The Intake Air Temperature Sensor (IATS) is installed into the Mass Air Flow Sensor (MAFS). The IATS uses a thermistor whose resistance changes with the temperature. The electrical resistance of the IATS decreases as the temperature increases, and increases as the temperature decreases. The 5 V power source in the ECM is supplied to the IATS via a resistor in the ECM. That is, the resistor in the ECM and the thermistor in the IATS are connected in series. When the resistance value of the thermistor in IATS changes according to the intake air temperature, the signal voltage also changes. Using this signal, the information of the intake air temperature, the ECM corrects basic fuel injection duration and ignition timing.
PCM monitors temperature difference betwen MAX. and MIN IATS in order to detect movement in IATS not only Start Test but Drive Test while enable condition is met. If PCM detects intake air temperature changes less than 3℃(5.4 °F) PCM determines that a fault exists and a DTC is stored. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 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. | ● Faulty IATS |
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 fault present ● IAT stored previous trip ● No IAT Tests pending | ||
Threshold value | ● Max IAT - Min IAT ≤ 3℃(5.4 °F) | ||
Diagnosis Time | ● Continuous (10 min.) | ||
MIL On Condition | ● 2 driving Cycles |
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 |
