Microwave shows F3 and may stop cooking; sometimes appears when using sensor cook or reheat functions.

Safety: Unplug the microwave before any disassembly. Avoid contact with the high-voltage section.

• Power cycle: Unplug for 5 minutes and retry. If F3 reappears during sensor cooking, suspect the sensor circuit.
• Check sensor location: On many GE over-the-range microwaves, the humidity/sensor is located in the top of the cavity or behind a small grill. Ensure it is not covered with food residue or grease; gently clean with a damp cloth and mild detergent, then dry thoroughly.
• Inspect wiring: Remove the outer cover only if you are comfortable and understand the risks. With power disconnected, visually inspect the sensor wiring harness for damage or disconnection.
• Resistance test (advanced): Using a multimeter and the service manual specs for your GE model, test the sensor's resistance at room temperature. If readings are out of range or open/shorted, the sensor is defective.
• Replace sensor: If the sensor or its harness is faulty, replace the oven temperature sensor or humidity sensor assembly. If the sensor tests good but F3 persists, the main control board may need replacement by a technician.