What's Happening

Sensor shorted or oven genuinely overheating.

How to Fix It

Turn off at breaker. Test sensor (~1,080 ohms). Replace if near 0.

Frequently Asked Questions
What does F3E2 mean on a KitchenAid oven?
F3E2 means the sensor reads too high.
Is it dangerous?
If the oven is actually overheating, yes. Turn off at breaker.
How do I test the sensor?
Measure resistance. About 1,080 ohms at room temp is normal.