- Appliances
- Cooktops
U1
Bosch U1 on an induction cooktop: incorrect input voltage
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On a Bosch induction cooktop, U1 means the input voltage is not within normal working limits. Stop using it, switch off its breaker and contact your electricity distributor, as Bosch advises.
Safety first
Stop and check this first
- Mains voltage: do not open the cooktop's terminal box or try to measure it yourself. That is work for a qualified electrician.
Safe checks you can perform
- Other appliances in the house
- Isolating at the breaker panel
- Voltage measured at the cooktop
Leave these tasks to a qualified professional
- Do not attempt this professional task: Supply voltage measurement
- Do not attempt this professional task: Cooktop check by Bosch service
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.
Supply voltage measurement
What they doAn electrician measures the voltage on the cooktop circuit with a multimeter and checks its protection at the breaker panel.
They must show youthe measured value against the rating plate.
In writingthe voltage measured, where it was measured and what was corrected in the wiring.
Cooktop check by Bosch service
What they doIf the voltage is correct and U1 stays, Bosch service checks the cooktop with its diagnostic equipment.
They must show youthe electrician's report and the cooktop's diagnostic reading.
In writingthe diagnosis, any part replaced 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.
Other appliances in the house
- Who:
- you, no tools.
- How:
- watch whether lights dim or flicker or other appliances fail at the same time. Note it if neighbours report similar problems.
- Result that matters:
- whether the problem looks house-wide or limited to the cooktop.
- If more than one appliance fails:
- points to the supply; call the distributor.
- If only the cooktop fails:
- points to its circuit or connection; call an electrician.
- Evidence to keep:
- note of which appliances failed, when and how.
Evidence: Bosch Induction Cooktop Error Codes
Isolating at the breaker panel
- Who:
- you, at the breaker panel.
- How:
- switch off the cooktop's circuit breaker and do not use it until the voltage has been checked. Do not open the terminal box or the cooktop.
- Result that matters:
- keeping the cooktop unpowered until the voltage is verified.
- If U1 does not show when you switch back on:
- note it for the electrician anyway.
- If U1 returns as soon as power is back:
- keep it switched off.
- Evidence to keep:
- how many times it appeared and the dates.
Evidence: Bosch Induction Cooktop Error Codes
Voltage measured at the cooktop
- Who:
- a qualified electrician or the distributor, never you.
- How:
- ask them to measure the voltage reaching the cooktop circuit and compare it with the rating plate.
- Result that matters:
- whether the voltage is inside or outside the cooktop's range.
- If it is out of range:
- the cause is the supply or the wiring; the cooktop needs no repair for now.
- If it is in range and U1 stays:
- call Bosch service with the report.
- Evidence to keep:
- the measured value in writing and a photo of the rating plate.
Measuring mains voltage needs instruments and training: only a qualified electrician or the distributor.
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 U1
- Bosch cooktop U1 voltage
- Bosch induction U1
- Bosch placa U1 tensión
- Bosch U 1 cooktop
- Bosch U 1 inducción
- Bosch U1 placa
- placa inducción Bosch U1
What it means
Bosch defines U1 as incorrect input voltage, outside normal working limits, and points to the electricity distributor. The cooktop's electronics monitor the incoming voltage and warn when it is not as expected. The cause can be the supply network, the home wiring or the cooktop's connection; the code does not tell them apart and does not prove the cooktop is faulty. Measuring voltage is work for an electrician or the distributor. The table is Bosch's US induction cooktop guide; check your model's manual to confirm the code means the same.
Warnings and stop conditions
- Mediumeditorial warning
Mains voltage: do not open the cooktop's terminal box or try to measure it yourself. That is work for a qualified electrician.
Evidence: Bosch Induction Cooktop Error Codes
Symptoms and causes
Probable causes · in order
- Supply voltage out of rangePossible
Fits if other appliances or lights in the house dip or fail at the same time; Bosch points to the electricity distributor.
Evidence: Bosch Induction Cooktop Error Codes
- Wiring or cooktop connectionPossible
Fits if U1 has shown since installation or after kitchen work, with the rest of the house fine. An electrician confirms it.
Evidence: Bosch Induction Cooktop Error Codes
- Cooktop electronicsLess common
Only considered if an electrician measures correct voltage at the cooktop and U1 stays; then it goes to Bosch service.
Evidence: Bosch Induction Cooktop Error Codes
Virtual technician
Does U1 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
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