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 | P0099, P2199
Low Reference | -- | P0098, P0099 | P0098, P0099 | P0098, P0099 | P0099, P2199

### Typical Scan Tool Data

#### IAT Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine Running Parameter Normal Range: Varies with ambient temperature
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: Varies with ambient temperature
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 5V to the IAT sensor signal circuit and a ground for the low reference circuit.

The intake air temperature (IAT) sensor 2 is integrated with the intake air pressure and temperature 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 5V to the IAT sensor 2 signal circuit and a ground for the low reference circuit.

The purpose of this diagnostic is to analyze the performance of the 2 sensors by comparing them to each other under various operating conditions to determine if they are within an acceptable temperature range of each other.

### 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 is greater than 30°C (54°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

• | When the engine is cold, at ignition ON, a properly functioning IAT sensor will gradually increase the scan tool IAT Sensor parameter. This is due to the heat that is generated by the MAF sensor heating elements.

• | 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 intake air pressure signal circuit can 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

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. If the ignition has been OFF for 8 hours or greater, the IAT sensor, the IAT sensor 2 and the engine coolant temperature (ECT) sensor should be within 9°C (16°F) of each other. Ignition ON, observe the scan tool IAT Sensor, IAT Sensor 2 and the ECT Sensor parameters. Compare those sensor parameters to each other to determine if the condition is current.
2. 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.
3. Engine running, observe the scan tool IAT Sensor 2 parameter. The reading should be between -39 to +130°C (-38 to +266°F) depending on the current ambient temperature and the vehicle operating conditions.
4. 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. Verify that the induction system components are properly positioned and connected.
2. Ignition OFF for 90 seconds, disconnect the harness connector at the B75B MAF/IAT sensor.
3. Test for less than 5 Ω between the MAF sensor ground circuit terminal B and ground.

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

4. Test for less than 5 Ω between the IAT low reference circuit terminal D 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 ECM.

5. Disconnect the harness connector at the intake air pressure and temperature sensor.
6. Test for less than 5 Ω between the low reference circuit terminal 1 or A 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 ECM.

7. Disconnect the X1 and X2 harness connectors at the K20 ECM.
8. Test for less than 5 Ω between the B75B MAF/IAT sensor signal circuit terminal E and the K20 ECM, terminal 50 X2.

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

9. Test for less than 5 Ω between the IAT sensor 2 signal circuit terminal 2 or B and the K20 ECM, terminal 86 X1.

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

10. If the circuits test normal, test both the B75B MAF/IAT sensor and the IAT sensor 2.

### Component Testing

Measure and record the resistance of the B75B MAF/IAT sensor and the IAT sensor 2 at various ambient temperatures, then compare those measurements to the 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