Microwave displays F3 and will not start a cook cycle; sometimes appears immediately after pressing START.

Safety first: Disconnect power at the breaker or unplug the Café microwave before any inspection.

Steps to try:

• Power cycle: Remove power for 5–10 minutes, then restore. If F3 appears immediately, the control is detecting a sensor circuit fault.
• Check for moisture: Excess steam from cooking may enter sensor openings. Leave the door open for 30 minutes to dry the cavity, then try again.
• Visual harness check: If accessible by removing the top grille and control panel, inspect the small two-wire harness going to the cavity temperature sensor for burns, cuts, or disconnection.
• Likely repair: In most Café microwaves, F3 indicates a failed cavity thermistor that must be replaced. The sensor is usually mounted behind the cavity liner and is not easily accessible without significant disassembly.
• Call a technician: Because accessing the sensor requires working near the high-voltage system and cavity shielding, have an authorized Café technician test the sensor resistance and replace the sensor or main control board as needed.