BSI REQUIRED BRAIN

I had problems in the vehicle 2001 model 406 st engine immobiliser fault error, I was on the way, I gave 500 TL, the problem was fixed but it was better than before, the brain boy said BSI brain is defective said the brain may be needed, this BSI brain indicator is my brain how much is the price or engine immobiliser fault this problem What causes it? The keymaker said that this problem is done from the brain and the indicators that are not related to the key are closing occasionally. Can you help?

Think of the brain as the center where all the brains of the vehicle receive and give information