Microwave stops heating shortly after start or will not start heating; error E02 appears on the display.

Safety first: Unplug the microwave. Internal components can retain high voltage even when unplugged. Do not touch the high-voltage section (transformer, capacitor, magnetron) unless properly trained.

Step-by-step checks:

• 1. Check ventilation: Ensure the Grundig microwave has adequate clearance on all sides as specified in the user manual. Remove any obstructions from rear and side vents. Clean dust and grease from vents with a soft brush.
• 2. Inspect the cooling fan: Remove the outer cabinet. Locate the cooling fan motor (usually near the magnetron and vents). Spin the fan blades by hand; they should rotate freely without scraping. If seized or noisy, the fan motor likely needs replacement.
• 3. Test thermal cut-outs: Locate the cavity thermal fuse and the magnetron thermal cut-out (small round or rectangular thermostats clipped to the cavity or magnetron). With the unit unplugged, disconnect one wire from each and test for continuity with a multimeter. An open reading indicates a blown device.
• 4. Replace blown thermal devices: Replace any open thermal fuse or thermostat with the exact temperature rating specified for Grundig models. Do not bypass or short these devices; they are critical safety components.
• 5. Check for blocked air channels: Inspect internal air ducts for grease buildup or foreign objects that could restrict airflow around the magnetron and cavity.

If E02 returns after restoring airflow and replacing faulty thermal devices, the control PCB may be misinterpreting temperature feedback and should be evaluated by a professional.