Fill a dishwasher-safe bowl with 1 cup of white distilled vinegar. Position the bowl in the bottom rack of the dishwasher. Place a lemon half face-down on the top rack.
Run the dishwasher on a regular cycle with hot water. The steam created by the vinegar loosens limescale while the lemon deodorizes your dishwasher.
Remove the bowl and lemon half from the dishwasher. Discard the lemon half.
Wet a sponge in the leftover vinegar. Sprinkle baking soda over the surface of the sponge.
Scrub inside the dishwasher to remove the limescale loosened by the vinegar during the wash cycle. Use a scrub brush to work on areas where limescale is particularly stubborn. Add more vinegar and baking soda to the sponge or scrub brush as needed.
Wipe the inside of the dishwasher with a damp cloth to rinse it. Dry it with another cloth. Leave the dishwasher door open for 30 minutes so the inside can air dry completely.