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 (303°F). |
| • | Conditions 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 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. Refer to Temperature vs Resistance .
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.
-
This test will determine if the PCM can recognized an open sensor.
-
This step will determine if the problem is a short to ground or a malfunctioning 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? | -30°C (-22°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 any 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: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
9 |
Does the Scan Tool indicate that the diagnostic 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 |
