Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Intake Air Temperature (IAT) Sensor

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OPERATION



See Figure 1



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Fig. Fig. 1: Intake air temperature sensor location

There are two different types of intake air temperature sensors. The 1984 E15ET uses an air temperature sensor located, in the air flow meter assembly. The sensor measures the temperature of the incoming air and transmits a voltage signal to the ECM. The ECM will use this input to optimize the fuel mixture, according to the specific air temperature.

Beginning in 1995, the GA16DE and SR20DE engines use an IAT sensor. The sensor is mounted in air cleaner housing and detects changes in the intake air temperature. As the temperature of the incoming air increases the resistance of the sensor decreases proportionally. Changes in temperature are transmitted to the ECM and are used to detect problems with the On Board Diagnostic system. The sensor has no direct affect on the engine control system.

TESTING



1.5L (E15ET) Engine
  1. Disconnect the air flow meter electrical connector.
  2.  
  3. Connect an ohmmeter between 30 and a known good engine ground.
  4.  
  5. The resistance measurement should be as follows:

    Below 68°F (20°C)-Above 2.1 k-ohms
     
    Above 68°F (20°C)-Below 2.9 k-ohms
     

  6.  
  7. If the value obtained is not within specifications, replace the air flow meter assembly.
  8.  

1.6L (GA16DE) and 2.0L (SR20DE) Engines

See Figures 2 and 3



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Fig. Fig. 2: Intake air temperature sensor testing-1995-96 engines



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Fig. Fig. 3: Intake air temperature sensor resistance graph-1995-96 engines

  1. Disconnect IAT sensor electrical connector.
  2.  
  3. Remove the IAT sensor from the air cleaner housing.
  4.  
  5. Place the sensor bulb in a pot of water.
  6.  


WARNING
Place only the temperature sensing portion of the sensor in the water. Do NOT submerge the entire sensor in the water.

  1. Connect an ohmmeter across the IAT sensor terminals.
  2.  
  3. Heat the water and measure the resistance at different temperatures.

    At 68°F (20°C) resistance should be 2.1-2.9 kilo ohms.
     
    At 122°F (50°C) resistance should be 0.68-1.0 kilo ohms.
     
    At 176°F (80°C) resistance should be 0.27-0.38 kilo ohms.
     

  4.  

If sensor resistance values is not parameters, replace the sensor.

REMOVAL & INSTALLATION



1.5L (E15ET) Engine

The intake air temperature sensor is an integral component of the air flow meter. If the air temperature sensor is found to be defective, replace the air flow meter assembly.

1995-96 1.6L (GA16DE) and 2.0L (SR20DE) Engines
  1. Disconnect the IAT sensor electrical connector.
  2.  
  3. Remove the two retaining screws and separate the IAT sensor from the air cleaner housing.
  4.  

To install:
  1. Position the sensor to the air cleaner housing and secure in place using the two retaining screws.
  2.  
  3. Reconnect the wiring harness.
  4.  

 
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