Err04 displayed, unit powers but buttons are unresponsive or random characters appear

Safety: Disconnect the power cord before opening the control housing.

• 1. Power reset: Unplug the unit for 5 minutes to discharge the control. Plug back in and check if Err04 clears.
• 2. Inspect keypad and cable: Remove the control cover. Check the keypad ribbon cable for kinks, corrosion, or loose connections at the control board. Reseat the connector carefully.
• 3. Check for moisture: Look for signs of water intrusion or condensation on the control board. If present, dry the area thoroughly and correct any leaks from the brine well or plumbing above.
• 4. Test button response: With power restored, try each button. If some or all buttons do not respond, the keypad membrane or control board is likely defective.
• 5. Replace components: If reseating the cable and drying the board do not resolve Err04, replace the electronic control board. On some North Star models, the keypad and display are integrated with the board and replaced as a single assembly.