Microwave will not start; display shows E1 immediately after pressing START.

Safety first: Unplug the microwave. High-voltage components inside can retain a dangerous charge even when unplugged. Do not touch the capacitor or magnetron area unless you are trained.

Step-by-step checks:

• Inspect the door: Open and close the door several times. Ensure it closes evenly and the latch hooks fully engage. Look for cracked or loose plastic latch hooks on the door.
• Check for play in the door: If the door feels loose or sags, the hinges or latch may be misaligned. Gently lift the door while closing to see if the error clears temporarily—this indicates misalignment.
• Access the interlock switches: Remove the outer cabinet (usually screws on the back and sides). The door switches are mounted on a plastic interlock bracket near the latch opening.
• Test switches with a multimeter: Label wires, then remove them from each switch. In continuity mode, verify:
  • Primary and secondary switches: continuity when door is closed, open circuit when door is open.
  • Monitor switch (if present): opposite behavior—continuity when door is open, open circuit when closed.
  Replace any switch that does not change state correctly.
• Inspect the interlock bracket: If the plastic bracket is cracked or loose, the switches may not actuate fully. Tighten mounting screws or replace the bracket if damaged.
• Reassemble and test: Refit the cabinet, plug in, and test operation. Confirm E1 no longer appears when starting a cycle.

When to stop: If you see burn marks, melted plastic around the interlock, or are unsure about high-voltage safety, stop and contact a qualified technician.