Subaru Forester 1998-05

Knock Sensor (KS)

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Operation



The sensor is used to detect engine vibrations caused by preignition or detonation and provides information to the ECM, which then retards the timing to eliminate detonation.

Removal & Installation



  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner case.
  4.  
  5. Remove the collector cover, as required.
  6.  
  7. On DOHC engine, remove the intercooler.
  8.  
  9. Disconnect the sensor connector.
  10.  
  11. Remove the sensor from its mounting.
  12.  

To install:

  1. Installation is the reverse of the removal procedure.
  2.  
  3. Tighten the sensor to 17.4 ft. lbs.
    NOTE
    The extraction area of the knock sensor wire must be positioned at a 60 degree angle relative to the engine rear.

  4.  

Testing



  1. Remove the sensor from the vehicle.
  2.  
  3. On 1998-2004 vehicles, equipped with SOHC engine, measure the resistance between the connector terminal of the sensor, (terminal 2) and ground.
  4.  
  5. On 2005 vehicles, equipped with SOHC engine and 2004-2005 vehicles, equipped with DOHC engine, measure the resistance between the connector terminal of the sensor, (terminal 1) and ground.
  6.  
  7. If measured value is less than 700 kohms, replace the sensor.
  8.  

 
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