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.
Checking output signals of IATS under detecting condition, if an ouput signal is intermittently over 4.9V, PCM sets P1111.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Monitor the signal of IAT sensor | ● Poor connection ● Open or short to battery in harness ● Open in ground harness ● Faulty IATS ● Faulty PCM |
Enable Conditions | ● Engine running state ● No Vehicle speed sensor fault ● No ECTS fault ● No MAFS fault ● Intake airflow < 15 g/s ● Vehicle speed < 25kph(9.3mph) ● Engine coolant temperature > 50℃(122℉) | |
Threshold value | ● Intermittently Intake air temperature sensor’s voltage > 4.9V | |
Diagnosis Time | ● Continuous | |
MIL On Condition | ● DTC only(NO MIL ON) |
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 |
