Circuit Description
The intake air temperature (IAT) sensor contains a semiconductor which changes the resistance based on the temperature. The IAT sensor mounts in the air intake passage of the engine air induction system. The IAT sensor has a signal circuit and a ground circuit. The PCM applies approximately 5 volts on the signal circuit to the sensor. The PCM monitors changes in this voltage caused by changes in the resistance of the sensor in order to determine the IAT.
When the intake air is cold, the sensor resistance is high, and the PCM's signal voltage is only pulled down a small amount through the sensor to ground. The PCM senses a high signal voltage, indicating a low temperature. When the intake air is warm, the sensor resistance is low, and the signal voltage is pulled down more. This causes the PCM to sense a low signal voltage, indicating a high temperature.
When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC sets.
Conditions for Running the DTC
| • | DTCs P0102, P0103, P0117, P0118, P0502, and P0503 are not set. |
| • | The engine run time is more than 100 seconds. |
| • | The engine coolant temperature (ECT) is more than 0°C (32°F). |
| • | The ECT is less than 153°C (275°F). |
| • | The vehicle speed is at least 40 km/h (25 mph). |
| • | The mass air flow (MAF) is less than 15 g/s. |
Conditions for Setting the DTC
| • | The IAT is less than -35°C (-31°F). |
| • | The intermittent condition exists for a total of 5.5 seconds during a 100-second period. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
Important:
• Remove any debris from the PCM connector surfaces before servicing
the PCM. When you diagnose or replace the PCM, inspect the PCM connector gaskets.
Ensure that the gaskets are installed correctly. The gaskets prevent
contaminate intrusion into the PCM. • For any test that requires probing the PCM or probing a component
harness connector, use the J 35616
connector test adapter kit. Using this kit prevents damage to
the harness or component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
If the engine has sat overnight, the engine coolant temperature and intake air temperature values should display within a few degrees of each other. If the temperatures are not within 3°C (5°F), refer to Temperature Versus Resistance .
For an intermittent condition, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If DTC P0113 also failed, a hard failure is present. When a hard failure is present, both the hard and the intermittent DTCs set.
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When moving related connectors, inspect the connectors for the following conditions:
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When moving the related wiring harnesses, inspect the wiring for the following:
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Using the Freeze Frame/Failure Records data help to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data can help to determine how many miles have occurred since the DTC set. The Fail Counter and the Pass Counter can also help to determine how many ignition cycles have occurred since the diagnostic reported a pass and/or a fail. In order to isolate when the DTC failed, operate the vehicle within the same Freeze Frame conditions that you observed. These conditions include:
| • | Poor mating of the connector halves, or a terminal that is not fully-seated in the connector body. |
| • | Improperly formed or damaged terminals--Carefully reform or replace all connector terminals in the related circuits in order to insure proper terminal contact tension. |
| • | Poor terminal to wire connection--Inspect for poor crimps, and for crimping that is over the wire insulation rather than over the wire. |
| • | Dirt or corrosion on the terminals--Inspect for missing connector seals and inspect for damage to the connector seals. |
| • | Wire insulation that is rubbed through, causing an intermittent short |
| • | Wiring broken inside the insulation |
| • | The RPM |
| • | The vehicle load |
| • | The vehicle speed |
| • | The temperature |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
Did DTC P0113 fail this ignition cycle? | Go to DTC P0113 | Go to Step 3 | |
Does the sensor value change abruptly while a related connector is being moved? | Go to Step 6 | Go to Step 4 | |
Observe the affected sensor value on a scan tool while moving the related wiring harnesses. Does the sensor value change abruptly while moving the related electrical harnesses? | Go to Step 7 | Go to Step 5 | |
Does the scan tool indicate that this diagnostic failed this ignition? | Go to Step 8 | Go to Diagnostic Aids | |
6 | Repair any damaged connectors or terminals. Refer to Connector Repairs in Wiring Systems. Is the action complete? | Go to Step 9 | -- |
7 | Repair the faulty wiring. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | Go to Step 9 | -- |
8 |
Is the action complete? | Go to Step 9 | -- |
9 |
Does the DTC run and pass? | Go to Step 10 | Go to Step 2 |
10 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |
