Getting too much boost!?!?!

Today i took the car for a drive and noticed that when on teh gas hard i could peak at 15psi and thats too high for a stock t25 and that was on the LOW settin on my greddy boost controller. So i figured someone messed with a knob or pressed a button but i couldnt figure out how to bring the boost down. I tried turning the unit off so it would run stock PSI but it still goes well over 13 psi with the unit off. So is there something messed up under the hood or is my profec B fucked? I want stock boost untill I get the EBC re-set so how do I go about this?
Thanks cars a 89 240sx with sr20

sure your gauge isnt the problem

Check the vacuum line going to the wastegate… sounds like its not working which is VERY dangerous on a stock SR.