KitchenAid Over-the-Range Microwave Code F4E1: Cavity thermistor circuit

What F4E1 means

On KitchenAid over-the-range microwave hood combinations, including the KMHS120ESS and KMLS311HSS, F4E1 means the cavity temperature thermistor or its wiring may have a problem. The thermistor tells the control how warm the cooking cavity is. When its reading is lost, the display shows F4E1 and the microwave will not run a normal cycle. Hood fan and lamp commonly keep running, which can make the unit look healthier than it is.

Common causes of F4E1

Cavity temperature thermistor with a reading outside its range
Loose or damaged wiring on the thermistor circuit

✓ One safe check you can try

1. Press Cancel so the display returns to normal. 2. Unplug the microwave or switch off its breaker for one minute, then restore power. 3. Make sure the interior is empty, dry and free of foil. 4. Try a short cycle with a cup of water; if F4E1 reappears, stop and call us.

! Why to stop there

Reaching the thermistor means taking the microwave off the wall bracket or removing its cover.
The high-voltage capacitor inside a microwave can hold charge when unplugged.
We tell you the exact price in writing before we begin.

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.

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Other Microwave codes

SEKitchenAid Over-the-Range Microwave Code SE: Keypad or user interface problem 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 F6 E3KitchenAid Built-In Microwave Code F6 E3: Appliance manager and converter control FC E3KitchenAid Over-the-Range Microwave Code FC E3: Router or Wi-Fi module connection lost F6 E7KitchenAid Combination Microwave Code F6 E7: Manager board for the upper cavity

F4E1F4E1 questions

Is F4E1 a hood or a microwave problem?

It is a microwave cooking problem. The thermistor lives in the cooking cavity, so the hood fan and light may keep working while the microwave side shows the code.

Will unplugging fix it?

Sometimes a brief power loss clears a one-time glitch. If F4E1 comes back after a plain test with water, the thermistor circuit needs a technician.

Do you carry parts for these models?

We stock common microwave sensors and order others once the diagnosis is confirmed. The part and labor price is given to you in writing first.