KitchenAid Combination Oven Code F4 E8: another microwave inverter entry

What F4 E8 means

The upper microwave cavity of a KitchenAid combination microwave-wall oven, such as the KOCE500ESS or KOCE507ESS, may report F4 E8 when the microwave inverter or its wiring has a problem. The display shows the code, and the microwave section may heat poorly or not at all. The wiring and the inverter are both named, and because inverters work at high voltage, only a technician should handle either of them.

Common causes of F4 E8

Microwave inverter failing
Wiring between the inverter and control damaged

✓ One safe check you can try

1. Press Cancel and empty the microwave. 2. Switch off the oven breaker for a full minute, then restore power. 3. Run a short test with a cup of water only. 4. If F4 E8 appears again, stop and call us. The inverter must never be touched by owners.

! Why to stop there

Inverters operate at high voltage and can hold charge.
The wiring and the inverter both produce this code.
We give a written quote first, and repairs carry our 30-day workmanship 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.

→Same appliance

Other Wall Oven codes

Probe or Insert ProbeKitchenAid Wall Oven Code Probe or Insert Probe: Meat probe input missing PUSH or PSHKitchenAid Wall Oven Message PUSH or PSH: Press start to begin Registration ErrorKitchenAid Wi-Fi Wall Oven Message Registration Error: Check internet connection Sabbath ModeKitchenAid Wall Oven Sabbath Mode: Bake-Only operation explained Sabbath, Sab, 5Ab, or 5A7KitchenAid Wall Oven Display Sabbath, Sab, 5Ab or 5A7: Cancelling the mode Temperature Reached Insert FoodKitchenAid Steam Oven Message Temperature Reached Insert Food: Preheat complete Locked, Lock or LocKitchenAid Wall Oven Message "Locked": the lock feature is on PF / PF id=27 / PF id=30KitchenAid Oven Display PF, PF id=27 and PF id=30: Power failure message

F4 E8F4 E8 questions

Does F4 E8 mean the same thing as F4 E0?

Both name the microwave inverter or its wiring, so the diagnosis is alike. Each code is a different entry in the control's list, and we test the inverter circuit either way before quoting.

Why is high severity listed?

Inverters work with dangerous voltages, so any hands-on checking by owners is unsafe. The breaker reset and a short water test are the only things we suggest, and then you should call us.

Can the lower oven still be used?

Use it only if it runs normally and shows no code of its own. Treat the microwave section as unavailable until a technician has tested the inverter and its wiring.