Mazda 323/MX-3/626/MX-6/Millenia/Protégé 1990-1998 and Ford Probe 1993-1997

Intake Air Temperature (IAT) Sensor

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OPERATION



The intake air temperature sensor is a variable resistor that is influenced by temperature. Which means, as the temperature changes, so does the resistance inside the sensor. The computer reads this change in resistance to determine the temperature of the incoming air. It uses this reading to determine proper air/fuel mixture and ignition timing settings.

TESTING



See Figure 1

Vehicles which use a plate or cone type mass air flow meter have the IAT sensor built into the meter. Refer to the air flow meter testing earlier in this section.

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the IAT sensor connector.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Measure the sensor resistance by connecting an ohmmeter across the two terminals. This sensor reads infinte indicating it is bad

  1. Connect an ohmmeter across the sensor connectors.
  2.  
  3. Measure the resistance of the sensor and compare to the following values:

    77°F (25°C)-29.7-1.3 kohms
     
    185°F (85°C)-3.3-3.7 kohms
     

  4.  
  5. If not as specified, replace the sensor.
  6.  

REMOVAL & INSTALLATION



See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the IAT sensor from the air cleaner housing or intake air pipe.
  4.  



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the IAT sensor mounting

To install:
  1. Install a new sealing washer to the thermosensor.
  2.  

 
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