When your Thermador oven shows error code E005 or E009, it’s signaling a serious communication breakdown between the user interface and the electronic oven control board. These two modules constantly exchange data to manage temperature, timing, and overall operation. When that communication stops, the oven can become unresponsive, stop heating, or fail to start completely.
Why the Problem Occurs
This issue usually appears after a power surge, electrical interruption, or internal wiring failure. The wire harness connecting the control board and the display can loosen or degrade over time from heat exposure. In other cases, moisture or grease infiltration causes corrosion on the connectors, blocking the signal path. Both codes — E005 and E009 — point to the same root issue: the control system is not “talking” to the front panel.
How to Fix Thermador Oven E005 and E009
Before doing anything, disconnect the oven from power. This step isn’t optional — it prevents shock and protects electronic parts.
Once it’s safe, remove the oven’s top or rear panel to access the main control board. Check each wiring connector leading from the display to the control board. If any plug feels loose, press it in firmly until it locks. Often, a single poor connection can trigger a Thermador oven E005 fix instantly.
If the wiring looks burnt, melted, or brittle, it’s time to replace the entire wire harness. Damaged wires can’t be safely repaired, and reusing them will cause recurring communication errors.
When to Replace the User Interface
If you’ve confirmed the wiring is fine but the problem persists, the user interface board may be malfunctioning. This board handles your inputs — buttons, touch controls, and display — and transmits them to the control board. When it fails, it can cause the Thermador oven E009 communication error even if all wiring is intact. Replacing the user interface usually restores control responsiveness and clears both error codes.
When the Control Board Is the Culprit
In some cases, the issue lies in the electronic control board itself — the “brain” of the oven. If it fails, it can’t receive or send signals correctly, leading to complete operational loss. A new control board is often the final step to resolve persistent Thermador oven not working or Thermador oven error E005/E009 issues. After replacement, the oven typically resets automatically and resumes normal operation.
Professional Diagnosis and Repair
While Thermador ovens are known for their durability and performance, complex electrical errors like these require careful handling. If you’re not comfortable with electronics or don’t have the right tools, calling a professional technician is the best solution. Certified specialists can test voltage, continuity, and signal flow between the control systems using diagnostic tools that confirm which board is at fault.