How do I check if my dishwasher drain is clogged?

To check if your dishwasher drain is clogged, you need to inspect filter, drain hose, air gap, and garbage disposal connection for blockages. First, check filter: remove lower rack, locate cylindrical filter at bottom of dishwasher tub, twist counterclockwise to remove, rinse under running water and scrub with old toothbrush to remove food, grease, and debris, clean sump area underneath with paper towel. Second, check standing water: if water remains in bottom after cycle and does not drain, drain is likely clogged. Third, check drain hose: look under sink where dishwasher drain hose connects to garbage disposal or sink drain, ensure hose is not kinked, pinched, or clogged, disconnect hose and flush with hot water. Fourth, check air gap: if you have a small chrome cylinder on sink, remove cap and clean out debris that blocks airflow. Fifth, check garbage disposal: if dishwasher drains through disposal, run disposal to clear food clog and ensure knockout plug was removed if new disposal installed. Sixth, run diagnostic: after cleaning filter and hose, run empty Normal cycle with 2 cups vinegar to flush, listen for drain pump humming, if pump hums but water not draining, pump may be clogged with glass or food and needs removal. Seventh, check for error codes like F9E1 or OE indicating drain failure. If water still does not drain after cleaning filter and hose, drain pump may have failed and needs replacement.