Circuit Description
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The IAT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. If the ECM detects an excessively high IAT signal voltage, which is a low temperature indication, this DTC sets.
The following table illustrates the difference between temperature, resistance, and voltage:
IAT | IAT Resistance | IAT Signal Voltage |
|---|---|---|
Cold | High | High |
Warm | Low | Low |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage
Conditions for Running the DTC
| • | DTCs P0117, P0118, and P0502 are not set. |
| • | The engine run time is more than 120 seconds. |
| • | The engine coolant temperature is more than 70°C (158°F). |
| • | The calculated air flow into the engine is less than 15 g/s. |
| • | The vehicle speed is less than 25 km/h (16 mph). |
| • | The engine coolant temperature (ECT) is above between 70°C (158°F). |
| • | The calculated air flow is less than 15 g/s. |
| • | This DTC runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the IAT sensor parameter is less than -38°C (-36°F) for more than 4 seconds.
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
| • | Test the IAT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a driveability condition. |
| • | If the vehicle has set overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F). Refer to Temperature Versus Resistance . |
| • | A high resistance on either the IAT sensor signal circuit or the IAT sensor low reference circuit may not set a DTC. Refer to Circuit Testing in Wiring Systems. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |
2 |
Did the DTC fail this ignition? | 4 minutes | Go to Step 4 | Go to Step 3 |
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids |
4 |
Is the voltage more than the specified value? | 5.2 V | Go to Step 5 | Go to Step 6 |
5 |
Important: The sensor may be damaged if the circuit is shorted to a voltage source. Test the signal circuit of the IAT sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
6 |
Important: The DTCs must be cleared or a temperature of 20°C (68°F) will be displayed on the scan tool. Is the IAT sensor parameter above the specified value? | 149°C (300°F) | Go to Step 10 | Go to Step 7 |
7 |
Is the IAT sensor parameter above the specified value? | 149°C (300°F) | Go to Step 9 | Go to Step 8 |
8 | Test the IAT sensor signal circuit for an open circuit or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
9 | Test the IAT sensor low reference circuit for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
10 | Test the IAT sensor signal circuit for a short to any 5-volt reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 |
11 | Test for shorted terminals and for poor connections at the IAT sensor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 |
12 | Test for shorted terminals and for poor connections at the engine control module (ECM). 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 15 | Go to Step 14 |
13 | Replace the IAT sensor. Refer to Intake Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
14 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
15 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 16 |
16 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
