Microwave stops heating shortly after start and displays E02 or will not start heating at all with E02 on the display.

Safety first: Unplug the microwave. High voltage is present inside even when not operating. Do not touch the magnetron or capacitor terminals.

User-level checks:

• Ensure the microwave has adequate ventilation: at least the clearance specified in the Hoover manual at the sides, top, and rear. Move it away from walls or cabinets if necessary.
• Check that the air intake and exhaust vents are not blocked by dust, grease, or objects. Clean external vents with a soft brush and vacuum.
• Allow the microwave to cool for 30–60 minutes, then try again with a cup of water. If E02 reappears quickly, an internal overheat condition persists.

Technician-level checks:

• Remove the outer cover and locate the magnetron thermal cut-out (TCO) and cavity thermal cut-out on the waveguide or cavity wall.
• Test each thermal cut-out with a multimeter for continuity. A tripped/open TCO must be replaced; do not bypass it.
• Check the cooling fan motor for free rotation and power supply during operation. Replace the fan motor if seized or not receiving power due to wiring faults.
• Inspect the magnetron for signs of overheating (discoloration, burning smell). If the magnetron has overheated repeatedly, replace it along with the TCOs.

Note: Magnetron and high-voltage work should only be performed by a qualified technician due to risk of electric shock and microwave radiation leakage.