Thermador Range Error Code FF

The FF code on a Thermador range indicates a bad analog-to-digital converter reading, which means the control board is receiving an invalid or unreadable signal from the oven temperature sensor. This applies to S, SM, and SMW series models. The fault is typically caused by a defective temperature sensor or a failed main power/relay board. The range will not operate normally until the underlying cause is identified and repaired.

No, it is not safe to operate the oven while the FF code is active. The error means the control cannot accurately read the oven temperature, so it has no way to regulate heat properly. Continued use risks uncontrolled temperature conditions inside the oven cavity. The range should remain out of service until the sensor or board is repaired.

Repair costs vary depending on which component is at fault. Replacing the oven temperature sensor is typically the less expensive fix, with parts generally ranging from around 20 to 80 dollars depending on the specific model, plus labor if a technician performs the work. If the main power/relay board requires replacement, parts costs are considerably higher and can range from 150 to 400 dollars or more, again depending on the model. Getting a diagnostic evaluation before committing to parts is advisable.

The recommended diagnostic sequence is to start by replacing the oven temperature sensor, as this is the most common cause of the FF code. If the error continues after sensor replacement, the next step is to replace the main power/relay board, which contains the A/D converter circuit. It is also worth inspecting the sensor wiring harness and connectors for damage or loose terminals before replacing the board, as a poor connection can produce the same fault.

Resetting the range by cutting power at the breaker may temporarily clear the FF display, but the code will return if the underlying component fault has not been corrected. If the temperature sensor or relay board is failing intermittently, the error may reappear during the next heating cycle or come back without warning. A reset is not a repair and should only be used as part of the diagnostic process.