Diagnosis
A high-pitched noise during wash cycles typically originates from the circulation pump. Debris or a worn pump impeller are the primary suspects.
How to Fix It
First, check for a clog. Remove the lower spray arm and the filter assembly (the fine mesh and flat filters). Inspect the pump sump area underneath for glass, bone, or other debris. Clear any obstructions. Reassemble and run a test cycle.
If That Didn't Work
The circulation pump itself may be failing. Listen closely; if the noise is metallic and correlates directly with the pump's operation, the pump motor or impeller shaft is likely worn.
Heads Up
Running the dishwasher with this noise can cause further damage. Avoid using heavy soil or sanitize cycles until the issue is resolved, as they run the pump at maximum speed.