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.
The purpose of this diagnosis is to detect a stuck intake air temperature signal. The diagnostic function checks whether after a variation of the calculated intake air temperature also a variation of the measured intake air temperature is detected.ECM sets DTC P0111 when the variation of measured intake air temperature from engine start is smaller than threshold while variation of calculated intake air temperature by ECM is greater than threshold.
Item | Detecting Condition | Possible Cause | |
DTC Strategy | case1) | ● Check intake air temperature signal stuck. | |
case2) | ● Difference between maximun and minimum air temperature | ||
Enable Conditions | ● Time after engine start > 400sec. ● Coolant temp. > 74℃(165.2℉) for more than 0.5sec. ● Coolant temp. increasing after start > 40℃(104℉) ● Accumulated time for vehicle speed > 70km/h(44mph) for more than 100sec. ● No relevant failure ● Battery Voltage >6V | ||
Threshold Value | case1) | ● Variation of Intake Air Temperature after starting <5.25℃ | |
case2) | ● Maximum intake air temp. - minimum intake air temp. < 1.5 at below 30℃(or 3 at below 60℃)) | ||
Diagnostic Time | ● 5 sec. | ||
Mil On Condition | ● 2 Driving Cycles | ||
Temp.(°C) | Temp.(°F) | Resistance(kΩ) | Temp.(°C) | Temp.(°F) | Resistance(kΩ) |
-10 | 14 | 8.5~9.7 | 20 | 68 | 2.3~2.5 |
0 | 32 | 5.4~6.1 | 30 | 86 | 1.6~1.7 |
10 | 50 | 3.5~3.9 | 80 | 176 | Approx. 0.3 |
