Circuit Description
The intake air temperature (IAT) sensor is a thermistor which measures the temperature of the air entering the engine. The powertrain control module (PCM) applies 5 volts through a pull up resistor. When the intake air is cold, the sensor resistance is high and the PCM will monitor a high signal voltage on the IAT sensor signal circuit. As the intake air warm, the sensor resistance becomes lower causing the PCM to monitor a lower voltage. If the PCM detects an excessively high IAT sensor signal voltage, which indicates a low temperature, indicated), DTC P0113 will set.
Conditions for Running The DTC
| • | DTCs P0101, P0102, P0103, P0117, P0118, P0125, P0128, P0501, P0502, P1114, or P1115 are not set. |
| • | The engine has been running for more than 3 minutes. |
| • | The vehicle speed is less than 8 km/h (5 mph). |
| • | The mass air flow (MAF) is less than 8 grams per second. |
| • | The engine coolant temperature (ECT) is more than 60°C (140°F). |
Conditions for Setting the DTC
| • | The IAT signal voltage indicates an intake air temperature less than -38°C (-36°F). |
| • | The above conditions are present for at least 20 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | 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 emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions .
If a short to a separate 5-volt source occurs this DTC may set. If this is found to be a problem, a continuity test to all other PCM circuits will be necessary to diagnose the specific circuit.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step verifies that the fault is present.
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If DTC P0113 can be repeated only by duplicating the Failure Records conditions, use the Temperature vs. Resistance table in order to test the IAT sensor at various temperatures in order to evaluate the possibility of a shifted sensor that may be open above or below a certain temperature. If this is the case, replace the IAT sensor. Refer to IAT sensor replacement. If the IAT sensor appears OK, the fault is intermittent.
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Use a fused jumper during this test. If the IAT signal circuit is shorted to battery or ignition positive voltage the fuse in the jumper will open, indicating a short in the signal circuit.
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The new PCM must be programmed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Does the parameter measure less than the specified value? | 37°C (34°F) | Go to Step 4 | Go to Step 3 | |
Does the DTC reset? | -- | Go to Step 4 | Go to Diagnostic Aids | |
4 |
Does the parameter measure more than the specified value? | 135°C (275°F) | Go to Step 6 | Go to Step 5 |
Does the parameter measure more than the specified value? | 135°C (275°F) | Go to Step 7 | Go to Step 8 | |
6 | Test the signal circuit of the IAT sensor for a short to voltage. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find, and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
7 | Test the low reference circuit of the IAT sensor for high resistance or an open. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find, and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Test the signal circuit of the IAT sensor for an open. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find, and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
9 | Inspect for faulty IAT sensor low reference or signal circuit connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a problem is found, repair as necessary. Refer to Connector Repairs in Wiring Systems. Did you find, and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 | Inspect for faulty connections at the IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a problem is found, repair as necessary. Refer to Connector Repairs in Wiring Systems. Did you find, and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
11 | Replace the IAT sensor. Refer to Intake Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | |
13 |
Does the DTC run, and pass? | -- | Go to Sep 14 | Go to Step 2 |
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
