Vibe 2003-2005

Intake Air Temperature Sensor

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Operation



IAT sensor is a thermistor that is an integral part of the mass air flow (MAF) sensor. The electrical resistance of the IAT sensor is high when the air temperature is cold, and the resistance is low when the air temperature is warm. The IAT sensor is wired in series with a fixed resistor located in the powertrain control module (PCM). The PCM applies 5 volts to the IAT sensor. The PCM monitors the voltage across the IAT sensor and converts the voltage into a temperature reading. The voltage measured by the PCM will be high when the air temperature is cold, and low when the air temperature is warm.

Removal & Installation



  1. Refer to the Mass Air Flow (MAF) sensor replacement.
  2.  

Testing



  1. Turn OFF the ignition.
  2.  
  3. Remove the IAT sensor.
  4.  
  5. Place the sensor on a work surface away from any heat source.
  6.  
  7. Allow the sensor to reach the ambient air temperature for 30-60 minutes.
  8.  
  9. Observe and record the ambient air temperature of the vehicle environment using an accurate thermometer.
  10.  
  11. Measure the resistance of the IAT sensor 2 and record the value.
  12.  
  13. Compare the resistance measurement of the IAT sensor to the ambient air temperature on the Temperature vs. Resistance chart illustration. If not within specification, replace the sensor.

    Click image to see an enlarged view

    Fig. Temperature versus resistance chart

  14.  

 
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