--- title: "La Cornue cooktop error code U400" description: "La Cornue cooktop error code U400: La Cornue error code U400 is an electrical-connection message rather than an appliance failure." url: "https://la-cornuemiami.support/error-codes/u400/" date_modified: "2026-09-04" Appliance type: "Cooktops and rangetops, Ranges" --- # La Cornue cooktop error code U400 ### What U400 means, in the maker’s own words La Cornue error code U400 is an electrical-connection message rather than an appliance failure. The control shuts off after about a second and then leaves the code on the display permanently, which is deliberate: it is not a transient warning you can cook around. In practice it turns up after something changed — a new installation, a breaker or panel replaced, a range moved, electrical work in the kitchen — and it means the supply reaching the appliance is not what the appliance requires. It is one of the few messages on this make where the honest answer may be that nothing inside your range is broken. ### Quoted rather than interpreted > The cooker has been incorrectly connected. The control will switch off after approximately 1 second and the error code will be permanently displayed. From the CornuFé 110 induction installation and user guide (U111136-03, January 2023), in a User Guide & Service Manual downloaded from La Cornue’s own site. Nothing on this page is decoded beyond what that sentence says. ### Where this code actually appears On the induction hob’s own display, and nowhere else. Most of this appliance cannot tell you anything at all: the vaulted gas oven has no window and no display, the gas top is mechanical valves behind brass knobs, and the Château install and user guide contains no troubleshooting section. All three of the codes La Cornue publishes anywhere — this one, U400, and Er followed by a number — appear in the induction sections of its guides and on the induction panel. Photograph what the hob shows before cutting the power: a reset erases it, and on a make this quiet the code is most of the diagnosis. ### Which machines this one applies to La Cornue induction cooktops and rangetops, and the electric and multifunction ovens. La Cornue publishes three codes in the whole of its US documentation and its Château guide carries no troubleshooting section, so a behavior missing from this archive is not proof that your appliance cannot do it — the maker simply never wrote a table for it. What its guides do document, they document in sentences, and those are on this site under the maker’s own wording. The model number, and which top the range was ordered with, settle what any of it means. ### What to do about it - Find out what changed. A latched U400 almost always dates from a specific day’s work on the kitchen, the panel or the range itself. - Do not keep power-cycling it. The code is designed to stay until the connection is correct, so clearing it proves nothing and tells you nothing. - Have the supply and the connection at the appliance measured against La Cornue’s own gas and electrical requirements document. - Expect the finding in writing if the problem is upstream of the range. That is a report to take to whoever did the work, not a part to buy. - Have it corrected by someone qualified to work on the supply. This is not a reset. ### Where this goes next The job this usually becomes is [cooktop control and wiring repair](/services/cooktop-control-and-wiring-repair/), and every one of those pages carries a starting figure and the reasons that move it. If it turns out to be nothing — and on this make a real share of these are modes rather than problems — the visit ends there and you pay the diagnostic and nothing else, or call [(305) 614-3699](tel:+13056143699) and describe what the display is doing before booking anything. La Cornue induction cooktops and rangetops, and the electric and multifunction ovens What this one means What U400 means, in the maker’s own words La Cornue error code U400 is an electrical-connection message rather than an appliance failure. The control shuts off after about a second and then leaves the code on the display permanently, which is deliberate: it is not a transient warning you can cook around. In practice it turns up after something changed — a new installation, a breaker or panel replaced, a range moved, electrical work in the kitchen — and it means the supply reaching the appliance is not what the appliance requires. It is one of the few messages on this make where the honest answer may be that nothing inside your range is broken. Quoted rather than interpreted The cooker has been incorrectly connected. The control will switch off after approximately 1 second and the error code will be permanently displayed. From the CornuFé 110 induction installation and user guide (U111136-03, January 2023), in a User Guide & Service Manual downloaded from La Cornue’s own site. Nothing on this page is decoded beyond what that sentence says. Where this code actually appears On the induction hob’s own display, and nowhere else. Most of this appliance cannot tell you anything at all: the vaulted gas oven has no window and no display, the gas top is mechanical valves behind brass knobs, and the Château install and user guide contains no troubleshooting section. All three of the codes La Cornue publishes anywhere — this one, U400, and Er followed by a number — appear in the induction sections of its guides and on the induction panel. Photograph what the hob shows before cutting the power: a reset erases it, and on a make this quiet the code is most of the diagnosis. Which machines this one applies to La Cornue induction cooktops and rangetops, and the electric and multifunction ovens. La Cornue publishes three codes in the whole of its US documentation and its Château guide carries no troubleshooting section, so a behavior missing from this archive is not proof that your appliance cannot do it — the maker simply never wrote a table for it. What its guides do document, they document in sentences, and those are on this site under the maker’s own wording. The model number, and which top the range was ordered with, settle what any of it means. What to do about it Find out what changed. A latched U400 almost always dates from a specific day’s work on the kitchen, the panel or the range itself. Do not keep power-cycling it. The code is designed to stay until the connection is correct, so clearing it proves nothing and tells you nothing. Have the supply and the connection at the appliance measured against La Cornue’s own gas and electrical requirements document. Expect the finding in writing if the problem is upstream of the range. That is a report to take to whoever did the work, not a part to buy. Have it corrected by someone qualified to work on the supply. This is not a reset. Where this goes next The job this usually becomes is cooktop control and wiring repair, and every one of those pages carries a starting figure and the reasons that move it. If it turns out to be nothing — and on this make a real share of these are modes rather than problems — the visit ends there and you pay the diagnostic and nothing else, or call [(305) 614-3699](tel:+13056143699) and describe what the display is doing before booking anything. --- **[Read full article: La Cornue cooktop error code U400](https://la-cornuemiami.support/error-codes/u400/)**