If your vehicle is showing squealing noise when turning the wheel to the extreme left or right, here are the most likely causes and the parts you'll need to fix each one.
The belt driving the power steering pump slips under the high pressure created when the steering wheel is turned to the extreme stops. This is often caused by a worn belt or improper tensioning after recent maintenance.
Low fluid levels cause the power steering pump to draw in air, creating a high-pitched squeal or whine, especially under the heavy load of full lock.
A failing tensioner cannot maintain proper tension on the belt, causing it to slip and squeal when the power steering pump demands maximum power at full steering lock.
Internal wear or a failing bearing in the power steering pump can cause it to squeal or whine loudly when forced to work at maximum pressure.
Internal blockages or failing bypass valves in the steering rack can cause extreme pressure spikes, severely overloading the pump and belt at full lock.