If your vehicle is showing high-pitched squealing noise from the engine that gets louder with rpms, here are the most likely causes and the parts you'll need to fix each one.
The rubber drive belt has stretched, dried out, or become glazed over time, causing it to slip against the engine pulleys and create a high-pitched squeal.
The spring-loaded tensioner that keeps the drive belt tight has weakened. Without proper tension, even a brand new belt will slip and squeal under load.
The internal bearings of a free-spinning idler pulley have dried out and are failing, resulting in a metallic squealing or chirping noise that matches engine speed.
A lack of fluid or internal wear in the power steering pump causes it to whine or squeal, which gets louder with RPMs and is usually worse when turning the steering wheel.
Coolant, engine oil, or power steering fluid was spilled onto the belt and pulleys during recent maintenance or from a leak, causing the belt to slip.
The bearings inside the alternator are wearing out. This creates a continuous high-pitched whine or squeal that rises in pitch as the engine spins faster.
The bearing on the air conditioning compressor pulley is failing. This often squeals continuously, but the pitch or volume may change when the A/C is turned on or off.
The water pump's internal bearing is collapsing. This causes a severe squeal or grind and is usually followed shortly by a coolant leak and engine overheating.