Microwave displays E15 and the interior light remains on even with the door closed, or the unit will not start.

Safety first: Unplug the microwave before servicing. Door switch circuits are safety-critical.

Step-by-step checks:

• 1. Check door alignment: Ensure the door closes evenly and the latch hooks engage smoothly. Look for sagging hinges or bent door frame.
• 2. Listen for clicks: You should hear multiple clicks as the door closes. If one is missing or delayed, a switch may be misaligned.
• 3. Access door switches: Remove the outer cabinet and the control panel to expose the door switch cluster.
• 4. Identify monitor switch: The monitor switch is typically wired differently (often with heavier gauge wires). Refer to the wiring diagram if available.
• 5. Test switches: Using a multimeter, verify that the monitor switch opens and closes correctly relative to door position. Replace any switch that does not match the specified behavior.
• 6. Inspect wiring: Check for signs of arcing or melted insulation around the monitor switch wiring.

After replacing faulty switches and correcting alignment, reassemble and test. If E15 persists, the control PCB may be misreading the door circuit and should be evaluated by a technician.