DTC P0111 Intake Air Temperature Sensor Gradient Too High: Description

Fig 1: Intake Air Temperature Sensor Resistance Graph

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The intake air temperature sensor, in the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature becomes low, the resistance of the thermistor increases. When the temperature becomes 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 intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.

Resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, the voltage at terminal THA also varies according to changes in the intake air temperature. 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 condition below is met: The intake air temperature rise is large, from the previous trip warm-up to the following trip. (2 trip detection logic) The change in the intake air temperature after engine start is less than the threshold value.	Mass air flow meter