# Induction range shows U400 — incorrect electrical connection

> Induction range shows U400 — incorrect electrical connection: symptoms, likely causes and how a technician diagnoses it. Occasional AGA issue. Mon–Sun 8:00AM–8:00PM. Call or text 206-427-7323.

Occasional issue — here is how we diagnose it, which parts are usually involved, and when to call a pro.

**Occasional** · Professional repair only

## What you will notice

- U400 displayed permanently
- Control switches off after about one second

## What is usually behind it

- Range incorrectly connected to the supply (definitive)

## How a technician diagnoses it

1. This is an installation fault, not a component fault. Verify the supply connection against the wiring diagram and correct it.
2. Common on new installs and after a service disconnection.

## Appliances affected

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

> ⚠️ **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.

## Related AGA problems

- [Gas oven will not heat — bake ignitor glows but the gas valve never opens](https://aga.repair/aga-range-bake-ignitor-weak)
- [Range burner lights then goes out when the knob is released](https://aga.repair/aga-range-burner-wont-stay-lit)
- [Range cooktop burners will not spark, or spark continuously](https://aga.repair/aga-range-no-spark)

## Frequently asked questions

### Can I fix this myself?

Professional repair only. This fault involves gas or 240V electrical components — diagnosis and repair should be done by a licensed technician.

### How much does it cost to fix this issue?

Every visit starts with diagnostics and a written estimate — the diagnostic fee applies toward your repair when you proceed. We never start work without your approval.

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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.