DTC P0111 Intake Air Temperature Sensor Gradient Too High: Description

Fig 1: Resistance And Temperature Characteristic Graph

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The Intake Air Temperature (IAT) sensor, in the Mass Air Flow (MAF) meter, monitors the. IAT. The IAT sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the IAT is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM (included in the hybrid vehicle control ECU) as voltage changes (See Fig 1).

The IAT sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R. Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor changes, the voltage at terminal THA also varies according to changes in the IAT. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.

DTC TROUBLE DETECTION CONDITION CHART

DTC No.	DTC Detection Condition	Trouble Area
P0111	When either of following conditions are met (2 trip detection logic): In duration between engine warmed up and next engine starts, change in Intake Air Temperature (IAT) sensor output bellow threshold During engine warming up after cold engine starts, change in IAT sensor output bellow threshold	Mass air flow meter