Microwave display shows E04 and unit will not start; sometimes accompanied by a clicking sound from the relay area.

Safety first: Unplug the microwave before opening the cabinet. High voltage is present inside.

Step-by-step checks:

• 1. Power reset: Disconnect the microwave from mains for at least 5 minutes to allow the control board to fully discharge. Plug back in and test. If E04 returns immediately, proceed.
• 2. Visual inspection of control board: Remove the outer cabinet and control panel (note screw positions). Locate the main control PCB behind the keypad/display.
• 3. Check for burn marks: Inspect the board for darkened areas, cracked solder joints around the power relay, or swollen components.
• 4. Reseat connectors: Carefully unplug and replug the multi-pin connectors to the control board to clear any oxidation or loose contacts.
• 5. Relay test (advanced): With the board removed, a technician can test the relay coil and contacts with a multimeter and bench power supply. A relay with welded contacts or open coil must be replaced or the entire board swapped.

Warning: Because the control PCB interfaces with high-voltage circuits, component-level repair should only be done by experienced technicians. For most users, replacing the complete control board with the correct Privileg spare is the safest option.