# AGA Error Code U400

> AGA error code U400 — The range has been incorrectly connected (supply wiring fault). Which models show it, what causes it and how it is fixed. Mon–Sun 8:00AM–8:00PM. Call or text 206-427-7323.

The range has been incorrectly connected (supply wiring fault) — what this fault code means on AGA induction hob / range error codes, and how we fix it.

**Fault code** · AGA induction hob / range error codes · Installation

## What code U400 means

The range has been incorrectly connected (supply wiring fault)

## Which models show it

- [AGA Elise](https://aga.repair/aga-elise-repair)
- [AGA Mercury](https://aga.repair/aga-mercury-repair)
- [AGA Professional](https://aga.repair/aga-professional-repair)
- [AGA ERA](https://aga.repair/aga-era-repair)

Models: AEL361IN, AEL481IN, AMC36IN, AMC48IN, AMPRO36IN, AEL36INRT, AEL48INRT, AMC36INRT, AMC48INRT, AGA ERA induction

## How it is fixed

The control switches off after approximately 1 second and the code is permanently displayed. Consult the installer or a qualified engineer and correct the mains connection.

> ⚠️ **Safety & DIY disclaimer:** guides on this site are for information only. Appliance repair involves 240V electricity, gas connections, refrigerant and heavy cast-iron parts — anything you do yourself is at your own risk and can damage the appliance or cause injury. The safe option is to book a qualified technician.

## Problems linked to this code

- [Induction range shows U400 — incorrect electrical connection](https://aga.repair/aga-induction-u400)

## More codes on this platform

- [E2 — The electronic unit is too hot](https://aga.repair/aga-error-code-e2)
- [E6 — Cookware / load fault (AGA ERA)](https://aga.repair/aga-error-code-e6)
- [Er + number — Internal technical fault that cannot be rectified by the user](https://aga.repair/aga-error-code-er-plus-number)
- [(no display operation) — Over-voltage or loss of supply voltage to the range](https://aga.repair/aga-error-code-no-display-operation)

## Frequently asked questions

### What does AGA error code U400 mean?

The range has been incorrectly connected (supply wiring fault)

### Can I keep using my AGA with code U400?

A power cycle at the breaker (60 seconds) may clear a one-off code. If the code returns, stop using the affected zone or appliance and book service — continuing to run can turn a small fault into a board-level repair.

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## Book a repair

- Call or text: 206-427-7323 (Mon–Sun 8:00AM–8:00PM, Pacific Time)
- Book online: https://aga.repair/contact/
- Email: service@aga.repair
- Service at your home across the Seattle–Tacoma metro, WA. Diagnostic fee applies toward your repair.

Independent service company — not affiliated with or authorized by AGA / AGA Rangemaster (Middleby). We repair out-of-warranty AGA appliances.