I think the serpentine belt is making a noise. It sounds like a chirping sound that goes away when the car is moving, but returns when I idle.
It is possible that the belt has become stretched, and when the engine is running at lower RPMs such as idle, the belt will slip on the pulleys, causing the noise you are hearing. When the RPMs rise, due to the crankshaft pulley spinning faster, the belt is unable to slip because the extra speed takes up the slack in the belt. I would recommend having your serpentine belt system inspected by a certified mechanic. If any pulleys or the belt tensioner are damaged, have them replaced with the belt to ensure the system is operating correctly.
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