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

Safety first: Unplug the Clatronic microwave from the mains. Microwaves contain high-voltage components that can retain a charge even when unplugged. Do not touch the high-voltage capacitor or magnetron area unless you are trained and have discharged the capacitor properly.

Step-by-step checks:

• Inspect the door and latch hooks: Open and close the door several times. Check that the plastic latch hooks on the door are not cracked or bent and that they fully engage the latch openings in the cabinet.
• Check for door misalignment: Look at the door from the front and sides. If it sags or rubs, the hinges may be loose. Tighten hinge screws carefully with the unit unplugged.
• Test door switches (interlock switches): Remove the outer cabinet (unplugged). Locate the door switch cluster near the latch assembly. Using a multimeter on continuity, test the primary interlock switch and secondary interlock switch while opening/closing the door. Replace any switch that does not change state reliably.
• Inspect switch mounting bracket: Ensure the metal or plastic bracket holding the switches is not cracked or bent. A loose bracket can prevent proper actuation.
• Reassemble and test: Refit the cabinet, plug in, and test. If E1 persists after switch replacement, stop and contact a qualified technician.

Warning: If you are not comfortable working around high-voltage appliances, do not remove the cabinet. Call a professional microwave technician.