Thermador Dishwasher Error E24: Not Draining / Blocked Drain Path

What E24 indicates

E24 is a drainage fault on the Bosch-platform control. After the wash and rinse phases, the drain pump should evacuate the tub within a set time; if the control still senses water (via the flow logic and water level) after the pump has run, it stops and reports E24. The fault points to a mechanical restriction downstream of the pump rather than to the pump motor being electrically dead.

Likely causes

• Kinked, looped, or clogged corrugated drain hose
• Disposer knockout plug not removed, or a clogged disposer inlet
• Stuck or debris-blocked drain-pump check valve / non-return flap
• Clogged countertop air gap restricting flow
• Heavy grease and food buildup in the sump narrowing the drain path

What causes E24

The most common cause is a kinked, looped, or clogged drain hose, or a disposer with the knockout plug still installed. The drain-pump check valve or non-return flap can stick shut with grease and food debris, and the air gap on the countertop can clog. Standing water from a previous cycle, food soil, and grease buildup all contribute. A high-looped hose installed incorrectly can siphon and confuse the level logic.

Symptoms you may notice

• Standing dirty water in the bottom of the tub at the end of a cycle
• E24 displayed at or near the end of the cycle
• Drain pump hums but little or no water leaves the machine
• Dishes come out wet with food residue
• Gurgling at the sink air gap or backflow into the disposer side

Parts typically replaced for E24

• Drain hose — Replace if internally collapsed, split, or permanently kinked and cannot be cleared
• Drain pump / check valve assembly — Replace if the check valve is damaged or the pump impeller is cracked or jammed and will not clear
• Air gap insert — Replace the air gap cap and insert if clogged and not cleanable

Owner-safe checks for E24

• Remove the lower rack and clear the cup-shaped filter and any debris in the sump by hand
• Check that the drain hose under the sink is not kinked, pinched, or looped on the floor
• If connected to a new disposer, confirm the knockout plug was removed
• Clean the countertop air gap by twisting off the cap and rinsing the insert, then run a drain cycle

When to call a technician

If clearing the filter, hose, and air gap does not resolve it, a technician needs to access the drain pump and check valve, test the pump electrically, and verify the install loop and connections. Diagnosing whether the restriction is in the pump versus the plumbing requires partial disassembly.