Q: When I start my 2005 Cadillac CTS there's a loud screeching noise then it goes away

There are a few possible causes for a squeal when the vehicle is first started. Typically, this is a sign that there is a worn belt, a worn tensioner, or a pulley that is either worn or out of alignment. It will be necessary to do an inspection to verify what the actual cause of the noise is. Most of the time, this problem will present itself upon first start (when cold) and go away as the engine runs for a few minutes. Over time, if not remedied, the noise will become constant, and the likelihood of the part failing completely increases exponentially. If you take a look at the belt, look for cracks on either side, as a sign that the belt is due for replacement. If this is something you feel you could use a hand to identify and/or repair, consult a certified mechanic, like those available at YourMechanic.com.