Brake booster solenoid valve

[walter1]

Hello all.
I'm new on here, I've read many posts but not found what I need yet. I have an incredible machine known as the xc90 but it has come up with a fault.
Antiskid service required an Brake assist service required. Local garage read the codes and it comes up with 313/(OE-Factory code:139) Brake booster solenoid valve.
Now, I have looked on Google images and it shows various parts under that part name.
I have attached 3 images but like say, I'm new on here and not sure if it's worked.
I have changed part in image 1 as it was mounted to the air filter box. Image 2 is bolted to the engine behind the large diameter hose on the front of the engine for the egr valve. I have no idea of the location of image 3.
Please help.....and thanks for reading