KitchenAid Built-In Microwave Code F8 E4: Exhaust fan air sensor circuit

What F8 E4 means

On KitchenAid built-in microwaves and combination microwave-wall ovens such as the KMBP100ESS, F8 E4 means the exhaust fan air temperature sensor, or the wiring serving it, may have a problem. The sensor tracks how warm the exhausted air is. When it misreads, F8 E4 appears and the unit may stop heating. The microwave heating and the fan are both stopped until the reading returns, so reheating food is not possible.

Common causes of F8 E4

Exhaust fan air temperature sensor with an unusable reading
Wiring to that sensor that is loose or damaged

✓ One safe check you can try

1. Press Cancel and check that no vents on the unit or trim kit are covered. 2. Switch off the breaker for one minute, then restore power. 3. Listen for the cooling fan when you start a short cycle with a cup of water. 4. If F8 E4 returns, stop using the unit and book a visit.

! Why to stop there

The sensor is behind built-in trim and cabinetry.
We would rather test than replace a good fan or board by mistake.
The written price is shared before work begins.

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

→Same appliance

Other Microwave codes

Probe or Insert ProbeKitchenAid Combination Microwave Message "Probe" or "Insert Probe": Seat the meat probe in its jack PUSH or PSHKitchenAid Built-In Microwave Message PUSH or PSH: The oven is waiting for Start Registration ErrorKitchenAid Over-the-Range Microwave Message "Registration Error": Check the home network and try again Sabbath, Sab, 5Ab, or 5A6KitchenAid Built-In Microwave Display Sabbath, Sab, 5Ab or 5A6: Sabbath Mode is on SEKitchenAid Over-the-Range Microwave Code SE: Keypad or user interface problem F4 E7KitchenAid Combination Microwave Code F4 E7: Meat probe or its receptacle not detected F9KitchenAid Over-the-Range Microwave Code F9: Two boards and their wiring are suspect ":" or "." in displayKitchenAid Built-In Microwave Display ":" or ".": The clock needs setting

F8 E4F8 E4 questions

Do F8 E4 and F8 E5 point to the same part?

Both name the exhaust fan air temperature sensor in the listed meaning. They are separate codes, so we note which one your display shows and test that circuit.

Does F8 E4 mean the fan is broken?

Not directly. The code points to the sensor reading the fan's air temperature, or its wiring. The fan itself is checked during the visit. The fan is checked during the visit as well.

Can poor ventilation set it off?

Keep the vents clear. The listed cause is still the sensor or wiring, which must be tested. Dust and grease on the grille are worth wiping, though the listed cause stays the sensor or wiring itself.