--- title: "Thermador induction cooktop showing U400" description: "What U400 means on Thermador induction cooktops, what to check before booking, and when it is not a failure at all." url: "https://cooktoprepair.center/error-codes/thermador-u400/" --- # Thermador induction cooktop showing U400 U400 means the cooktop measured incoming voltage that is too high or too low. ## What U400 actually means. U400 means the cooktop measured incoming voltage that is too high or too low. It points to the circuit feeding the cooktop. Thermador cooktop display What to do when U400 shows on the cooktop ### Kind of code Induction power and coils An induction zone could not drive its coil as the board planned: no pan was detected, the current ran too high or too low, or the power stage reported trouble. The pan base, the supply voltage and a clogged air intake are checked before the coil or the power board is replaced, and a top that trips its breaker is left switched off until then. ### Usually leads to Induction board and coil repair Induction zones that stop sensing pans, cut out, buzz or show codes, traced to the power boards, the coils, their sensors and the links to the controls. ### Shows up as Cooktop Tripping Breaker The circuit breaker for the cooktop trips as a burner or zone switches on, at one particular setting, or a few minutes into cooking. ### Make Thermador A BSH-owned luxury brand that lists gas, electric and induction cooktops alongside pro-style rangetops. ### Source Thermador induction cooktop error codes (US support) Listed on Thermador's induction cooktop page. ## Before you book, in this order. Each step comes from Thermador's own guidance for U400 on its cooktops. Follow it to the end: the last card says whether this is a visit. 01 Turn the breaker off. 02 Do not work inside the junction box under the cooktop yourself. 03 Ask the utility or an electrician to check the supply; if it is normal and U400 remains, book a visit. ### Still there? It usually turns into [induction board and coil repair](https://cooktoprepair.center/services/induction-board-and-coil-repair/). Book with the code and the model number. ### What not to do U400 is not caused by cookware and is not cleared by cooking through it. It points to the circuit feeding the cooktop, not to a failed zone. ## What you may notice with it. The cooktop problems U400 tends to arrive with. Answer these at the cooktop before anyone is booked. [All problems](https://cooktoprepair.center/problems/) Before you call ### [Cooktop Tripping Breaker](https://cooktoprepair.center/problems/cooktop-tripping-breaker/) [All 6 causes, cheapest first](https://cooktoprepair.center/problems/cooktop-tripping-breaker/) It also comes with - [**Cooktop Controls Unresponsive**](https://cooktoprepair.center/problems/cooktop-controls-unresponsive/) - [**Cooktop Error Code**](https://cooktoprepair.center/problems/cooktop-error-code/) Gas, fire, broken glass or live current ### Cooktop Tripping Breaker 6 causes, cheapest first Where U400 usually leads ## Induction board and coil repair. **Induction power board, coil or sensor · moderate to highest.** Book a visit [What the job involves](https://cooktoprepair.center/services/induction-board-and-coil-repair/) ## Thermador cooktops. A BSH-owned luxury brand that lists gas, electric and induction cooktops alongside pro-style rangetops. [Thermador cooktop repair](https://cooktoprepair.center/brands/thermador/) More Thermador codes [dE](https://cooktoprepair.center/error-codes/thermador-de/) [F0](https://cooktoprepair.center/error-codes/thermador-f0/) [F1](https://cooktoprepair.center/error-codes/thermador-f1/) [F2](https://cooktoprepair.center/error-codes/thermador-f2/) [F5](https://cooktoprepair.center/error-codes/thermador-f5/) [F8](https://cooktoprepair.center/error-codes/thermador-f8/) [F9](https://cooktoprepair.center/error-codes/thermador-f9/) [E9000](https://cooktoprepair.center/error-codes/thermador-e9000/) [E9011](https://cooktoprepair.center/error-codes/thermador-e9011/) [E7010](https://cooktoprepair.center/error-codes/thermador-e7010/) [E8204](https://cooktoprepair.center/error-codes/thermador-e8204/) [E8205](https://cooktoprepair.center/error-codes/thermador-e8205/) [All 14 Thermador codes](https://cooktoprepair.center/error-codes/#codes-thermador) Induction power and coils on other makes [Bertazzoni U400](https://cooktoprepair.center/error-codes/bertazzoni-u400/) [Bosch U400](https://cooktoprepair.center/error-codes/bosch-u400/) [Dacor C2](https://cooktoprepair.center/error-codes/dacor-c2/) [Fulgor Milano U400](https://cooktoprepair.center/error-codes/fulgor-milano-s700-u400/) [Gaggenau E9000](https://cooktoprepair.center/error-codes/gaggenau-e9000/) [KitchenAid FC E0](https://cooktoprepair.center/error-codes/kitchenaid-fc-e0/) [Samsung C2](https://cooktoprepair.center/error-codes/samsung-c2/) [SKS F33~F45](https://cooktoprepair.center/error-codes/sks-f33-f45/) [All 22 codes of this kind](https://cooktoprepair.center/error-codes/#family-induction) Thermador builds this ### Gas cooktop A gas cooking surface dropped into a countertop cutout, with its gas line and power cord running down into the cabinet underneath. Thermador builds this ### Induction cooktop A glass cooktop in the counter that heats the pan itself through magnetic coils, run by power boards and cooled by a fan underneath. Thermador builds this ### Rangetop A pro-style gas cooking top with its knobs across the front, set into a notch above a base cabinet, often with a griddle or char-broiler beside the burners. ## In Thermador's own words > The supply voltage is incorrect. It is outside the normal operating range. [Thermador induction cooktop error codes (US support)](https://www.thermador.com/us/support/induction-cooktops/error-codes) Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. Listed on Thermador's induction cooktop page. ## Thermador U400 cooktop repair, 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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Turn the breaker off. If it comes back, it needs a visit. ### Why would my Thermador show U400 only in the evening? Voltage can sag when demand on the neighborhood grid is high. A measurement at that time helps the utility or electrician. ### Should I reset the breaker until U400 goes away? No. Leave it off and have the supply checked first. ### Does Thermador list U400 alongside E9000 and E9010? Thermador gives U400 the same meaning as E9000 and E9010: supply voltage outside the normal operating band. All three call for the circuit to be checked before the cooktop. If the supply measures normal, a visit looks at the cooktop. --- **[Read on the site: Thermador induction cooktop showing U400](https://cooktoprepair.center/error-codes/thermador-u400/)** **[Book a visit with CooktopRepair.center](https://cooktoprepair.center/schedule/)**