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 PCM is supplied to the IATS via a resistor in the PCM. That is, the resistor in the PCM 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 PCM corrects basic fuel injection duration and ignition timing.
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
? Max IAT - Min IAT = 3°C
? Start Test Counter = 120
? Idle Test Counter = 120
MIL On Condition
? 2 driving Cycles
Temp. (°C/°F)
Resistance (k?)
-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