Cleaning a Dishwasher with Vinegar and Bicarbonate of Soda

You will need

Remove the racks, utensil holders, and filter (some filters simply twist off, but others will require tools to unscrew them). Take them out and place them in a mixture of warm water and 1 cup of vinegar. Leave them to soak for at least 30 minutes.
Whilst the racks are soaking, wipe the spray arms inside the dishwasher and the side walls, especially in the corners at the top and bottom. Check the dishwasher filter and dispenser, and look inside all the tiny holes and slots where water sprays out. If you see food particles or other debris lodged in tiny crevices like these, use a toothbrush and/or toothpick to clean them out.
Wipe down the racks and other dishwasher parts with a cloth and place them back inside the dishwasher.
Fill a dishwasher-safe bowl with 1 cup of vinegar and place it on the bottom of the dishwasher. Set the dishwasher to run on a hot water cycle, the longest setting at the highest temperature. The vinegar will break down any remaining bits of food, grease, soap scum, residue, and any other leftover grime.
When the first cycle ends, remove the bowl and sprinkle 1 cup of Bicarbonate of Soda along the bottom of the dishwasher. Run it on a short cycle, no longer than an hour. The baking soda will remove stains and freshen the dishwasher.
Use hot, soapy water to wipe down the door and outsides of the dishwasher, removing any stubborn stains as you go. Finish by drying with a cloth.