The Intake Air Temperature (IAT) sensor measures the temperature of engine intake air. The Intake Air Temperature (IAT) sensor is a thermistor (a variable resistor that changes along with outside air temperature) in series with a fixed resistor in the PCM. The PCM applies 5volts to the IAT sensor. The PCM monitors the voltage across the IAT sensor and converts it into a temperature reading. When the outside air temperature is cold the IAT sensor resistance is high, and when the outside air temperature is warm the IAT sensor resistance is low. Therefore, when the air temperature is cold the PCM will receive a high voltage input, and when the air temperature is warm the PCM will receive a low voltage input. The signal from IAT sensor is used for injection time correction (Cold post start correction), ignition angle correction(Air temperature correction) and idle speed correction(Air-density correction).
PCM monitors difference between MAX. and MIN IATS in order to detect movement in IATS therough Start Test and Drive Test while enable condition is met. If PCM detects intake air temperature does not change, PCM determines that a fault exists and a DTC is stored.
MIL(Malfunction Indicatin Lamp) turns on when the malfunction lasts till cosecutive 2 driving cycle.
Item | Detecting Condition | Possible cause | |
DTC Strategy | Case 1 | ● Start Test: Monitors the difference between max and min IAT in order to detect movement in IAT for a certain time. | ● Poor connection ● Open or short in harness ● IATS ● PCM |
Case 2 | ● Drive test: Performs the max and min delta check while driving under load for a length of time followed by an idle for a certain time. | ||
Enable Conditions | ● Engine soaked time > 360min ● Engine Running State ● No disabling fault present ● IAT stored previous trip ● No IAT Tests pending | ||
Threshold Value | Case 1 | ● Max IAT - Min IAT ≤ 3°C ● Start Test Counter ≥ 120 | |
Case 2 | ● Max IAT - Min IAT ≤ 3°C ● Idle Test Counter ≥ 120 | ||
MIL On Condition | ● No MIL ON (DTC only) |
Temp. (°C/°F) | Resistance (kΩ) | Temp. (°C/°F) | Resistance (kΩ) |
-40(-40) | 95.95 ~ 105.78 | 20(68) | 3.42 ~ 3.61 |
-20(-4) | 27.4 ~ 29.77 | 40(104) | 1.43 ~ 1.5 |
0(32) | 9.08 ~ 9.72 | 60(140) | 0.66 ~ 0.69 |
10(50) | 5.49 ~ 5.83 | 80(176) | 0.33 ~ 0.34 |
