Air Temperature Sensor ( Ambient / Intake ): Description and Operation

Of NTC type, the temperature sensor is located in the intake manifold before the throttle. The engine control module measures the temperature of the air in the intake manifold by applying 5 V to the sensor from pin 46 via an integral 2.74 k ohm resistor. The sensor is grounded via pin 67. The voltage across the resistor in the engine control module is proportional to the temperature of the intake air.

In combination with the pressure in the intake manifold, the voltage is used to determine the density of the intake air and with it the engine load. Fuel injection time is proportional to engine load.

In the event of sensor failure or a break in the circuit, the engine control module will set a default temperature of 80 °C (46 °F).