General Information

Engine Control
P0111 Intake Air Temperature Sensor 1 Circuit Range / Performance - General Information

Component Location





General Description

The Intake Air Temperature Sensor (IATS) is installed into the Barometic Pressure Sensor (BPS). 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.

DTC Description

PCM monitors temperature difference between MAX. and MIN IATS in order to detect movement in IATS not only Start Test but Drive Test while enable condition is met. If PCM detects intake air temperature changes less than 5.4 °F. PCM determines that a fault exists and a DTC is stored. PCM monitors temperature changes resulting from soaking the vehicle. Therefore, Coolant temperature and Intake temperature should be changed. If PCM detects intake air temperature correlated to coolant temperature does not change PCM determines that a fault exists and a DTC is stored.

DTC Detecting Condition





Specification





Diagnostic Circuit Diagram





Signal Waveform & Data












Fig.1) Normal waveform of IATS
Fig.2) Normal data of IATS & ECTS & EOTS at ig on
Fig.3) Normal data of IATS & ECTS & EOTS after warming up.

The output signals of IATS & ECTS change smoothly without any rapid changes. These 2 sensor have almost the same characteristic signal during the early period after start. It means that the temperatures of intake air and engine coolant are depended on the temperature of atmosphere. Meanwhile, During engine warm up the output signal of the ECT will change quicker than the IAT signal. even it may not change almost.