KitchenAid Over-the-Range Microwave Code F3T4: magnetron temperature thermistor

What F3T4 means

KitchenAid over-the-range microwave hood combinations like the KMHS120ESS and KMLS311HSS show F3T4 when there may be a problem with the magnetron temperature thermistor, or its wiring. The magnetron makes the microwave energy and gets hot. The thermistor keeps it in a safe range, so a lost reading stops cooking and displays F3T4.

Common causes of F3T4

Magnetron thermistor failing
Wiring to the thermistor loose
Magnetron running hot and tripping the protection

✓ One safe check you can try

1. Press Cancel and leave the door open so the cavity cools. 2. Make sure the vents on the microwave are not blocked. 3. Reset the power by unplugging for a minute. 4. Test with a short run and a cup of water. 5. If F3T4 returns, call us.

! Why to stop there

The magnetron area holds dangerous high voltage
Only a technician should test this thermistor
We provide the price in writing before we start, and offer a 30-day warranty

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

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 Probe or Insert ProbeKitchenAid Combination Microwave Message "Probe" or "Insert Probe": Seat the meat probe in its jack F4E4KitchenAid Over-the-Range Microwave Code F4E4: Humidity thermistor or its wiring F9Q1KitchenAid Over-the-Range Microwave Code F9Q1: Touch pad and its wiring F4E9KitchenAid Over-the-Range Microwave Code F4E9: Smart Pop control or wiring flagged

F3T4F3T4 questions

Why is F3T4 rated higher?

It involves the part that generates microwave energy, so overheating protection matters more here.

Is the magnetron broken?

Not necessarily. The code names the thermistor, but we check the magnetron temperature during diagnosis.

Can I wait a few weeks?

We recommend not running the unit meanwhile. An overheated magnetron can fail and cost more to replace.