Harvey water softener displays E04 and the valve remains in one position, often stuck mid-cycle

Safety: Disconnect power and close the inlet and outlet valves. Open a nearby tap to relieve pressure before removing any covers.

• Listen for motor operation: With the cover on, briefly restore power and command a manual regeneration. If you hear no motor noise at all, suspect the motor or its wiring.
• Inspect wiring: Remove the top cover of the Harvey control head. Check the motor plug and position sensor connector are fully seated and free of corrosion.
• Check for mechanical jam: With power off, gently try to rotate the cam/gear (if accessible) by hand as per the service manual. If it is completely seized, there may be debris or a broken gear inside.
• Clear debris: If comfortable and the manual allows, remove the valve cover and inspect for broken plastic pieces, resin beads, or foreign objects obstructing movement. Carefully remove any debris.
• Test cycle: Reassemble, restore water and power, then run a full regeneration. Observe that the valve steps through each stage without stopping.

If E04 persists, the valve motor or position sensor assembly will likely need replacement by a professional familiar with Harvey control valves.