Intake Air Temperature Sensor: Operation

• The intake air temperature sensor functions to convert the temperature of the air (taken into the engine) to voltage, and to input that voltage (as signals) to the engine control unit. The engine control unit, based upon those signals, then corrects the amount of fuel injection, etc.
• The 5-volt power supply within the engine control unit is supplied, by way of the resistance within the unit, to the intake air temperature sensor. It passes through the intake air temperature sensor, which is a type of resistor, and is grounded at the engine control unit. Note that the resistance of the intake air temperature sensor decreases when the temperature of the intake air increases. See Fig 1 .
• The intake air temperature sensor terminal voltage becomes higher when the resistance of the intake air temperature sensor increases, and becomes lower when the resistance decreases. Consequently, the intake air temperature sensor voltage varies in accordance with the temperature of the intake air, becoming lower when the temperature of the intake air increases.

Fig 1: Identifying Intake Air Temperature Sensor Circuit

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.