Circuit Description
The intake air temperature (IAT) sensor is a thermistor which measures the temperature of the air entering the engine. The powertrain control module (PCM) applies 5 volts through a pull up resistor to the IAT sensor. When the intake air is cold, the sensor resistance is high and the PCM will monitor a high signal voltage on the IAT signal circuit. If the intake air is warm, the sensor resistance is lower causing the PCM to monitor a lower voltage. DTC P1111 will set when the PCM detects an intermittently high signal voltage on the intake air temperature sensor signal circuit.
Conditions for Running the DTC
| • | DTC's P0101, P0102, P0103, P0117, P0118, P0125, P0128, P0502, P0503, P1114 and P1115 are not set. |
| • | Vehicle speed is less than 56 km/h (35 mph). |
| • | Mass air flow is less than 12 g/s. |
| • | The engine coolant temperature (ECT) is more than 60°C (140°F). |
| • | Engine run time more than 3 minutes. |
Conditions for Setting the DTC
| • | IAT signal voltage indicates an intake air temperature intermittently less than -37°C (-35°F). |
| • | The conditions are present for up to 5 seconds. |
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 | With a scan tool, select diagnostic trouble codes (DTCs). Is DTC P0113 also set? | Go to DTC P0113 | Go to Step 3 |
3 | Is DTC P1106, P1115, and/or P1121 also set? | Go to Step 6 | Go to Step 4 |
4 | Inspect for a faulty low reference circuit connection at the IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 5 |
5 | Inspect for a faulty signal circuit connection at the IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 6 |
6 | Test the signal circuit of the IAT sensor for an intermittent open. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 7 |
7 | Test the signal circuit of the IAT sensor for an intermittent short to voltage. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
8 | Inspect for a faulty sensor low reference circuit connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
9 | Test the low reference circuit of the IAT sensor for an intermittent open or a faulty splice. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Intermittent Conditions |
10 |
Does the DTC set? | Go to Step 2 | System OK |
