Safety First
Remember to always practice safety first. Disconnect the dishwasher from the electric source before attempting any do-it-yourself repairs. Unplug the machine from the wall socket or shut off the electrical power at the circuit breaker or fuse box. Be sure to wear rubber or safety gloves and rubber soled shoes to avoid conducting electricity. Handle all tools by their insulated end. Capacitors or other internal parts can store an electrical charge even after the dishwasher has been unplugged.
Inlet Valve
Attempt to locate the source of the whistling sound coming from your Bosch dishwasher. Determine if it is an "air" or "water" sound or a sound of metal to metal. The whistling noise may be a problem caused by a faulty inlet water valve. The valve is located at the bottom of the dishwasher, just to the left of the pump. A screen inside the valve may be clogged by debris or food. Clean the filters with soapy water and an old soft toothbrush. Rinse well and replace.
Pump Problem
The whistling sound problems may be caused by food, debris or a chip of glass that is stuck inside the pump and preventing the impeller from moving freely. The problem may clear itself after running a few loads of dishes. However, it is a good idea to watch for water leaking from under the dishwasher in case the pump seal was damaged.
Safety Recall
Older models of Bosch dishwashers may overheat due to a faulty electrical connection. In January 2009, the U.S. Consumer Product Safety Commission and Bosch Home Appliance recalled 476,500 models of Bosch and Siemen dishwashers. The dishwashers were manufactured between May 1999 and July 2005. These units may present a fire hazard and consumers are advised to stop using them immediately. Contact your Bosch appliance dealer or the company website for a free repair if your unit is affected.