If your dishwasher is not draining, or there is too much water left over at the end of the cycle, it might be due to food particles blocking the sump area, or it could be cause by a clogged dishwasher drain hose or a defective part like the motor or drain pump.
It’s normal for some water to remain in the dishwasher after the cycle to keep the seals in your dishwasher from drying out. However, standing water that covers the heating element or that is more than one cup of water is not normal and could indicate a drainage problem.
This is the easiest fix, so start here first. Use a towel and some hand protection (there could be broken glass or sharp food particles where you cannot see them) to clean the area around your sump, below the sprayer arms. These items could be clogging your drainage system.
After turning off the water and power to your dishwasher, check the drain hose for kinks in the hose line or clogs. Have a bucket and towels handy to catch any water residing in the hose. Disconnect the hose from the dishwasher and check for clogs.
You can also disconnect it from where it meets up to your plumbing or garbage disposal and look for clogs on that end. Check the inlet to the garbage disposal. Food remnants and gunk might be clogging up the entrance to the disposal and it might need to be cleaned out. Use an old tooth brush to clean out the area.
A dirty or kinked dishwasher drain hose can be replaced and this might solve your dishwasher drainage problems.
Do you hear the drain pump and motor assembly turning on, or does it make a buzzing or humming noise? If your dishwasher is not draining and you hear a humming or buzzing sound, this might indicate a problem with the motor. You can test this part with a multimeter to see if the part is defective or not. Replace the dishwasher motor if defective.
Another common part that fails is the drain pump which drains the water from the dishwasher. Some models of dishwashers add a separate drain pump motor for draining the water from the tub, so be sure to use your dishwasher’s model number to find online schematics for your dishwasher.
The drain impeller pushes the water out of the dishwasher. It is attached to the pump, so you will need to access the pump to inspect the drain impeller for damage and to make sure it turns and operates freely.
Other parts that could be causing your dishwasher not to drain could be the dishwasher timer, solenoid kit, the check valve, check ball, or water pump belt.