Diagnosis
The F3 error indicates a temperature sensor circuit failure. The oven's internal temperature sensor is reporting a value out of expected range, likely due to a faulty sensor or a wiring disconnect.
How to Fix It
Unplug the oven. Access the sensor by removing the inner top panel and vent assembly. Locate the sensor probe near the top rear of the oven cavity. Check its wiring connection to the main control board. If the connection is secure, the sensor itself requires replacement. You must use the exact OEM sensor part for the CMW-200.
If That Didn't Work
A persistent F3 code with a verified good sensor points to a failure on the main control board. The board is not receiving or processing the sensor signal correctly. The entire main control assembly must be replaced.
Heads Up
The sensor is a delicate component. Do not attempt to clean or adjust it. Any physical damage will cause the error to return immediately after reassembly.