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Error code · Cooktop

Thermador Cooktop U400 Voltage Error Code

The cooktop will not start and the display reads U400. This is the same condition Thermador describes for E9000 and E9010 on both its electric and induction platforms: the voltage coming into the cooktop is outside…

Moderate · have it inspected
Code
U400
Appliance
Cooktop
Brand
Thermador
Warranty
30-day workmanship

What U400 means

The cooktop will not start and the display reads U400. This is the same condition Thermador describes for E9000 and E9010 on both its electric and induction platforms: the voltage coming into the cooktop is outside the range it is designed to run on. The unit stops to protect itself, so look at the supply, not the surface.

Usual causes of U400

  • A voltage problem in the home electrical supply
  • A circuit that does not match the cooktop's wiring requirements
✓ A safe check worth trying

1. Switch the cooktop off and avoid repeated restarts. 2. Do not remove covers or touch wiring. 3. Notice whether lights or other big appliances dim or act strangely. 4. Ask an electrician or the utility provider to check the voltage at the circuit.

! Why you should stop here
  • Verifying voltage is a job for an electrician or the utility, and an appliance repair cannot change what the home delivers.
  • Resetting the cooktop repeatedly will not change the voltage the house delivers.
Taking off a panel yourself does not by default void a manufacturer warranty, yet it can lead to accidental damage, and some manufacturers attach their own service terms. Read your warranty paperwork, or ask us, before you decide.
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U400U400 questions
Why does my cooktop show U400 while a friend's shows E9000?

Thermador documents both for the same voltage problem. Which one appears can depend on the control platform of the specific cooktop, so they are not two different problems. So there is only one underlying problem to chase.

Could my breaker panel be the cause?

It is possible. A loose or mismatched circuit is one of the listed causes, which is why an electrician should confirm the supply before the cooktop is blamed.

Will the cooktop work again once the supply is fixed?

Normally yes. The code reflects the incoming voltage, so when the supply is back in range the cooktop can resume without a repair. No parts are usually involved.

Request service

Is U400 still showing?

Our technician checks it in your home and hands you a written price before touching anything.