Thermador Refrigerator Error Code E05 — Defrost System Failure
What this means
Error E05 on Thermador refrigerators indicates the defrost system has not completed a defrost cycle successfully. During normal operation, the refrigerator enters a defrost cycle every 8–12 hours to melt any frost on the evaporator coils. If the defrost heater does not raise the evaporator temperature above the threshold within the allotted time, E05 is triggered. Ice will gradually accumulate on the evaporator, blocking airflow and causing the refrigerator to warm up. Causes include a burned-out defrost heater, a faulty defrost thermostat (bi-metal), a failed defrost timer or control board defrost relay.
Alternate codes: Er 05, Err 05
Step-by-step fix
3 stepsManually defrost the evaporator
Remove all food from the freezer and fresh food compartments. Remove the evaporator cover inside the freezer to expose the evaporator coils and heater. If the evaporator is encased in ice, use a hair dryer on medium heat to melt the ice. Have towels ready to catch water.
Do not use a heat gun or sharp tools to remove ice — they can damage the evaporator coils and cause a refrigerant leak.
Test the defrost heater
With the ice cleared, locate the defrost heater — it is a long glass tube or wire element mounted along the bottom of the evaporator. Disconnect its wire connectors and test for continuity with a multimeter. A good heater reads 20–60 ohms. An OL (open) reading means the heater has burned out.
Thermador uses the same BSH defrost heaters as Bosch refrigerators — Bosch replacement parts work perfectly.
Test the defrost thermostat (bi-metal)
The defrost thermostat is a small round sensor clamped to the evaporator tubing. It should have continuity (closed circuit) when cold (at freezer temperature) and open when warm. Test it while it is still cold from the freezer. If it shows no continuity when cold, it is faulty and must be replaced.
If the thermostat is at room temperature, you can chill it with ice to close the circuit for testing. It should click closed below about 30°F.
When to call a professional
If both the heater and thermostat test good, the defrost timer or the defrost relay on the main control board may be at fault. Board-level defrost diagnostics require professional tools.
Related error codes
Information compiled from manufacturer service manuals, official troubleshooting documentation, and appliance repair industry resources. This guide is for informational purposes only — always consult a qualified technician for complex repairs.
Learn more about our sourcesParts you may need
Defrost Thermostat (Bi-Metal)
Part #00618930 · $15–$30
If thermostat does not close when cold
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