--- title: "Thermador E12 — limescale in heat pump" description: "What E12 means on Thermador E12 — limescale in heat pumps, what to check before booking, and when it is not a failure at all." url: "https://appliancemaintenance.center/error-codes/thermador-e12/" --- # Thermador E12 — limescale in heat pump Thermador's own support page states E12 as limescale build up in the heat pump, and its own answer text recommends a descaler for hard water deposits and using softener salt where the unit has a built-in softener, to help prevent the issue in future. ## What E12 actually means. Thermador's own support page states E12 as limescale build up in the heat pump, and its own answer text recommends a descaler for hard water deposits and using softener salt where the unit has a built-in softener, to help prevent the issue in future. Thermador home appliance display · also shown as E-12 What to do when E12 shows on the home appliance ### Kind of code Scale and descaling Minerals from the water supply have built up where the appliance heats or freezes water: a steam oven's generator, a built-in coffee system, a dishwasher's heating path, an ice maker's mold and valve. The appliance asks for a descale because scale slows heating and blocks small passages. Run the descaling program with the descaler the maker names, check the water-hardness setting against your local water, and put the next descale on the calendar. ### Usually leads to Water filter and descaling service Fresh filters in dispensers and ice makers, and scale cleared from steam ovens, ice makers and dish care machines. ### Shows up as White Scale on Appliance Water Parts: Steam Ovens, Ice Makers, Dish Care White scale on appliance water parts is a chalky white or tan crust on a steam oven tray, an ice mold or plate, a dispenser outlet or the inside of a dishwasher, left by hard water. ### Make Thermador A Thermador kitchen asks for upkeep in several places at once: star-shaped burner ports, steam oven scale, a column unit's coil and the hood's baffle filters. ### Source Thermador US support, dishwasher error codes Confirmed on Thermador's own US support error-code page for its dish care line. ## Before you book, in this order. Each step comes from Thermador's own guidance for E12 on its home appliances. Follow it to the end: the last card says whether this is a visit. 01 Run a descaling program using a descaler made for the appliance. 02 Check and top up softener salt if the unit has a built-in water softener. 03 If E12 returns soon after a completed descale, book a visit to have the heat pump checked. ### Still there? It usually turns into [water filter and descaling service](https://appliancemaintenance.center/services/water-filter-and-descaling-service/). Book with the code and the model number. ### What not to do E12 does not mean the heat pump has failed; Thermador's own guidance is descaling and salt use, not replacement. A unit that will not heat water at all after a proper descale is a separate problem. ## What you may notice with it. The home appliance problems E12 tends to arrive with. Answer these at the home appliance before anyone is booked. [All problems](https://appliancemaintenance.center/problems/) Before you call ### [White Scale on Appliance Water Parts: Steam Ovens, Ice Makers, Dish Care](https://appliancemaintenance.center/problems/scale-on-water-parts/) [All 6 causes, cheapest first](https://appliancemaintenance.center/problems/scale-on-water-parts/) It also comes with - [**Appliance Maintenance Code or Reminder Light: Filter, Descale, Vent Check**](https://appliancemaintenance.center/problems/appliance-maintenance-code/) Problem ### White Scale on Appliance Water Parts: Steam Ovens, Ice Makers, Dish Care 6 causes, cheapest first Where E12 usually leads ## Water filter and descaling service. **Water filters replaced and flushed, inlet screens checked, descaling run on a steam oven, ice maker or dish care machine · low.** Book a visit [What the job involves](https://appliancemaintenance.center/services/water-filter-and-descaling-service/) ## Thermador home appliances. A Thermador kitchen asks for upkeep in several places at once: star-shaped burner ports, steam oven scale, a column unit's coil and the hood's baffle filters. [Thermador home appliance maintenance](https://appliancemaintenance.center/brands/thermador/) More Thermador codes [E22](https://appliancemaintenance.center/error-codes/thermador-e22/) Scale and descaling on other makes [Bertazzoni Descaling needed. Press OK to start (~45min)](https://appliancemaintenance.center/error-codes/bertazzoni-coffee-descaling-needed/) [Bosch E12](https://appliancemaintenance.center/error-codes/bosch-e12/) [Cove Descale Unit. Check manual.](https://appliancemaintenance.center/error-codes/cove-descale-unit/) [DCS CLEAN](https://appliancemaintenance.center/error-codes/dcs-outdoor-ice-clean/) [Fisher & Paykel DESCALING NEEDED](https://appliancemaintenance.center/error-codes/fisher-and-paykel-coffee-descaling-needed/) [Fulgor Milano PLEASE DESCALE!](https://appliancemaintenance.center/error-codes/fulgor-milano-coffee-please-descale/) [Gaggenau E:2060](https://appliancemaintenance.center/error-codes/gaggenau-e-2060/) [JennAir DESCALE! MEDIUM CUP](https://appliancemaintenance.center/error-codes/jennair-descale-medium-cup/) [All 16 codes of this kind](https://appliancemaintenance.center/error-codes/#family-scale) Thermador builds this ### Cold storage Upkeep for everything in the house that keeps things cold: refrigerators, freezers, wine and beverage units and ice makers, cleaned and checked before they start struggling. Thermador builds this ### Cooking appliances Upkeep for ovens, ranges, cooktops, hoods, microwaves, steam and speed ovens: burners and igniters cleaned, gas joints checked, grease filters and descaling done on time. Thermador builds this ### Dish care Upkeep for dishwashers and disposers: filters rinsed, spray arms cleared, the door seal and drain loop checked, and hard-water scale kept off the parts that heat and spray. ## In Thermador's own words > E12 - There is limescale build up in the heat pump. Use a descaler to remove hard water deposits and limescale buildup. To help avoid this issue in future instances, use softener salt in your dishwasher if it comes with a water softener. [Thermador US support, dishwasher error codes](https://www.thermador.com/us/support/dishwashers/error-codes) Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. Confirmed on Thermador's own US support error-code page for its dish care line. ## Thermador E12 home appliance maintenance, where we come out. The same visit in every metro below: the code, the model number, and a diagnosis before any part is ordered. 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Run a descaling program using a descaler made for the appliance. If it comes back, it needs a visit. ### Does using softener salt fully prevent E12? Thermador's own wording frames it as a way to help avoid the issue in future, not a guarantee, so periodic descaling is still worth doing even in a home that uses softener salt. ### Is E12 more common in hard-water areas? Yes, though Thermador's page does not name water hardness directly for this exact model line, limescale build-up in a heat pump is a well-documented hard-water effect across the brand's dish care line. ### Can a household descaler be used instead of Thermador's own? The support page's own instruction is to use a descaler; check the appliance's operating instructions for the specific product it recommends before substituting a different one. --- **[Read on the site: Thermador E12 — limescale in heat pump](https://appliancemaintenance.center/error-codes/thermador-e12/)** **[Book a visit with ApplianceMaintenance.center](https://appliancemaintenance.center/schedule/)**