Display shows E3 and unit stops mid-cycle during regeneration

Safety first: Place the softener in BYPASS, shut off power, and relieve pressure by opening a nearby faucet.

Steps to troubleshoot E3 (position sensor):

• 1. Inspect cam and sensor: Remove the control head cover. Locate the valve cam and the small position sensor or microswitch assembly. Check for broken plastic tabs, loose screws, or a sensor that has shifted out of alignment.
• 2. Clean and reseat: If the cam or sensor is dirty with iron or scale, clean gently with a soft brush and cloth. Reseat the sensor so it aligns with the cam marks or magnet as per Aquasana’s alignment marks.
• 3. Check wiring: Ensure the sensor harness is firmly connected to the control board and not pinched by the cover.
• 4. Manually index the valve: With power off, gently rotate the cam to the service position (usually marked). Then power up and initiate a manual regeneration to see if the error clears.
• 5. Replace faulty parts: If the cam is cracked or the sensor tests open/shorted, replace the cam position sensor/microswitch or the valve cam assembly as needed.

If E3 persists after these steps, the control board may not be reading the sensor correctly and may require replacement by a professional.