Thermador Oven Error Code F22

The F22 error code on a Thermador oven indicates that the upper oven cancel key has been detected in a shorted-low condition. This means the control board is reading the cancel key input as continuously active, as if the button is being held down, even when it is not physically pressed. The cancel key is part of the membrane keypad or touchpad assembly, which sends discrete electrical signals to the main control board. When that signal line is pulled low and held there, the board interprets it as a fault rather than a valid user input.

The most common source of this fault is a failure within the touchpad or keypad membrane itself. Over time, the conductive traces or membrane layers inside the keypad can degrade, crack, or develop moisture contamination, causing two contact points to bridge and create a persistent short to ground on the cancel key circuit. This type of failure is internal to the keypad assembly and is not repairable at the component level, making full keypad replacement the standard corrective action.

In some cases, the ribbon cable connecting the touchpad to the control board can develop a short due to pinching, wear, or debris between the cable layers. It is also possible, though less common, for the control board itself to have a failed input circuit that incorrectly reads the cancel key line as low. Proper diagnosis involves inspecting the ribbon cable for damage and, if possible, disconnecting the keypad to see whether the fault clears, which would confirm the keypad assembly as the failed component rather than the board.