Attempt to locate the drain problem by removing the bottom rack of the dishwasher. Turn the assembly in a counter-clockwise, one-quarter turn. Lift out the assembly and visually inspect the object trap for debris. Built-up mineral deposits, a broken toothpick, a glass chip or fruit pit, for instance, can interfere with operation. Turn the trap upside down and gently tap on a hard surface to dislodge debris. Wash the trap with soapy water and a soft brush. Return the trap to its installed position. Turn the ring handle on the assembly cover a one-quarter turn clockwise until it locks. The arrow on the filter handle and the filter should be in alignment.
The pump in your Bosch DLX dishwasher is responsible for ejecting water from the machine. The dishwasher pump is composed of several components. It is quite difficult to detect a malfunction or defective element, and troubleshooting requires disassembling the pump. Bosch recommends that if the pump is the problem, it is best to call a certified Bosch service technician.
Inspect the drain hose connecting the dishwasher to the home plumbing line or garbage disposal. The hose may be crimped or clogged. A hose replacement kit is available online from appliance repair websites that specialize in Bosch kitchen appliance replacement parts. Alternatively, contact your local Bosch dealer.
The clog that is preventing your Bosch dishwasher from draining may be in the main plumbing line. Lint, soap scum and mineral deposits build up over time. A plumber's auger may be required to snake the line.