US Water Systems softener shows ERR5 and will not accept new settings or loses time frequently

Safety: Unplug the transformer from the wall before working on the control head.

• Power cycle: Disconnect power for 5 minutes, then reconnect. Sometimes a temporary memory error can be cleared by a full reset.
• Check transformer output: Use a multimeter to verify the transformer is providing the correct AC voltage (commonly 24 VAC) to the control head. Replace the transformer if voltage is low or unstable.
• Inspect the board: Remove the control cover and inspect the circuit board for burn marks, swollen components, or corrosion around connectors. Reseat all plug-in connectors.
• Factory reset: If supported by your specific US Water Systems controller, perform a factory reset following the manual. Re-enter hardness, capacity, and regeneration settings.
• Replace control board: If ERR5 persists after reset and power checks, replace the control board with the correct US Water Systems replacement for your valve model.