What is this squeaking sound, coming from passenger side I believe

just started happening yesterday

 

2007 tl

 

Maybe one of the bearings running the drive belt? Grab a automotive stethoscope, long screwdriver, piece of pipe, etc. and try to narrow down where the noise is coming from. Take the belt off - is noise gone? Does anything produce noise when spinning by hand? Does any pulleys feels "crunchy" when spun by hand? Have any side to side play? Are idler or tensioner pulley spinning for a very long time when turn by hand?

 

Thank you for this info,
I put water on the inside of the belt and it stopped squeaking, I believe I just need a new belt then?

 

If the sound eventually returns after the sprayed water dries off then your belt is likely worn.
I also had same sound and I solved it by replacing with Bando serpentine belt (part # 6PK2135).

 

Belt or tensioner pulley