Thermador Dishwasher E27 Error: Low Supply Voltage
Thermador dishwasher E27 error indicates low supply voltage. Stop using the appliance and call a Thermador-certified technician immediately for diagnosis. What Does Thermador Dishwasher Error Code E27 Mean? The E27 error code on a Thermador Sapphire, Star-Sapphire, or Emerald dishwasher means the appliance is detecting an electrical supply voltage that is too low for safe […]
Quick Assessment
Answer to continue safely
Is it safe to keep using?
No. Operating the dishwasher under E27 conditions risks damaging the control board, pump motor, and heating element. Stop using the dishwasher and have the electrical supply inspected before proceeding.
Can I reset the code?
No. E27 is an electrical supply problem. A reset will clear the code temporarily, but E27 returns whenever the voltage condition recurs. The underlying electrical issue must be corrected.
When to stop immediately?
Stop if you notice: Visible burn marks near the outlet or junction box, Lights dim noticeably when the dishwasher starts.
Symptoms You May Notice
Dishwasher starts but multiple functions seem slow or weak
Cycles run but the pump sounds sluggish, heat takes longer than normal, and the control panel response feels delayed.
E27 appears consistently after home electrical work or storms
The error first appeared after a thunderstorm, a power utility switching event, or after an electrician worked on the home panel.
Other appliances on the same circuit also behave abnormally
Lights on the same circuit dim when the dishwasher starts, or other appliances in the kitchen show erratic behavior.
Possible Causes
Household supply voltage below 110V
The utility supply or home wiring is delivering less than the minimum operating voltage the dishwasher requires.
Requires ProfessionalOverloaded or undersized circuit
The dishwasher is sharing a circuit with other high-draw appliances, causing voltage to sag when multiple loads operate simultaneously.
Requires ProfessionalLoose or corroded wiring connection at the terminal block
A loose wire at the dishwasher power terminal block or in the junction box creates a resistance that drops the effective supply voltage.
Requires ProfessionalSafe Checks You Can Do
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1
Check whether other appliances are on the same circuit
Identify which circuit breaker controls the dishwasher. Note whether any other appliances — a refrigerator, microwave, or garbage disposal — share that breaker. If so, avoid running them simultaneously with the dishwasher.
Thermador Emerald and Star-Sapphire dishwashers draw significant current during the heating phase. A shared circuit can drop below the minimum voltage at that moment and trigger E27.
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2
Inspect the wall outlet or terminal block
Do not open the dishwasher electrical compartment unless you are a qualified electrician. Instead, check that the power cord plug is firmly seated in the outlet, or if the unit is hardwired, that no visible wire damage has occurred at the junction box.
A visible burn mark near the dishwasher outlet or on the cord is a sign of loose wiring and must be addressed by an electrician before operating the appliance.
When to Call a Professional
Contact a qualified technician if:
- Voltage at the outlet measures below 110V AC
- Circuit breaker trips when the dishwasher starts a heating phase
- Loose wire connection confirmed at the dishwasher terminal block
Need Professional Help?
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