Waste Disposal/Sink trap

• Empty your food waste disposal unit if your dishwasher's hooked up to one. If it's not empty, the old food inside it will back water up into your machine. Check that your sink trap isn't blocked by unscrewing it from the base of your sink if you don't have a food waste disposal unit. Make sure your dishwasher or any other appliances connected to it are not running when you do so.
  
  

Incomplete Cycle

• You may have opened your dishwasher's door mid-cycle before it's had a chance to drain. Check the progress indicator on your machine's control panel. The structure of this will differ depending on which Frigidaire model you're using, but it should show the point your machine has reached in its cycle. If this is the cause of the problem, close your dishwasher's door and let it finish.
  
  

Drainage Pipe

• Inspect the drain pipe that runs from your machine to your waste disposal unit or sink. If this is kinked or has been squashed under another appliance or a base unit, the waste water inside your dishwasher will be unable to escape. Check that water can flow through your waste pipe freely.
  
  

Filter

• Remove the bottom shelf from inside your machine and take out the plate covering the filter area. If you don't rinse your plates before you put them into your washer, food debris could block your filter and stop water from reaching your drainage pipe. You can unblock your filter with your fingers. Turn off your machine's power before you attempt to do so.