Error code
Frigidaire F3
FRIGIDAIREF3
Error Code· Shown on the appliance's control panel.
What it means
Open oven temperature sensor (RTD).
Per Frigidaire Range/Oven Fault Codes
The RTD is open/shorted.
Per Frigidaire Range/Oven EOC Fault Code Guide, p2
Not affiliated with Frigidaire. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.