Identify what this plug is off
 

Car is a 2009 Impreza 330s

Got a turbo put in the car last week there but we have a spare blue loom connector/plug left over that dunno what its off :( you can see the plug just to right beside expansion bottle - we looped it up over there just for reference but looks like it belongs somewhere under the manifold

was thinking its maybe off the secondary air valve solenoids or something but cant see it anything - no light on dash but all secondary air system is disabled and codes removed on my car hence thinking its linked to that.

car is running fine - no issues

That's the plug off the original 2 port boost solenoid, so what's your solenoid wired into ?

there is a 3 port on it now, so i assume the 3 port harness adapter aint connected to anything on the other end!

Was the turbo uprated or different from the one previously fitted? If so the person who fitted it might have left the solenoid disconnected until you have a remap? Although they probably should have told you!

The turbos wastegate has a spring which 'mechanically' limits the boost to roughly 10 psi on a stock sti turbo, a sort of failsafe mechanism (assuming that the small hoses on the turbo are still attached as per the stock layout)

uprated turbo, was a mate fitting it. we sat and looked for ages for the plug connector but couldnt see it. will go for a nosey here in a minute to see whats what

id have thought the boost solenoid disconnected would have thrown an CEL

that was it cheers :) 3 port harness adapter had tucked itself under the wee metal shield out of site!