor 2 parameter response to be sluggish or become stuck at a given value.

### 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

| Important: Determine the ambient temperature by using an accurate thermometer.

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

• | Engine running, observe the scan tool IAT Sensor parameter. The reading should be between -39 to +120°C (-38 to +248°F) depending on the current ambient temperature and the vehicle operating conditions.

• | Engine running, observe the scan tool IAT Sensor 2 parameter. The reading should be between -39 to +140°C (-38 to +284°F) depending on the current ambient temperature and the vehicle operating conditions.

### Circuit/System Testing

1. Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
2. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the MAF sensor ground circuit and ground.

⇒ | If greater than the specified range, test the MAF sensor ground circuit for an open/high resistance.

3. Ignition OFF, test for less than 5 ohms of resistance between the IAT low reference circuit 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 OFF, disconnect the IAT sensor 2 harness connector at the boost pressure sensor.
5. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit 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.

6. Ignition OFF, disconnect the ECM.
7. Ignition OFF, test for less than 5 ohms of resistance on the IAT sensor signal circuit.

⇒ | If greater than the specified range, test the IAT sensor signal circuit for an open/high resistance.

8. Ignition OFF, test for less than 5 ohms of resistance on the IAT sensor 2 signal circuit.

⇒ | If greater than the specified range, test the IAT sensor 2 signal circuit for an open/high resistance.

9. If the circuits test normal, test both the IAT sensor and the IAT sensor 2.

### Component Testing

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Mass Airflow Sensor Replacement

• | Intake Air Pressure and Temperature Sensor Replacement

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