--- title: "La Cornue CornuFé showing U400 at power-up" description: "What U400 means on La Cornue CornuFés, what to check before booking, and when it is not a failure at all." url: "https://stoverepair.center/error-codes/la-cornue-u400/" --- # La Cornue CornuFé showing U400 U400 is the CornuFé's signal that its electrical connection is not correct. ## What U400 actually means. U400 is the CornuFé's signal that its electrical connection is not correct. About a second after power-up the control shuts itself off, and the code stays on the display until the connection is fixed. La Cornue stove display What to do when U400 shows on the stove ### Kind of code Control board and power The main board failed its own start-up check, lost contact with the display, or saw the supply voltage sag too low, often after a storm, a power outage or a spill that ran down behind the panel. The breaker, the cord and the outlet are ruled out before a board is replaced. A stove that sparks, smells of hot wiring or keeps heating while this code shows is switched off at the breaker first. ### Usually leads to Control board and display repair Stoves with a blank or flashing display, touch keys that do not answer, codes that keep returning or a stove that will not turn on, traced to the board, the keypad or the power to them. ### Shows up as Stove Error Code The stove shows letters and numbers, a flashing symbol or a short message, beeps, and the oven or a burner stops or will not start. ### Make La Cornue A French stove maker, part of the Middleby group, whose pieces are assembled by hand and finished to order. ### Source La Cornue CornuFé induction user and installation guide CornuFé 90 and 110 induction models; the code concerns the connection to the house supply. ## Before you book, in this order. Each step comes from La Cornue's own guidance for U400 on its stoves. Follow it to the end: the last card says whether this is a visit. 01 Turn the stove off at its breaker. 02 Do not keep switching it back on to test it. 03 Book a visit to have the hookup to the supply inspected before anyone uses the stove again. ### Still there? It usually turns into [control board and display repair](https://stoverepair.center/services/control-board-and-display-repair/). Book with the code and the model number. ### What not to do U400 does not mean the induction coils or boards inside the stove are damaged. It points to how the stove was hooked up, so the connection is checked first. ## What you may notice with it. The stove problems U400 tends to arrive with. Answer these at the stove before anyone is booked. [All problems](https://stoverepair.center/problems/) Before you call ### [Stove Error Code](https://stoverepair.center/problems/stove-error-code/) [All 8 causes, cheapest first](https://stoverepair.center/problems/stove-error-code/) It also comes with - [**Stove Won't Turn On**](https://stoverepair.center/problems/stove-wont-turn-on/) Problem ### Stove Error Code 8 causes, cheapest first Where U400 usually leads ## Control board and display repair. **Control board, keypad or display · moderate.** Book a visit [What the job involves](https://stoverepair.center/services/control-board-and-display-repair/) ## La Cornue stoves. A French stove maker, part of the Middleby group, whose pieces are assembled by hand and finished to order. [La Cornue stove repair](https://stoverepair.center/brands/la-cornue/) More La Cornue codes [E2](https://stoverepair.center/error-codes/la-cornue-e2/) [Er](https://stoverepair.center/error-codes/la-cornue-er/) [U](https://stoverepair.center/error-codes/la-cornue-u/) [E](https://stoverepair.center/error-codes/la-cornue-e/) [H](https://stoverepair.center/error-codes/la-cornue-h/) [L](https://stoverepair.center/error-codes/la-cornue-l/) Control board and power on other makes [AGA CE](https://stoverepair.center/error-codes/aga-ce/) [BlueStar F20](https://stoverepair.center/error-codes/bluestar-f20/) [Bosch e005](https://stoverepair.center/error-codes/bosch-e005/) [Café F97](https://stoverepair.center/error-codes/cafe-f97/) [Dacor C-F0](https://stoverepair.center/error-codes/dacor-c-f0/) [Electrolux Err](https://stoverepair.center/error-codes/electrolux-err/) [Fisher & Paykel F](https://stoverepair.center/error-codes/fisher-and-paykel-f/) [Frigidaire F3](https://stoverepair.center/error-codes/frigidaire-f3/) [All 79 codes of this kind](https://stoverepair.center/error-codes/#family-board) La Cornue builds this ### Gas stove A stove with gas burners on top, whether its oven below runs on gas too or on electricity, fed by one gas line behind it and plugged into a wall outlet for the spark. La Cornue builds this ### Induction stove A stove with a flat glass top that heats the pan itself through a magnetic field, run by touch keys and power boards, with an electric oven underneath. La Cornue builds this ### Heritage stove Classic stoves built the old way, from AGA cast-iron heat storage stoves to French and Italian enamel stoves with brass trim, kept for decades and repaired rather than replaced. ## In La Cornue's own words > The cooker has been incorrectly connected. The control will switch off after approximately 1 second and the error code will be permanently displayed. [La Cornue CornuFé induction user and installation guide](https://d2a7uujil7d64c.cloudfront.net/file/450) Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. CornuFé 90 and 110 induction models; the code concerns the connection to the house supply. ## La Cornue U400 stove 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 stove off at its breaker. If it comes back, it needs a visit. ### My new CornuFé shows U400 on day one. Did it leave the factory defective? U400 describes an incorrect connection, not a failed part, so the installation is the first suspect. Turn the breaker off and book a visit. ### Why does my CornuFé turn itself off one second after I switch it on? If U400 is showing, that is the behavior La Cornue describes for a wrong connection. Keep the stove off at the breaker until the wiring has been looked at. ### Could U400 on my La Cornue follow a panel upgrade in the house? It could, if the stove's circuit was reconnected differently. Tell us about the electrical work when you book. --- **[Read on the site: La Cornue CornuFé showing U400 at power-up](https://stoverepair.center/error-codes/la-cornue-u400/)** **[Book a visit with StoveRepair.center](https://stoverepair.center/schedule/)**