The intake air temperature (IAT) sensor is a variable resistor, sometimes called a thermistor. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT signal circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance lowers. With high sensor resistance, the ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT signal circuit. If the ECM detects an excessively high IAT signal voltage, indicating a low temperature, DTC P0113 sets.
This diagnostic procedure supports the following DTC:
DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage
• | The ignition is ON. |
• | The battery voltage is between 10-16 volts. |
The ECM detects that the IAT signal voltage is more than 4.95 volts.
• | The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
• | The ECM uses an IAT value of -29°C (-20.2°F) for the engine starting. |
• | The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records. |
• | The ECM uses an IAT value of 25°C (77°F) for engine running. |
• | The ECM closes the exhaust gas recirculation (EGR) valve and holds it in the closed position. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | Clear the MIL and the DTC with a scan tool. |
Important: The MAF sensor is heated and as a result the IAT sensor may indicate a higher than normal intake air temperature.
• | When the vehicle is at ambient temperature, the IAT sensor and engine coolant temperature (ECT) sensor temperature should be relatively close to each other. |
• | Use the Temperature vs. Resistance table to test the IAT sensor at various temperature levels to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability concerns. Refer to Temperature Versus Resistance . |
• | If an intermittent condition is suspected, refer to Intermittent Conditions . |
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No | ||||
---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||
3 |
Is the DMM voltage more than the specified value? | 4.5 V | Go to Step 4 | Go to Step 5 | ||||
4 |
Important: The IAT sensor may be damaged if the circuit is shorted to a voltage source.
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||
Is the IAT Sensor parameter more than the specified value? | 118°C (244°F) | Go to Step 9 | Go to Step 6 | |||||
6 |
Is the IAT Sensor parameter more than the specified value? | 118°C (244°F) | Go to Step 8 | Go to Step 7 | ||||
7 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||
8 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||
9 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||
10 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||
11 | Replace the IAT sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||
12 |
Important: The new ECM must be programmed. Replace the ECM. Refer to Engine Control Module Programming and Setup , Engine Control Module Replacement/Restore Fuel Rate Data , and Fuel Injector Flow Rate Programming . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 | ||||
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |