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

Safety first: Unplug the microwave before any disassembly. Microwaves contain a high-voltage capacitor that can retain a dangerous charge even when unplugged. Do not touch internal high-voltage components (capacitor, transformer, magnetron). If you are not experienced, contact a qualified technician.

Step-by-step checks:

• 1. Inspect the door and latch: Check that the door closes evenly and fully. Look at the plastic latch hooks on the door for cracks or wear. If the door feels loose or does not click firmly, the interlock switches may not be engaging.
• 2. Clean the door area: Food debris or grease around the door frame can prevent proper closure. Clean the door frame and latch area with a mild cleaner and soft cloth, then test again.
• 3. Check hinge alignment (external): With the unit unplugged, gently lift the door up and down. Excessive play can misalign the latch with the interlock switches. Tighten accessible hinge screws if loose.
• 4. Internal switch test (advanced): Remove the outer cabinet (after unplugging). Locate the door interlock switch bracket on the side where the door latches. There are typically 2–3 microswitches (primary, secondary, monitor). Using a multimeter on continuity, test each switch while pressing the actuator. Replace any switch that does not change state reliably.
• 5. Replace the door switch assembly: If multiple switches are worn or the bracket is loose/warped, replace the entire door interlock switch assembly designed for your Westinghouse model.

When to stop: If you are unsure how to safely access or test the switches, or if the error persists after replacing obvious faulty switches, stop and call a professional technician.