The Intake Air Temperature (IAT) sensor measures the temperature of engine intake air. The Intake Air Temperature (IAT) sensor is a thermistor (a variable resistor that changes along with outside air temperature) in series with a fixed resistor in the ECM. The ECM applies 5volts to the IAT sensor. The ECM monitors the voltage across the IAT sensor and converts it into a temperature reading. When the outside air temperature is cold the IAT sensor resistance is high, and when the outside air temperature is warm the IAT sensor resistance is low. Therefore, when the air temperature is cold the ECM will receive a high voltage input, and when the air temperature is warm the ECM will receive a low voltage input. The signal from IAT sensor is used for injection time correction (Cold post start correction), ignition angle correction(Air temperature correction) and idle speed correction(Air-density correction).
If IAT sensor output voltage is lower than 4.5 V, the ECM judged as a fault and DTC is set.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Resistance of sensor(Rats) is monitored | ● Poor connection ● Open or short to battery in IAT sensor circuit ● Defective IAT sensor ● Defective ECM |
Enable Conditions | ● Time after start > 2sec | |
Threshold value | ● Resistance, Rats ≥ 50kΩ(4.57v) | |
Diagnosis Time | ● Continuous | |
MIL On Condition | ● 2 driving cycles |
