German engineers designed Bosch dishwashers to be water saving, energy efficient and exceptionally quiet. They are normally trouble free. However, with time and use, parts may wear and a maintenance or repair problem may arise. If your Bosch dishwasher is making a high-pitched sound, try several troubleshooting tips before incurring the expense of calling a service technician.
Inlet Water Valve
The Bosch dishwasher has an inlet valve that is covered by a filter screen. If mineral deposits build up and cause a clog in the screen, water can make a high-pitched, whistling sound as it attempts to go through the filter. Remove and clean the filter with soapy water and an old toothbrush, rinse well and replace. If the sound is caused by the inlet valve, this should fix the problem.
Attempt to pinpoint the noise. The sound may be generated by overly high water pressure in the line that fills the dishwasher. If excessive water pressure is causing the sound, try adjusting the intake valve to reduce the water pressure.
Clean The Filters And Drain
A whistling sound may indicate a problem with the drain pump. If the pump runs continuously, it will cause a whistling noise once it runs out of water. The drain pump may continue to run if it is clogged by food debris, mineral deposits or excess suds. Cleaning the filters and drain should repair the problem.
Fire Hazard Recall
If you own an older Bosch dishwasher, you may have one that has been recalled for a safety issue. The U.S. Consumer Protection Association and Bosch Home Appliance Company have issued a recall for more than 450,000 Bosch dishwashers manufactured between May 1999 and June 2005. The dishwashers present a fire hazard. If your dishwasher is affected by the recall, stop using the dishwasher immediately and call the Bosch Home Appliance hotline or your Bosch appliance dealer to arrange for Bosch to repair your unit.