Microwave displays E4 and will not heat; may beep repeatedly when START is pressed.

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

• Power cycle: Disconnect power for 5–10 minutes, then reconnect and test. Sometimes transient faults clear after a reset.
• Check for obvious damage: Inspect the interior cavity for melted plastic, foil arcing, or burned areas that might have overheated the sensor.
• Sensor location: On many Danby models, the cavity temperature sensor is mounted behind the interior wall or near the top of the cavity. Access usually requires removing the outer cabinet, which should only be done if you are comfortable with appliance disassembly.
• Wiring inspection (advanced): With the cabinet removed and power disconnected, visually inspect the sensor wiring harness and connector for burns, breaks, or loose connections. Do not disturb the high-voltage wiring.
• Next step: If E4 persists, the thermistor or control board is likely faulty. Replacement of the sensor is usually straightforward but requires safe access; consider a professional technician.