It is the Subaru Strut in the front wheel assembly of your vehicle that helps you control the vertical motion of your vehicle when an obstacle is encountered.
The strut is the suspension component that has replaced the shocks and springs that were used in the past on rear wheel drive cars and truck made by Subaru. Because the strut is smaller in size while still performing the same functions as the larger and older shocks and springs, there is now amble room for the drive components of the front wheel drive vehicles to be utilized.
Since the Subaru strut is a vertical control suspension component, the test to make sure it is still functioning properly is the bounce test. This test can be performed by the owner of the Subaru by them depressing one of the front fenders down then releasing the pressure.
When the pressure is released from on top of the fender, the body of the vehicle will move up and down. If the strut is functioning properly, this movement will be up then back to a resting position. If there is excessive wear on this suspension component, then the body of the vehicle will continue to move up and down. The greater the number of times the body moves up and down, the more wear that is on your suspension component.
A visual inspection of the struts on the front of your vehicle can also be accomplished by the owner of the Subaru. This is done by looking for leaking hydraulic fluid or the shaft of this component being bent at any angle.
If any of these conditions are noticed in either of the tests, all of the suspension control devices on your vehicle should be replaced so a smooth ride can be obtained by the driver and passengers of your vehicle.