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 120 sec. under detecting condition, if an ouput signal is over 4.9V for more than 4 sec., PCM sets P1111.
Item
Detecting Condition
Possible Cause
DTC Strategy
? This code detects a continuous short to high in either the signal circuit or the sensor
? Poor Connection
? Open or short in signal circuit
? Open in ground circuit
? Faulty IATS
? Faulty PCM
Enable Conditions
Case 1
? No VSS Fault Active (No P0501)
? No Coolant Short Active Fault Present
? No MAF Active Fault Present
? Engine Air Flow < 15 g/s
? Vehicle Speed < 25kph
? Engine Coolant Temperature > 50°C( 122 °F)
? Engine Running Time > 120 sec.
Case 2
? Ignition off time > 360 min.
? Engine Coolant Temperature > -10°C( 14 °F)
? Engine Running
Threshold value
? IATS signal > 4.9V
Diagnosis Time
? Continuous
MIL On Condition
? DTC only (NO MIL ON)
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