F1 Serious Moderate DIY
Frigidaire Microwave F1 — Control board / thermistor open
Frigidaire Microwave · Error code F1
What F1 Means
F1 indicates the main control board has detected a fault, commonly an open thermistor circuit or a self-diagnostic failure on the control. The unit usually will not run until cleared.
Symptoms
- F1 displayed
- Microwave will not start
- Display dim or stuck
- Continuous beep on power-up
Common Causes
1
Failed control board (ERC)
Most common — internal logic fault triggers a hard F1.
2
Open or shorted oven cavity thermistor
Some models alias thermistor faults to F1; check resistance per tech sheet.
3
Loose harness connector to control
Vibration or service work left a connector partially seated.
How to Fix It
- Unplug for 5 minutes to attempt a soft reset.
- If F1 returns immediately, open the control compartment and reseat all connectors on the main board.
- Locate the cavity thermistor in the tech sheet — measure resistance at room temp (typically 50–100 kΩ depending on model).
- Replace the thermistor if resistance is open or wildly out of spec.
- If thermistor is good and connectors are tight, replace the electronic control board.
Parts You May Need
If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.
More Frigidaire Microwave Codes
Child Lock 'Lock' / 'L' — Child lock engaged Cooling Fan 'Cooling Fan' / Fan-runs-after-cooking — Vent fan stuck on Demo 'Demo' / 'd' — Showroom demo mode on door 'door' message — Door not fully closed F10 F10 — Analog-to-digital / keypad communication error F2 F2 — Shorted thermistor / over-temp sensor
Verified against manufacturer documentation: frigidaire.com
Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.