Air Temperature Sensor ( Ambient / Intake ): Description and Operation
PURPOSEMeasure intake air temperature and signal the ECU.
LOCATION
Integral component of air flow meter.
OPERATION
The thermosensor is a negative temperature coefficient thermistor. Negative temperature coefficient means as temperature increases, resistance decreases. Cold air is more dense than warm air. The ECU measures the resistance of the thermosensor, calculates the temperature of the incoming air, and uses this information to help regulate the following: fuel injection quantity, idle speed control, and purge control. Normal sensor resistance is:
TEMPERATURE / RESISTANCE (K OHMS)
-4°F (-20°C) / 13.6K - 18.4K
68°F (20°C) / 2.2K - 2.7K
140°F (60°C) / 0.4K - 0.7K