Microwave shows E8 and stops mid-cycle, often during longer cooking times.

Safety first: Unplug the microwave and allow it to cool completely before working on it.

Airflow and cleanliness:

• Check installation: Ensure the microwave (especially over-the-range Emerson models) has proper clearance and that top and rear vents are not blocked by cabinets or filters.
• Clean filters: If equipped with grease or charcoal filters, remove and clean/replace them according to the manual. Clogged filters can cause overheating.
• Clean vents: Use a brush and vacuum to remove dust and grease from intake and exhaust vents.

Inspect cooling system:

• Remove the outer cabinet and locate the cavity thermostat and cooling fan.
• Spin the fan by hand; if stiff or noisy, replace the fan motor.
• Test the cavity thermostat for continuity at room temperature (if it is a resettable type, it should be closed). Replace if open and not resetting.

Test operation: After cleaning and any part replacement, reassemble and run the microwave with a cup of water for several minutes, monitoring for E8.