KitchenAid Combination Microwave Code F4 E3: Exhaust air temperature sensor

What F4 E3 means

On KitchenAid combination microwave-wall ovens like the KOCE500ESS, F4 E3 points to the microwave exhaust air temperature sensor or the wiring that serves it. This sensor watches the air leaving the upper cavity so the control can protect the unit from running hot. When it misreads, the display shows F4 E3 and the microwave half usually stops until the reading returns.

Common causes of F4 E3

Exhaust air temperature sensor sending a reading the control rejects
Damaged or loose wiring leading to that sensor

✓ One safe check you can try

1. Clear the display with Cancel. 2. Make sure the oven's vent openings are not covered by trim, towels or stored items. 3. Cut power at the breaker for a minute and then restore it. 4. If F4 E3 comes back during a short test, stop using the microwave side and schedule a visit.

! Why to stop there

Heat protection depends on this sensor, so running the unit around the error is not worth the risk.
The sensor sits inside the built-in cabinet, where opening panels exposes live parts.
We confirm the cause with a measurement and tell you the price before any part is ordered.

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

F4 E3F4 E3 questions

Why does an air sensor stop the microwave?

The control uses the exhaust air reading to keep the unit from overheating. If that reading is missing or implausible, the microwave half stays off as a precaution until it is repaired.

Is a blocked vent a cause of F4 E3?

The listed cause is the sensor or its wiring, not airflow. Still, clear the vent area and try a reset, since it costs nothing and rules out a simple nuisance.

How long does the repair take?

Sensor and wiring checks on a built-in combination oven are normally handled in one visit, and we quote the work in writing first. Any parts needed are quoted separately beforehand.