Volkswagen Golf/Jetta/Cabriole 1990-1999

Intake Air Temperature Sensor (IAT)

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OPERATION





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Fig. Connect the probes of a digital multimeter to the intake air temperature sensor



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Fig. Checking the resistance of the IAT sensor

IAT sensor is located on the rear upper intake manifold of the 2.8 VR6 engine. On the 2.0L engine this sensor can be found by the right center of the engine compartment.

The Intake Air Temperature (IAT) sensor determines the air temperature inside the intake manifold. Resistance changes in response to the ambient air temperature. The sensor has a negative temperature coefficient. As the temperature of the sensor rises the resistance across the sensor decreases. This provides a signal to the PCM indicating the temperature of the incoming air charge. This sensor helps the PCM to determine spark timing and air/fuel ratio. Information from this sensor is added to the pressure sensor information to calculate the air mass being sent to the cylinders.

TESTING



  1. Turn the ignition switch OFF .
  2.  
  3. Disconnect the wiring harness from the IAT sensor.
  4.  
  5. Measure the resistance between the sensor terminals.
  6.  
  7. If the resistance is not within specification, the IAT may be faulty.
  8.  
  9. Connect the wiring harness to the sensor.
  10.  

REMOVAL & INSTALLATION




NOTE
The IAT sensor is part of the wiring harness connector for the fuel injector. You may not be able to purchase it separately at a local auto parts store. To date, VW offers the part only as a unit.

The IAT sensor is located in the side of the intake manifold.

  1. Remove the negative battery cable.
  2.  
  3. Remove the wiring harness from the sensor.
  4.  
  5. Unscrew the sensor.
  6.  

To install:

  1. Install the new sensor.
  2.  
  3. Attach the wiring harness to the sensor.
  4.  
  5. Install the negative cable.
  6.  

 
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