Thermador Dishwasher E18 Shows Low Water Level or Poor Pumping

What E18 means

The dishwasher starts, but the wash seems weak or the cycle stops, and E18 appears. Thermador documents this code as water sitting too low in the tub, or not being pumped properly. The control is waiting for a level it never reaches, and since it will not wash without enough water, it halts. Without an adequate fill the wash cannot do its job, so the number stays until the cause is corrected.

Usual causes of E18

Household water pressure or flow that is too low
An inlet hose that is restricted
A water-pump part that has failed

✓ A safe check worth trying

1. Turn the dishwasher off and check that the supply valve under the sink is fully open. 2. Look for a bend or pinch in the inlet hose along the part you can see. 3. Run the kitchen tap and note whether it flows strongly; Thermador specifies a minimum supply of 10 l/min. 4. Restart the cycle once the supply looks right.

! Why you should stop here

If the home's flow genuinely falls short of the required minimum, a plumber is the right call, not an appliance repair.
When supply and hose are fine, the pump needs testing inside the unit.

Taking off a panel yourself does not by default void a manufacturer warranty, yet it can lead to accidental damage, and some manufacturers attach their own service terms. Read your warranty paperwork, or ask us, before you decide.

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E18E18 questions

How can I tell if my house flow is the problem?

Slow water at other taps points to the house plumbing instead of the dishwasher. Mention that when you call so we start in the right place.

Where does the 10 l/min figure come from?

It is the minimum supply flow Thermador specifies for the dishwasher. Below that, the unit may not fill correctly, so it is a useful reference when checking the supply.

Is a failed pump likely?

It is one of three possibilities and usually the last one we reach. We confirm the supply and the hose first, then test the pump, so you are not paying for a part you do not need.