--- title: "AGA Elise or Mercury induction range showing U400" description: "What U400 means on AGA Elise or Mercury induction ranges, what to check before booking, and when it is not a failure at all." url: "https://rangerepair.center/error-codes/aga-u400/" --- # AGA Elise or Mercury induction range showing U400 U400 means the induction range has been wired wrongly. ## What U400 actually means. U400 means the induction range has been wired wrongly. The control switches off after about a second and the code stays on the display permanently until the connection is corrected. AGA range display What to do when U400 shows on the range ### Kind of code Controls and communication The display, the main board or the induction power board lost contact with one another, or one of them failed its own self-check. A power dip, a loose cable or moisture from a boil-over is ruled out before a board is replaced, and a range that keeps heating while this code shows is switched off at the breaker. ### Usually leads to Knobs, switches and controls Knobs that spin or crack, touch keys that do nothing, blank displays, clocks that reset and control boards that switch the wrong thing. ### Shows up as Range Error Code The range display shows letters, numbers or a flashing symbol, beeps, and stops the oven, a cooking zone or a clean. ### Make AGA A British cooking name, owned by Middleby, that sells cast-iron heat-storage cookers and more conventional dual-fuel and induction ranges in the US. ### Source AGA Elise 36 Induction Owner's Guide Elise and Mercury induction ranges; usually seen at first power-up after installation or after electrical work. ## Before you book, in this order. Each step comes from AGA's own guidance for U400 on its ranges. Follow it to the end: the last card says whether this is a visit. 01 Switch the range off at the breaker and leave it off. 02 Book a visit to have the electrical connection checked; do not keep resetting it. ### Still there? It usually turns into [knobs, switches and controls](https://rangerepair.center/services/knobs-switches-and-controls/). Book with the code and the model number. ### What not to do U400 is not caused by cookware or cooking habits, and it will not clear with use. ## What you may notice with it. The range problems U400 tends to arrive with. Answer these at the range before anyone is booked. [All problems](https://rangerepair.center/problems/) Before you call ### [Range Error Code](https://rangerepair.center/problems/range-error-code/) [All 6 causes, cheapest first](https://rangerepair.center/problems/range-error-code/) It also comes with - [**Range Control Panel Not Responding**](https://rangerepair.center/problems/control-panel-not-responding/) Problem ### Range Error Code 6 causes, cheapest first Where U400 usually leads ## Knobs, switches and controls. **Knobs, keypad or control board · moderate.** Book a visit [What the job involves](https://rangerepair.center/services/knobs-switches-and-controls/) ## AGA ranges. A British cooking name, owned by Middleby, that sells cast-iron heat-storage cookers and more conventional dual-fuel and induction ranges in the US. [AGA range repair](https://rangerepair.center/brands/aga/) More AGA codes [FE](https://rangerepair.center/error-codes/aga-fe/) [VE](https://rangerepair.center/error-codes/aga-ve/) [CE](https://rangerepair.center/error-codes/aga-ce/) [S](https://rangerepair.center/error-codes/aga-s/) [007](https://rangerepair.center/error-codes/aga-007/) [010-014](https://rangerepair.center/error-codes/aga-010-014/) [020-024](https://rangerepair.center/error-codes/aga-020-024/) [060-100](https://rangerepair.center/error-codes/aga-060-100/) [110-116](https://rangerepair.center/error-codes/aga-110-116/) [120-124](https://rangerepair.center/error-codes/aga-120-124/) [130-136](https://rangerepair.center/error-codes/aga-130-136/) [139](https://rangerepair.center/error-codes/aga-139/) [All 21 AGA codes](https://rangerepair.center/error-codes/#codes-aga) Controls and communication on other makes [BlueStar F20](https://rangerepair.center/error-codes/bluestar-range-f20/) [Bosch e005](https://rangerepair.center/error-codes/bosch-e005/) [Café F7](https://rangerepair.center/error-codes/cafe-f7/) [Dacor C-d0](https://rangerepair.center/error-codes/dacor-range-c-d0/) [Electrolux Err](https://rangerepair.center/error-codes/electrolux-err-number/) [Fisher & Paykel F + number](https://rangerepair.center/error-codes/fisher-and-paykel-range-f-number/) [Frigidaire F1](https://rangerepair.center/error-codes/frigidaire-f1/) [Fulgor Milano F15](https://rangerepair.center/error-codes/fulgor-milano-f15/) [All 63 codes of this kind](https://rangerepair.center/error-codes/#family-communication) AGA builds this ### Electric range Coil elements or radiant elements under a smooth glass top, with an electric oven below, all running on a dedicated 240-volt circuit. AGA builds this ### Dual-fuel range Gas burners on top and an electric oven below, the combination most professional-style ranges use, needing both a gas line and a 240-volt circuit. AGA builds this ### Induction range A glass top that heats the pan itself through copper coils and power boards, over an electric oven, with electronics doing almost all the work. ## In AGA's own words > The range has been incorrectly connected. [AGA Elise 36 Induction Owner's Guide](https://d181zs8i7gehnm.cloudfront.net/file/357) [AGA Elise 36 Induction Owner's Guide](https://d181zs8i7gehnm.cloudfront.net/file/357) Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. Elise and Mercury induction ranges; usually seen at first power-up after installation or after electrical work. ## AGA U400 range 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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Switch the range off at the breaker and leave it off. If it comes back, it needs a visit. ### My new AGA Elise shows U400 right away. What went wrong? The wiring to the range does not match what the induction top expects. The installer or an electrician needs to correct it before the range is used. ### Is it safe to keep resetting U400 on an AGA Mercury? No. Leave the range off at the breaker, since the code reports a connection problem that resets do not change. --- **[Read on the site: AGA Elise or Mercury induction range showing U400](https://rangerepair.center/error-codes/aga-u400/)** **[Book a visit with RangeRepair.center](https://rangerepair.center/schedule/)**