Circuit Description
The Intake Air Temperature (IAT) sensor is a thermister that controls signal voltage to the PCM. When the air is cold, the sensor resistance is high, therefore the PCM will see a high signal voltage. As air warms, sensor resistance becomes less and voltage drops. This is a type B DTC.
Conditions for Setting the DTC
| • | Engine coolant temperature less than 42.5°C (109°F). |
| • | Intake air temperature greater than or equal to 151°C (304°F). |
| • | Conditions met for 2 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails. |
| • | The PCM will record operating conditions at the time the diagnostic fails. The first time the diagnostic fails, this information will be stored in Failure Records. If the diagnostic reports a failure on the second drive trip, the operating conditions at the time of failure will be written to Freeze Frame and the Failure Record will be updated. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL off after three consecutive trips without a fault condition. |
| • | A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle. |
| • | Use of a Scan Tool |
Diagnostic Aids
Check harness routing for a potential short to ground in the signal circuit. Scan Tool displays intake air temperature in degrees centigrade. Refer to Intermittent Conditions . A skewed sensor could result in poor driveability complaints.
Test Description
Number(s) below refer to the Step number(s) on the Diagnostic Table.
-
This Step determines if P0112 is a hard failure or an intermittent condition.
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This test will determine if the PCM can recognized an open sensor.
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This step will determine if the problem is a short to ground or a faulty PCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing DTCs use the Scan Tool Capture Info to record freeze frame and failure records for reference, as data will be lost when Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Is the IAT display greater than or equal to the specified value? | 151°C (303°F) | |||
Does the IAT display a temperature colder than or equal to the specified value? | -40°C (-40°F) | |||
Is the resistance at the specified value? | Infinite | |||
5 | DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored, refer to those table(s). Are additional DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids |
6 | Repair the short to ground in the IAT signal circuit. Is the action complete? | -- | -- | |
7 | Replace the IAT sensor. Refer to Intake Air Temperature Sensor Replacement . Is the action complete? | -- | -- | |
8 | Replace the faulty PCM. Important: If the PCM is faulty, the new PCM must be programmed. Go to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
9 |
Does the Scan Tool indicate that this diagnostic Ran and Passed? | -- | ||
10 | Using the Scan Tool, select Capture Info, Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC Table | System OK |
