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.
Checking output signals of IATS every 20 sec. under detecting condition, if an ouput signal is below 0.1V for more than 10 sec., PCM sets P1112.
Item
Detecting Condition
Possible Cause
DTC Strategy
? This code detects a continuous short to ground in either the signal circuit or the sensor
? Poor Connection
? Short to ground in signal circuit.
? Faulty IATS
? Faulty PCM
Enable Conditions
Case 1
? Engine Run State
? No VSS Fault Active
? Vehicle Speed > 50kph(31mph)
? IAT Short Low Enable Criteria Met
Case 2
? Engine Running Time > 120sec.
? IG "OFF" time > 360min.
Threshold value
? IATS signal < 0.1V
Diagnosis Time
? Continuous (More than 10 sec. failure for every 20 sec. test)
MIL On Condition
? DTC only
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