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The open door of a built-in home steam oven in a clean kitchen, its empty stainless cavity and water tank drawer in view, a clear jug of water on the counter beside it, nobody in the frame.

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.

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Mon–Sat, 8am–8pm

  • Scale and descaling
  • Water filter and descaling service
  • Source: Thermador

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or call (844) 879-5178

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 codeScale 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 toWater 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 asWhite 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.

MakeThermador

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.

SourceThermador 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. 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

Before you call

White Scale on Appliance Water Parts: Steam Ovens, Ice Makers, Dish Care

All 6 causes, cheapest first

It also comes with

Close view into the open door of a built-in steam oven in a home kitchen wall, the stainless evaporator tray at the bottom of the cavity coated with a chalky white crust, the removable water tank set beside it on the counter with a white mineral ring inside, soft daylight. 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

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

More Thermador codes

E22

Scale and descaling on other makes

Bertazzoni Descaling needed. Press OK to start (~45min)Bosch E12Cove Descale Unit. Check manual.DCS CLEANFisher & Paykel DESCALING NEEDEDFulgor Milano PLEASE DESCALE!Gaggenau E:2060JennAir DESCALE! MEDIUM CUP
All 16 codes of this kind
A tidy home kitchen with a tall built-in stainless column refrigerator and freezer pair set into light wood cabinetry, the toe grille at floor level removed and leaning against the cabinet, a technician seen only from the shoulders down kneeling on a gray mat and drawing a long soft coil brush out from under the unit, a small canister vacuum beside him, even daylight from a side window. 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.

 A home kitchen with a stainless pro-style gas range and a matching hood above it against a light tile backsplash, the grates lifted off and laid on a folded towel on the counter, a technician seen only from the shoulders down wiping a brass burner cap with a soft cloth, a clean baffle filter leaning beside the towel, all burners off, soft daylight. 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.

 An open built-in dishwasher in a bright home kitchen with white cabinets, both racks pulled out and empty, the cylindrical filter lifted out and held over a stainless sink by a technician seen only from the shoulders down, a lower spray arm resting on a folded towel on the counter, soft daylight. 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

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.

All service areas

Tampa BayFL · 31 areas

OrlandoFL · 30 areas

Miami / South FloridaFL · 47 areas

New York MetroNY · 75 areas

HoustonTX · 36 areas

ChicagoIL · 50 areas

Los AngelesCA · 95 areas

San DiegoCA · 31 areas

San Francisco Bay AreaCA · 74 areas

A family sharing breakfast in a bright, well-kept home kitchen.
For the heart of your home.

Questions
about E12.

Can I clear E12 myself?
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.

Back to your everyday

Still showing E12?

A booking goes further when it has the reminder or code as shown, the model number from the rating plate, and a word on when that filter, screen or tub was last cleaned. With those three, the office can pack the right filter or cleaner for your appliance.

Schedule maintenance Call (844) 879-5178
(844) 879-5178 Schedule maintenance