Dishwasher shows E12, often associated with heavy limescale and poor heating performance.

Safety first: Allow the appliance to cool and disconnect power before internal inspection.

• 1. Check salt level: Open the salt reservoir and ensure it is filled with proper dishwasher salt (not table salt). Refit the cap securely.
• 2. Adjust water hardness setting: Refer to the Constructa manual and set the water softener to match your local water hardness. This prevents further scaling.
• 3. Run a descaling program: Use a dishwasher descaler product according to its instructions. Run the hottest program with the machine empty.
• 4. Inspect heater (advanced): If accessible, visually inspect the heater body for heavy white deposits. Severe scaling may require heater replacement.

When to call a technician: If E12 persists after descaling and correct salt use, the heater or softener system may need professional service.