For 1990-2009 cars
Engine Controls Components
Fuel System
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The intake air temperature (IAT) sensor uses a thermistor to control the signal voltage to the Powertrain Control Module (PCM). The PCM supplies a 5 volt reference and a ground to the sensor. When the air is cold the resistance is high, therefore the IAT signal voltage will be high. If the intake air is warm, resistance is low, therefore the IAT signal voltage will be low.

### Conditions for Running the DTC

• | The engine run time is greater than 320 seconds.

• | The engine coolant temperature (ECT) is greater than -40°C.

• | The vehicle speed sensor indicates that vehicle speed is less than 24 km/h (15 mph).

### Conditions for Setting the DTC

The IAT sensor signal voltage indicates that the intake air temperature is less than -40°C for 3.125 seconds.

### Action Taken When the DTC Sets

• | The malfunction indicator lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with fault active.

• | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.

• | A history DTC is stored.

• | Coolant fan turns ON.

• | The PCM will default to 60°C (140°F) for intake air temperature. The scan tool will not the show the defaulted value.

### Conditions for Clearing the MIL/DTC

• | The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.

• | A history DTC will clear after 40 consecutive warm-up cycles without a fault.

• | The MIL/DTCs can be cleared by using the scan tool.

### Diagnostic Aids

• | If the vehicle is at ambient temperature compare the IAT sensor to the ECT sensor. The IAT sensor and the ECT sensor should be relatively close to each other.

• | Use the Temperature vs. Resistance Values table, refer to Temperature vs Resistance to evaluate the possibility of a skewed sensor.

### Test Description

The number(s) below refer(s) to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data for later reference.

2. This step simulates a DTC P0112. If the PCM senses the change, the PCM and wiring are OK.

3. This step will determine if the reason that the PCM did not sense the change was due to the following condition(s):

• | Open ground circuit

• | Short to voltage in the signal circuit

• | Malfunctioning PCM

4. Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Techline information for PCM programming and the Crankshaft Position System Variation Learn for the crankshaft position system variation learn procedure.

#### DTC P0113-Intake Air Temperature (IAT) Circuit-High Voltage

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn ON the ignition switch leaving the engine OFF.
2. Install a scan tool.

Is the IAT sensor value less than the specified value?

-30°C (-22°F)

Go to Step 4

Go to Step 3

3 |

1. Review the Freeze Frame data and record the parameters.
2. Start the engine.
3. Operate the vehicle within the Conditions for Running this DTC as specified in the supporting text.

Is the IAT sensor value less than the specified value?

-30°C (-22°F)

Go to Step 4

Go to Diagnostic Aids

4 |

1. Turn OFF the ignition switch.
2. Disconnect the IAT sensor electrical connector.
3. Connect a fused jumper wire between the following circuits at the IAT sensor electrical connector:

• | IAT sensor signal circuit terminal

• | IAT sensor ground circuit terminal

4. Turn ON the ignition switch leaving the engine OFF.

Is the IAT sensor value greater than the specified value?

130°C (266°F)

Go to Step 6

Go to Step 5

5 | Connect a fused jumper wire to the IAT sensor signal circuit terminal to a known good ground. Is the IAT sensor value greater than the specified value? | 130°C (266°F) | Go to Step 7 | Go to Step 8
6 |

1. Turn OFF the ignition switch.
2. Check for poor electrical connections at the IAT sensor electrical connector.
3. Repair the electrical connections as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 10

7 |

1. Turn OFF the ignition switch.
2. Check for an open in the IAT sensor ground.
3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 9

8 |

1. Turn OFF the ignition switch.
2. Check the IAT sensor signal circuit for the following conditions:

• | Open circuit

• | Short to voltage

3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 9

9 |

1. Check for the following conditions in the PCM electrical connector(s):

• | Poor IAT sensor ground circuit terminal connection

• | Poor IAT sensor signal circuit terminal connection

2. Repair the circuit terminal(s) as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 11

10 | Replace the IAT sensor. Refer to the Intake Air Temperature Sensor Replacement . Is the action complete? | -- | Go to Step 12 | --
11 | Replace the PCM. Refer to the Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 12 | --
12 |

1. Using the scan tool, clear the DTCs.
2. Start the engine.
3. Idle the engine at the normal operating temperature.
4. Operate the vehicle within the conditions for running this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has ran and passed?

--

Go to Step 13

Go to Step 2

13 | Check to see if any additional DTCs are set. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to applicable DTC table | System OK