- Appliances
- Cooktops
U400
Bosch U400 on induction cooktop: incorrect supply voltage
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
Your Bosch induction cooktop shows U400 because the supply voltage is incorrect and outside the normal range. If the cooktop is new, have the installer check the connection; otherwise, contact your electrical utility provider or Bosch service.
Safety first
Stop and check this first
- Do not handle the cooktop electrical connection: it is mains voltage. Checking it is a job for a qualified installer or electrician.
Safe checks you can perform
- Read the code and when it appears
- Switch the cooktop off at the breaker
- Connection and voltage check
Leave these tasks to a qualified professional
- Do not attempt this professional task: Connection check against the diagram
- Do not attempt this professional task: Supply voltage measurement
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Connection check against the diagram
What they doThe installer or an electrician checks the cooktop terminal box against the manufacturer diagram.
They must show youthe connection checked, or a photo of it.
In writingwhat was found and corrected.
Supply voltage measurement
What they doAn electrician measures the voltage reaching the cooktop with an instrument.
They must show youthe measured value against the rating plate range.
In writingthe measurement and, if the cooktop is repaired, the replaced part with its reference and the final test.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Read the code and when it appears
- Who:
- you.
- How:
- if you only see an E, press and hold the zone touch key to read the full code, as Bosch explains, and note whether it appeared at first start up or after months of use.
- Result that matters:
- knowing whether it points to installation or supply.
- If it appeared when new:
- the connection is most likely; tell the installer.
- If it worked fine before:
- watch whether other appliances fail and contact the utility or Bosch.
- Evidence to keep:
- a photo of the code and the installation date.
Evidence: Bosch Induction Cooktop Error Codes · ¿Error E en tu placa de inducción? Significado y solución
Switch the cooktop off at the breaker
- Who:
- you.
- How:
- switch the cooktop circuit breaker off and leave it off until a professional checks it.
- Result that matters:
- not using a cooktop on incorrect voltage.
- If the warning does not show after switching back on:
- note it anyway for the electrician or utility.
- If it shows again:
- keep it switched off.
- Evidence to keep:
- a note of how many times it appeared.
Evidence: Bosch Induction Cooktop Error Codes
Connection and voltage check
- Who:
- the installer or a qualified electrician, never you.
- How:
- ask them to check the cooktop connection against its diagram and measure the supply voltage on its circuit.
- Result that matters:
- confirming or ruling out installation and supply.
- If they find a wrong connection or voltage out of range:
- the cause is not the cooktop.
- If everything is fine and U400 remains:
- call Bosch service with the report.
- Evidence to keep:
- the report with the measured voltage and what was checked.
The connection and mains voltage measurement may only be done by a qualified installer or electrician, with the power cut to handle the connection.
Evidence: Bosch Induction Cooktop Error Codes
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Appliances
- Brand
- Bosch
- Product type
- Cooktops
Known code variants
- Bosch cooktop U400
- Bosch U400
- Neff E9011 placa
- Neff hob E9011
- Neff hob U400
- Neff hob U400 connection
- Neff U 400 inducción
- Neff U 400 induction
- Neff U400 placa
- placa inducción Bosch U400
- placa Neff U400 conexión
- U 400
What it means
In its induction cooktop code guide, Bosch defines U400 as incorrect supply voltage, outside the normal operating range, and refers you to the utility provider or its service. The cooktop monitors the voltage it receives, so the warning can come from the supply, the home wiring or a cooktop connection that does not follow its diagram. The code alone does not prove a cooktop fault: the supply and the connection must be verified with an instrument.
Warnings and stop conditions
- Mediumeditorial warning
Do not handle the cooktop electrical connection: it is mains voltage. Checking it is a job for a qualified installer or electrician.
Evidence: Bosch Induction Cooktop Error Codes
Symptoms and causes
Probable causes · in order
- Cooktop connection not following its diagramPossible
The warning appears at first start up or after moving the cooktop; the installer must check the connection.
Evidence: Bosch Induction Cooktop Error Codes
- Supply voltage out of rangePossible
It matches failures of other appliances or supply problems; Bosch refers you to the utility provider.
Evidence: Bosch Induction Cooktop Error Codes
- Cooktop faultLess common
With connection and voltage verified, the warning remains; it is a job for Bosch service.
Evidence: Bosch Induction Cooktop Error Codes
Virtual technician
Does U400 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Bosch Induction Cooktop Error Codes
Bosch · 2026 · official_doc
- 2
¿Error E en tu placa de inducción? Significado y solución
Bosch · 2026 · official_doc
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