Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Knock Sensor (KS)

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OPERATION



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Cutaway view of a typical knock sensor

Some engines use a knock sensor mounted in the engine block to prevent internal engine damage caused by engine detonation. The sensor contains a piezoelectric crystal which emits a voltage signal when it is subjected to shock or vibration caused by detonation. The ECM receives this signal and retards the ignition timing.

TESTING



1991-94 2.0L (SR20DE) Engine

See Figure 2



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Fig. Fig. 2: Knock sensor terminal identification-1991-94 SR20DE engine

  1. Disconnect the KS connector.
  2.  
  3. Using a high-impedance ohmmeter (at least 10 meg-ohm), check the resistance between KS terminal A and a known good engine ground
  4.  
  5. Replace the KS if continuity is not present.
  6.  


WARNING
Replace the KS if it falls or is struck.

1995-96 1.6L (GA16DE) and 2.0L (SR20DE) Engines

See Figure 3



Click image to see an enlarged view

Fig. Fig. 3: Knock sensor terminal identification-1995-96 GA16DE and SR20DE engines

  1. Disconnect the KS connector.
  2.  
  3. Using a high-impedance ohmmeter (at least 10 meg-ohm), check the resistance between KS terminal 2 and a known good engine ground
  4.  
  5. Resistance should be 500-620 ohms at 77°F (25°C). If resistance is not within specifications, replace the knock sensor.
  6.  


WARNING
Replace the KS if it falls or is struck.

REMOVAL & INSTALLATION



  1. Disconnect the electrical connector from the sensor.
  2.  
  3. Remove the KS from the engine block.
  4.  

To install:
  1. Position and secure the KS to the engine block using the retaining bolt.
  2.  
  3. Connect the electrical connector to the KS.
  4.  

 
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