Any food scraps left on plates, cookware and cutlery are a potential blockage hazard. When the jets of water from the spray arms wash the scraps into the bottom of the dishwasher they have a tendency to block the main drain. Items, such as cellophane wrapping, that fall through the bottom rack of the dishwasher and settle over the top of the drain also cause clogs.
Open the dishwasher and slide the lower dish rack out of the appliance to gain the best access to the drain filter on the floor around the lower spray arm. Using a cloth, wipe up any scraps of food or debris accumulated around the main drain. Use a mix of water and dishwasher detergent to clean up any stains or finer material trapped on the filter.
Material small enough to pass through the fine filter above the main drain sometimes accumulates in the drain pipe and air gap assembly and causes a pump-out failure. Often the first indication of a pump problem is an error code on the dishwasher's display. Call a plumber if the blockage is somewhere in your household pipe-work.
Always scrape food scraps off plates into your compost container before loading the dishwasher. Be careful not to leave teabags inside mugs or pieces of food stuck to the bottom of baking trays. Rinse the plates quickly in the sink to remove any remaining food scraps.