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Error code reference

KitchenAid Oven Error Code F4-E3

Temperature sensor (microwave) shorted.

KitchenAid codesKitchenAid oven codes

Temperature sensor (microwave) shorted.

First step from the service manual

1. Check microwave sensor connection. 2. Measure sensor resistance: 280k ohms at 70°F (21°C), 1k ohms at 392°F (200°C). If resistance is not valid, replace sensor. 3. If sensor resistance and connections are good, check for welded-closed relays on the control; if relay shorted, replace control.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What F4-E3 means on a KitchenAid oven

The F4-E3 error code on a KitchenAid oven indicates a shorted temperature sensor in the microwave cavity. Unlike a conventional oven temperature sensor, this sensor monitors heat levels within the microwave portion of a combination oven unit. A shorted sensor means the sensor's internal resistance has dropped abnormally low or has fallen to near zero, causing the control board to receive an out-of-range signal it cannot interpret as a valid temperature reading.

The microwave temperature sensor is a thermistor, meaning its resistance changes predictably with temperature. At 70°F (21°C), a properly functioning sensor reads approximately 280k ohms. At 392°F (200°C), that resistance drops to approximately 1k ohm. When the sensor shorts internally or through a wiring fault, resistance collapses outside this expected curve, triggering the F4-E3 fault. Common causes include a failed sensor element, damaged wiring insulation that allows conductors to contact each other, or a loose connector creating an unintended electrical path.

If sensor resistance and wiring connections both check out within spec, the fault may originate at the control board itself. A relay on the control board that has welded closed can send continuous voltage to the microwave heating circuit, driving temperatures beyond what the sensor can represent accurately. In that case, the control board requires replacement. Systematic testing starting at the sensor connector, then the sensor itself, then the control board is the correct diagnostic sequence.

Source: manufacturer service documentation.

Common causes of F4-E3

  1. 01

    Failed microwave temperature sensor

    Part replacement

    The thermistor inside the microwave cavity can fail internally, causing its resistance to drop far below the expected range of 280k ohms at room temperature. Measuring resistance at the sensor terminals will confirm this if the reading is well outside specification.

  2. 02

    Damaged or pinched sensor wiring

    Wiring / connection

    Wiring insulation that has worn through, been pinched, or been exposed to heat can allow conductors to short against each other or against the chassis. Inspect the sensor harness from the connector back to the sensor body for visible damage or contact points.

  3. 03

    Loose or corroded sensor connector

    Wiring / connection

    A connector that is not fully seated or has corroded pins can create unintended resistance paths that mimic a shorted sensor. Disconnecting and reseating the connector while inspecting the terminals for corrosion or bent pins is an important early diagnostic step.

  4. 04

    Welded relay on the control board

    Part replacement

    A relay on the control board that has welded shut can continuously energize the microwave heating circuit, pushing the sensor signal out of its valid range. This is diagnosed only after confirming the sensor and wiring are both within specification.

See the test procedure for each cause

Frequently asked questions about F4-E3

What does F4-E3 mean on a KitchenAid oven?
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.
Can I fix the F4-E3 error myself?
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.
Is it safe to use my KitchenAid oven while the F4-E3 code is active?
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.
How much does it cost to repair the F4-E3 error on a KitchenAid oven?
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.
Will resetting the oven clear the F4-E3 error code?
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.

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