Thermador Dishwasher E03 Error: Auxiliary Heater Relay Fault
thermador dishwasher e03 error indicates auxiliary heater relay fault. Stop using the appliance and call a Thermador-certified technician immediately for diagnosis. What Does Thermador Dishwasher Error Code E03 Mean? The E03 error code on a Thermador Sapphire, Star-Sapphire, Emerald, or Topaz dishwasher indicates a fault in the auxiliary heater relay on the main control board. […]
Quick Assessment
Answer to continue safely
Is it safe to keep using?
Maybe. If the dishwasher washes but does not dry, it is safe to run mechanically — but dishes will need hand-drying. The failed auxiliary relay does not create a direct safety hazard unless the control board shows burn marks. Schedule service within a week.
Can I reset the code?
Yes. A breaker reset clears E03 temporarily if the fault was transient. If E03 returns at the drying phase on the next cycle, the auxiliary relay or heating element circuit has failed and professional service is required.
When to stop immediately?
Stop if you notice: E03 returns every cycle at the drying phase, Burning smell from the control panel or door area during the drying phase.
Symptoms You May Notice
Dishes come out wet even though the drying cycle ran fully
The dishwasher runs a complete drying phase but dishes on both racks emerge wet, indicating the auxiliary heating circuit that supports drying is not operating.
E03 appears at or near the drying phase of the program
Unlike E01 or E02 which appear at startup or in the wash phase, E03 typically surfaces during or at the end of the program when the drying heat circuit is active.
Interior of the tub feels cooler than expected after a cycle
After the cycle completes, the interior tub temperature is noticeably lower than normal, suggesting the supplemental heater that assists the final rinse and drying phase did not activate.
Possible Causes
Failed auxiliary relay on the control board
The secondary relay that switches power to the supplemental heating circuit has failed open, preventing the auxiliary element or heating circuit from receiving power.
Requires ProfessionalFault in the auxiliary heating element circuit
On Thermador Emerald models with Zeolite heat-pump drying, the auxiliary PTC heater element that assists the Zeolite adsorption cycle has failed, causing the relay feedback to read incorrectly.
Requires ProfessionalLoose wiring connector on the auxiliary heater circuit
The wiring harness connecting the control board auxiliary relay output to the secondary heater has come loose at a connector, creating an open circuit that registers as a relay fault.
Requires ProfessionalSafe Checks You Can Do
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1
Perform a 60-second hard reset at the breaker
Switch the circuit breaker off for 60 seconds and restore power. Allow the control board to fully initialize before starting a new cycle. A power reset can clear E03 if the fault was a transient relay feedback error during the previous drying cycle.
If the following cycle completes with acceptably dry dishes and no E03, the fault was transient. If E03 returns at the drying phase again, the auxiliary relay or its wiring has a genuine fault.
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2
Confirm rinse aid is filled and the dispenser is functioning
Open the rinse aid dispenser on the door and verify it is filled to the maximum line. A completely empty rinse aid dispenser significantly worsens drying performance and can exacerbate the visible symptoms of an E03 fault.
Rinse aid reduces surface tension on dishes, helping water sheet off more completely during the drying phase. Always maintain a full dispenser on Thermador Sapphire and Emerald dishwashers for best drying results.
When to Call a Professional
Contact a qualified technician if:
- Auxiliary relay output tests open when coil is energized
- Auxiliary heating element shows open circuit with wiring harness disconnected
- Zeolite heat-pump drying module on Emerald models shows no PTC heater continuity
Need Professional Help?
Find qualified technicians in your area for proper diagnostics and repair.
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