Microwave displays E2 and will not start heating; sometimes appears after several minutes of use.

Safety first: Unplug the microwave. Internal components can carry lethal voltage. Do not touch the high-voltage section (transformer, capacitor, magnetron) unless you are trained.

Basic checks:

• Ventilation: Ensure the microwave's side, rear, and top vents are not blocked by cabinets, walls, or items on top. Hamilton Beach countertop microwaves require several inches of clearance around vents.
• Cool-down reset: Let the unit sit unplugged for 20–30 minutes to cool completely. Plug back in and test. If E2 returns quickly, proceed.

Sensor inspection (for models with temperature sensor/probe):

• If your model uses a cavity temperature sensor or food probe, inspect the sensor connection inside the cavity and at the control board.
• Remove the outer cabinet (screws at back and sides). Carefully lift it off, avoiding sharp metal edges.
• Locate the small sensor (often near the top or side of the cavity) with two wires leading to the control board. Check for burnt, broken, or disconnected wires.
• If you have a multimeter and are qualified, test the sensor for continuity and resistance according to the service manual specs. An open or shorted sensor must be replaced.

If parts are faulty:

• Replace the cavity temperature sensor / thermistor if readings are out of range or wiring is damaged.
• If the sensor and wiring are good but E2 persists, the electronic control board is likely defective and should be replaced by a professional.

Warning: Do not bypass or jumper temperature sensors; this is a fire and safety hazard.