JennAir Combination Wall Oven Code F4 E2: microwave sensor or magnetron thermistor

What F4 E2 means

On JennAir combination wall ovens with a microwave, F4 E2 means a possible problem with the microwave sensor or thermistor, the microwave appliance manager, or the wiring. On the JMW2430D series it is described as a magnetron thermistor error. You will see F4 E2 on the display, and the microwave may stop or refuse to start. Food placed inside may not warm at all.

Common causes of F4 E2

Microwave sensor or thermistor out of range
Magnetron thermistor failing on JMW2430D-series ovens
Appliance manager misreading the sensor

✓ One safe check you can try

1. Press Cancel and allow the microwave to cool for ten minutes. 2. Check that vents are not blocked. 3. Cut power at the breaker for about a minute to let the magnetron thermistor reading reset, then restore it. 4. Restore power and run a short water test. 5. When F4 E2 shows up again, please call us rather than reset the magnetron thermistor a third time.

! Why to stop there

The magnetron thermistor monitors the hottest part of the microwave, so its reading matters.
Checking it requires access to the inside of the microwave section.
Without a test, the sensor, manager and wiring are indistinguishable.

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 Wall Oven codes

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F4 E2F4 E2 questions

What is the magnetron thermistor?

It is the sensor that watches the temperature of the magnetron, the part that makes microwave energy. If it misreports, the control shuts the microwave down.

Could poor ventilation cause F4 E2?

Heat can build when airflow is limited, so clear vents are worth checking. A reading problem can also exist with a cool microwave, so a test is needed.

What is next after a persistent code?

Call us. We test the sensor, the manager board and the wiring, quote in writing and warrant our work for 30 days. We state the sensor and board prices separately so you can see where the cost lies.