Thermador Dishwasher Error E15: Water in Base / Anti-Flood (Aquastop) Triggered

What E15 indicates

Thermador dishwashers use a Bosch-platform anti-flood system: a polystyrene float sits in the base pan and rides up if any water leaks below the tub. When it lifts, a microswitch tells the control to lock out the cycle, keep the drain pump running, and stop filling. E15 (sometimes shown as the tap/faucet symbol) indicates that float has been triggered, which almost always points to a genuine leak somewhere in the wash system rather than a sensor glitch.

Likely causes

• Active leak from the sump, pump seal, or tub-to-base joint allowing water into the base pan
• Leaking or perished door gasket or tub gasket letting water escape downward
• Cracked or detached spray-arm feed hose or internal fill hose
• Excessive suds from too much or wrong detergent overflowing into the base
• Waterlogged or stuck anti-flood foam float keeping the switch closed

What causes E15

Water reaches the base from a leaking door or tub gasket, a cracked or loose sump, a weeping pump seal, a split spray-arm feed or fill hose, or a leaking heat exchanger. Hard-water mineral buildup and an overdose of detergent can cause excessive sudsing that overflows into the base. On older units the float foam can absorb water and stick up, but a true leak should always be ruled out first.

Symptoms you may notice

• Dishwasher will not start and the drain pump runs continuously, even with the door open
• E15 code or a faucet/tap icon on the display
• Standing water or dampness under the unit or on the kitchen floor
• Cycle stops mid-wash and the machine keeps humming (pump running)
• Resetting power makes the pump run immediately rather than starting a cycle

Parts typically replaced for E15

• Sump / tub gasket and seals — Replace cracked sump, perished gaskets, or a leaking pump shaft seal that is dripping into the base
• Door or tub gasket — Replace when worn or distorted gasket is the leak source
• Anti-flood (Aquastop) float and microswitch assembly — Replace only if the float foam is waterlogged or the switch fails to reset after the base is dried and proven leak-free
• Internal fill or spray-arm feed hose — Replace if split, cracked, or popped off its fitting

Owner-safe checks for E15

• Turn the dishwasher off at the breaker and look for standing water or dampness under and around the unit
• Check that you are using dishwasher detergent (not liquid soap) and not overdosing, which causes suds overflow
• Make sure the unit is level so water is not pooling toward one corner
• Do not tip the machine or remove the base panel yourself; note whether the pump runs as soon as power is restored

When to call a technician

E15 means water is already in the base, so the cause is almost always a real leak that must be located by removing the lower panel and pressure-testing the sump, pump, and hoses, then drying the base and resetting the float. Running the machine without finding the leak risks repeat trips and floor or cabinet damage.