KitchenAid Oven Error Code F4-E3

F4-E3 indicates that the microwave cavity temperature sensor has shorted. The control board monitors this sensor's resistance to track cavity temperature, and a short causes the resistance to fall outside the valid operating range. The oven generates this code to prevent operation under an unknown or unsafe temperature condition. The most likely cause is a failed sensor, though wiring faults and control board relay failures are also possible.

It is not recommended to continue using the microwave function while this fault is active. The control board cannot reliably monitor the microwave cavity temperature with a shorted sensor, which removes a key safety check during operation. The conventional oven functions may still operate, but the microwave section should remain unused until the fault is resolved.

Disconnecting power to the oven for several minutes may temporarily clear the code from the display, but the fault will return if the underlying cause has not been corrected. A shorted sensor will continue to produce an out-of-range signal every time the control board attempts to read it. A proper repair targeting the sensor, wiring, or control board is required for a lasting fix.

A knowledgeable DIYer can perform the diagnostic steps, which include inspecting the sensor connector, and measuring sensor resistance with a multimeter. If the sensor reads far outside 280k ohms at room temperature, replacing it is a straightforward repair. Diagnosing a welded relay on the control board is more advanced and may be better suited to a technician.

If only the temperature sensor requires replacement, parts and labor typically fall in the range of $100 to $250 depending on the model and service rates in your area. If the control board has a failed relay and needs replacement, costs generally range from $250 to $500 or more. Performing the sensor resistance test yourself first can help avoid unnecessary parts replacement.