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Dishwasher Drain hose and air gap: What It Does and Signs It's Failing

The corrugated hose that carries waste water from the drain pump to the sink drain or garbage disposal. Some installs run it through an air gap, the small chrome cap on the countertop or sink deck that keeps sink water from siphoning back into the dishwasher.

How it works

The drain pump pushes water up the hose, which is looped high under the counter or run through the air gap so dirty water can't flow back. Bosch, for example, wants part of the hose raised 33 to 43 in (84 to 110 cm) above the cabinet floor, and LG says to keep the end at least 12 in (30 cm) up. From there it empties into the disposal inlet or a sink tailpiece.

Signs it is failing

• Water left in the tub after the cycle
• Water spurting out of the countertop air gap during draining
• Drain codes with clean filters
• A kinked or crushed hose behind the machine
• Leaks at the hose clamp under the sink

Long-drain and 'didn't drain' codes very often come from this hose, a clogged air gap or a new disposal whose knockout plug was never removed.

Can you replace it yourself?

Pull the air gap cap and clear any gunk, check the hose for kinks, and on a new disposal make sure the knockout plug was punched out. Those checks are easy. Swapping the hose means shutting off power and water and sliding the machine out, which most handy owners can manage.

Buying the right part

Universal drain hoses exist, but the pump end often needs a model-specific fitting. Buy the OEM hose if the old one has a molded connector.

Error codes linked to the drain hose and air gap

• E15Water detected in the base (leak protection)Bosch
• E24Dishwasher is not draining (blocked drain path)Bosch
• i20Didn't drain completelyFrigidaire
• i40 / iF0Clogged filter or sumpFrigidaire
• C1 / C2Draining is taking too longGE
• C3 / FTD / F56Dishwasher won't drainGE
• F9E1Long drain (water not pumping out)KitchenAid
• F9E2Drain motor errorKitchenAid
• OENot drainingLG
• Drain indicator flashingDrain light flashing, program stoppedMiele
• 5C / 5E / SC / SEDishwasher is not drainingSamsung
• OC / 0C / OEToo much water in the tub (overfill)Samsung
• LC / LELeak detectedSamsung
• F9E1Long drain (slow or no drain)Whirlpool

Last reviewed 2026-10-19.