Remove the bottom rack of your dishwasher and examine the area around the heating element. If there are food particles built up around the element, add a small amount of liquid dish soap to a nylon scrubbing sponge and scrub around the element.
Pour 1 to 2 cups of white vinegar into the bottom of your empty dishwasher. Make sure that the vinegar covers your heating element.
Let the vinegar sit in the bottom of your dishwasher for at least an hour.
Run the empty dishwasher through a full wash cycle with the hottest water possible.