My 2002 car had the common belt squeal on my test drive. It is the ancillary serpentine belt. Sorted by the dealer before I picked the car up. It had about 30k mileage.
It came back after a couple of thousand miles. I took it off ( released the alternator to get slack). The belt was in good condition. I cleaned the pulleys with brake cleaner on a cloth, wiped the belt clean and replaced it. Reset the tension. No squeals after that. It still looks new, no cracks, hardening, fraying.
Gomog site gives one fix as getting a slightly narrower belt. The dimensions of the belt are printed on it and any motor factor/parts place can get them.
