Thermador Range Error Code F123

F123 indicates that the range has detected a disconnected or failed communication link between the keyboard and the Display Board. Specifically, the fault points to the connection at connector J1 on the keyboard and connector P5 on the Display Board. The range cannot accept keypad input when this error is active. The problem is either a loose connection or a failed keyboard or Display Board component.

A power reset by turning off the circuit breaker for one to two minutes may temporarily clear the error display, but if the underlying connection problem or component failure still exists, the F123 code will return. A reset is useful for confirming whether the fault is intermittent, but it does not fix a loose connector, damaged wiring, or failed keyboard or Display Board.

If the fix is simply reseating a connector, the cost is limited to a service call fee, which typically ranges from around 75 to 150 dollars depending on your area. If the keyboard requires replacement, parts and labor generally run between 150 and 350 dollars. Replacing the Display Board tends to be the more expensive repair, often ranging from 250 to 500 dollars or more, and replacing both components simultaneously will increase the total cost accordingly.

If the cause is simply a loose connector, a confident DIYer comfortable working with appliance electronics can reseat the connections at J1 and P5 after disconnecting power to the range. However, if the keyboard or Display Board itself has failed, replacing those components requires correctly identifying the right parts and handling the electronics carefully. If you are not comfortable with appliance disassembly and electrical components, a qualified technician is the safer choice.

The F123 error indicates a loss of keyboard communication, which means the control panel may not respond correctly to input. Operating the range in this condition is not recommended because you may not be able to reliably control cooking functions or cancel operations. Disconnect power and address the fault before resuming normal use.