Circuit Description
The intake air temperature (IAT) sensor is a thermistor which controls the signal voltage to the powertrain control module (PCM). The PCM supplies a 5 volt reference and a ground to the sensor. When the air is cold, the resistance will be high. Whenever the intake air is warm, the resistance will be low.
Conditions for Running the DTC
| • | No active ECT DTCs |
| • | No active VSS DTCs |
| • | The engine run time is more than 320 seconds. |
| • | The vehicle speed sensor indicates that vehicle speed is more than 15 mph (24 km/h). |
Conditions for Setting the DTC
The IAT sensor signal voltage indicates that the intake air temperature is more than 128°C (262°F) for 3.125 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles. |
| • | The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tools Freeze Frame and Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
| • | When the vehicle is at ambient temperature, compare the IAT sensor to the ECT sensor. The IAT sensor and the ECT sensor should be relatively close to each other. |
| • | Use the temperature vs resistance values table to evaluate the possibility of a skewed sensor. Refer to Temperature Versus Resistance . |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This step simulates a DTC P0113 condition. If the scan tool displays the specified value, the IAT signal circuit and the PCM are OK.
-
The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Does the IAT sensor value read more than the specified value? | 128°C (262°F) | ||
3 | Operate the vehicle within the Freeze Frame conditions and Conditions for Setting the DTC as specified in the supporting text. Does the IAT sensor value more than the specified value? | 128°C (262°F) | Go to Diagnostic Aids | |
Does the IAT sensor value read below the specified value? | -30°C (-22°F) | |||
5 |
Did you find and correct the condition? | -- | ||
6 |
Does the test lamp illuminate? | -- | ||
7 |
Does the test lamp illuminate? | -- | ||
8 | Repair the short to ground in the IAT sensor signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
9 |
Did you find and correct the condition? | -- | ||
10 | Replace the IAT sensor. Refer to Intake Air Temperature Sensor Replacement . Did you complete the replacement? | -- | -- | |
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||
12 |
Does the DTC reset? | -- | System OK |
