If the filter and air gap are clear, the clog is likely located in the drain hose—the ribbed tube connecting your dishwasher to your garbage disposal or sink drain.
Fortunately, most clogs can be cleared with basic DIY steps before you need to call a professional. Common Signs of a Clogged Drain dishwasher drain is clogged
Unusual sounds coming from the secondary drain or the sink while the dishwasher is running. If the filter and air gap are clear,
Food particles or a filmy residue are left on your "clean" dishes. dishwasher drain is clogged