Thermador Oven Error Code E204

E204 indicates a shorted temperature sensor in the lower oven cavity, referred to as Cvt 2 or Cavity 2 in Thermador schematics. A shorted sensor means its resistance has collapsed to near zero, preventing the control board from accurately reading the oven temperature. The oven displays this code and suspends normal operation to avoid unsafe conditions. Diagnosis should begin with the wiring diagram labeled Diagram 2/4 for the specific unit.

It is not recommended to continue using the oven while E204 is active. The lower cavity temperature sensor is essential for accurate heat regulation, and a shorted sensor means the control board cannot monitor oven temperature correctly in that cavity. Continuing to operate the oven in this condition could result in uncontrolled heating or further component damage.

Start by disconnecting the lower cavity sensor connector and measuring the sensor's resistance with a multimeter. A shorted sensor will read near 0 ohms. If the sensor reads a normal resistance value, reconnect it and then inspect the wiring harness between the sensor and the control board for pinched or melted insulation. Referencing Diagram 2/4 for the specific model will show the correct connector locations and circuit path to test.

Cycling power to the oven by turning off the circuit breaker for 30 seconds may temporarily clear the error display, but the code will return if the underlying short circuit in the lower cavity sensor circuit is still present. A reset does not repair a failed sensor or damaged wiring. The root cause must be identified and corrected before the oven will operate normally.

Repair costs depend on which component has failed. A replacement lower cavity temperature sensor typically costs in the range of $30 to $80 for the part alone. If the control board requires replacement, parts can range from $150 to $400 or more depending on the model. Adding professional labor, total repair costs generally fall between $150 and $500, with more complex wiring or board repairs at the higher end.