E16 error and the display shows abnormal inlet pressure or protection shutdown

Safety: High water pressure can cause leaks or bursts. Do not exceed the pressure rating on the Cillit data plate.

• Measure pressure: Use a pressure gauge on a nearby tap to measure static pressure. If it exceeds the maximum allowed (often 8 bar), install or adjust a pressure reducing valve upstream of the softener.
• Check for spikes: If a well pump or booster pump is used, verify that its pressure switch is correctly adjusted and that an expansion vessel is installed if required.
• Inspect internal regulator/sensor: On models with an integrated pressure sensor or regulator, check for blockages or damage. Replace the Cillit pressure sensor module if readings are clearly incorrect compared to a mechanical gauge.
• Reset error: After correcting pressure issues, reset the controller and monitor operation for leaks or recurring errors.