Thermador Oven Error Code E124

E124 indicates a door switch error for the upper or single oven cavity (Cvt 1). The control board is receiving an undefined signal from the door switch, meaning it cannot determine whether the door is open or closed. This is typically caused by a failing door switch, damaged wiring, or a loose connector in the door switch circuit. Diagnosis should begin with Diagram 2/4 for the Cvt 1 door switch wiring layout.

It is not recommended to continue using the oven while E124 is active. The door switch tells the oven's control system whether the door is properly closed, and an undefined state means the oven cannot reliably monitor that condition. Operating the oven in this state could interfere with safety interlocks, particularly for functions like self-cleaning that require the door to be securely latched.

Repair costs for E124 vary depending on the root cause. A door switch replacement, including parts and labor, typically falls in the range of $150 to $350. If the wiring harness requires replacement or the control board is at fault, costs can be higher, potentially ranging from $300 to $600 or more depending on parts pricing and labor rates in your area.

Some causes of E124 are accessible to experienced DIYers, such as reseating a loose connector or inspecting visible wiring damage. However, replacing the door switch or wiring harness requires working with the oven's electrical system and disassembling parts of the door assembly, which is better suited for a qualified appliance technician. Always disconnect power to the oven before inspecting any wiring or components.

Resetting the oven by disconnecting power may temporarily clear E124, but the code will return if the underlying electrical or mechanical fault is not resolved. A reset is useful to confirm whether the fault is intermittent, but it is not a fix. The door switch, wiring, and connectors should be properly inspected and tested to identify the root cause.