Thermador Range Error Code F40

F40 on a Thermador range means the control system has detected a short in the upper meat probe circuit. The board monitors the resistance of the probe wiring and flags this code when resistance drops to an abnormal level. This can be caused by a damaged probe, pinched wiring, or a faulty control display PCB. The first step is to inspect header P2 on the control display PCB and check that no meat probe wires are pinched against the chassis.

An F40 code indicates a shorted probe circuit, which means the meat probe temperature monitoring system is not functioning correctly. If the probe feature is not needed for your immediate cooking task, the range may still operate, but it is best to resolve the fault promptly. Continuing to use the appliance with an undiagnosed wiring short is not recommended without first confirming the source of the short.

Repair costs vary depending on the root cause. If the meat probe itself is shorted and needs replacement, costs are generally in the range of $30 to $80 for the part plus labor. If the control display PCB is the cause, parts alone can range from $150 to $400 or more depending on the model, with additional labor costs on top of that. Getting a diagnostic visit from a technician first will help determine which component is at fault before committing to parts.

Some steps are accessible to a knowledgeable DIYer. You can unplug the meat probe and check whether the code clears, and you can visually inspect the probe wiring for obvious damage or pinching. However, inspecting header P2 on the control display PCB and replacing the board if needed requires disassembling part of the range and working near live components, which is better handled by a qualified appliance technician.

A power reset by turning off the breaker for 60 seconds may temporarily clear the display, but F40 will return if the underlying fault in the probe circuit is still present. The code is tied to an active hardware condition, so it will not stay cleared until the shorted wiring, damaged probe, or faulty PCB is repaired or replaced.