Microwave will not start; display shows E01 immediately after pressing Start.

Safety first: Unplug the microwave from the mains before any inspection. High voltage components can retain charge even when unplugged; do not touch the high-voltage capacitor or magnetron area.

Step-by-step checks:

• 1. Inspect the door and latch: Check that the door closes fully and evenly. Look for cracked or bent latch hooks on the door and damaged latch receivers on the cabinet. If the door feels loose or misaligned, the interlock switches may not engage.
• 2. Test door switches (interlock switches): Remove the outer cover (usually screws at the back and sides). Locate the door switch cluster near the latch area. You will typically see a primary, secondary, and monitor switch. Using a multimeter set to continuity, test each switch while opening and closing the door. Replace any switch that does not change state correctly.
• 3. Check switch wiring: Inspect the wiring harness and connectors to the door switches for loose terminals, heat damage, or broken wires. Reseat any loose connectors.
• 4. Reassemble and test: Refit the cover, ensuring all screws are tight (they also act as safety grounds). Plug in and test. If E01 persists after replacing faulty switches, the control board may be misreading the interlock circuit and should be diagnosed by a qualified technician.

Warning: If you are not experienced with microwave repair, limit yourself to visual inspection of the door and latch. Internal repairs should be done by a professional due to microwave radiation and high-voltage risks.