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Dishwasher Drain pump: What It Does and Signs It's Failing

A small electric pump on the sump under the tub that pushes dirty water out through the drain hose after each wash and rinse. Some designs use one motor with two impellers instead, one for washing and one for draining. On Bosch and Miele machines you can reach the pump inlet from inside the tub: lift out the filters and there's a snap-in cover, the pump cover, sitting over the impeller.

How it works

When the control calls for a drain, the motor spins a plastic impeller that flings water into the drain hose. A one-way check valve or flapper on the outlet keeps the water in the hose from running back into the tub.

Signs it is failing

• Standing water in the bottom of the tub after a cycle
• Humming or buzzing during the drain with little water moving
• Grinding or rattling at drain time (often a piece of glass or a fruit pit on the impeller)
• Drain error codes that come back after you've cleaned the filter
• Dirty water flowing back into the tub

Most 'won't drain' and 'long drain' codes start with a clogged filter or a kinked hose, and only point at the pump once those are clear. Some brands also have a code for a blocked pump or a loose pump cover.

Can you replace it yourself?

Kill power at the breaker and bail out the water before you touch anything. On machines with a pump cover, clearing debris from behind it is a homeowner job; Bosch and Miele both walk owners through it, and both warn about glass splinters you can barely see. Swapping the pump itself means pulling the lower access panel or sliding the dishwasher out, which a handy owner can manage.

Buying the right part

Pumps vary even within one brand, so look the part up by the full model number from the label on the door or tub edge. An OEM pump is the safe bet for fit and comes with the matching seal.

Error codes linked to the drain pump

• E24Dishwasher is not draining (blocked drain path)Bosch
• E25Drain pump blocked or pump cover looseBosch
• E23Drain pump faultBosch
• i20Didn't drain completelyFrigidaire
• i50Drain or wash motor problemFrigidaire
• C1 / C2Draining is taking too longGE
• C3 / FTD / F56Dishwasher won't drainGE
• C4Overfill float stuck or sump cloggedGE
• F9E1Long drain (water not pumping out)KitchenAid
• F9E2Drain motor errorKitchenAid
• OENot drainingLG
• F11Water left in the wash cabinet (drain fault)Miele
• Drain indicator flashingDrain light flashing, program stoppedMiele
• 5C / 5E / SC / SEDishwasher is not drainingSamsung
• F9E1Long drain (slow or no drain)Whirlpool
• F9E2Drain motor errorWhirlpool

Last reviewed 2026-10-19.