Knock Sensor: Removal

Remove the collector cover.
Disconnect the ground cable from the battery.

Fig 1: Removing Collector Cover
Courtesy of SUBARU OF AMERICA, INC.
Remove the intake manifold. <Ref. to REMOVAL , Intake Manifold .>
Disconnect the knock sensor connector.
Remove the knock sensor from the cylinder block.

Fig 2: Locating Knock Sensor And Cylinder Block
Courtesy of SUBARU OF AMERICA, INC.