Circuit Description
The intake-air temperature (IAT) sensor contains a semi-conductor device, which is called a thermistor. This device changes the resistance which is based on temperature. The IAT sensor is part of the sensor assembly which is called the mass airflow/intake air temperature (MAF/IAT). The IAT sensor has a signal circuit and a ground circuit. The powertrain control module (PCM) applies a voltage, about 5-volts, on the signal circuit to the sensor. The PCM monitors changes in this voltage which is caused by changes in the resistance of the sensor in order to determine the IAT.
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, or P0503 are not set. |
| • | The engine operates for more than 30 seconds. |
| • | The vehicle speed is more than 40 km/h (25 mph). |
Conditions for Setting the DTC
| • | The engine coolant temperature (ECT) is less than 135°C (275°F). |
| • | The IAT is more than 139°C (282°F). |
| • | The intermittent condition exists for a total of 5.5 second during a 100 second time 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:
• Before you service the PCM or the throttle actuator control (TAC)
module, remove any debris from the module connector surfaces. Inspect the
module connector gaskets if you diagnose or replace the
modules. Verify that the gaskets are correctly installed. The gaskets
prevent debris from contaminating the PCM module or the TAC module. • For any test that requires probing the PCM or probing
a component harness connector, use the connector test adapter kit
J 35616
. Using
this kit prevents damage to the harness and component terminals.
Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | If the engine remained OFF for approximately 8 hours, the ECT and the IAT values should display within a few degrees of each other. If the temperatures are not within 3°C (5°F) of each other, refer to Temperature Versus Resistance table. |
| • | For an intermittent, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
If DTC P0112 failed this ignition, a hard failure is present. When a hard failure is present, both the hard and intermittent DTCs set.
-
When you move the related connectors, inspect the connectors for the following conditions:
-
When you move the related wiring harnesses, inspect the wiring for the following conditions:
-
Use the Freeze Frame/Failure Records in order to locate an intermittent condition. This information may help determine how many miles occurred since the DTC set. The Fail Counter and the Pass Counter may help determine the number of ignition cycles that the diagnostic test reported a pass or a fail. In order to isolate under what conditions the DTC failed, operate the vehicle within the same Freeze Frame conditions that you observed. Check the data regarding the following conditions:
| • | Faulty 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 the connector terminals in the related circuits in order to ensure proper terminal contact tension. |
| • | Faulty terminal to wire connection--Inspect for faulty crimps, or for crimping over wire insulation rather than over the wire. |
| • | Dirty, corroded, or damaged terminals. |
| • | Wire insulation that is rubbed through, causing an intermittent short |
| • | Wiring that is 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 P0112 also set? | Go to DTC P0112 | Go to Step 3 | |||||||||
Does the sensor value change abruptly while you move a related connector? | 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 you move 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 the damaged connectors and terminals. Refer to Repairing Connector Terminals in Wiring Systems. Did you complete the action? | Go to Step 9 | -- | ||||||||
7 | Repair the faulty wiring. Refer to Wiring Repairs in Wiring Systems. Did you complete the action? | Go to Step 9 | -- | ||||||||
8 |
Did you complete the action? | Go to Step 9 | -- | ||||||||
9 |
Does the DTC run, and then 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 | |||||||||
