Thermador induction cooktop
showing U400
U400 means the cooktop measured incoming voltage that is too high or too low.
Mon–Sat, 8am–8pm
- Induction power and coils
- Induction board and coil repair
- Source: Thermador
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What U400
actually means.
U400 means the cooktop measured incoming voltage that is too high or too low. It points to the circuit feeding the cooktop.
Thermador cooktop display
What to do when U400 shows on the cooktopKind of codeInduction power and coils
An induction zone could not drive its coil as the board planned: no pan was detected, the current ran too high or too low, or the power stage reported trouble. The pan base, the supply voltage and a clogged air intake are checked before the coil or the power board is replaced, and a top that trips its breaker is left switched off until then.
Usually leads toInduction board and coil repair
Induction zones that stop sensing pans, cut out, buzz or show codes, traced to the power boards, the coils, their sensors and the links to the controls.
Shows up asCooktop Tripping Breaker
The circuit breaker for the cooktop trips as a burner or zone switches on, at one particular setting, or a few minutes into cooking.
MakeThermador
A BSH-owned luxury brand that lists gas, electric and induction cooktops alongside pro-style rangetops.
SourceThermador induction cooktop error codes (US support)
Listed on Thermador's induction cooktop page.
Before you book,
in this order.
Each step comes from Thermador's own guidance for U400 on its cooktops. Follow it to the end: the last card says whether this is a visit.
Turn the breaker off.
Do not work inside the junction box under the cooktop yourself.
Ask the utility or an electrician to check the supply; if it is normal and U400 remains, book a visit.
Still there?
It usually turns into induction board and coil repair. Book with the code and the model number.
What not to do
U400 is not caused by cookware and is not cleared by cooking through it. It points to the circuit feeding the cooktop, not to a failed zone.
What you may
notice with it.
The cooktop problems U400 tends to arrive with. Answer these at the cooktop before anyone is booked.
All problems
Cooktop Tripping Breaker
6 causes, cheapest first
Where U400 usually leads
Induction board and coil repair.
Thermador
cooktops.
A BSH-owned luxury brand that lists gas, electric and induction cooktops alongside pro-style rangetops.
Thermador cooktop repairMore Thermador codes
All 14 Thermador codesInduction power and coils on other makes
Gas cooktop
A gas cooking surface dropped into a countertop cutout, with its gas line and power cord running down into the cabinet underneath.
Induction cooktop
A glass cooktop in the counter that heats the pan itself through magnetic coils, run by power boards and cooled by a fan underneath.
Rangetop
A pro-style gas cooking top with its knobs across the front, set into a notch above a base cabinet, often with a griddle or char-broiler beside the burners.
In Thermador's own words
The supply voltage is incorrect. It is outside the normal operating range.
Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. Listed on Thermador's induction cooktop page.
Thermador U400 cooktop 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.
All service areasTampa BayFL · 31 areas
Miami / South FloridaFL · 47 areas
New York MetroNY · 75 areas
HoustonTX · 36 areas
ChicagoIL · 50 areas
Los AngelesCA · 95 areas
San DiegoCA · 31 areas
Questions
about U400.
Can I clear U400 myself?
Why would my Thermador show U400 only in the evening?
Should I reset the breaker until U400 goes away?
Does Thermador list U400 alongside E9000 and E9010?
Back to your everyday
Still showing U400?
Book with the code copied exactly, the full model number, and whether there is any smell of gas or burning — with a code in hand, that is where the diagnosis starts.