The short version
On this oven the code F4 E8 reports that the microwave inverter and its wiring failed the check the control runs before it will produce microwave power. The control has taken microwave power out of service, which is the right outcome for a supply it cannot verify. The first cause to rule out is a latched fault from a supply disturbance rather than a failed power supply, and it costs nothing to check.
The documented code reading
Reference| Code | Documented meaning |
|---|---|
| F4 E8 | There may be a problem with the Microwave Inverter, or the associated wiring. |
What is happening apart from the display
- The microwave runs, makes noise, and nothing heats — The turntable and the fan are on a different supply from the magnetron.
- A buzz or a click and then the cycle ends — The control removing power it could not confirm.
- NEAR MISS - the display is dead and nothing runs — That is a supply or console fault and it is a different page.
What is usually behind it
- A latched fault after a supply disturbance — Ranked first because it is the only cause with a free cure: a full power-down clears a state the control cannot clear by itself.
- Microwave inverter itself — Second: this is a high-voltage assembly that works hard, and when it fails the control loses the confirmation it needs.
Where to start, and what follows
- Power the appliance down at the breaker and bring it back — Free, and it clears a latched fault.
- Note whether the fault is immediate or takes seconds — Immediate and delayed point at different halves of the circuit.
- Stop there — Everything past the door is high-voltage work and not an owner check at any skill level.
The safe checks, step by step
- Switch off at the breaker, wait, and bring it back up — Clears a latched fault and is the entire owner-side procedure for a microwave power fault.
About 10 min
- Try one short heating attempt with a cup of water — Water heating means power is being produced; water staying cold with the code showing does not.
About 5 min
- STOP HERE - do not open the microwave cabinet — This is a service call at this point, with no exceptions.
What to do before any panel comes off
Safety
Microwave safety is different in kind from the rest of the kitchen. The capacitor in the power circuit stores a lethal charge after the appliance is unplugged, so unplugging is a precaution and not a fix. Unplug it or switch off its breaker, keep the cabinet shut, and leave the interlocks as the manufacturer fitted them.
When to call a technician
Call as soon as the code survives a power-down. A microwave power supply is not an owner repair at any level of experience: the capacitor stores a lethal charge after the appliance is unplugged. There is one case that does not wait for any of that. Stop using it and call now if you hear arcing, smell burning, or see scorch marks inside the cavity. Arcing inside a microwave cavity damages the waveguide cover and gets worse quickly.
The nearest codes in this set
What is deliberately not here
This is generalized information about one code across the microwave and combination model lines that use this power supply. It does not carry the numbers that belong to a specific unit: wiring colours, resistances and part numbers are family-specific, and they are the reason a service manual exists. If your family or model has its own page, read that one first - it is the more specific answer - and the code index below is where to look for it.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
