Thermador Dishwasher E20 Error: Heat Pump Electrical Fault
thermador dishwasher e20 error indicates heat pump electrical fault. Stop using the appliance and call a Thermador-certified technician immediately for diagnosis. What Does Thermador Dishwasher Error Code E20 Mean? The E20 error code on a Thermador Sapphire, Star-Sapphire, Emerald, or Topaz dishwasher indicates an electrical fault in the heat pump circuit. On models with a […]
Quick Assessment
Answer to continue safely
Is it safe to keep using?
No. An electrical short in the heat pump circuit risks tripping the circuit breaker repeatedly and can cause further damage to the control board. Stop using the dishwasher and arrange service. Do not reset and retry if the circuit breaker has tripped.
Can I reset the code?
Yes. A breaker reset can clear a transient E20 event. If E20 returns on the next cycle or the circuit breaker trips, the heat pump motor or its capacitor has a genuine electrical fault and must be replaced before the dishwasher is used again.
When to stop immediately?
Stop if you notice: Circuit breaker trips when the dishwasher starts, Burning smell from the base of the dishwasher during the wash phase.
Symptoms You May Notice
Wash water remains cold throughout the entire cycle
The heat pump fails to activate and the wash water temperature stays at room temperature — dishes emerge without the thermal cleaning and drying benefit that the heat pump provides.
Unusual silence during the phase where the heat pump normally runs
Thermador Emerald and Star-Sapphire dishwashers with heat-pump systems produce a distinctive hum during heat pump operation. E20 is accompanied by silence where this hum should be.
E20 appears during the main wash phase on the display
The fault code surfaces during or after the control board first commands the heat pump to operate, rather than at startup, indicating the pump energized but immediately faulted on its electrical circuit.
Possible Causes
Electrical short in the heat pump motor windings
The motor windings inside the heat pump have developed an internal short circuit, drawing excessive current and triggering the control board's overcurrent protection, which raises E20.
Requires ProfessionalOpen circuit in the heat pump wiring harness
A break in the wiring loom from the control board to the heat pump motor — at a connector, a chafe point, or a corroded terminal — prevents the motor from receiving power and causes the control to read zero current, flagging E20.
Requires ProfessionalHeat pump capacitor failure
The start or run capacitor for the heat pump motor has failed, preventing the motor from starting and causing the control board to detect an electrical fault in the heat pump circuit.
Requires ProfessionalSafe Checks You Can Do
-
1
Perform a hard reset at the circuit breaker
Switch the circuit breaker off for 60 seconds to discharge the control board capacitors completely. Restore power and allow the board to initialize for 10 seconds before pressing Start. Run a full cycle and listen for the heat pump hum during the main wash phase.
A power reset can clear E20 if the fault was caused by a transient overcurrent event rather than a failed motor winding. If E20 returns within the first few minutes of the wash phase, the fault is in the heat pump hardware.
-
2
Check that the circuit breaker for the dishwasher has not tripped
Inspect the electrical panel and confirm the dishwasher circuit breaker is fully in the ON position. A tripped breaker may have partially reset and still be causing intermittent power supply issues that register as E20.
If the breaker trips again when you start a new cycle after resetting, the heat pump motor has a hard short and must not be run again until the motor is replaced. A repeatedly tripping breaker indicates a serious electrical fault.
When to Call a Professional
Contact a qualified technician if:
- Heat pump motor windings measure a short circuit between phases or to ground
- Start capacitor shows bulging or electrolyte leakage on visual inspection
- Control board overcurrent latch trips within seconds of commanding the heat pump on
Need Professional Help?
Find qualified technicians in your area for proper diagnostics and repair.
Dishwasher Repair Service Schedule Appointment