Display shows E12; refrigerator may not enter or exit defrost properly, or may show erratic defrost behavior.

Safety first: Unplug the refrigerator before accessing the main control board.

Steps:

• Access main control: Typically located in a top compartment or rear control box. Remove the cover to expose the board.
• Visual inspection: Look for burned or cracked areas near the defrost relay, darkened spots, or bulging components.
• Manual defrost test (if available): Some Viking models allow forcing a defrost cycle via button combinations. Consult the tech sheet behind the grille. If the unit will not enter defrost, suspect the control.
• Check defrost circuit continuity: Verify that the defrost heater and thermostat test good. If they are good and the board is not sending power, the board is likely faulty.

Corrective action: Replace the main control board if the defrost relay or logic has failed. Ensure the replacement board is the exact Viking part and follow any included programming instructions.