Display shows ERR4 and unit will not enter regeneration

Safety: Disconnect power before opening the control housing.

• Hard reset: Unplug the softener for at least 10 minutes. While unplugged, press and hold any button on the control panel for 10 seconds to discharge residual power. Plug back in and reprogram the time and hardness settings.
• Check ribbon cable: Remove the control panel cover and inspect the ribbon cable between the display/keypad and the main control board. Ensure it is fully seated and not damaged or corroded.
• Inspect for moisture: Look for signs of condensation, water intrusion, or salt dust on the control board. If present, gently brush off dry debris and allow the board to dry completely before reconnecting.
• Reprogram system: Enter the setup menu and verify all parameters (time, hardness, capacity, regeneration type). Save settings and attempt a manual regeneration.
• Replace board if needed: If ERR4 persists and wiring is intact, the control board is likely defective. Replace with the correct AFWFilters control PCB for your valve model, following the manufacturer’s wiring diagram.