Bosch dishwashers are high-end appliances known for quality and durability. However, Bosch can eventually develop problems, like any other dishwasher, including a burning smell. In the Bosch SHX46b05UC model, this development could be the result of a wiring or melting problem; however, it is important to quickly ascertain the cause so your dishwasher does not become a fire hazard.
If the odor has the acrid smell of burned wires, the cause could be an electrical problem. Check the circuit breaker box to make sure the dishwasher hasn't popped a breaker and that a fuse has not blown. You may need to call an electrician to check the wiring inside the dishwasher, which he will access through the dishwasher's bottom panel. Faulty wiring or damaged wiring or nuts may be causing the odor and will require replacing.
A bad motor could also be the cause. Turn off power to your dishwasher and access the motor through the bottom access panel. Unscrew the panel and detach the two wires that run from the wiring harness to the motor. Use a multimeter tester and position it to the "R x 1" setting. Touch one of the multimeter's probes to one of the motor's terminals. Repeat with the other probe and motor terminal. If the motor is working properly, the resistance reading should be at zero or close to zero. Run a ground connection test. Position one probe on the motor's bare-metal housing. Position the other probe on one of the motor's terminals. Place the probe on the other terminal and repeat the process. If the motor is working properly, you should not get a reading on the meter. Otherwise, you will need to replace the motor.
If the burning smell also smells like plastic, you may have melted plastic on your heating element. Slide out the bottom rack to access the heating element. After letting the dishwasher cool, inspect for any melted material that has adhered to the heating element or the heating core. Gently remove any melted plastic material with a wooden spoon. Your dishwasher will now be safe to use.
A few other problems could cause the burning smell in your Bosch SHX46b05UC. Insulation could be adhering to wires in your door panel. Food debris could be caught in your dishwasher's mechanisms or the drain hose could be obstructed. If the water temperature is set too high, the plastic tub could be melting. If you have an error code on the dishwasher, call a service technician and provide him that number.