Microwave beeps and displays F1, often immediately at power-up or when a key is pressed; unit may not respond to further input.

Safety first: Unplug the microwave or switch off the dedicated circuit breaker before removing any panels. Microwaves can store high voltage even when unplugged; do not touch the high-voltage section (capacitor, transformer, magnetron).

• Power reset: Disconnect power for 5–10 minutes, then restore power and check if F1 clears. If it returns immediately, continue.
• Check for stuck keys: Gently press each key on the Viking keypad and confirm none are physically stuck or damaged. Wipe the keypad surface with a slightly damp cloth and dry thoroughly.
• Inspect keypad ribbon: Remove the control panel (usually by removing the top grille and one or two mounting screws). Carefully pull the membrane keypad ribbon cable from the main control board, inspect for corrosion or burn marks, and reseat it firmly.
• Isolate keypad vs. board: With power disconnected, leave the keypad ribbon unplugged from the control board, reassemble enough to power the unit safely, then restore power. If F1 no longer appears, the keypad/control panel is defective. If F1 persists with the keypad disconnected, the main control board is likely faulty.
• Replace failed part: Order the correct Viking membrane keypad or complete control panel assembly using the full model number from the door frame label. If the board is bad, replace the Viking main control board (PCB). Transfer wires one at a time to avoid miswiring.