I have a kitchenaide Superba Monterey 21, whisper quiet dishwasher that will not drain

Try a Power Reset. Before you go to bed, cut the power to it using the breaker, the plug, or isolation switch. Try next dinner time. Press and Hold the On switch before you turn it back on to fully dissipate power.

Other ideas

https://www.google.com/search?q=KitchenAid+Superba+Monterey+21%2C+Model+KDSM-21A+not+pumping+out+at+the+end+of+the+cycle

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There are several touch pad buttons that could activate the Child Lock feature on a Kitchenaid dishwasher. To toggle off the lock, try pressing and holding the 4-hour delay dry or the energy saver dry key pads for 4+ seconds. The Energy Saver Dry is used for the Child Lock on the Kitchenaid KUDS25SHWH1. This manual is here: https://c.searspartsdirect.com/mmh/lis_pdf/OWNM/L9050329.pdf . The 4-hour delay or Control Lock options are listed in this manual: https://www.kitchenaid.com/content/dam/global/documents/201605/owners-manual-W10596243-RevD.pdf . If neither of these steps work, you may have a problem with the keypad, the wiring between the keypad and the control board or the control board itself.

Please add a comment with the model of the dishwasher if you'd like me to try and find the parts list/diagram. If the machine is under warranty, you may want to contact Kitchenaid.

I hope this helps.

Cindy Wells

The pump may be worn so it doesn't pull all the water out.
Or a bad check valve so it allows water back into the washer after it was sucked out

Timer not sending signal to wash pump. Needs timer.

Hi,
You can use citric acid, Lemon Shine (Target) or even Glass Magic to the detergent to correct this problem. Just two tablespoons to detergent in the door is all you will need. Run a normal cycle with Hi-Temp option to get the best results.
If you do this on every load you should not have any more problems, Try this.... Its cheaper, is recommend by the manufacture of Finish..... Don't follow the direction on the box.....

I’m happy to help further over the phone at https://www.6ya.com/expert/gere_bf68e6055dd61249

Not familiar with that model, but one time I found a baby sock jamming the water outlet in a dishwasher, so check to make sure there's no foreign object blocking any exits. Other than that, I suspect it will need to be serviced, or at least taken apart for further inspection.

Very likely pump motor shaft seal leaks water into bearing casing buildup of rust and consequently noise. I just replaced $112 worth of pump assy and it's back to normal. I would also buy repair manual for $10 on-line to be sure how to disassemble the sump to get to the pump.

There is probably a problem with your drain hose being plugged or the drain valve/solenoid is jammed or defective.

You would need to check these two problems and repair or replace parts.

look in your air gap first make sure there is no debrie in there this will make you dishwasher drain really slow.