Hi my 06 ss/sc CEL came on the other day and the car would only boost to 3lbs so I checked the code it was a boost solenoid malfunction so I picked up a new one replaced it and erased the code and still does the same thing so I drove it around a little bit never changed but I don't have a CEL anymore so what could this be? I took the hose off the actuator that leads to the solenoid and with that disconnected it makes normal boost 12.5 or something close to that but when that hose gets hooked back up to the actuator it makes 3 so I'm really stumped at what it could be since the solenoid is brand new any help will be appreciated thanks

 

Could be a wiring fault to the solenoid holding it open. What was the specific code? Check for correct voltage/ground at the harness that connects to the solenoid itself.

 

The code was p0033

 

Now that you have the code, this problem does happen to these SC cars.... the best way to search for answers on this form is actually by googling.
Type "cobaltss.net" and then the thing you want to search for into Google, just like this: https://www.google.com/search?q=p003...ltss.net+p0033

 

If it's a circuit fault and you put a NEW solenoid on it, i'd suggest tracing the wiring and seeing that there's no spots where it has rubbed through or broken. It sounds as if the solenoid is pulling open all the time when it shouldn't be.

If you unplug the solenoid electrically, does it boost normally? Leaving the vacuum lines attached but pulling the plug on the solenoid.