How can you check if this solenoid is functioning ? When it is powered up with the engine running, should the ports be open ?, e.g you can blow through them. What is its default ? ports are closed then ECU makes them open ? or other way round, ports are open ( wasting ) and the ECU makes them close up.
My solenoid seems to be stuck in the closed position, making actuator pressure all the time.
I have been running a manual set up, but am going back to more smoother solenoid set up.
At the moment i have got the solenoid soaking with cleaning fluid sprayed in the ports.

 

What you should do is unclip the plug at the top and run a live to it. See if it clicks. If it does then it should be working.
Although my 3 port clicks and i'm running actuator pressure also.
If checked everything an still only .6 bar.

 

Well i bought a solenoid that works and im disappointed !! Yes the car boosts to 1.2bar, but only when i floor it ! I much prefer the manual set up, boost is available right through the rev range not just the top end

 

Not sure about the new age imprezas but on the classics if you connect the two cables with the green connectors which are located under the drivers side of the dash and turn the ignition on you will here the boost solenoid clicking, the cooling fans will run and the fuel pump.
This proves the boost solenoid is working if you remove the hoses of the solenoid and spray carb cleaner into the solenoid through the port while its operating this will clean the internals of the solenoid let the carb cleaner evaporate before reinstalling all the hoses and remember to disconnect the green connectors under the dash.