Safety: Turn off power and place the softener in bypass. Open a nearby faucet to relieve pressure.

Inspect the valve head: Remove the top cover. Check for obvious cracks or broken gears in the drive assembly.
Remove and inspect piston/seal pack: Unscrew the valve cover screws, pull the piston/seal pack straight out. Look for heavy iron buildup, sand, or scale. Clean with water and a soft brush; do not scratch sealing surfaces.
Lubricate seals: Apply a thin coat of silicone-based lubricant to O-rings and seals before reinstalling.
Check motor rotation: With the piston removed and water still bypassed, briefly power the unit and start a manual regeneration. If the motor still stalls or Err 4 appears, the motor or board is likely bad.
Verify power supply: Confirm the outlet provides stable voltage (typically 120 VAC in North America) and that the Culligan transformer is the correct model.

If you are not comfortable removing the piston/seal pack, contact a Culligan service technician.

Display shows “Err 4” and valve will not move into regeneration

Possible Causes