Thermador Oven Error Code F31

F31 means the upper oven temperature sensor circuit is open, meaning the oven control system has lost its electrical connection to the sensor that monitors oven temperature. Without a valid temperature reading, the oven cannot operate safely. The fault is detected through the relay board at pin header P3, which is the starting point for diagnosis.

Resetting the oven by cycling the power may temporarily clear the F31 code, but if the underlying cause is not corrected, the fault will return as soon as the oven attempts to operate again. A reset is useful for confirming whether the fault is intermittent, such as from a loose connection, but it is not a repair. The root cause in the sensor circuit must be addressed for the code to stay cleared.

If the repair only involves reseating a loose connector, there may be no parts cost at all, though a service call fee will apply if you use a technician. Replacing the upper oven temperature sensor typically costs between $50 and $150 for the part, plus labor. A relay board replacement, if needed, can range from $150 to $400 or more for the part alone, making professional diagnosis important before committing to that repair.

Some causes of F31 are DIY-friendly, particularly reseating a loose connector at pin header P3 on the relay board or replacing the upper oven temperature sensor. Testing the sensor with a multimeter and inspecting the wiring harness for visible damage are reasonable first steps for a knowledgeable homeowner. However, if the relay board itself needs replacement, a qualified technician is recommended.

No, you should not attempt to use the oven while F31 is active. The code indicates the oven has no reliable temperature feedback from the upper cavity sensor, which means the heating system cannot regulate temperature properly. Operating the oven in this condition could result in overheating or uncontrolled heating cycles.