Circuit Description
The Intake Air Temperature (IAT) sensor is a thermister that controls the 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 the air warms, the sensor resistance becomes less and the voltage drops. This is a type B DTC.
Conditions for Setting the DTC
| • | The engine coolant temperature is less than 42.5°C (109°F). |
| • | The intake air temperature is greater than or equal to 151°C (304°F). |
| • | The conditions were met for 2 seconds. |
Action Taken When the DTC Sets
A possible poor performance problem may exist during cold weather operation.
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 after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle). |
| • | Use of a Scan Tool will clear the DTC codes. |
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. Refer to Temperature vs Resistance .
Test Description
The 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.
-
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 malfunctioning PCM or the signal wire is shorted to ground. The normal resistance across the IAT sensor connector harness is 4000-5000 ohms.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the Scan Tool Capture Info in order to record the Freeze Frame and the failure records for reference, as the data will be lost when the 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? | -30°C (-22°F) | |||
Is the resistance at the specified value? | Infinite | |||
5 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs were stored, refer to those table(s). Are there 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 PCM. Important: If the PCM is malfunctioning, 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 | Use the Scan Tool in order to select Capture Info, Review Info. Are there any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC Table | System OK |
