---
title: "Thermador dishwasher error code E12"
description: "Thermador dishwasher error code E12: thermador error code E12: hard water has left enough scale in the heat pump to change how it heats."
url: "https://thermadormiami.support/error-codes/error-code-e12-dishwasher/"
date_modified: "2026-08-18"
Appliance type: "Dishwashers"
---


# Thermador dishwasher error code E12

Error code

# Thermador dishwasher error code E12

Thermador error code E12: hard water has left enough scale in the heat pump to change how it heats. What the code covers, what to check first, and what it does not tell you — on dishwashers.

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## Book a diagnostic visit

Your model number and a line about what it is doing is enough to get started.

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What we can confirm

## Code E12, from the manufacturer’s own documentation

A code is only meaningful together with the generation showing it — the same two digits mean different things across generations.

The code

E12

Hard water has left enough scale in the heat pump to change how it heats

or call [(305) 846-7685](tel:+13058467685)

What it narrows down to

Limescale in the heat pump

What you are probably seeing

[Dishwasher not cleaning properly](https://thermadormiami.support/symptoms/dishwasher-not-cleaning/)

Diagnostic

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What it looks like from the kitchen

## The symptom this code usually arrives with

A code names the subsystem; the symptom is what sent you to look at the display in the first place. That page says what it usually turns out to be, cheapest cause first.

- Dishwasher not cleaning properly
					Grit left on plates, a film on glasses, or detergent still sitting in the cup at the end. On hard water most of this is chemistry and loading before it is ever a part.

														Grit or food left on the lower rack

														A cloudy film on glassware

														Detergent still in the dispenser afterwards

								[

				What it usually means

			](https://thermadormiami.support/symptoms/dishwasher-not-cleaning/)
Grit left on plates, a film on glasses, or detergent still sitting in the cup at the end. On hard water most of this is chemistry and loading before it is ever a part.

- Grit or food left on the lower rack
- A cloudy film on glassware
- Detergent still in the dispenser afterwards
In more detail

## About Thermador dishwasher error code E12

### What this one means

Hard water has left enough scale in the heat pump to change how it heats. It is a code the manufacturer publishes for this appliance, not one we have worked out — and it is decoded here rather than left as three characters on a display.

### The other ways your machine may say it

The same condition is published under more than one label, because it has been carried across generations of this appliance:

- **E12, E2060** — the same condition, on machines of different ages

### What the code covers

A published cause names a circuit rather than a component, which is the single most useful thing to know before ordering a part. This one covers:

- The heat pump’s heat exchanger
- The water softener, if it is empty of salt
- Months of South Florida water

### What to try yourself

- Run a descaler through an empty machine
- If the machine takes softener salt, refill it — the reservoir is in the tub floor

### Then what

Miami-Dade water is hard enough that this is maintenance rather than a failure. It comes back if the salt stays empty.

This code is published for dishwashers. The [full list of codes](https://thermadormiami.support/error-codes/) has the rest of them, searchable, including the labels older and newer machines use for the same conditions.

This article is based on:

- Official manufacturer documentation
- Internal repair procedures
- Technician repair history
- Company quality standards

## Tell us the model number and what it is doing.

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